Management of rainfed agriculture
Management of dry land agriculture has two parts or there are two methods, which should be applied to manage dry land agriculture these are:
1) Conservation of water
2) Efficient use of conserved water
- Conservation of water:
- Steps of water conservation are as follows:
i) Reduced runoff: Reduction of runoff can be done by leveling, bunding, terracing, contour tillage, breaking the hardpan, deep ploughing etc.
ii) Reduce water loss through evaporation: Prevention of water loss through evaporation can be achieved through mulching. There are two types of mulch i.e. organic (straw, stubble, FYM, saw dust, rice husk etc) and synthetic (petroleum product like ESSO or ENCAP form thin layer on soil surface, polythene mulch etc).
iii) Reduce water loss through transpiration: Use of anti-transpirants like:
a) Light reflecting chemicals e.g kaolin, kaolinite (chalk like substances) which are able to reflect the light if spread over the surface of leaf and reduce the leaf temperature and transpiration.
b) Film forming chemicals: Emulsions of plastics, wax, latex which form a film over green surface. This films over green surface check the escape of water.
c) Stomata closing chemicals: Stomata are closed due to reduced turger pressure of gourd cell. Size of the stomata is reduced by spraying chemicals like phenylmercuric acetate @ 40 gm in 1000 liters of water.
iv) Water harvesting
Where rainfall is not sufficient to grow crops in all the areas, water from upper elevation (donor area) to lower elevation (recipient area) can be collected and grow crops easily. To induce the runoff from the donor area to recipient area, various materials like asphalt’s spray, plastic film or water repellents like sodium methyl silicanolate can be used. These chemicals have dispersion capacity of rainfall water.
Methods of water harvesting
a) Water harvesting in small tank: The 4m x 3mx 2m sized tanks are getting popularity for water harvesting now a days. The collected water can be used for irrigation purpose.
b) Inter row water harvesting: It provides ridge and furrow system. It is done in case of winter and spring crops. Crops are grown in the furrows in winter and spring and ridges in rainy season.
c) Broad raised bed and furrow: On the bed mixed cropping lime maize + arhar or sorghum + arhar can be grown. In the furrows rain water is collected which is utilized by the crops. If there is excess water from furrows could be led to the tanks.
d) Inter plot water harvesting: Rain water falling in the micro-catchments is harvested in to the cultivated strips. Micro catchment is sloping towards cultivated strips. Example: 40 cm rain becomes 70 cm rain to cropped area (addition of 30 cm). If the flat is there, then earthwork is needed and if undulated land and then try to adjust the slope lime this. This can be done in light soil because of high infiltration.
2. Efficient use of conserved water through agronomic management
i) Selection of crops
For dry areas short duration, quick growing, deep rooted, drought tolerant, photo-insensitive, thermo-insensitive, high photosynthetic efficiency, high harvest index, less water requiring crop should be selected. Example: sorghum, bajara, cotton, groundnut, cluster bean, gram, barley castor, saff-flower, mustard, linseed etc.
ii) Selection of cropping season
Crop should be grown in the season when most favorable balance between evapo-transpiration (ET) demand and soil moisture supply presents. Generally, only one crop is grown in a year in dry areas. Generally, crop is grown in rainy season and land is kept fallow during winter where rainfall distribution in rainy season is uncertain land is fallow during rainy season and crop is grown in winter season. If the rainfall is relatively high in rainy season and winter rain is also received and proper soil moisture conservation practices is done, two short duration crops can also be grown within a year. If heavy textured soil, there may be greater storage of soil moisture for winter planting. If soil profile store 15 cm available soil moisture wheat crop can be grown.
iii) Intercropping
Intercropping should be widely adopted. It gives better utilization of moisture and fertility apart from insurance. Example: Bajara + cluster bean, Bajara + Mung, castor + mung, Castor + cowpea, cotton + groundnut. Gram + linseed etc.
iv) Land preparation
Two or three harrowing is done followed by planking during winter season. During rainy season after onset of rain, one deep ploughing is done to increase the infiltration. Two harrowing is done before sowing. Immediately after ploughing planking is done in dry areas.
vi) Sowing time
Decision of sowing time is difficult in dry farming. Rainy season crops are sown after the onset of rain. Winter planting is dependent on rainy season residual moisture. So it should be done as early as possible. If upper layer of soil is lack moisture, land preparation should be done after deep ploughing. So that lower moisture will come up. If deep ploughing is done, depth of sowing is very important. Upper layer of soil becomes lack of moisture, so seed should be placed deeper to the moist zone. But if moist zone is very deep, emergence of seedling is difficult. So make deep furrow and put the seed and covers by soil quantity as in normal planting or only by 2-3 cm soil. Planking is very desirable to come in the contact of seed with soil.
vii) Row direction
Crop row should be sown north-south direction. It is assumed that the sun light and moisture are fully utilized in north-south direction than east-west row direction. Crop sown in north-south direction have been given more yield than sown in east-west direction in various experiments.
viii) Fertilizer dose
It is reduced from 25-50% than applied in irrigated areas. Fertilizer should be placed in moist zone by ferti-seed drill. If it is not available, fertilizer should be applied behind the plough in the furrow during the last ploughing. Two third (2/3rd) to three fourth (3/4rth) nitrogen is applied at sowing and remaining N (as 3% urea solution) after 30-40 days of sowing as foliar spray has been found better to get high fertilizer use efficiency.
ix) Intercultural operation and weed control Intercultural operation should be done properly otherwise weeds will take moisture loss from the field.
