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Irrigation in sorghum

Irrigation in sorghum

Sorghum is mainly grown under rainfed situation. Only about 8% of sorghum area is irrigated. Sorghum crop is exposed to drought conditions very often during its growth and consequently the yields are lower than the potential yield. So, if the farmers want higher sorghum yields even during the rainy season, the answer is irrigation if water is available.

Irrigation helps sorghum crop throug

  • Allows efficient use of inputs
  • Increases yield
  • Improves quality of grain
  • Improves reliability and reduces risk
  • Increases profitability

Adequate soil moisture at sowing assure uniform plant stand and contributes to early plant growth. Pre-plant irrigation can supply this moisture when early rains do not fill the root zone prior to planting. If the seedbed contains sufficient moisture for good germination and early plant growth but subsoil moisture is lacking, water may be supplied by irrigating the crop after emergence. Allowing seed to remain in dry soil for several days may result in poor germination and seedling vigour. So, irrigation prior to sowing is recommended if water is available. Whether irrigating before or after planting, apply no more water than required to fill the effective root zone. Encourage deep rooting by maintaining only moderate soil moisture levels during early vegetative growth. Moderate plant moisture stress during early vegetative growth normally does not significantly limit grain yield. However, adequate moisture must be available by the boot stage. Irrigation at the milk to soft dough stages also has consistently maintained high yield potential.

Irrigation intervals and the amount of water to apply is determined by:

  1. rainfall
  2. soil's water-holding characteristics
  3. Plant rooting depth and
  4. other climatic conditions like air temperature etc.

The visible signs for giving the irrigation to the crop or the moisture requirement of crop are:

  • drooping and withering of leaves during morning period,
  • leaves feel some what warm during noon instead of cool, and
  • cracking of the soil surface of the field.

Plan irrigations to provide adequate soil moisture during these high water requirement periods.

Irrigation for a ratoon crop

  1. Irrigate immediately after cutting the main crop.
  2. Irrigation should not be delayed for more than 24 hours after cutting.
  3. Irrigate on 3rd or 4th day after cutting.
  4. Subsequently irrigate once in 7-10 days.
  5. Stop irrigation on 70-80 days after ratooning.

Drought Contingency Plan For Rainy Season Crop

  1. Early onset of monsoon followed by a long gap: Repeated intercultivation operations for some moisture conservation like hoeing, weeding and mulching are suggested. Under severe moisture stress, reduce the plant population by 2/3 by thinning for judicious use of moisture.
  2. Delayed onset of monsoon: Normal recommendation can be followed.In case there is delay in monsoon by 2-3 week, short duration cultivars such as CSH 6 and CSH 14 can be preferred.

 Summary: Light Soils

Crop Stage
Irrigation
After Sowing
Germination and establishment

2

            1st day 4th day
Regulate irrigation during vegetative phase      1,2

            15th day 28th day
Flowering phase (copious irrigation)

1.2,3

      40th day 52nd day 64th day
Maturity phase (control irrigation)      1,2             75th day 88th day
Stop irrigation thereafter
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Summary:Heavy Soils

Crop Stage

Irrigation

After Sowing

Germination or establishment

        1,2

1st day, 4th day

Regulate irrigation during vegetative phase        1,2

  17th day, 30th day

  

Flowering phase (copious irrigation)

  1,2,3

        45th day, 60th day
Maturity phase (control irrigation

 1

90th day

Stop irrigation thereafter
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