Sorghum

Nutrient Management

Nutrient Management

Introduction

  • Relatively little fertilizer was used on sorghum before 1960s. Then due to development of early-maturing varieties, use of hybrids with high yield potentials and growing sorghum under irrigated conditions all resulted to increase the fertilizer use in sorghum.
  • Sorghum is a relatively heavy user of nitrogen (N), phosphorus (P) and potassium (K). Hence, application of fertilizers is essential to boost the yield and get higher returns.
  • The deficiency of micro nutrients in some soils may also limit the production.

Estimating Requirements

  • Take soil samples and analyse for the nutrient status before raising the crop. Apply the NPK fertilizers as per soil test recommendations. If soil test recommendations are not available apply full dose of recommended fertilizer.

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Major And Micro Nutrients

Nitrogen

  • Nitrogen is essential for protein synthesis, growth and root development.
  • A kilogram of nitrogen increase yield by 15-18 kg of grain yield.
  • Nitrogen requirement for sorghum is 90 kg/ha. Apply half the dose basally before planting. If basal application is not possible the same could be top dressed within 24 hours. Apply the balance , 30 days after sowing and irrigate.

Phosphorus

  • It is an essential component of many plant compounds. Deficiency of phosphorus delays flowering and maturity. Marginal leaf necrosis and chlorosis are symptoms of deficiency.
  • Grain yield increases between 7 to 20 kg per kg of phosphorus applied .
  • The recommended dose is 45 kg / ha and has to be applied basally.

Potassium

  • Deficiency result in leaf margin drying, weak roots, chaffy grains and increased susceptibility to diseases.
  • Apply basally 45 kg of potassium/ha.

Zinc

  • Deficiency symptom first appear in newly formed leaves at 20 to 30 days of age. Older leaves have yellow streaks or chlorotic striping between veins.
  • Mix 12.5 kg of micronutrient mixer formulated by Department of Agriculture, Tamil Nadu with sand to make the quantity of 50 kg and apply over furrows or spread the mixture evenly on the flat beds in zinc deficient soils.
  • If micronutrient mixture is not available, apply basally 25 kg zinc sulphate/ha.

Iron

  • Initially iron deficiency results in interveinal chlorosis. If deficiency continues entire leaf including veins exhibit chlorotic symptoms. The entire crop may exhibit bleached appearance, dry and finally die.
  • To correct the deficiency, basal application of ferrous sulphate @ 50kg/ha. is recommended.

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Biofertilizers

Introduction

  • Bioterfilizers are microbial preparations containing live or latent cells of microorganisms. When mixed with seed or applied to the soil they multiply and fix nitrogen or solubilize phosphates in root region of the crop.

Types

  • Biofertilizer are broadly classified into two major types.
      1.  Nitrogen fixers - Azospirillum
      2.  Phosphate solubilizer / mobilizers - Phosphobacteria.

Nitrogen Fixers

  • Azospirillum is associative symbiotic nitrogen fixing bacterium that lives in close association with root system of sorghum plant. They not only remain on root surface but also penetrate into cortical cell.
  • The nitrogen fixing capacity of this organism is very high resulting in yield increase by 25%.

Phosphate Solubilizer

  • The phosphobacteria viz., Pseudomonas and Bacillus can solubilize the insoluble inorganic phosphate and make it available to plants.
  • Seed or soil inoculation with phosphobacteria increase the uptake of phosphorus by sorghum plants.

Method Of Application

Azospirullum

  • Mix 2 kg (or 10 packets) of Azospirillum with 12.5 kg of FYM or composted coir pith and apply in one hectare before ploughing. or
  • Treat the seeds with Azospirillum before sowing @ 600 gm/ha. Prepare a slurry by mixing the Azospirillum with rice kanji and thoroughly coat the seeds with slurry.

Phosphobacterium

  • Same as in Azospirillum

Advantages

  • Biofertilizers reduce quantity of inorganic fertilizers to be applied and at the same time increase the crop yield. They also maintain soil fertility.
  • The use of Azospirillum increases the yield by 18.22% besides reducing the requirement of inorganic nitrogenous fertilizers.
  • Phosphobacterium increases the availability of phosphorus resulting enhanced growth and yield. If it is used, only 75% of recommended dose of phosphorus will be sufficient.
  • Biofertilizers are economical ecofriendly and effective renewable energy source.
  • They do not alter the soil properties as noticed in inorganic fertilizers.

Precautions

  • Store biofertilizers in cool and dry places.
  • Biofertilizers should not be applied along with insecticides, fungicides and chemical fertilizers.
  • Apply biofertilizers during morning hours.
  • Biofertilizers are to be used after treatment with fungicides.

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Organic manures

Introduction

  • The organic manures or fertilizers recommend for sorghum crop are farm yard manure and composted coir pith. They are important sources of macro and micronutrients.
  • It is suggested that organic matter level of 5 to 6% or 2.5 to 3% organic carbon in soil will lead to sustainable crop production.
  • Organic manures improves the soil fertility, tilth and aeration.
  • They increase water holding capacity of soil.
  • Stimulate the activity of micro organisms that convert the complex organic materials into simple substances that are readily absorbed by plants.
  • The quantity and method of application is given in land preparation.

Nutrient Composition

Nutrients
FYM %
Composted coir pith %
Nitrogen
0.68
1.10
Phosphorus
0.50
0.10
Potassium
0.38
1.20
Zinc
-
12.50
Iron
-
0.09
Carbon
16.60
24.2
C/N ratio
24.1
22.00
Moisture
36.80
-

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Tamilnadu

Sorghum

Sorghum Management