Dryland Agriculture

• Growing of crops entirely under rainfed conditions is known as dry land agriculture. In Andhra Pradesh, out of 148 lakh hectares of cultivable land, nearly 105 lakh hectares is under rainfed agriculture, with 65% area under red soils and 25% area under black soils.
• Variation in crop yields is more in dry lands due to non receipt of timely rainfall and prolonged dryspels during crop periods. Adoption of following soil and moisture conservation measures and improved management practices will help in getting higher yields.

Soil and Water Conservation

Red soils

• These soils are shallow in depth with low water holding capacity. Rainwater is lost as runoff causing erosion resulting in loss of fertile top layer of the soil and nutrients. Research efforts were made to reduce these losses and soil conservation measures were found useful in reducing runoff and soil loss.
• When soil depth is 20cm or more, deep tillage once in three years helps in better infiltration of rainwater and reduces pest and weed problems.
• Cultivation across the slope reduces runoff.
• If slope is multiple and more than 2% construction of contour bunds with a cross section of 0.63 m 2 at 50m horizontal interval helps in conservation of soil and water in areas where annual rainfall is more than 750mm, graded bunds are recommended.
• In soils where surface crusting is a major problem, application of sand @40 t/ha before sowing helps in decreasing the crust strength facilities better inflitration of water into the soil and improves germination and crop stand.
• To avoid water stagnation on down stream side of contour bunds, formation of compartmental bunds with spacing of 15m x 10m before emergence of the crop of formation of conservation furrows with receipt of rainfall after 20 days of sowing of the crop help in reducing the water stagnation on down stream side of contour bunds and facilities better infilitration of water in to the soil.
• Intercropping groundnut with mixed pulses like horsegram, cowpea and redgram in 11.1 ratio helps in reducing the runoff losses and increases net returns.

Black Soils

Water holding capacity of these soils is very high, but deep cracking, low in permeability and poor drainage are the major problems. Soil conversation and improved management practices helps in getting higher yield of crops.

• Formation of graded bunds with a cross section of 0.8m 2 is recommended in these soils. Formation of a channel with a slope of 0.1 – 0.25% along the graded bunds and merging these channels in to a grassed waterway help in drainage of water without any soil erosion.
• Formation of ridges and furrows is useful for deep black soils. Sowing should be done on the ridges. Furrows facilitate easy drainage of water (or) formation of raised bed with 3m width at 20cm height help in getting increased yields of crops, as the furrows facilitate better drainage of water.
• Application of FYM @ 20 t/ha help in better infitration of water.

Rainwater Management

Red soils

• Runoff of rain water can be prevented by practicing soil conservation measures.
• Mulching with groundnut shells @5t/ha, within 10 days after sowing of the crop help in prevention of evaporation losses.
• Runoff constitutes 25% of rainfall in red soils. Water harvesting in farm ponds and subsequent use as supplemental irrigation helps in increasing the yields of rainfed crops. Water harvested from 5 ha can be used to irrigate one hectare in scarce rainfall zone. In other zones where rainfall is high, water harvested from 5 ha is sufficient to provide supplemental irrigation to 2 ha. Seepage losses were minimum when farm pond is lined with Cuddapah slabs. The size of farm period may range from 150 m 3 to 350 m 3. Groundnut crop responds to even to 10 mm of irrigation water during dryspell.

Suitable Crops

Red soils

• Groundnut, sorghum, pearl millet, fox tail mitlet, redgram, greengram, cowpea, castor and horsegram are suitable crops. Groundnut + redgram, groundnut+castor, sorghum + redgram are the profitable intercrops which help in prevention of crop loss during drought years.
• Depending on the time of receipt of rainfall the crops to be taken up should be decided. If the rains are received during June, castor or redgram can be sown. If rains are received during July or August first week intercrop of groundnut – redgram profitable. If rainfall is received after 15 August, the suitable contingent crops are fodder pearl millet, fodder sorghum greengram, cowpea and horsegram. If rainfall is received after 15 September, sorghum (fodder), pearl millet (fodder) and horsegram are suitable.

Black soils

• Cotton chillies, sunflower, bengalgram, sorghum, safflower and coriander are suitable crops. Sorghum and sunflower if sown during first fortnight of September give higher yield.
• Application of zinc sulphate @50kg/ha once in three seasons is necessary, if zinc deficiency is observed.
• If iron deficiency is observed, spraying of ferrous sulphate @2g/l of water is necessary.

Nutrient Management

• Basal application of 20kg N, 40kg P 2O 5 and 40 kg K 2O/ha are necessary for groundnut and groundnut + redgram. For horsegram, apply 10kg N and 30kg P 2O 5/ha.
• It is better to apply phosphorus and potassium based on soil test values. For groundnut crop grown in alfisols, the following schedule is recommended.

• For correcting zinc deficiency in groundnut, spraying of 0.2% zinc sulphate recommended at 35 and 45 days after sowing.

Weed Management

• Intercultivation should be practiced at 25 and 40 days after sowing. In area where labour is a shortage broadcasting of fine soil mixed with pendimethalin @ 2.5 l/ha or spraying pendimethalin @5ml/l is recommended, within two days after sowing of the crop.

Pest and Disease Management

• Since the farmers are less resourceful, IPM is a suitable technology. To reduce the cost of pest and disease management, these aspects are to be considered.
  • Pest monitoring and prediction.
  • Monitoring of natural enemies.
  • Forewarning of pest outbreak.
  • Critical stage of chemical intervention.
• Relationship between weather parameters and occurrence of pests and diseases has been established in many crops.

Sorghum

Stem borer :

• Infestation varies with time of sowing. More on late and early sown sorghum. Rainfall determines the time of emergence of adults.

Shoot fly :

• Extreme temperature and continuous heavy rains adversely affect the population. Rainfall influences peak emergence of adults. Maximum temperature (20-30 0C) is condusive for egg laying and larval development. RH (above 60%) favours intersity of attack.

Midge :

• Mean temperatures (25-30 0C). RH (above 60%). Adult midges emerge after accumulation of 43 0C heat units (based on mean daily 10cm soil temperature) above a threshold of 14.8 0C whereas 679 and 973 heat units are required for 50 and 95% emergence.

Groundnut

Leaf Miner :

• A sudden rise in maximum temperature by 2 0C followed by dryspell of more than one week resulted in incidence of the pest. If rain occurs, the incidence gets reduced during Kharif.

Red hairy caterpillar :

• Rainfall received between last week of June and September causes the emergence of RHC moths. The emergence is noticed on 2 nd day after the occurrence of rainfall of 10mm and more. If heavy rainfall of 80cm and above is received in one day during June / July, heavy emergence of RHC will take place at a time and subsequent emergence will be less. However, the moths emerged during September though they lay eggs, but mortality of eggs and larvae is observed due to the parasitisation and thereby the influence on the crop will be less.

Late leaf spot :

• Morning relative humidity of 80% and more coupled with night temperature around 22 0C causes the initiation of the late leaf spot disease on groundnut. If the weather conditions exist for a week, the disease spread will be more. Added to this the leaf wetness index of 2.3 coupled with 10% LLS incidence requires the control measures.

Rust :

• The rust incidence on groundnut will occur late in the crop period i.e. around 90 days. Morning relative humidity of 90% and more coupled with night temperature 20 0C causes the initiation of the disease.

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