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  Nutrient Management

Organic Manures > Chemical Fertilizers > Integrated Nutrient Management >


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Nutrient Management

Introduction

  • Of the several inputs essential for crop production, fertilizer/nutrient management is of paramount importance.
  • Widespread deficiency of N.P.K. and micro-nutrients like zinc show the need to apply for getting optimum yield of maize.
  • The maize plant is a heavy feeder, requiring an intelligent fertilizer programme. It requires a lot of nitrogen, phosphorus, potassium and zinc.
  • It responds very well to heavy nitrogen fertilisation, at a concentration that would normally cause lodging of other cereal crops.
  • The nutrients are to be replenished through balanced fertilizer application and integrated use of nutrients. These principles are not new to crop production but assumes significant importance in view of steep hike in fertilizer prices and abolition of subsidies.
  • Hence there is need to get acquainted with N.P.K. and Zn nutrition and their management as they are not replenished in sufficient quantities to produce optimum corn yields.

Organic Manures

  • A Judicious application of organic manure such as well rotten compost or FYM at the rate of 10-12 t/ha about 25 days before sowing the crop has been found to be most ideal for an increased crop yields.

 
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Chemicalfertilizers

Nitrogen

  • Maize plants throughout the cropping season take up nitrogen.
  • There is gradual increase in the requirement of nitrogen by the growing maize crop, the highest nitrogen requirement being exhibited at the flowering stage. Subsequently, the demand for nitrogen starts declining.
  • Therefore, it is utmost important that adequate nitrogen supply should be ensured from germination to the flowering stage.

Deficiency Symptoms

  • In young plants, N deficiency causes the whole plant to be pale, yellowish green and have spindly stalks.
  • Yellowing on the tips of the leaves appear later. Yellowing begins on the older lower leaves and progress up the plant.

V-shaped yellowing

Dosage

  • The N recommendation for major maize growing areas of Karnataka are as follows
  • Kharif Maize : Irrigated – 150 Kg ha-1
  • Rainfed – 90 to 100 Kg ha-1
  • Rabi Maize : Irrigated – 150 Kg ha-1

Time of Application

  • To achieve adequate nitrogen supply, nitrogen is usually applied in three equal splits at sowing, knee high stage and tasseling stages.
  • In non-sandy soils, uniform supply of nitrogen can also be accomplished by two equal application – 50% at sowing and remaining half at knee high stage.

Phosphorus

  • It is the next most important plant nutrient after nitrogen which is found deficient in most maize growing areas of Karnataka.
  • It has beneficial effect on root growth and maximum root development is completed until knee high stage. Thus the nutrient should be applied initially at the early stages.

Deficiency Symptoms

  • Phosphorus deficient plants will be dark green with reddish purple tips and leaf margins. Plants are smaller, grow slowly, and remain shorter throughout the growing season.

Dosage

  • The P2O5 recommendation for major maize growing areas of Karnataka are as follows :
  • Kharif Maize : Irrigated – 75 Kg ha-1
  • Rainfed – 50 Kg ha-1
  • Rabi Maize : 50 to 60 kg ha-1

Time of application

  • Since it plays major role in root development, entire dose of phosphorus should be applied in the early stages.
  • Because of its low solubility in water, it should be applied in moist zone to be transformed quickly for early absorption by plant.
  • It’s application in single dose as a placement below seed (band placement) is highly desirable.

Potassium

  • ;It is essential for vigorous growth of the plant and for so many other metabolic activities. The young seedling does not need much potassium, but the rate of uptake jumps upto a peak level during three weeks prior to tasseling.

symptoms


Shorting of internodes
  • Shortening of internodes, yellowing of leaves and firing at the margins of lower leaves.
  • Deficiency symptoms usually appears during the time, the plant is one foot tall to the time of tassel emergence.

Dosage

  • Potassium is not found deficient in most of the maize growing soils. However, placement of 30-40 kg ha-1 K2O, a little away from the seed is generally bound to be quite adequate.
  • Aa there is negligible amount of leaching and most of uptake is completed early, entire potassium is to be applied as basal dose along with phosphorus at the time of sowing.

Zinc

  • Higher uptake of other nutrients increases the demand of Zinc. Zinc deficiency symptoms are described as “White bud” in maize.

Deficiency symptoms

  • Appears rather early and plants become severely stunted owing to the restricted growth of inter nodes and leaf lamina.
  • Deficient plants show a broad band of bleached tissues on each side of the leaf midrib, beginning from the base.

Correction measures

  • Basal application of Zinc sulphate at 20-25 kg ha-1 after every three to four maize harvests becomes essential.
  • At later stages of growth deficiency can be corrected by foliar application of 5% ZnSO4 dissolved in water with half the quantity of lime.

Guidelines

  • All the three major nutrients should be applied in proper quantity & proportion and at a right time and place, also right method of application should be followed to obtain optimum grain yields of maize.

Fertilizer Management

  • Maize requires a regulated and assured supply of nutrients particularly nitrogen throughout its growing period right from seedling stage to grain filling stage.
  • The nitrogen utilization pattern is found to be increased from seedling of knee-height and reaches to the peak at tasseling stage when the plants remove nearly 4-5 kg N/ha/day.
  • Plants respond to a dose of 120 to 150 kg N/ha and so is the recommendation for hybrids and composite varieties, however, in certain cases the economical yield of maize grains has been obtained even upto the application of 200 kg N per hectare.
  • The best results from applied nitrogen may be achieved when nitrogen is applied in three splits viz., 1/3rd at sowing, 1/3rd at knee-heigh stage (about 35-40 days after sowing) and remaining 1/3rd at tasseling stage. Amongst the method of fertilization placement below the seed and side dressing of nitrogen at second and third split applications gave the best results. The crop needs relatively lesser nitrogen when grown during winter season, which may be accounted for higher uptake and lower loss of the nutrient from the field. Similarly,, during spring season when the crop is taken after potato, peas or gram it needs low nitrogen contents. On an average it is found that 100 to 125 kg N/ha becomes sufficient but the mode of application should be same as in kharif season.
  • The average uptake of minerals by a corn crop of 5000 kg grain/ha yield, is 105 kg N, 50 kg P2O5, 75 kg K2O, 10 kg CaO, 10 kg MgO and 6 kg S. In addition micro-nutrients such as manganese, zinc, boron and copper are absorbed in the order of 100 g/ha.

 
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Integrated Nutrient Management

  • Plant nutrients can be supplied from different sources viz., organic manures, crop residues, bio-fertilizers and chemical fertilizers. For better utilization of resources and to produce crops with less expenditure, integrated nutrient management is the best approach. In this approach, all the possible sources of nutrients are applied based on economic consideration and the balance required for the crop is supplemented with chemical fertilizers.
  • Farm yard manure application to the crops is being practiced for long. Well decomposed FYM in addition to supplying plant nutrients acts as binding material and improves the soil physical properties. Beneficial effects of earthworms and their cast were known as early as in Darwin’s era. But the potential of vermicompost to supply nutrients and to support beneficial microbes is being recognised recently. Since vermicompost is rich in humus forming microbes, nitrogen fixers and drying of the vermicompost has not deteriorated the microbial population. Hence, these characters recognised the vermicompost as biofertilizer.
  • At the same time only organics alone do not produce spectacular increase in the crop yields, due to their low nutrient status. Dependency on chemical fertilizers alone may not provide a viable economic option. Therefore to maintain soil productivity on a sustainable basis, an integrated nutrient management approach, using both organic and inorganic sources of nutrient should be adopted. In the present context, the use of manures must be given prime importance and fertilizer use should be limited to balance the nutrient requirement of the crops. Sustainable yield could be achieved by integrated use of chemical fertilizers and organics. Continuous use of crop residues and organics help to build up soil humus and beneficial microbes besides improvement of soil physical properties. Whereas, chemical fertilizers provide one or more essential plant nutrients which the soil can’t supply in adequate quantities. Thus judicious combination of organics and chemical fertilizers help to maintain soil productivity maize has high production potential specially under irrigated condition when compared to any other cereal crop. The productivity of maize is largely dependent on its nutrient management particularly that of nitrogen. It is well known that maize is a heavy feeder for nitrogen and demands 150 to 200 Kg N ha-1. In order to sustain soil fertility and to reap rich harvests of maize, it is imperative that both organic manuring and mineral nutrition have to be given adequate attention.

Effect of Vermicompost

  • The vermicompost is an aerobically degraded organic matter which has undergone chemical disintegration by the enzymic activity in the gut of worms and so also enzymes of the associated microbial population. Vermicompost is rich in both macro-nutrients (0.56 per cent N 1.48 per cent P2O5 and 0.36 per cent K2O) and micro-nutrients besides having plant growth promoting substances, humus forming microbes and nitrogen fixers. Recently it has been found that use of vermicompost in field crops.

Practical implications of the Integrated Nutrient Management (INM)

  • We can reduce 25 per cent of the inorganic nitrogen (37.5 kg/ha) and phosphorus (18.75 kg/ha) with the application of 12 t FYM/ha and seed inoculation with Azotobacter chroococcum and Aspergillus awamorii.
  • The low cost technologies like seed inoculation with Azotobacter chroococcum (N fixer) and Aspergillus awamorii (P. solubilizer) may be followed with 100 per cent of the recommended nitrogen and phosphorus to achieve higher yields and economics.
  • A leguminous crop like cowpea can be grown with the residual effect of 75 per cent of the recommended inorganic nitrogen and phosphorus either through single super phosphate or rock phosphate with 12 t FYM/ha with or without bio-inoculates for maize.
  • By following integrated nutrient management (with the application of P either through single super phosphate/rock phosphate at 112.5 : 56.25 kg N : P2O5 + 12 t FYM/ha with or without bio-inoculants) higher gross returns, net returns and benefit : cost ratio can be obtained in maize (summer) and cowpea (Early kharif).

 
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