Fertilizers: Application & efficient Use

Fertilizers: Application & efficient Use

Contents

Preface

I.          Introduction

II.         Time of Fertilizer Application 

III.        Methods of Fertilizer Application

IV.        Efficient use of Fertilizers

V.         Integrated Nutrient Supply

 

Preface

Efficient use of fertilizer means maximizing the production and minimizing the cost through fertilizer application. But farmers are unaware of these two facts. This booklet gives sufficient knowledge on time and methods of fertilizer application. This enables the farmer to use the fertilizers efficiently and timely.

I. Introduction

Increased agricultural productivity usually comes as a result of the effective adoption of improved technologies. Wortman and Cummings Jr (1978) of John Hopkins University--Baltimore recognized four requisites which should be met to enable farmers, regardless of size of holding, to increase productivity. The four requisites are discussed below.

1.An improved farming system: a combination of materials and practices which are clearly more productive and profitable with an acceptable low level of than those he currently uses, must be available log to the farmer.

2. Instruction at farmers' field: the farmer must be shown on his own farm or nearby how to put the practices into use, and he should understand why they are better than the prevailing ones.

3. Supply of inputs: the inputs required, including fertilizer, and, if necessary, credit to finance their purchase,  must be available to the farmer when and where he needs them, and at reasonable cost

4. Availability of markets: the farmer must have access to a nearby market that can absorb increased supplies without excessive price drops.

The third requisite, supply of inputs to which fertilizer Ion belongs, is indeed one of the most important factors for increasing yield. But merely making the inputs available to the farmers is not a complete solution in itself. Farmers must know how to make the most productive use of these inputs. Here the second requisite comes to play a key role. Although Indian soils are very responsive to fertilizer application because of their inherent low fertility, farmers find it very difficult to apply the recommended doses of Plant fertilizers because of their low purchasing power. So our effort should be not just to get increased production by fertilizer application but to get maximum possible production from a unit land area with the least amount of fertilizer applied. This concept is called efficient use of fertilizers.

To get higher responses than existing ones, time and method of application of fertilizers should be so designed as to suit properly the type of the crop grown, As such, prevailing soil and climatic conditions, and of course the nature of the fertilizer to be used.

 

II. Time of Fertilizer Application

Most of the crop plants generally require nitrogen throughout their growth period. Irrespective of the crop, all plants tend to grow at a slow pace in the beginning, rapidly in the "grand growth period" (the period at which elongation of cells, tissues and formation of organs take place) and again slow during maturity. Accordingly,  nitrogen is also taken up by the plants in keeping with the pace of plant growth. Hence use of nitrogenous fertilizers should be so timed as to ensure its supply to the to plant throughout its growth period especially during  grand growth period. Nitrogenous fertilizers are very soluble in water, hence liable to be leached. As such it is necessary to apply nitrogenous fertilizers in split doses of two-four, depending on the type of soil and the duration of the crop. When the fertilizer is applied at sowing time, it is called basal dressing; and the dose applied in standing crop is called top dressing.

Plants require phosphorus mainly during the early root development and early growth period. Besides, almost all phosphatic fertilizers release phosphorus very slowly to the plant growth unlike nitrogenous fertilizers. They are, therefore, applied only at the time of sowing i.e. basal dressing.

Intake of potash by plant is similar to nitrogen whereas time its availability is like that of phosphorus. Soils rich in so clay fix the applied potassium and release it very slowly. As such, it is advisable to apply the entire quantity of  potassic fertilizer at sowing time. However, mixtures of nitrogen and potassium can be applied in standing crop as well.

 

III. Methods of Fertilizer Application

As per crop requirement and growth pattern, plant nutrients are applied in different methods. The following are the important methods of fertilizer application.

 

A. Broadcasting

The fertilizer is spread all over the field with a view to distributing the whole quantity of fertilizer uniformly. This method of fertilizer application should not be practised where placement of fertilizers in the root zone is feasible because in this practice more amount of fertilizer is required to produce the same yield. Broadcasting of fertilizers is carried out at two stages.

1. At the time of planting: Depending on the crop, broadcasting of the fertilizer is carried out prior to sowing/planting or just before the last ploughing and incorporated in the field. Broadcasting of fertilizers at the time of planting is generally done under conditions: (a) when the soils are highly deficient in nitrogen and (b) when the previous crop has been exhaustive such as sugarcane, jowar, maize, etc.

2During crop growth period : Broadcasting in standing crop is done mainly for nitrogenous fertilizers and mostly for close spaced crop like paddy and wheat. It is called top dressing. Muriate of potash is also applied as top dressing in some crops but this is not a general practice.

Procedure

Measure the field, divide the field into convenient units, calculate and weigh the fertilizer for each unit and spread the fertilizer uniformly on the entire surface of each unit. Division of plot and quantity of fertilizer ensures greater uniformity in fertilizer application.

 

B. Placement

Fertilizers are placed in the soil before sowing irrespective of the position of the seed. Placement in standing crop can also be done in widely spaced crop growing in a limited area. For example, in young maize crop fertlizer add can be manually placed 3-4 cm away from the stem. Placement of fertilizer restricts the surface area of the fertilizer coming in contact with soil particles and thus decreases the fixation of phosphorus and potassium.

1. Plough furrow or single band placement

Fertilizer is placed in a continuous band at the bottom of the furrow opened during ploughing. Each band is covered with soil after the application. In single band placement fertilizer is applied on one side of the planted row.

Procedure

-Open the furrow with the help of plough.

-Count the number of furrows and measure the total  area of operation.

-Calculate and weigh the required dose of fertilizer for each furrow and 

                                      place the ferti1izer in the furrow.

-Cover the furrow with the soil.

2. Double band placement

In double band placement method, ferti1izer is placed and on both the sides of the row. Furrows can be opened with the help of two tyned harrow (if available); keeping the planted row in the centre. After fertilizer is placed, the furrows are covered with the soil by planking..

Placement of fertilizer is generally employed for the application of nitrogenous, phosphatic and potassic fertilizers in the intensive agriculture and in orchards.

Deep placement of fertilizer is generally practised for application of nitrogenous and phosphatic fertilizers in paddy fields. In this method, 15-20 cm deep furrows are opened with the help of plough and ammoniacal the fertilizer is placed in them. They are covered with soil usually by planking. This operation is done after draining out water from the field. After placement of fertilizer, field can be flooded again. This practice is also useful for concentration dry land areas. In dry land areas moisture is found  to be deeper layers of soil. Therefore deep placement can be adopted for both seed sowing and fertilizer application.

3. Ring placement

Ring placement method is mostly practised for the fruit trees in orchard or for individually grown trees..

 

Procedure

-open a ring like trench of one foot wide and four to six inches deep around the fruit tree with the help of spade corresponding to the circumference of the shoot system of the tree.

-Calculate and weigh the amount of fertilizers for each plant separately.

-Apply fertilizer uniformly in the trench

-Cover the ring with soil.

 -Apply irrigation if required.

 

C. In  situ application

When fertilizers are applied on a specific spot, it is called 'in situ' application or localized application of fertilizer in wide fertilizers. The following are the kinds of in-situ application of fertilizers.

1. Drill application

Drill application refers to the drilling of fertilizer at sowing time. Drilling the fertilizer together with seed should be avoided as it may adversely affect the germination or the young plants may get damaged due to high or concentration of chemicals in the root zone. It is advisable in to use a separate attachment for seed and fertilizer drilling. This is one of the best methods for applying phosphatic (P) and potassic (K) fertilizers to closely spaced row planted crops like wheat, maize, jowar, bajra etc. This method is also better for applying nitrogenous fertilizers. However, it is safer to drill only small quantities  of fertilizers so that germination may not be adversely

affected.

 

Procedure

-Attach the fertilizer drilling tu be to the plough.

-Measure the area of operation.

-Calculate and weigh the required fertilizers.

-Drill the fertilizer taking care of the uniform distribution in the field.

2. Dollop method

The entire quantity of fertilizer is calculated per plant and is applied on both the sides of the plant with the help of a cup by dividing it into two parts. This is considered to be very efficient method of applying nitrogenous fertilizer in widely spaced crops like cotton and fruit trees.

 

Procedure

-Count the number of plants in the area of operation.

-Calculate and weigh the required fertilizer.

-Put a mark in the fertilizer cup for the desired quantity of fertilizer for each plant.

-Dig a hole on both the side of the plants with the help of spade/appropriate tools to a depth of 10 cm.

-Apply the fertilizer equally in both the holes and cover it with soil.

3. Pellet application

In pellet method, the fertilizer is mixed with the soil in the ratio of I :10 (one part fertilizer and ten parts of soil) and made into a paste. Then small pellets of convenient size are prepared. These pellets are then applied cost to the field by depositing them in soft mud.

This method is especially useful for the application (of nitrogenous fertilizers in paddy field. This practice greatly increases the nitrogen use efficiency of paddy crop.

D. Foliar application

Foliar application refers to the spraying of fertilizer solution on. foliage (leaves) of. growing plants. .Normally, these solutions are prepared in low concentration (2-3 %) either to supply anyone plant nutrient or a combination of nutrients.

3. Av Advantages

-Foliar spraying is useful to correct the nutrient deficiency growing crops.

-In extremely dry weather condition where the plants can not take up nutrients from soil because of low moisture contents of soil, foliar spray is useful.

-When quick response of fertilizer (especially nitrogenous fertilizer) is required.

-When the widely spread foliage of plant poses difficulty, for soil application,

 

Disadvantages

-.Marginal leaf burns or scorching, may occur if strong solutions are used.

-As a solution of low concentration, only a small quantity of nutrients can be supplied at a time,

-Several applications are needed. This increases the cost of application unless it is combined with other spraying operations.

-It cannot be recommended as a sole method of application of fertilizer.

-Only Urea and micro nutrients can be applied through this method.

 

E. Precautions taken while applying fertilizers

I. Note that there is sufficient moisture in the field before applying fertilizers.

2. Ensure uniform distribution of fertilizer on the entire area of operation,

3. Avoid hot-hours or the day while applying (broad-casting) a fertilizer.

4. Choose a fair weather day preferably for broadcasting

5. Do not top dress the fertilizer when the crop leaves are wet otherwise burning and scorching of leaves may occur.

6. Confirm the compatibility of fertilizers before mixing

7. Place the fertilizer at least 5-8 cm below the soil surface.

8. Cover the fertilized furrow immediately.

9. In double band placement open the bands by keeping nitrogen the planted row in centre.

10. In ring placement open the ring near the active root zone of fruit plants (corresponding to the circumference of shoot system).

11. Avoid drilling of fertilizers and seed together especially of legumes as even a small amount of fertilizer may damage germination.

]2. Check choking of the tube from time to time.

]3. Select only spray-grade urea for foliar spray.

14. Prepare fresh solution for each spray.

15. Avoid spraying during hotter period of the day. Spraying in the evening is preferred. Spray again if it rains immediately after spraying.

16.Urea used for foliar application must not contain more than 1.5% biurate, a compound  which is highly harmful to the plants.

17. Foliar application of fertilizers should be avoided on the crops having very small leaves, i.e. compound leaf system.

18. Bulky organic manures should be applied to the field soil one month before sowing while cakes 8-10 days before sowing so that decomposition may take place properly and, nutrients are available for crop growth.

IV. Efficient Use of Fertilizers

Researches have shown that plants cannot utilize which cou more than 60% of nitrogen and 20% of phosphorous applied through fertilizers, even though the best management practices are adopted. Under ordinary conditions plants hardly avail more than 30% nitrogen and 10% .phosphorus applied through fertilizers. Major part of the nitrogenous fertilizer is either lost to the atmosphere in the form of gas or leached down in the soil along with soil water. Likewise a large portion of phosphorous is fixed with the soil particles and plants cannot avail it. Therefore, the following measures should be considered in order to obtain maximum benefit with the may minimum dose of fertilizer applied.

1. Fertilizer scheduling should be based upon soil test and crop need

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 gives the idea whether or hly not the soil contains sufficient nutrients to meet the requirement of a particular crop. In case of a nutrient deficiency, it should be added to the soil through fertilizers.

Soil testing also gives the information about soiI 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 % 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, can be compared with field information from year to year. This information is a valuable gauge of progress in soil fertility management and fertilizer scheduling.

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

3. Mixing should be done carefully

Fertilizers of different kinds are mixed before their application in order to save appIication in order to save application cast and for some other reasons too. Before mixing fertilizers, the compatibility chart should be referred (refer booklet MFS-8). Mixed fertilizers should not be stored for longer time. Otherwise their nutritive value is reduced.

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.

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 an 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 me 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.

6. Use of micronutrients

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

7. Use of amendments

Except a few, most of the crops respond very well to commonly used fertilizers like urea, single super-phosphate and muriate 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.

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.

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 counteract the acidic or alkaline residual impact of fertilizers. On the other hand, in presence of fertilizer- nutrients, organic manures release plant nutrients more rapidly.

10. Use of bio-fertilizers

Researches carried out at IARI, New Delhi, have shown 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’ biofertilizer. Another biofertilizer called, mvcorrhiza which has not yet come to the market as a biofertilizer, 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.

 

II. Use of slow release fertilizers

Recently, slow release nitrogenous fertilizers like U.F. 30, urea super granules (US G) have been developed. Their 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.

12. 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 n 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 coaltar 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 powder thoroughly. A thin -The exp coating of neem cake over urea granules takes place. Coaltar 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 in 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 practised 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.

 V. Integrated Nutrient Supply

Fertilizers alone cannot meet the vast requirement of plant nutrients. This is largely because of the rising cost of fertilizers and partly because of inherent draw backs with the fertilizers themselves. It calls our attention towards the concept of “integrated nutrient supply". The concept of integrated nutrient supply is a broad one which embraces following considerations:

-Nutrient cycle between the soil, the crop and the animal and atmosphere.

-The question of correct nutrient balance in fertilizer use including micronutrients.

-Combined use of organic manures and fertilizers i.e. at least 40 %of nutrient requirement of a crop should be met in the form of organic manure..

-The exploitation of biological sources of nutrients.

-The matching of nutrient supply to the clopping system as a whole and not merely to the needs of specific crops.

On the basis of 1972 cattle census of India, total production of dung and urine by cattle, sheep, goats and poultry is estimated at approximately 780 million tonnes  which contains 2.2 million tonnes of nitrogen, 0.82 million tonnes of phosphorus and 1.87 million tonnes of potash. The night soil from a population of 800 million contain more plant nutrients than those in animal waste. Nutrients from all these waste products exceed the amount of nutrient currently applied through the fertilizers in our country.

If the farm wastes (urine dung and crop residues) are used in biogas plants, greater part of their nitrogen content can be preserved, while large amount of organic can also be made available for improving properties. The manurial benefits of biogas slurry are two folds. In the first place the organic matter improves . biological activity in the soil and promotes the stability of soil aggregates thereby improving the moisture retention capacity of the soil. Secondly, the direct nutrient effects  are considerable.

Biological nitrogen fixation has a tremendous potential to meet the nutrition needs. Although bio-fertilizers are becoming popular among poor and marginal farmers but still there are miles to go in that direction. Azolla and blue-green algae have been found to replace nitrogenous fertilizer as much as 30-35 per cent. They supply not only nitrogen but also many tonnes of organic matter (vital component of the soil) to a hectare of land. The utility of green manuring by dhaincha, sunhemp and other crops is already well established and the practice is very popular in some parts of the country. Millions of litres of sewage effluent, if used properly, can supply handsome amount of nutrients to the soil.

Dr. K.T. Chandy, Agricultural & Environmental Education