Fertilizer

Fertilizer

Materials added to the soil, or applied directly to crop foliage, to supply elements needed for plant nutrition. These materials may be in the form of solids, semisolids, slurry suspensions, pure liquids, aqueous solutions, or gases.

The chemical elements nitrogren, phosphorus, and potassium are the macronutrients, or primary fertilizer elements, which are required in greatest quantity. Sulfur, calcium, and magnesium, called secondary elements, are also necessary to the health and growth of vegetation, but they are required in lesser amounts compared to the macronutrients. The other elements of agronomic importance, called micronutrients and provided for plant ingestion in small (or trace) amounts, include boron, cobalt, copper, iron, manganese, molybdenum, and zinc. All these fertilizer elements, along with other chemical elements, occur naturally in agricultural soils in varying concentrations and mineral compositions which may or may not be in forms readily accessible to root systems of plants. The addition of fertilizer to soils used for the production of commercial crops is necessary to correct natural deficiencies and to replace the components absorbed by the crops in their growth.

Crop requirements of fertilizer components could be satisfied by the spreading of individual materials for each element deficient in the soil. However, economy favors the single application of a balanced mixture that satisfies all nutritional needs of a crop. Many commercial fertilizers therefore contain more than one of the primary fertilizer elements.

The compositions of fertilizer mixtures, in terms of the primary fertilizer elements, are identified by an N-P-K code: N denotes elemental nitrogen; P denotes the anhydride of phosphoric acid (P2O5); K denotes the oxide of potassium (K2O). All are expressed numerically in percentage composition, or units of 20 lb each per short ton (10 kg per metric ton) of finished fertilizer as packaged. Formula 8-32-16 thus contains a mixture aggregating 8 wt % N in some form of nitrogen compounds, 32 wt % P2O5 in some form of phosphates, and 16 wt % K2O in some form of potassium compounds, to give a product with a total of 56 fertilizer units. The commercial N-P-K formulas are generally in whole numbers. None of the N-P-K formulas totals 100% plant nutrients because the formulas indicate only the nutrient portions of the primary-element compounds and do not account for any other materials present.

Aqueous solutions of urea, ammonia, and ammonium nitrate (UAN solutions) are used directly by the farmers as well as in the preparation of granular N-P-K products by mixing with other materials. UAN solutions are also spread directly by field application or used to prepare complete N-P-K fertilizer solutions or suspensions. Suspension fertilizers consist of aqueous slurries of fine crystals in saturated solutions that are stabilized by small amounts of gelling materials, such as attapulgite clay. Suspensions can be maintained in uniform composition during spreading on the fields, and give better dispersion than granular material. See also Fertilizing.

Organic fertilizers are organic materials of vegetable and animal origin which contain certain macro, secondary, or micro nutrients that can be utilized by plants after application to agricultural soils. The primary nutrient sources of vegetable origin are crop residues, green manures, oilseed cakes, seaweeds, and miscellaneous food processing and distillery wastes. Also included in this category is biologically fixed nitrogen from legumes in association with root-nodulating bacteria of the genus Rhizobium. Animal sources include animal manures and urine, sewage sludge, septage, latrine wastes, and to a lesser extent materials such as blood meal, bone meal, and fish scraps. Often organic fertilizers are of mixed animal and vegetable origin, such as most farmyard manures, rural and urban composts, and sewage effluents and sludges

Fertilizers, natural or artificial substances composed of the chemical elements that enhance plant growth and productivity by adding nutrients to soil, have been used since the earliest days of agriculture. The three major fertilizer elements are nitrogen, phosphorus, and potassium. Natural fertilizers include manures, compost, plant ashes, lime, gypsum, and grasses. Chemical fertilizers may be derived from natural sources or may be synthetic compounds.

Commercial chemical fertilizers have only been in general use since the nineteenth century. Early American colonists used natural fertilizers, but overuse and lack of crop rotation quickly depleted both the nutrient poor coastal soil and the more fertile soil of the prairies. Eighteenth-and nineteenth-century European chemists experimented with the effects of chemical fertilization. In 1840, Justus von Liebig published Organic Chemistry in Its Application to Agriculture and Physiology. His research demonstrated that adding nitrogen, phosphorus, and potassium to the soil stimulated plant growth. By 1849, mixed chemical fertilizers were sold commercially in the United States, though their use did not become widespread until after 1900.

Fertilizers represent one of the largest market commodities for the chemical industry. On modern farms, machines are used to apply synthetic fertilizers in solid, gaseous, or liquid form. There is also a growing movement, dating to the 1940s, toward organic agriculture, which rejects the use of chemically formulated fertilizers, growth stimulants, antibiotics, and pesticides in favor of traditional natural fertilizers, of plant or animal origin, and crop rotation.

Fertilizers

Fertilizers (also spelled fertilisers) are compounds given to plants to promote growth; they are usually applied either through the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves. Fertilizers can be organic (composed of organic matter), or inorganic (made of simple, inorganic chemicals or minerals). They can be naturally occurring compounds such as peat or mineral deposits, or manufactured through natural processes (such as composting) or chemical processes (such as the Haber process).

Fertilizers typically provide, in varying proportions, the three major plant nutrients (nitrogen, phosphorus, and potassium), the secondary plant nutrients (calcium, sulfur, magnesium), and sometimes trace elements (or micronutrients) with a role in plant nutrition: boron, chlorine, manganese, iron, zinc, copper, and molybdenum.

In the past, both organic and inorganic fertilizers were called "manures" derived from the French expression for manual tillage, but this term is now mostly restricted to organic manure.

Though nitrogen is plentiful in the earth's atmosphere, relatively few plants engage in nitrogen fixation (conversion of atmospheric nitrogen to a biologically useful form). Most plants thus require nitrogen compounds to be present in the soil in which they grow.

History

While manure, cinder and ironmaking slag have been used to improve crops for centuries, the use of fertilizers is arguably one of the great innovations of the Agricultural Revolution of the 19th Century.

Key people

In the 1730s Viscount Charles Townshend first studied the improving effects of the four-crop rotation system that he had observed in use in Flanders. For this he gained the nickname of Turnip Townshend.

Chemist Justus von Liebig contributed greatly to the advancement in the understanding of plant nutrition. His influential works first denounced the vitalist theory of humus, arguing first the importance of ammonia, and later the importance of inorganic minerals. Primarily his work succeeded in setting out questions for agricultural science to address over the next 50 years. In England he attempted to implement his theories commercially through a fertilizer created by treating phosphate of lime in bone meal with sulphuric acid. Although it was much less expensive than the guano that was used at the time, it failed because it was not able to be properly absorbed by crops.

At that time in England Sir John Bennet Lawes was experimenting with crops and manures at his farm at Harpenden and was able to produce a practical superphosphate in 1842 from the phosphates in rock and coprolites. Encouraged, he employed Sir Joseph Henry Gilbert, who had studied under Liebig at the University of Giessen, as director of research. To this day, the Rothamsted research station that they founded still investigates the impact of inorganic and organic fertilizers on crop yields.

In France, Jean Baptiste Boussingault pointed out that the amount of nitrogen in various kinds of fertilizers is important.

Metallurgists Percy Gilchrist and Sidney Gilchrist Thomas invented the Thomas-Gilchrist converter, which enabled the use of high phosphorus acidic Continental ores on steelmaking. The dolomite lime lining of the converter turned in time into calcium phosphate, which could be used as fertilizer known as Thomas-phosphate.

In the early decades of the 20th Century the Nobel prize-winning chemists Carl Bosch of IG Farben and Fritz Haber developed the process[1] that enabled nitrogen to be cheaply synthesised into ammonia, for subsequent oxidisation into nitrates and nitrites.

In 1927 Erling Johnson developed an industrial method for producing nitrophosphate, also known as the Odda process after his Odda Smelteverk of Norway. The process involved acidifying phosphate rock (from Nauru and Banaba Islands in the South Pacific) with nitric acid to produce phosphoric acid and calcium nitrate which, once neutralized, could be used as a nitrogen fertilizer.

Industry

The Englishmen James Fison, Edward Packard, Thomas Hadfield and the Prentice brothers each founded companies in the early 19th century to create fertilizers from bonemeal. The developing sciences of chemistry and Paleontology, combined with the discovery of coprolites in commercial quantities in East Anglia, led Fisons and Packard to develop sulfuric acid and fertilizer plants at Bramford, and Snape, Suffolk in the 1850s to create superphosphates, which were shipped around the world from the port at Ipswich. By 1870 there were about 80 factories making superphosphate[2]. After World War I these businesses came under financial pressure through new competition from guano, primarily found on the Pacific islands, as their extraction and distribution had become economically attractive.

The interwar period[3] saw innovative competition from Imperial Chemical Industries who developed synthetic ammonium sulfate in 1923, Nitro-chalk in 1927, and a more concentrated and economical fertilizer called CCF based on ammonium phosphate in 1931. Competition was limited as ICI ensured it controlled most of the world's ammonium sulfate supplies. Other European and North American fertilizer companies developed their market share, forcing the English pioneer companies to merge, becoming Fisons, Packard, and Prentice Ltd. in 1929. Together they were producing 80,000 tonnes of superphosphate per annum by 1934 from their new factory and deep-water docks in Ipswich. By World War II they had acquired about 40 companies, including Hadfields in 1935, and two years later the large Anglo-Continental Guano Works, founded in 1917.

The post-war environment was characterized by much higher production levels as a result of the "Green Revolution" and new types of seed with increased nitrogen-absorbing potential, notably the high-response varieties of maize, wheat, and rice. This has accompanied the development of strong national competition, accusations of cartels and supply monopolies, and ultimately another wave of mergers and acquisitions. The original names no longer exist other than as holding companies or brand names: Fisons and ICI agrochemicals are part of today's Yara International[4] and AstraZeneca companies.

Inorganic fertilizers (mineral fertilizer)

Naturally occurring inorganic fertilizers include Chilean sodium nitrate, mined rock phosphate, and limestone (a calcium source).

Macronutrients and micronutrients

Fertilizers can be divided into macronutrients or micronutrients based on their concentrations in plant dry matter. There are six macronutrients: nitrogen, phosphorus, and potassium, often termed "primary macronutrients" because their availability is usually managed with NPK fertilizers, and the "secondary macronutrients" — calcium, magnesium, and sulfur — which are required in roughly similar quantities but whose availability is often managed as part of liming and manuring practices rather than fertilizers. The macronutrients are consumed in larger quantities and normally present as a whole number or tenths of percentages in plant tissues (on a dry matter weight basis). There are many micronutrients, required in concentrations ranging from 5 to 100 parts per million (ppm) by mass. Plant micronutrients include iron (Fe), manganese (Mn), boron (B), copper (Cu), molybdenum (Mo), nickel (Ni), chlorine (Cl), and zinc (Zn)

Macronutrient fertilizers

Synthesized materials are also called artificial, and may be described as straight, where the product predominantly contains the three primary ingredients of nitrogen (N), phosphorus (P), and potassium (K), which are known as N-P-K fertilizers or compound fertilizers when elements are mixed intentionally. They are named or labeled according to the content of these three elements, which are macronutrients. The mass fraction (percent) nitrogen is reported directly. However, phosphorus is reported as phosphorus pentoxide (P2O5), the anhydride of phosphoric acid, and potassium is reported as potassium oxide (K2O), which is the anhydride of potassium hydroxide. Fertilizer composition is expressed in this fashion for historical reasons in the way it was analyzed (conversion to ash for P and K); this practice dates back to Justus von Liebig (see more below). Consequently, an 18-51-20 fertilizer would have 18% nitrogen as N, 51% phosphorus as P2O5, and 20% potassium as K2O, The other 11% is known as ballast and may or may not be valuable to the plants, depending on what is used as ballast. Although analyses are no longer carried out by ashing first, the naming convention remains. If nitrogen is the main element, they are often described as nitrogen fertilizers.

In general, the mass fraction (percentage) of elemental phosphorus, [P] = 0.436 x [P2O5]

and the mass fraction (percentage) of elemental potassium, [K] = 0.83 x [K2O]

(These conversion factors are mandatory under the UK fertilizer-labelling regulations if elemental values are declared in addition to the N-P-K declaration.[5])

An 18−51−20 fertilizer therefore contains, by weight, 18% elemental nitrogen (N), 22% elemental phosphorus (P) and 16% elemental potassium (K).

Agricultural versus horticultural

In general, agricultural fertilizers contain only one or two macronutrients. Agricultural fertilizers are intended to be applied infrequently and normally prior to or along side seeding. Examples of agricultural fertilizers are granular triple superphosphate, potassium chloride, urea, and anhydrous ammonia. The commodity nature of fertilizer, combined with the high cost of shipping, leads to use of locally available materials or those from the closest/cheapest source, which may vary with factors affecting transportation by rail, ship, or truck. In other words, a particular nitrogen source may be very popular in one part of the country while another is very popular in another geographic region only due to factors unrelated to agronomic concerns.

Horticultural or specialty fertilizers, on the other hand, are formulated from many of the same compounds and some others to produce well-balanced fertilizers that also contain micronutrients. Some materials, such as ammonium nitrate, are used minimally in large scale production farming. The 18-51-20 example above is a horticultural fertilizer formulated with high phosphorus to promote bloom development in ornamental flowers. Horticultural fertilizers may be water-soluble (instant release) or relatively insoluble (controlled release). Controlled release fertilizers are also referred to as sustained release or timed release. Many controlled release fertilizers are intended to be applied approximately every 3-6 months, depending on watering, growth rates, and other conditions, whereas water-soluble fertilizers must be applied at least every 1-2 weeks and can be applied as often as every watering if sufficiently dilute. Unlike agricultural fertilizers, horticultural fertilizers are marketed directly to consumers and become part of retail product distribution lines.

Nitrogen fertilizer

Nitrogen fertilizer is often synthesized using the Haber-Bosch process, which produces ammonia. This ammonia is applied directly to the soil or used to produce other compounds, notably ammonium nitrate and urea, both dry, concentrated products that may be used as fertilizer materials or mixed with water to form a concentrated liquid nitrogen fertilizer, UAN. Ammonia can also be used in the Odda Process in combination with rock phosphate and potassium fertilizer to produce compound fertilizers such as 10-10-10 or 15-15-15.

The production of ammonia currently consumes about 5% of global natural gas consumption, which is somewhat under 2% of world energy production.Natural gas is overwhelmingly used for the production of ammonia, but other energy sources, together with a hydrogen source, can be used for the production of nitrogen compounds suitable for fertilizers. The cost of natural gas makes up about 90% of the cost of producing ammonia.The price increases in natural gas in the past decade, among other factors such as increasing demand, have contributed to an increase in fertilizer price.

Nitrogen-based fertilizers are most commonly used to treat fields used for growing maize, followed by barley, sorghum, rapeseed, soyabean and sunflower.

Health and sustainability issues

Inorganic fertilizers sometimes do not replace trace mineral elements in the soil which become gradually depleted by crops grown there. This has been linked to studies which have shown a marked fall (up to 75%) in the quantities of such minerals present in fruit and vegetables.[9] One exception to this is in Western Australia where deficiencies of zinc, copper, manganese, iron and molybdenum were identified as limiting the growth of crops and pastures in the 1940s and 1950s. Soils in Western Australia are very old, highly weathered and deficient in many of the major nutrients and trace elements. Since this time these trace elements are routinely added to inorganic fertilizers used in agriculture in this state.

In many countries there is the public perception that inorganic fertilizers "poison the soil" and result in "low quality" produce. However, there is very little (if any) scientific evidence to support these views. When used appropriately, inorganic fertilizers enhance plant growth, the accumulation of organic matter and the biological activity of the soil, while reducing the risk of water run-off, overgrazing and soil erosion. The nutritional value of plants for human and animal consumption is typically improved when inorganic fertilizers are used appropriately.

There are concerns though about arsenic, cadmium and uranium accumulating in fields treated with phosphate fertilizers. The phosphate minerals contain trace amounts of these elements and if no cleaning step is applied after mining the continuous use of phosphate fertilizers leads towards an accumulation of these elements in the soil. Eventually these can build up to unacceptable levels and get into the produce. (See cadmium poisoning.)

Another problem with inorganic fertilizers is that they are presently produced in ways which cannot be continued indefinitely. Potassium and phosphorus come from mines (or from saline lakes such as the Dead Sea in the case of potassium fertilizers) and resources are limited. Nitrogen is unlimited, but nitrogen fertilizers are presently made using fossil fuels such as natural gas. Theoretically fertilizers could be made from sea water or atmospheric nitrogen using renewable energy, but doing so would require huge investment and is not competitive with today's unsustainable methods. Innovative thermal depolymerization biofuel schemes are trialling the production of byproducts with 9% nitrogen fertilizer sourced from organic waste[10][11]

Organic fertilizers

Naturally occurring organic fertilizers include manure, slurry, worm castings, peat, seaweed, sewage , and guano. Green manure crops are also grown to add nutrients to the soil. Naturally occurring minerals such as mine rock phosphate, sulfate of potash and limestone are also considered Organic Fertilizers.

Manufactured organic fertilizers include compost, bloodmeal, bone meal and seaweed extracts. Other examples are natural enzyme digested proteins, fish meal, and feather meal.

The decomposing crop residue from prior years is another source of fertility. Though not strictly considered "fertilizer", the distinction seems more a matter of words than reality.

Some ambiguity in the usage of the term 'organic' exists because some of synthetic fertilizers, such as urea and urea formaldehyde, are fully organic in the sense of organic chemistry. In fact, it would be difficult to chemically distinguish between urea of biological origin and that produced synthetically. On the other hand, some fertilizer materials commonly approved for organic agriculture, such as powdered limestone, mined rock phosphate and Chilean saltpeter, are inorganic in the use of the term by chemistry.

Although the density of nutrients in organic material is comparatively modest, they have some advantages. Some or all organic fertilizer can be produced on-site, lowering transport costs. The majority of nitrogen supplying organic fertilizers contain insoluble nitrogen and act as a slow-release fertilizer.

Modern theories of organic agriculture admit the obvious success of Leibig's theory, but stress that there are serious limitations to the current methods of implementing it via chemical fertilization. They re-emphasize the role of humus and other organic components of soil, which are believed to play several important roles:

● Mobilizing existing soil nutrients, so that good growth is achieved with lower nutrient densities while wasting less

● Releasing nutrients at a slower, more consistent rate, helping to avoid a boom-and-bust pattern

● Helping to retain soil moisture, reducing the stress due to temporary moisture stress

● Improving the soil structure

Organics also have the advantage of avoiding certain problems associated with the regular heavy use of artificial fertilizers:

● the possibility of "burning" plants with the concentrated chemicals (i.e. an over supply of some nutrients)

● the progressive decrease of real or perceived "soil health", apparent in loss of structure, reduced ability to absorb precipitation, lightening of soil color, etc.

● the necessity of reapplying artificial fertilizers regularly (and perhaps in increasing quantities) to maintain fertility

● extensive runoff of soluble nitrogen and phosphorus, leading to eutrophication

● the cost (substantial and rising in recent years) and resulting lack of independence

Organic fertilizers can have disadvantages:

● As, typically, a dilute source of nutrients when compared to inorganic fertilizers, applying significant amounts of nutrients in a distant location from the source would incur increased costs for transportation

● The composition of organic fertilizers tends to be more complex and variable than a standardized inorganic product.

● Improperly-processed organic fertilizers may contain pathogens from plant or animal matter that are harmful to humans or plants. However, proper composting should remove them.

In non-organic farming a compromise between the use of artificial and organic fertilizers is common, often using inorganic fertilizers supplemented with the application of organics that are readily available such as the return of crop residues or the application of manure.

Risks of fertilizer use

The problem of over-fertilization is primarily associated with the use of artificial fertilizers, because of the massive quantities applied and the destructive nature of chemical fertilizers on soil nutrient holding structures. The high solubilities of chemical fertilizers also exacerbate their tendency to degrade ecosystems, particularly through eutrophication.

Storage and application of some nitrogen fertilizers in some weather or soil conditions can cause emissions of the greenhouse gas nitrous oxide (N2O). Ammonia gas (NH3) may be emitted following application of inorganic fertilizers, or manure or slurry. Besides supplying nitrogen, ammonia can also increase soil acidity (lower pH, or "souring"). Excessive nitrogen fertilizer applications can also lead to pest problems by increasing the birth rate, longevity and overall fitness of certain pests.

The concentration of up to 100 mg/kg of Cadmium in phosphate minerals (for example, minerals from Nauru and the Christmas islands) increases the contamination of soil with Cadmium, for example in New Zealand. Uranium is another example of a contaminant often found in phosphate fertilizers.

For these reasons, it is recommended that knowledge of the nutrient content of the soil and nutrient requirements of the crop are carefully balanced with application of nutrients in inorganic fertilizer especially. This process is called nutrient budgeting. By careful monitoring of soil conditions, farmers can avoid wasting expensive fertilizers, and also avoid the potential costs of cleaning up any pollution created as a byproduct of their farming.

It is also possible to over-apply organic fertilizers; however, their nutrient content, their solubility, and their release rates are typically much lower than chemical fertilizers. By their nature, most organic fertilizers also provide increased physical and biological storage mechanisms to soils, which tend to mitigate their risks.

Global issues

The growth of the world's population to its current figure has only been possible through intensification of agriculture associated with the use of fertilizers. There is an impact on the sustainable consumption of other global resources as a consequence.

The use of fertilizers on a global scale emits significant quantities of greenhouse gas into the atmosphere. Emissions come about through the use of:

● animal manures and urea, which release methane, nitrous oxide, ammonia, and carbon dioxide in varying quantities depending on their form (solid or liquid) and management (collection, storage, spreading)

● fertilizers that use nitric acid or ammonium bicarbonate, the production and application of which results in emissions of nitrogen oxides, nitrous oxide, ammonia and carbon dioxide into the atmosphere.

By changing processes and procedures it is possible to mitigate some, but not all, of these effects on anthropogenic climate change.

Introduction to Biofertiliser and organic manure

BIOFERTILIZER

1. What is Biofertilizer?

Biofertilizers are ready to use live formulates of such beneficial microorganisms which on application to seed, root or soil mobilize the availability of nutrients by their biological activity in particular, and help build up the micro-flora and in turn the soil health in general.

2. Why should we use biofertilizers?

With the introduction of green revolution technologies the modern agriculture is getting more and more dependent upon the steady supply of synthetic inputs (mainly fertilizers), which are products of fossil fuel (coal+ petroleum). Adverse effects are being noticed due to the excessive and imbalanced use of these synthetic inputs. This situation has lead to identifying harmless inputs like biofertilizers. Use of such natural products like biofertilizers in crop cultivation will help in safeguarding the soil health and also the quality of crop products.

3. What are the benefits from biofertilizers?

· Increase crop yield by 20-30%.

· Replace chemical nitrogen and phosphorus by 25%.

· Stimulate plant growth.

· Activate the soil biologically.

· Restore natural soil fertility.

· Provide protection against drought and some soil borne diseases.

4. What are the advantages of bio-fertilizers?

1. Cost effective.

2. Suppliment to fertilizers.

3. Eco-friendly (Friendly with nature).

4. Reduces the costs towards fertilizers use, especially regarding nitrogen and phosphorus.

5. What types of biofertilizers are available?

1. For Nitrogen

o Rhizobium for legume crops.

o Azotobacter/Azospirillum for non legume crops.

o Acetobacter for sugarcane only.

o Blue –Green Algae (BGA) and Azolla for low land paddy.

2. For Phosphorous

o Phosphatika for all crops to be applied with Rhizobium,

o Azotobacter, Azospirillum and Acetobacter

3. For enriched compost

o Cellulolytic fungal culture

o Phosphotika and Azotobacter culture

6. What biofertilizers are recommended for crops?

· Rhizobium + Phosphotika at 200 gm each per 10 kg of seed as seed treatment are recommended for pulses such as pigeonpea, green gram, black gram, cowpea etc, groundnut and soybean.

· Azotobacter + Phosphotika at 200 gm each per 10 kg of seed as seed treatment are useful for wheat, sorghum, maize, cotton, mustard etc.

· For transplanted rice, the recommendation is to dip the roots of seedlings for 8 to 10 hours in a solution of Azospirillum + Phosphotika at 5 kg each per ha.

7. How biofertilizers are applied to crops?

1. Seed treatment:
200 g of nitrogenous biofertilizer and 200 g of Phosphotika are suspended in 300-400 ml of water and mixed thoroughly. Ten kg seeds are treated with this paste and dried in shade. The treated seeds have to be sown as soon as possible.

2. Seedling root dip:
For rice crop, a bed is made in the field and filled with water. Recommended biofertilizers are mixed in this water and the roots of seedlings are dipped for 8-10 hrs.

3. Soil treatment:
4 kg each of the recommended biofertilizers are mixed in 200 kg of compost and kept overnight. This mixture is incorporated in the soil at the time of sowing or planting.

8. How could one get good response to biofertilizer application?

· Biofertilizer product must contain good effective strain in appropriate population and should be free from contaminating microorganisms.

· Select right combination of biofertilizers and use before expiry date.

· Use suggested method of application and apply at appropriate time as per the information provided on the label.

· For seed treatment adequate adhesive should be used for better results.

· For problematic soils use corrective methods like lime or gypsum pelleting of seeds or correction of soil pH by use of lime.

· Ensure the supply of phosphorus and other nutrients.

9. What would be probable reasons for not getting response from the application of biofertilizers?

1. On account of quality of product

o Use of ineffective strain.

o Insufficient population of microorganisms.

o High level of contaminants.

2. On account of inadequate storage facilities

o May have been exposed to high temperature.

o May have been stored in hostile conditions.

3. On account of usage

o Not used by recommended method in appropriate doses.

o Poor quality adhesive.

o Used with strong doses of plant protection chemicals.

4. On account of soil and environment

o High soil temperature or low soil moisture.

o Acidity or alkalinity in soil.

o Poor availability of phosphorous and molybdenum.

o Presence of high native population or presence of bacteriophages.

10. What precautions one should take for using biofertilizers?

· Biofertilizer packets need to be stored in cool and dry place away from direct sunlight and heat.

· Right combinations of biofertilizers have to be used.

· As Rhizobium is crop specific, one should use for the specified crop only.

· Other chemicals should not be mixed with the biofertilizers.

· While purchasing one should ensure that each packet is provided with necessary information like name of the product, name of the crop for which intended, name and address of the manufacturer, date of manufacture, date of expiry, batch number and instructions for use.

· The packet has to be used before its expiry, only for the specified crop and by the recommended method of application.

· Biofertilizers are live product and require care in the storage

· Both nitrogenous and phosphatic biofertilizers are to be used to get the best results.

· It is important to use biofertilizers along with chemical fertilizers and organic manures.

· Biofertilizers are not replacement of fertilizers but can supplement plant nutrient requirements.

11. Where can I get further information on biofertilizers?

You may visit the following Internet sites:
http://www.ikisan.com/links/up_riceBiofertilizers.shtml#top
http://www.entireindia.com/YellowPg/YpCatList.asp?s=1159&cnm=Biofertilizers
http://www.glsbiotech.com/products.htm#biofertilizers
http://www.us.erc.org/greenchannel/gc7/innovativebiotechnologicalproductsforagriculture.php www.suvash.com
http://www.kumarbuilders.com/bio.htm,

http://www.vasat.org/learning_resources/OrganicFAQs/biofertilizer.htm

Frequently Asked Questions
About
Organic Manures and Fertilizers

ORGANIC MANURE

1. What are organic manures?

Organic manures are natural products used by farmers to provide food (plant nutrients) for the crop plants. There are a number of organic manures like farmyard manure, green manures, compost prepared from crop residues and other farm wastes, vermicompost, oil cakes, and biological wastes - animal bones, slaughter house refuse.

2. How are organic manures beneficial in the cultivation of crops?

Organic manures increase the organic matter in the soil. Organic matter in turn releases the plant food in available from for the use of crops. However, organic manures should not be seen only as carriers of plant food. These manures also enable a soil to hold more water and also help to improve the drainage in clay soils. They provide organic acids that help to dissolve soil nutrients and make them available for the plants.

3. How are organic manures differing from fertilizers?

Organic manures have low nutrient content and therefore need to be applied in larger quantities. For example, to get 25 kg of NPK, one will need 600 to 2000 kg of organic manure where as the same amount of NPK can be given by 50 kg of an NPK complex fertilizer.

The nutrient content of organic manures is highly variable from place to place, lot to lot, and method of preparation. The composition of fertilizers is almost constant. For example, urea contain 46% N regardless of which factory makes it any where in the world.

4. How much of plant nutrients are provided by organic manures?

Just as different fertilizers contain different amounts of plant nutrients, organic manures are also not alike.

Average quality of farmyard manure provides 12 kg nutrients per ton and compost provides 40 kg per ton.

Most of the legume green manures provide 20 kg of nitrogen per ton.

Each ton of sorghum/rice/maize straw can be expected to add 26 kg of nutrients.

5. What is green manuring

Green manuring is the practice of growing a short duration, succulent and leafy legume crop and ploughing the plants in the same field before they form seeds.

6. What is green leaf manuring?

Green leaf manuring refers to adding the loppings from legume plants or trees to a field and then incorporating them into the soil by ploughing.

7. What green manure crops are beneficial?

Sesbania, Crotalaria, ‘Pillipesara’, Cowpea etc are good for green manuring.

8. What are the popular green leaf manuring plants?

Glyricidia, Pongamia, Leucina are common green leaf manuring plants.

9. What is compost?

Compost is well decomposed organic wastes like plant residues, animal dung, and urine earth from cattle sheds, waste fodder etc.

10. How good compost is prepared?

Compost making is the process of decomposing organic wastes in a pit. Site for compost making is selected should be at a high level and water should not pond during monsoon season. Pit should be of 3’ depth and 6’ to 8’ width. Length may be of any convenient size. The process is as follows:

1. Make slurry of the cattle dung with water.

2. Prepare 6” layer of organic wastes – plant residues, sweepings from the cattle shed, waste fodder, dried plants stalks and leaves etc. and sprinkle water to just moisten it. (Over watering should be avoided).

3. Cover with the layer with urine earth and cattle dung slurry.

4. Add 5 to 10 kg of super phosphate for every 10 tons of organic wastes.

5. Repeat the process of putting such layers till the pit is full.

6. Close the pit with urine earth, waste fodder and then heap the soil till it gets convex shape (about 1 to 1.5’ above the ground) so that the rainwater rolls away.

7. After six months compost is ready to apply to the fields.

The pit can be filled up if sufficient organic wastes are available. Otherwise a temporary partition can be made in the pit with bamboos or stalks and the pit can be filled up over time filling each partitioned area as and when the material is available for composting.

11. Why super phosphate is added in compost making?

Due to quick heating and drying during the decomposition of organic wastes, nitrogen in the organic wastes will be lost due to volatilization. Addition of super phosphate decreases such nitrogen losses. It will also increase the phosphate content of compost.

12. What is vermicomposting?

Vermicomposting is a type of compost making in which earthworms are used to convert organic wastes into valuable material to supply nutrients for crops.

13. Where can I get more information on vermicomposting?

Please click on the following Internet sites for more details on vermicomposting.
http://www.vusat.org/learning/agri/VC/index.htm
http://www.erfindia.org/local.asp
http://www.ddsindia.com/vermicompost.htm
http://agri.and.nic.in/vermi_culture.htm

FERTILIZER

1. What is fertilizer?

A fertilizer is a chemical product either mined or manufactured material containing one or more essential plant nutrients that are immediately or potentially available in sufficiently good amounts.

2. Is application of fertilizers harmful to the soil/ plants/ humans?

Fertilizer applications at the recommended rates are not at all harmful. It is wrong to carry such doubts to the farmers and the consumers of farm products. Fertilizers carry the similar chemical elements which a soil or atmosphere contain. Secondly, the raw materials used for manufacturing fertilizers are natural products. For example, the air we breathe contains 79% nitrogen and is used to manufacture nitrogenous fertilizers like urea. Natural minerals like sulfur, rock phosphate are used to manufacture phosphatic fertilizers like super phosphate.

3. Why people comment that fertilizers are harmful ?

Such comments are due to lack of sufficient knowledge about fertilizers. Farmers should clearly understand the role of fertilizers in crop production, use them where needed in a balanced way, and avoid excessive use of them even if they are given free not that they are harmful but it is waste of money to use for that crop.

4. What is fertilizer grade?

Fertilizer grade refers to the guaranteed content (analysis) of plant nutrient/s in a fertilizer. That is percentage of the major plant nutrients; NPK in that order, present in a fertilizer reflects the grade of that fertilizer. Thus 14-14-14-fertilizer grade refers to the fertilizer guaranteed to contain a minimum of 14% nitrogen (N), 14% of phosphorus (P₂O₅) and 14% of potassium (K₂O).

5. What types of fertilizers are available in the market ?

Three types of fertilizers are available in the market. They are straight fertilizers, Complex fertilizers, and Mixed Fertilizers.

Straight Fertilizers supply single plant nutrient either nitrogen (N), or phosphorus (P), or potassium (K). Example: Urea supplies 46% N; Super phosphate provides 7% P or 16% P₂O₅.

Complex Fertilizers supply more than one plant nutrient. Example: Di-Ammonium Phosphate (DAP) contains 18% N and 20% P (46% P₂O₅).
Mixed Fertilizers are physical mixture of two or more straight and/or complex fertilizers to supply particular combination of plant nutrients. Example: one can buy DAP and Muriate of Potash and mix them in a ratio to get a fertilizer mixture containing a grade of 12-32-16 of N, P₂O₅, and K₂O.

6. What are the advantages of Complex Fertilizers ?

1. The possibility of adulteration is generally less.

2. Each granule is homogenous in nutrient content.

3. Being granular, the drilling of fertilizer is easy.

4. They are cheaper than straight or mixed fertilizers.

5. Phosphorus availability is not affected (fixation is less) as the phosphorus in the granules will have less contact with soil particles.

7. Are there any disadvantages with Complex Fertilizers ?

The disadvantage with Complex Fertilizers is that the ratios of the nutrients are fixed and the farmers may have to supplement with straight fertilizers to meet the crop requirements.

8. What are the advantages of Mixed Fertilizers ?

1. There will be considerable saving in time and labor in application to the crops, as all the nutrients required are present in the same packing.

2. One can ensure balanced nutrient application if suitable mixture is chosen.

3. Micronutrients can also be included in the mixtures.

9. Are there any disadvantages with Mixed Fertilizers ?

1. There is possibility for adulteration with inert material.

2. Farmers themselves can mix the fertilizers provided they are knowledgeable about what fertilizers cannot be mixed together.

ORGANIC FARMING

1. What is organic farming?

Organic farming is a system, which avoids or largely excludes the use of synthetic inputs (such as fertilizers, pesticides, hormones, feed additives etc) and to the maximum extent feasible relies upon crop rotations, crop residues, animal manures, off-farm organic waste, mineral grade rock additives and biological system of nutrient mobilization and plant protection.

2. Is there a need to practice organic farming?

With the increase in population our compulsion would be not only to stabilize agricultural production but also to increase it further in sustainable manner. Excessive use over years of agro-chemicals like pesticides and fertilizers may affect the soil health and lead to declining of crop yields and quality of products. Hence, a natural balance needs to be maintained at all cost for existence of life and property. The obvious choice would be judicious use of agro-chemicals and more and more use of naturally occurring material in farming systems.

3. What are the benefits of organic farming?

1. It helps in maintaining environment health by reducing the level of pollution.

2. It reduces human and animal health hazards by reducing the level of residues in the product.

3. It helps in keeping agricultural production at a higher level and makes it sustainable.

4. It reduces the cost of agricultural production and also improves the soil health

5. It ensures optimum utilization of natural resources for short-term benefit and helps in conserving them for future generation.

6. It not only saves energy for both animal and machine, but also reduces risk of crop failure.

7. It improves the soil physical properties such as granulation, and good tilth, good aeration, easy root penetration and improves water-holding capacity.

8. It improves the soil’s chemical properties such as supply and retention of soil nutrients, and promotes favorable chemical reactions.

NITROGEN FERTILIZERS

1. What are the popular fertilizers available in the market to supply nitrogen to the crops?

Ammonium sulfate contains 20% N i.e. a bag of 50 kg of Ammonium Sulfate will provide 10 kg of nitrogen.

Urea contains 46% N i.e. a bag of 50 kg of Urea will provide 23 kg of nitrogen.

Calcium Ammonium Nitrate (CAN) contains 20% N i.e. a bag of 50 kg of Calcium Ammonium Nitrate will provide 10 kg of nitrogen.

2. What soil conditions decide the suitability or unsuitability of the above N fertilizers?

Fertilizer	Suitable	Unsuitable
Ammonium Sulfate	Saline and alkali soils	Continuous use in acidic Soils without liming
Urea	All types of soils	In light paddy soils with possible leaching losses

3. What are the principles governing the time of application of nitrogen?

1. Plants throughout its growth take nitrogen.

2. Nitrogen fertilizers are soluble in water. They are also mobile and is liable to be lost easily through leaching, especially in light soils.

Hence, it is better not to apply all nitrogen in one dose or at a time. Apply in split doses. This will ensure nitrogen supply to growing plants during the entire growth period.

For all cereal crops like rice, wheat, maize, pearl millet etc. it is recommended to apply nitrogen in 3 equal split doses, the first at sowing, the second at 30 days after sowing (active growing period), and the third at boot leaf stage. Application beyond boot leaf stage will not significantly increase yield.

Each application should be followed by light irrigation or there should be sufficient moisture in the soil at the time of the application of fertilizer.

In heavy soils, single application is as good as split application for sorghum.

4. Between ammonium sulfate and urea, which is to be preferred?

For most crops and soils both ammonium sulfate and urea are equally effective.

However as urea contains 46% N compared to 20% N in ammonium sulfate, the cost of transport, storage and handling will be very much less. Hence, urea could be preferred where both fertilizers are equally effective.

In acidic soils urea is preferred, as the acidity will not increase with regular use of urea compared to ammonium sulfate. Under waterlogged conditions where sulfide injury is suspected urea alone is recommended.

However, soils deficient in sulfur (not common in Andhra Pradesh) ammonium sulfate is useful.

5. What storage and handling characteristics of urea and ammonium sulfate?

Urea: The fertilizer absorbs moisture. So, use the entire bag as far as possible. Store bag in dry place. Inspect the bags frequently during rainy season and take needful precautions to separate the bags that are moist.

Ammonium sulfate: No difficulties in storing and handling.

PHOSPHATE FERTILIZERS

1. What are the popular fertilizers available in the market to supply phosphorus to the crops?

Super Phosphate contains 16% P₂O₅ i.e. a bag of 50 kg of Super Phosphate will provide 8 kg of phosphorus (P₂O₅).

Triple Super Phosphate contains 40% P₂O₅ i.e. a bag of 50 kg of Triple Super Phosphate will provide 20 kg of phosphorus (P₂O₅).

Both these fertilizers are equally effective.

2. How can phosphatic fertilizers best applied to crops?

Phosphatic fertilizers give better response when placed in bands near the plant rows. This placement helps in reduced contact with soil particles and results in more availability of the nutrient phosphorus than broadcast application.

3. Can phosphorus be applied as top dressing or it should be only a basal application?

It is always advisable to apply phosphate fertilizers as basal application i.e. at sowing or planting. This is for the reasons that phosphorus requirement is high during the early growth period and most of the phosphorus is taken up by plants in early stages of growth.

The primary advantage of early application is that it promotes early root growth, which in turn leads to better exploitation of soil nutrients.

4. How much of phosphorus need to be applied for crops?

Phosphatic fertilizers are applied to bring the available P₂O₅ to a critical limit for a crop. By critical limit is meant the level below which no economic responses are possible to applied phosphates.

Knowing the initial soil test value and recovery of added phosphates, it will be possible to work out the amount of fertilizer phosphorus needed to build up the soil phosphate to a given critical limit. The critical value is found to be about 35 kg P₂O₅ per ha for crops like sorghum, pearl millet, rice, and maize.

If the initial soil phosphorus level is high, then maintenance application will be enough.

POTASSIC FERTILIZERS

1. What are the popular fertilizers available in the market to supply potash (K) to the crops?

Muriate of potash contains 60% K₂O i.e. a bag of 50 kg of Muriate of potash will provide 30 kg of potash (K₂O).

Potassium sulfate contains 48% K₂O i.e. a bag of 50 kg of Potassium sulfate will provide 24 kg of potash (K₂O).

2. When should potassic fertilizers be applied?

Potassic fertilizers can be applied in one dose as basal application. However, in sandy soils where there is possibility of potash being lost due to leaching, the recommended rate of potash should be applied in two equal splits, the first as basal and the second at flowering stage. Similarly for long duration crops like sugarcane, cotton etc. and also for crops where potash plays an important role like potato, potassic fertilizers are applied in 2 or 3 splits.

MICRONUTRIENT FERTILIZERS

1. Is there a need to apply micronutrients to crops?

Application of good quantities of organic manures usually supplies the required micronutrients to crops. If the farmer is not able to apply such organic manures, then over time soils will be deficient in micronutrients. In such a situation, the soil analysis will help in identifying the deficiency of micronutrients in the soil and application of deficient micronutrients will lead to increased yields.

2. What are some good sources of micronutrients?

Organic manures (FYM, compost, green manure and green-leaf manure) are good sources. Other specific sources include:

Boron	Borax or boric acid
Zinc	Zinc sulfate
Iron	Ferrous sulfate
Manganese	Manganese sulfate
Molybdenum	Sodium molybdate, ammonium molybdate, lime

3. How micronutrients are applied to the crops?

As micronutrients needed in small quantities, they are applied as foliar sprays.

For more information on Micronutrients, please visit the Internet site
http://www.vusat.org/learning/agri/MN/index.htm

METHODS OF APPLICATION OF FERTILIZERS

1. What are the different methods of application of fertilizers?

Generally 3 methods of application of fertilizers are in practice.

1. Broadcasting: Uniform distribution over the whole cropped field.

2. Placement: Application in bands or in pockets near the plants or plant rows.

3. Foliar application: Using low or high volume sprayers, the fertilizers are sprayed covering the plants.

2. Is there a choice to practice a particular method of application?

The method of application has to be chosen to suit the particular nutrient, the crop, as well as method of cultivation.

Nitrogen is generally applied as broadcast to irrigated crops. Phosphorus needs to be placed near the plant rows. Potassium is also applied as broadcast.

As all the 3 nutrients are applied using a complex fertilizer at the time of sowing or planting, it is a good practice to apply the fertilizer as placement.

Micronutrients are mostly applied as foliar sprays.

3. When is broadcasting of fertilizers practiced?

· On all crops with a dense stand and not sown in rows.

· In the case of plants whose roots spread widely in the soil.

· On very fertile soils

· When high rate of fertilizers are used

· When readily soluble nitrogenous fertilizers are applied

· When potassic fertilizers are applied in light soils.

4. What are the drawbacks with broadcast application?

· May stimulate weed growth with the result that the crop does not derive full benefit of fertilizers.

· Fertilizers may come in contact with a large volume of soil and are likely to be fixed and unavailable for that crop. This is particular in the case of super phosphate application.

5. What are the different methods of placing the fertilizers?

· Banding i.e. placing fertilizers in bands to one or both sides of the rows. This is also called as side dressing.

· Drilling in between rows.

· Spot placement i.e. by placing in between the plants. This is mostly practiced for vegetable crops.

· By placing in a circular band away from the base of the plants as in the case of fruit trees.

No single method can be considered best for all the crops. The method of placement varies with the crop, fertilizer, and weather.

6. When is placement of fertilizers practiced?

· When small quantities of fertilizers are to be distributed.

· When phosphatic fertilizers are applied in acidic soils where fixation of phosphorus is a problem.

· In the case of crops sown in wide rows.

· In the case of shallow rooted plants.

· On soils with low fertility.

7. What are the advantages of band placement?

· Placing fertilizers below the seeds without touching the seeds stimulates early growth of seedlings.

· For application of phosphatic fertilizers as phosphates are less mobile. Broadcast application will result in unavailability to roots.

· More availability of phosphates to crops grown in acidic soils where fixation of phosphates is a problem.

· Early root development will be rapid and extensive and plant growth will be stimulated.

· Under rainfed conditions, due to extensive and deeper root development, plants will be able to draw moisture from lower depths of soil and better withstand drought.

8. What is seed cum fertilizer drill?

Seed cum fertilizer drill is an implement useful to sow the seed in rows as well as to apply the fertilizers at the same time. The implement is designed to place the fertilizer 5 cm (2”) below the seed and 5 cm (2”) away from the seed avoiding fertilizer injury to the seed.

Separate hoppers are provided for the seed and fertilizer. There is also arrangement to regulate the seed and fertilizer rates as per the crop requirement. This is efficient way of applying fertilizer and sowing the seed. Additionally, the drill ensures uniform stand and growth of plants.

9. What is foliar application of fertilizers?

Fertilizers are dissolved in water and such diluted solutions are sprayed directly on the plants foliage. Hand operated sprayers are used for smallholdings. On individual farms a tractor drawn low volume sprayers can be used while on large scale aircrafts are used for foliar spraying.

10. Can any chemical fertilizer be sprayed on crops?

· Only those fertilizers that do not scorch (burn) leaves are sprayed.

· Usually micronutrients, which are required in low rates, are foliar sprayed.

· Urea sprays are used for supplying nitrogen.

· Ammonium phosphate fertilizer is also used to spray to improve seed setting in multicut fodder legumes like Berseem.

· For the reason that low concentration of fertilizers needs to be sprayed most of the fertilizers are not used for foliar application.

11. What are the precautions to be observed for spraying urea?

· Size of sprayer’s nozzle is important. The increase in concentration depends on the nozzle type. The sprays should be fine as mist but not as droplets of water.

· Bigger droplets fall off from the leaf surfaces and are wasted. Also, leaves may be scorched if the droplets are retained on the leaves.

· Sprayings are best done after 0400 hours in the evening.

· While spraying the nozzle should be kept at least 1 to 2 feet away from the vegetative growth.

· The weather should not be cloudy.

· The concentration of urea should not exceed 3% in case of knapsack sprayers and 20% in case of power prayers (low volume high pressure sprayers).

· It is advisable to mix 1% of sugar or jaggery with the urea solution for better absorption.

12. Can pesticides and herbicides be mixed with urea spray?

Yes. Pesticides and herbicides can be mixed with the urea spray.

13. What is the optimum concentration for spraying micronutrients?

Zinc sulfate	0.2%
Borax	0.1%
Ferrous sulfate	0.2%
Molybdic acid	0.05%
Manganese sulfate	0.2%
Copper sulfate	0.2%

14. Can nutrients be applied through foliar sprays to fruit trees?

· Plant nutrients are generally applied as foliar sprays on fruit trees to prevent nutritional disorders of micronutrients.

· Nutrient deficiencies of nitrogen, phosphorus, potassium, calcium, and magnesium can be corrected through foliar sprays.

· Nutrient sprays can be applied at any time during the growing season to improve the appearance of foliage and color, size and quality of fruits.

· For most fruit crops, plant nutrients are sprayed along with the regular spray program of pesticides.

· The compatibility of nutrients and the pesticide chemicals should be ascertained before such mixtures are sprayed.

FERTILIZER CALULATIONS

1. How one can convert the nutrient recommendations to the quantity of fertilizers to be applied?

It is common to recommend the crop nutrient requirements in terms of the nutrient values. For example, recommendation for sorghum is 60-15-0 NPK per ha. But the field application has to be on the basis of the quantities of fertilizer/s required to meet the recommended rates of NPK. This conversion involves some amount of calculations.

For the procedure to calculate the amount of fertilizer/s, please click on the following ICRISAT web site.

http://www.icrisat.org/text/training/index.asp?i=Fertilizer%20Calibration

2. How to economize fertilizer use?

· The fertilizer recommendations should be based on soil test values.

· Balanced use of fertilizer should be advocated for better economic returns.

· Use of nitrogenous fertilizer in split doses economizes fertilizer use.

· Micronutrient deficiencies should be corrected as and when needed.

· Fertilizer schedule should be adopted for the whole crop sequence instead of a single crop.

· To get the maximum benefit from the applied fertilizers, crops should be irrigated at the critical growth stages.

3. How do you identify which fertilizer is less expensive?

Fertilizers are compared based on the unit values. One % of nutrient ingredient present in one ton of fertilizer is treated as one unit. The unit value of nutrient ingredient is the price of one ton (or per bag of 50 kg of fertilizer) divided by the % content of that particular nutrient ingredient.

Example:
1. Urea with 46% N is priced at Rs.5000 per ton (Rs. 250 per bag of 50 kg). Then,
Unit value of Urea is = 5000 / 46 = Rs.108.70

2. Ammonium sulfate with 20% N is priced at Rs.2880 per ton (Rs.288 per bag of 100 kg). Then,
Unit value of Ammonium sulfate is = 1440 / 20 = Rs. 144

Comparing the unit value of Urea and Ammonium sulfate (Rs. 108.70 with R.144), one can conclude that Urea is cheaper than Ammonium sulfate.
Note: Ammonium sulfate also contains 16% sulfur, which will be added advantage over urea. Hence Ammonium sulfate may give better response than urea in soils deficient in sulfur. Such points also need to be considered before making any comparisons.

4. How do you evaluate complex fertilizers containing more than one nutrient?

In the case of complex fertilizers, standard unit values of nutrient ingredients are considered in the calculation. The formula is:

Unit value of N in a complex fertilizer (CF) with N and P₂O₅ =

(Price per ton of CF x Unit value of N in Urea) / Unit values of N from Urea and
P₂O₅ from Super phosphate

Example: Di-Ammonium Phosphate (DAP) containing 18% N and 45% P₂O₅ costs
Rs.4800 per ton.
Unit value of Urea for N is Rs.108.70;
Unit value of Supper phosphate for P₂O₅ is Rs.105
Unit values of N from Urea and P₂O₅ from Super phosphate =
(108.70+105.00) = Rs. 213.70
Then:
Unit value of N in DAP = (4800 X 108.70 / 213.70) / 18 = Rs.135.64
Unit value of P₂O₅ in DAP = (4800 X 105 / 213.70) / 45 = Rs.52.41

5. How to know that fertilizer application is economical?

Use of fertilizer by the farmer for increased crop production depends almost entirely on its economics. Response per unit area or per unit nutrient applied usually indicates the profitability from fertilizer use.

The profitability from fertilizer use is calculated by deducting the costs of fertilizer/s and their application from the extra crop yields achieved from fertilizer application. A positive balance indicates the profitability.

For example:
Fertilizer recommendation for dry land sorghum is 30 kg N and 15 kg P₂O₅,

The sorghum yield with fertilizer application was 1800 kg per ha and without fertilizer application was 920 kg per ha.

The cost of the fertilizers applied (including labor to apply) were Rs.3866
The additional yield of sorghum with fertilizer = 1800 – 920 = 880 kg
The value of additional sorghum yield = 880 kg x Rs.8 per kg of sorghum
= Rs.7040
So, the profit from fertilizer application is = Rs.7040 – Rs 3866
= Rs. 3174

6. What is the calculation procedure for foliar sprays?

Suppose the recommended foliar spray of Urea is 2% concentration. This means that 100 parts of spray solution should have 2 parts of Urea. To get this, 2 kg of urea should be dissolved in 100 liters of water or 4 kg of Urea in 200 liters of water and so on.

If the amount of water required to cover one hectare is 400 liters, then a 2% spray liquid is prepared by dissolving 8 kg of Urea in 600 liters of water.

The same calculation procedure is used for micronutrient foliar sprays.

EFFICIENT USE OF FERTILIZERS

1. What are the tips for efficient use of fertilizers?

1. Select the most fertilizer responsive and best-suited crops and their varieties for the locality.

2. High yielding varieties (HYV) of crops give higher yield than local varieties without fertilizer application as well as a higher unit response to fertilizers, even at the lower rate of application.

3. Balanced fertilization should be practiced based on soil test. Fertilizer recommendations should be based on the crop sequence and not on individual crop basis.

4. While all of phosphate and potash are applied as basal dressing, nitrogen should be applied in split doses.

5. Urea can be cured with soil for top dressing to reduce nitrogen losses by thoroughly mixing 1 part of urea with 5 to 10 parts of moist soil and keeping it for 24 hours.

6. Phosphate should be placed 4 to 6 cm below and 4 to 6 cm away from the seeds to ensure maximum availability.

7. Top dressing nitrogen and potassic fertilizers should be mixed properly with the layer of soil.

8. To the extant possible irrigate the field with just enough water. In dry soil, fertilizers should be placed only in the moist zone.

9. Weeds if not effectively controlled during the first 40 days of crop growth, take away about 30 to 40% of plant nutrients applied to the crops. Therefore, it is necessary to control the weeds particularly during the early stage of crop growth.

10. Sowing of crop should be done at the normal time suited for the locality to get the benefit of maximum efficiency of applied fertilizers.

11. Optimum plant population of the crop needs to be maintained by adopting proper plant spacing.

12. Timely control of pests and diseases will help in realizing maximum effectiveness from fertilizers.

2. What is balanced fertilizer application?

Balanced fertilizer application refers to the practice of applying the required plant nutrients after taking into account available nutrients in the soil, crop requirement, cropping sequence and crop management practices like weed control, irrigation etc.

3. What is integrated nutrient management?

Integrated nutrient management (INM) refers to the practice of integrated use of all natural and man-made resources of plant nutrients so that the crop productivity increases efficiently and environmentally friendly manner without sacrificing the soil productivity of the future generations.

Sufficient and balanced application of organic manures and fertilizers is the key component of INM.

Fertilizer needs of some crops

1. DRY LAND CROPS

1. Is it desirable to apply fertilizers to dry land crops? Will not fertilizers applied use up even existing moisture and scorch the crops?

This is a common belief among farmers, which is not true. Contrary to this belief, fertilizer application will help the plants to put up vigorous early growth and develop deep and extensive root system. Thus, the plants will be able to draw moisture from deeper soil layers and withstand any drought at a later stage.

2. What is the best method of application of fertilizers for dry land crops?

Under dry land farming, placement of fertilizers is important. Broadcast application is not efficient as the applied fertilizer will be above the feeding zone. Seed cum fertilizer drill is very useful under dry land conditions as better stand and early vigor of seedlings are important.

3. When should be fertilizers applied to dry land crops?

Phosphatic and potassic fertilizers need to be applied as a single dose at the time of sowing. In heavy soils nitrogenous fertilizers can be applied in single dose as basal application. This is particularly true for rabi crops.

Split application of nitrogen is preferred in lighter soils where leaching of nitrogen beyond the root zone is likely occur. The first application is at the time of sowing and the second application should be made keeping soil moisture in view.

2. Sorghum and Pearl millet

1. What is the recommendation of fertilizers for sorghum and pearl millet?

For rainfed sorghum 40 to 60 kg N is recommended. In heavy soils this dose of N may be applied in two equal splits, the first one as basal and the second dose could be either after 30 days of sowing or at flowering depending on soil moisture. In lighter soils and for rabi crop, the recommended rate is applied as basal dose only.

The phosphorus and potash application need to be applied based on soil tests. In the absence of soil test information about 30 kg P₂O₅ per ha could be applied. As most of Indian soils contain enough potassium to meet sorghum requirement, the application could be skipped.

The above fertilizer recommendations hold good for pearl millet also.

Phosphorus placement in sorghum (observe the difference in seedling growth-left: phosphorus placed; right: broadcast application of phosphorus.)		Response of sorghum to phosphorus application (Observe flowering of crop with P application at the back and crop yet to be flower with no phosphorus at the front of the picture.)

3. Groundnut

1. Is it necessary to apply nitrogen to groundnut crop?

Groundnut is capable of utilizing atmospheric nitrogen for its growth through nodulation with the help of a type of bacteria. But the bacterial nodules do not develop on the roots until the plants are 15 to 20 days. Hence, during the early stages when the plants require easily available nitrogen for their good growth, a starter dose of nitrogen is important.

It is recommended to apply a starter dose of 10 to 20 kg N per ha at sowing time preferably by drilling the fertilizer along with phosphorus.

2. Should groundnut be top dressed with nitrogen?

Top dressing of nitrogen to groundnut depends on the type of groundnut cultivated.

Runner types are good at fixing atmospheric nitrogen. These types have dark green foliage. Top dressing of nitrogen to runner types may not be necessary.

Bunch types are comparatively poor nitrogen fixers. These types have pale green foliage. Hence, it is advisable to top dress with nitrogen at 15 to 20 kg N per ha at the time of 50% flowering stage or pegging stage depending on the soil moisture.

As available soil nitrogen decreases nodulation and there by the amount of nitrogen fixation. Hence, it is good to apply this top dressing of nitrogen by foliar application. With the high volume sprays, a 3% solution of urea may be used. With the low volume sprays, the urea concentration can be increased to 12 to 20%.

3. Is phosphorus application necessary for groundnut?

Yes. Phosphorus requirement of groundnut is high. So, it is recommended to apply 45 kg of P₂O₅ to groundnut as a basal dose. Phosphorus application enhances the root development and extension, which helps in better soil moisture utilization.

4. Which complex fertilizer is best suited for groundnut and why?

Among the available complex fertilizers, Diammonium Phosphate suits very well as this fertilizer contains the required proportion of nitrogen and phosphorus for groundnut to be applied as basal dose i.e. 18% N and 46% P₂O₅.

5. Is calcium important for groundnut?

Calcium is an important nutrient for pod development and kernel formation in groundnut. Low availability of calcium leads larger number of unfilled pods called pops. Adequate supply of calcium results in healthy pods and well developed kernels.

Calcium absorbed by roots is not tanslocated to developing pods, which require calcium for proper kernel development. However, it is fortunate that pegs and developing pods could directly absorb calcium. Hence, calcium needs to be applied near the plants so that the pegs and developing pods could take up the applied calcium.

The best method of supplying calcium to the pegs and developing pods is by dusting well ground gypsum at 300-500 kg per ha around the plants at the time of early flowering i.e. 30 to 35 days after sowing. The gypsum falls around the plants in the zone of pod formation and will be available at the time when the need for calcium is great.

6. What are the micronutrients to be applied for groundnut?

Less availability of zinc and boron are usually observed in groundnut growing areas. Applications of these two micronutrients will help in increasing the groundnut yields.

7. In what form and dose the zinc is to be applied to groundnut?

Zinc is to be applied as zinc sulfate. Zinc sulfate is to be applied as basal dose at 10 kg per ha for the rainfed crop and 20 kg for irrigated groundnut.

8. Are there any precautions to be taken in the application of groundnut?

As the quantity of to be applied is small, zinc sulfate should be evenly distributed by mixing the chemical with the soil in the plough furrow. Secondly, zinc sulfate and phosphatic fertilizers should not be mixed and applied. They need to be applied separately so that the zinc is not converted into unavailable form.

9. Is boron nutrition is important for groundnut ?

The boron deficiency symptoms are smaller leaves with irregularly shaped margins, stubby roots with dark areas at the internodes, cracked stem, delayed flowering, and production of less number of pegs and single kernel pods.
Sufficiency, deficiency and toxic limits of boron are very narrow. Hence, one should be careful about boron application. If any above symptoms are noticed confirm about boron deficiency from the soil test results.

Depending on the severity of deficiency, 3 to 5 kg of borax per ha may be applied before sowing along with the other fertilizers. For immediate recovery of plants, foliar spray of 0.1% borax may be practiced.

4. Pigeonpea

1. Is there a need to apply fertilizers to pigeonpea crop?

Fertilizers are not applied to pigeonpea in traditional systems perhaps due to the wrong belief that the crop does not respond to applied fertilizers. This belief may be partly true if long duration types are grown as intercrop. But, intensively grown short duration types require good amount of nutrients to produce good yields.

2. Is it necessary to apply nitrogen to pigeonpea crop?

Pigeonpea is capable of utilizing atmospheric nitrogen for its growth through nodulation with the help of a type of bacteria. But the bacterial nodules do not develop on the roots until the plants are 15 to 20 days. Hence, during the early stages when the plants require easily available nitrogen for their good growth, a starter dose of nitrogen is important.

It is recommended to apply a starter dose of 15 to 20 kg N per ha at sowing time preferably by drilling the fertilizer along with phosphorus.

3. Is phosphorus application necessary for pigeonpea?

Yes. Response to phosphorus application to pigeonpea crop was observed. So, it is recommended to apply 17 to 26 kg of P₂O₅ to pigeonpea as a basal dose. Phosphorus needs to be applied by placement at a depth of 10 to 15 cm in the soil.

4. Is potassium application necessary for pigeonpea?

If soil tests show low levels of available potassium in the soils, then potassic fertilizers can be applied at 20 to 30 kg per ha as Muriate of Potash (MOP). Pigeonpea seedlings are prone to chloride injury if MOP is placed too near the plant rows.

The potassium deficiency observed in a standing crop can be rectified by foliar spray of Muriate of Potash.

5. Is there a need to apply any micronutrients to pigeonpea?

If the soil tests show low levels of available zinc in the soil, then 5 kg of zinc sulfate need to be applied at the time of sowing.

5. Chickpea

1. Is nitrogen application necessary for chickpea?

A small starter dose of 15 to 20 kg per ha of nitrogen stimulates early growth of chickpea. 30 to 34 kg N was found to be profitable in rainfed chickpea crop.

2. Is phosphorus application necessary for chickpea?

The range of 17 to 54 kg of P₂O₅ response to phosphorus application was observed depending available phosphorus in the soil.

3. Is potassium application necessary for chickpea?

There will be no response, if not negative response, to potassium application to chickpea in soils with high levels of available potassium. If soils are low in available potassium, an application of 17 to 25 kg K₂O is recommended.

4. What are the micronutrients usually respond to their application to chickpea?

Deficiency of zinc usually occurs in soils with high pH and in chickpea-rice cropping system. Basal application of zinc sulfate at 10 to 25 kg per ha gives a positive response.

In calcareous soils with high pH chlorosis of leaves is caused by the non-availability of iron under waterlogged conditions. This deficiency can be corrected by foliar spray of 0.5% ferrous sulfate.

6. MAIZE

1. Is fertilizers application important for maize?

Maize is very sensitive to the deficiency of plant nutrients. Hence, maize is considered to be a test plant for identifying the availability of many nutrients.

Maize crop should have a continuous supply of nitrogen at all stages of growth till grain formation. Nitrogen deficiency in maize plants even in the early stages of growth will reduce the yields substantially.

Young maize plants need higher amounts of phosphorus in the early stages. There after contribution of phosphorus through fertilizers decreases rapidly though plants take up phosphorus up to near maturity.

Maize utilizes large quantities of potassium from knee-high stage to post flowering. So top dressing potassium fertilizers can correct any deficiency of potassium observed in the early stages.

2. What is the fertilizer recommendation for maize?

For rainfed maize 80 to 100 kg nitrogen and 45 kg phosphorus are recommended. All phosphorus and 75% of nitrogen is to be applied as basal and the balance 25% nitrogen after 30 days of sowing.

For irrigated maize, application of 120 to 150 kg nitrogen and 60 to 80 kg phosphorus are recommended. Nitrogen is to be applied in 3 equal splits. The first application of nitrogen is applied at sowing along with phosphorus. The second dose of nitrogen is applied after 30 days of sowing and the third dose at tasseling stage of crop.

3. Is there any recommendation for micronutrient application to maize?

Many hybrid maize-growing areas may be deficient in zinc. Soil application of 25 to 50 kg of zinc sulfate is recommended once in every 3 years. If soil application is not done and zinc deficiency is observed on plants, 0.2% zinc sulfate solution is to be sprayed 2 or 3 times at weekly intervals till the symptoms do not reappear.

7. RICE

1. Is it necessary to fertilize rice nursery?

The nutrients contained in paddy grain are sufficient for about 14 days’ growth of the seedling. Beyond this period, application of fertilizers is necessary for raising healthy seedlings. Healthy seedlings well supplied with nutrients establish quickly and grow rapidly after transplanting.

2. Is it necessary to apply nitrogen as basal application to rice?

In soils with reasonable fertility there is no difference in yield whether the nitrogen meant for basal application is applied after final puddling or 15 to 20 days after transplanting. However, for soils of low fertility basal nitrogen application i.e. before transplanting is essential.

The nitrogen should be incorporated after draining the water and then water is allowed in the field after 2 to 3 days. Nitrogen fertilizers should not be applied in standing water.

3. What are the main guidelines for nitrogen application?

The optimum time and the rates of nitrogen application depend on various local factors such as soil type, water management, weather conditions etc. However, the following are some guidelines:

· Number of top dressings: Where flooding is not a problem, top dressings may be given every 2 to 3 weeks interval from transplanting till about a week after panicle initiation.

· Amount of nitrogen per top dressing: Preferably not more than 20 to 30 kg nitrogen per ha. However, this depends on the total quantity of nitrogen recommended.

· Soils with low nitrogen: More nitrogen at planting should be given.

· Soils with adequate nitrogen: Small amounts at transplanting and more nitrogen through top dressings.

· Low tillering variety: Relatively more nitrogen at early stages of growth.

· Early maturing variety: Relatively more nitrogen at early stages of growth.

· Long duration variety: More nitrogen as top dressings.

· Cool weather: Due to slow initial growth under cool conditions nitrogen should be applied more as top dressings.

· Direct sown crop: Less nitrogen at sowing, more as top dressings but to be completed by about 50 days after sowing.

· Rainfed crop: A few small top dressings on rainy days preferably coinciding with the physiological stages like tillering, panicle initiation, boot leaf stage, grain formation and grain filling stages.

4. How much of phosphorus to be applied for rice crop?

The texture of the soil is important while considering phosphorus application. Recovery of phosphorus from added fertilizer is much less in heavy soils than in light soils. For example: in black clay soils the recovery is 20 to 40% compared 60 to 80% recovery in red sandy soils.

It is now known that the phosphorus status of soil should be built up to a particular level to achieve higher yields. At least 35 kg P₂O₅ per ha should be available in soil to get profitable returns to fertilizer application in rice. If soil analyses shows below this level, the phosphorus fertilizer requirement is calculated as given below:

Example: Optimal requirement is 35 kg P₂O₅
Soil test value is 20 kg P₂O₅
Say, the recovery of added phosphate is 25%
The amount of fertilizer needed to bring up the soil to 35 kg P₂O₅ per ha level is:

((35-20) x 100) / 25 = 60 kg P₂O₅ per ha

This amount of 60 kg P₂O₅ per ha in terms of super phosphate (16% P₂O₅) is:

((60x100) / 16) = 375 kg of super phosphate
Thus knowing the soil test value and percent recovery of added phosphate, it is possible to suggest the required rate of phosphorus to rice crop.

5. Is it advantageous to apply potassium to rice?

It is important to identify the need to apply potassium to a field from the soil test results.
If there is a need, then potassic fertilizer is to be applied as basal application.

The split application of potassium is recommended when:

1. The soils are very low in potassium,

2. If the soil is too light to hold the potassium against leaching,

3. If the potassium fixation power of the soil is very high as indicated in the soil test report.

Top dressing of potassium if needed is applied at the panicle initiation stage.

Also need for application of potassium should be based if high amounts of nitrogen and phosphorus are applied.