In dryland areas, crop production depends on amount and distribution of rainfall. Most of the farmers still grow long duration traditional varieties under conventional practices. The productivity of these crops varieties is affected due to uncertain rainfall. Hence, there is need to develop short duration varieties, crop plan and agronomic practices matching to rainfall pattern.
By climatic data all over India, suitable crops and varieties for early, the normal and late onset of monsoon, improved inter cropping, time of sowing and agronomic practices have been identified and developed. In arid part of Rajasthan short duration varieties of pearl millet, cluster bean, moth bean, mung bean and sesame have been developed to minimize the risk of crop failure. With the early onset of monsoon, pearl millet and sesame get preference. While with the late onset of monsoon cluster bean, mung bean and moth bean get preference. Since the moisture evaporates very fast, it is suggested to complete the sowing immediately after rains.
All operations carried out in the field, from land preparation to crop harvesting, with the aim of increasing the crop yield is included under agronomical practices. Certain simple agronomical practices like optimum tillage, administration of organic manure and suitable cropping pattern are effective in retaining soil fertility as well as giving satisfactory crop yield.
Tillage makes soil loose and hence prone to erosion. Timing and depth of tillage are the two important factors which need special attention. Tillage should be done immediately before the crop season to take advantage of one or two early showers for land preparation. In the arid region, land tilled into ridges and furrows across the wind direction has been found to reduce the effects of wind erosion during the summer months. Deep tillage improved the soil moisture storage, water use efficiency and grain yield of pearl millet (Saxena et al., 1997).
Farm lands should be levelled for efficient management of water. Level lands allow more infiltration, thus increasing soil moisture and leaching. This, in turn, reduces runoff and hence soil erosion. Levelling of irregular land is done by the cut and fill method. Soil from the elevated portions is removed and placed in the depressed portions to obtain a level land.
Mulching of open land surface is achieved by spreading stubble, trash or any other vegetation. The objectives of mulching are to minimize splash influence of rain drops on the base surface, reduce evaporation, increase absorption of the rainfall, obstruct surface flow thereby retarding erosion and allow microbiological changes to occur at optimum temperature. Studies conducted at CAZRI showed that mulch application improved the water use and water use efficiency in pearl millet (Table 4).
INCREASING WATER USE RELATIVE TO OTHER LOSSES
Evaporation of water directly from soil surface is an important component of the total water use of crops. Evaporation constitutes 19-46% of the total water on Vertisols, 21% on Alfisols and 12-18% on loamy sand soils. The best opportunity for water saving lies in methods increasing transpiration relative to other losses from the soil surface due to canopy shading. The elimination of weeds, optimum plant population and spacing and application of fertilizer/manure helped in better canopy growth and higher WUE of crops. Close row spacing and higher plant population are recommended in high rainfall areas or irrigated condition, but in an arid region, wide row spacing and low population are recommended. Paired row planting system helps in better canopy growth and hence evaporation from soil surface is restricted. Weeding improved the pearl millet yield by 44% over weedy condition (Table 5) in low rainfall season.
Table 5. Weeding enhances WUE (kg ha mm ) and yield (kg ha ) of pearl millet
- Central Arid Zone Research Institute