Efficient Use of Fertilizers: 12 Measures

This article throws light upon the twelve measures that should be considered for efficient use of fertilizers. Some of the measures are: 1. Fertilizer Scheduling should be Based upon Soil Test and Crop Response 2. Placement of Fertilizers 3. Mixing of Fertilizers 4. Soil Texture and duration of Crop 5. Water Management 6. Use of Micro-Nutrients 7. Use of Amendments 8. Proper Agronomic Practices and Others.

Measure # 1. Fertilizer Scheduling should be Based upon Soil Test and Crop Response:

The optimum requirement of a fertilizer for maximum production depends upon the requirements of the crop on the one hand and the presence of various nutrients in the soil on the other. Soil testing given an idea about the status of nutrients as well as fertilizer recommendations for crops.

Soil testing also given the information about soil reaction. The selection of fertilizer should be based on the soil reaction. In acidic soils only those fertilizers should be used which have alkaline residual effect.

In alkaline soils acid forming fertilizers should be preferred. Rock phosphate is always preferred to super phosphate for strongly acidic soils, because in acidic soils rock phosphate gets dissolved easily and becomes available to plants.

Secondly, rock phosphate exerts alkaline residual effect which counteracts acidity of the soil. In India, where about 30-40% of the cultivated land is acidic, use of rock phosphate is to be encouraged.

There are, of course many limitations to soil testing such as lack of skill in sample collection, non-availability of testing facilities and low reliability of testing methods. Yet the soil testing is a useful management tool for the farmer, in spite of its limitations.

Regular soil test results from the same lab, sampled at the same time of year, should be compared with field information from year to year. This information will be a valuable gauge of progress in soil fertility management and fertilizer scheduling.

Measure # 2. Placement of Fertilizers:

In most cases, placement of fertilizers is preferred to the broadcast application. This is especially important for phosphatic and potassic fertilizers. If phosphatic and potassic fertilizers come in contact with a large volume of soil particles, the amount of nutrients (P and K) fixed condition in them will be proportionately high.

The mobility of fertilizers is also very slow in the soil. Placement of fertilizers in the root zone (5-8 cm deep) increases availability of nutrients to the crop.

Measure # 3. Mixing of Fertilizers:

Fertilizers of different kinds are mixed before their application in order to save application in order to save application cast and for some other reasons too. Mixed fertilizers should not be stored for longer time. Otherwise their nutritive value is reduced.

Measure # 4. Soil Texture and duration of Crop:

In light sandy soils, fertilizers are very vulnerable to leaching, losses leaching losses. In these soils fertilizers should be given in split doses in order to avoid excessive concentration of nutrients in the soil at a time. In long duration crops fertilizers (especially nitrogenous fertilizers) should be given the in split doses so that life-long requirement of plant at all stages of its growth.

Measure # 5. Water Management:

For the movement of nutrients in the soil, soil must contain sufficient amount of moisture. There is a positive correlation between the moisture content of the soil and to the fertilizer use efficiency. Moisture is necessary for nutrient absorption from the soil while nutrient helps in the expansion of root system so as to enable plant to explore greater volume of soil for moisture.

In dry land conditions where water is scarce, some amount of nitrogen can be supplied to the plants through sprays. In dry land areas low rate of fertilizer applications and correct placement of fertilizers have been found to increase yield. Flooded condition is not favourable for fertilizer application.

Water of the field should be drained out at least a week before fertilizer application. But in the case of paddy, fertilizers (especially phosphatic and potassic) should be applied at the time of puddling to expedite the fertilizers to reach and get stored in the root zone of the soil.

Measure # 6. Use of Micro-Nutrients:

Very light sandy soils having too high calcium contents (calcareous) and the soils under very high cropping intensity are very often deficient in micro-nutrients like zinc, iron. Application of micro-nutrients results in spectacular increase in crop yield. Micro-nutrient application in those soils enhances crop response to nitrogenous, prevents phosphatic and potassic fertilizers as well.

Measure # 7. Use of Amendments:

Except a few, most of the crops respond very well to commonly used fertilizers like urea, single super-phosphate and mutriate of potash in neutral soil. Application of lime to the acid soil and gypsum to the alkaline soil should be carried out to bring the soil to neutral range of reaction i.e. 6.5-7.5 pH.

Continuous use of a particular type of fertilizer in the same field for a few years may push the soil reaction towards acidity or alkalinity depending upon the nature of fertilizer.

Use of neutralizers, is therefore, recommended for field. For different fertilizers, different amount of neutralizers is recommended. For example, for each 100 kg of ammonium sulphate, 110 kg of lime stone neutralizer should be used. If a field is receiving 100 kg ammonium sulphate every year, 330 kg of limestone should be applied to that field at every 3 years interval.

Measure # 8. Proper Agronomic Practices:

Weed control, use of pesticides, mulching, tillage and crop rotation should be carried out timely and properly. They should not be allowed to become limiting factor to crop yield.

Measure # 9. Use of Organic Manures:

Use farm yard manure, compost or green manure in the field at the interval of at least 3-4 years. Application of fertilizers coupled with organic manures has mutually beneficial effect on each other.

Organic manure prevents the loss of fertilizer nutrient from the soil and also counteracts the acidic or alkaline residual impact of fertilizers. On the other hand, in presence of fertilizer nutrients, organic manures release plant nutrients more rapidly.

Measure # 10. Use of Bio-fertilizers:

From several research investigations it has been found that certain micro-organisms such as Bacillus megatherium (a bacterium) solubilize the phosphorous years from ground rock phosphate and make it available to the growing plants, thereby increasing efficiency of phosphatic fertilizers. The bacterium is sold as ‘phosphobacterin’ bio-fertilizer.

Another bio-fertilizer called micorrhiza which has not yet come to the market as a bio-fertilizer, also holds promise to increase efficiency of phosphatic fertilizers.

Extensively grown, highly branched body of hate fungal micro-organism which is the main constituent of that micorrhiza helps plant roots explore greater soil volume for phosphorus, use of blue green algae and azolla also increases the recovery of fertilizer nutrients by plant roots from the soil.

Use of Slow Release Fertilizers:

Recently, slow release nitrogenous fertilizers like U.F. 30, urea super granules (US G) have been developed. There use is intended for flooded conditions. In flooded conditions ordinary urea is rapidly converted into gaseous form which is not available to the plants. USG and UF-30; the forms of urea itself, release nitrogen very slowly; thereby reducing the loss of nitrogen.

As a latest has development, nitrification inhibitors have also been found to slow down the rate of nitrogen release from urea. Urea is treated with these chemicals before application to the flooded field. Deep placement of urea in root zone, in the form of USG or in the mud balls (briquettes) is labour intensive and, therefore, a costly technique.

Use of Coated Urea:

Coating of urea before application to the flooded field is the cheapest way to increase urea efficiency in rice of plant in fields. Coating treatment also aims at slowing the rate of release of nitrogen from ordinary urea. Two materials are mainly used for coating:sulphur and neem cake.

Neem coated urea (NCU) is cheaper than sulphur coated (SCU) as the sulphur is very costly. Manufacturing of sulphur coated urea is also a complex process, while neem coated urea can be prepared by farmers themselves. NCU has performed well in trials with maize, potatoes, sugarcane and cotton.

(a) Procedure to Prepare NCU:

Take two litres of kerosene oil and thoroughly mix it with one kg of coal-tar or Arabic gum, in a seed dressing drum. Put 100 kg urea in the drum and mix the contents. Now mix 25 kg of neem cake power thoroughly. A thin-The exp coating of neem cake over urea granules takes place. Coal-tar or Arabic gum acts as a sticking agent. Use the fertilizer as soon as possible.

(b) Use of Untreated Urea in Paddy:

If untreated urea is used paddy field, mid-term drainage has been found to increase urea use efficiency. Water which is drained out from the field about 24 hours before fertilizer application. Drainage is repeated once more the night 20-30 days after first drainage.

This technique can be practiced only where plenty of water and drainage facilities, are available. Foliar application of urea during the late growth stage of paddy crop also helps plants to grow better.