The potential of irrigated agriculture has been exploited to a considerable extent; hence there will be increased dependence on rain-fed agriculture in future. There are three components of successful rain-fed agriculture: retaining precipitation/rainfall in soil, reducing evaporation losses of water, and sowing of crops that have drought tolerance characteristics and fit the rainfall pattern.
However, the main problem the dry-land producer faces is integrating these three components into a workable system. Crop management involves intelligent integration of variables such as soil, crop, rainfall, weather and management practices. There is a complex inter-action among crop production variables. And appropriate management of these variables may sustain crop yield under rain-fed conditions. The crop management system should be effective and efficient with sound scientific basis on one hand and practical and economical to the farming community on the other.
The aim of crop management in rain-fed area is greater crop production with less available water. The rain-fed agriculture is an enterprise of high risks and crop management should be such that it reduces the problem of risk to the absolute minimum. The first and foremost step in crop management in the rain-fed areas is putting the SECURE (Soil Erosion Control Under Risky Environment) into practice, as soil degradation implies that soil is no longer useful as growing medium and must be taken out of production. In rain-fed areas farmers’ decision about choice of crop, what and when to grow or keep the soil fallow are complex phenomena with no easy answers.
In Pakistan 60-70 per cent rainfall occur in June, July and August. The areas receiving rainfall less than 500 mm are not suited to continuous cropping, as there is simply not enough water to have intensive year-round production, nor there is guaranteed water supply that can minimise the risk of crop failure.
Mono-cropping is practiced in arid and semiarid areas. There are two options for mono-cropping, one is sowing the crop right during rainy season and second is preserving the moisture during rainy reason by tillage/chisel. Ploughing up to a depth of 20 cm that will increase water infiltration into the soil and more water will be available to incoming winter crop, mostly the wheat crop, wheat as mono crop is quite common in rain-fed regions and is sown on 19 per cent area with 10 per cent production. This indicate that wheat yield in rain-fed areas is about half to that of irrigated areas.
Is this low wheat yield economical, certainly not, the cultivation of groundnut, sorghum and pulses like, moong bean during rainy summer season may be more economical and at the same time provide cover to the soil and protect soil from erosion from torrential summer rains. The shift in cropping system from wheat to summer crops is not an easy task, as farmer’s conviction that he will raise his food from his own land is difficult to change.
Wheat is sown in winter and soil is kept fallow, leaving land un-cropped, in summer, hence dofasla, dosala (two crops in two years), concept is prevalent in Potohar region. The main objective of fallow is to conserve moisture in soil for future crop. The value and extent of moisture conservation depends on soil factors, texture and soil depth, management factors, type of fallow, time of tillage and rainfall itself Soil depth is critical factors for water storage. In long hot summer any plant available water in top 30-45 cm is usually lost by evaporation, only water stored below this depth is useful to next crop.
Shallow soil, therefore, have little value for water storage. If rainfall is less than 200 mm, then little water is stored in soil. During fallow period, the soil is kept weed free by chemicals or by cultivation, bare fallow or it is left to grow weeds, weedy fallow, to provide grazing for animals.
The mono-cropping system for rain-fed areas may be wheat-fallow, sorghum-fallow, wheat-wheat and sorghum-sorghum. Continuous sorghum may produce four times as much grain as wheat fallow cropping system. This is because sorghum has in built characteristics to use water efficiently and tolerate drought conditions. Barley, because of low water requirements, may be another option to replace wheat in low rainfall areas, 52 per cent production of barley is obtained from rain-fed areas.
About 93 per cent groundnut area is under rain-fed conditions and 9/10 production is obtained from Potohar region. The main share of edible oil in India is from groundnut. However, in Pakistan it is mostly used for table purposes and to some extent in confectionary. Calcium is known to alleviate water stress in groundnut, stress leaves with high calcium may have high water content. Gypsum applied at flower stage to genotypes subjected to drought increase pod initiation and yield of peanut crop. The summer sowing of moong bean or other leguminous crops will not only improve economic conditions of farmer but also enhance fertility of the soil.
The advantages of multiple cropping systems in comparison to mono-cropping system are, insurance against crop failure, more total yield per unit area and inclusion of legume will sustain soil fertility. The multiple cropping systems may result in better crop production, optimum use of available resources and more economic return to the farmer compared to sole crop. Millet/legume cropping system can be intensified and also made more productive by appropriate choice of cultivars, manipulating agronomic factors such as row management and densities of component crops.
However, this intercropping is not capable of stabilising yield in drought years. The combination of crops and perennial plant species like grasses and ber (Ziziphus spp) can give sustained production even in drought years.
Spatial intercropping system in which maturity time of two crops is identical, but the two crops differ invariably in crop canopy or root systems deserve focus in rain-fed areas. Millet/groundnut is typical example of spatial intercropping system and may be adopted keeping in view the soil and environmental conditions. In sub -humid and humid region the sequential cropping system may be adopted. The sequential cropping system is sowing two consecutive crops, second one sown after the harvest of first crop.
During the summer rain, maize and sorghum are cultivated while wheat, chickpeas are sown during winter months. This is most productive system, as cropping intensity is 100 per cent and two crops are not subjected to competition with each other.
Wheat here is usually sown as mono-crop and area under rain-fed wheat is 19 per cent of total wheat area. There should be enough moisture for germination of wheat in soil at sowing time, otherwise optimum growth and ultimately economical crop yield may not be achieved. Other winter crop in rain-fed areas is rapeseed and mustard and cover 26 per cent of rapeseed area. Gram is other important winter crop of rain-fed area that contributes to 89 per cent of total production. Gram is the main crop of Thar desert and is also sown in other arid and semi-arid areas like Dera Ismail Khan and Dera Ghazi Khan Districts. Sorghum in summer and barley in winter have in built characteristics to tolerate drought conditions.
In rain-fed conditions, millet/sorghum is sown over 67 per cent area and barley is sown on 53 per cent of total barley area.. Millet is common crop in arid and semi-arid region including Tharparkar area where the rainfall is 200-300 mm Maize is another import and crop of rain-fed areas, but its optimum yield can be obtained in sub-humid and humid regions. This is main crop in Murree and Swat rain-fed zone, where annual rainfall range between 500-1400 mm. The area under maize in this zone is more than area under wheat crop. In areas where rainfall is low, moisture shortage makes the maize a marginal crop and success of the crop is not guaranteed. Guar seed is sown totally under rain-fed conditions and can even flourish in sandy semiarid conditions of Thar desert.
The rain-fed area contributes to 89 per cent of total pulses production, moong and mash bean, cowpeas in summer and lentil in winter are sown under rain-fed conditions. Moth bean is also sown in dry areas and is mostly used as fodder rather than a pulse. Groundnut is another major crop of rain-fed region with an area of 93 per cent of total area under groundnut cultivation.. Groundnut is most suited to silty and loan soils. The leguminous crops sown in rain-fed area add to the fertility of soil and cause sustainability of rain-fed agriculture.
Whether to adopt mono cropping or sequential cropping, the rule of thumb is that areas with rainfall less than 500 mm are suited to mono-cropping.
Efforts are at hand to evolve drought resistance varieties of crop sown in barani areas. The area under rapeseed and mustard is to be shifted to canola cultivation that is must to cater the edible oil requirements of ever increasing population.. Soybean may be another option to meet the edible oil needs of the country and may be propagated in congenial environments suited for its cultivation. Taramira (Eruca sativa) is another drought tolerant crop that is mostly cultivated in sandy and shallow soils. The farmers level shallow soil that deteriorate the soil conditions, so leveling of land should not be practiced in rain-fed or riverain area indiscriminately. Safflower, linseed, castor and sesame are other options all crops that can be cultivated under un-irrigated conditions.
Castor is sown in southern Punjab and Sindh, In addition to crop plants, shrubs and trees specifically fruit trees are to be propagated in rain-fed area. Salicornia is edible oil plant and biomass is used as feed for animals. It withstands stress dry environments and is planted in Balochistan, but the area under this plant needs to be increased.
On the other extreme in northern areas there is prospect for increase in area under seabuckthorn. This plant fixes nitrogen in addition to a source of valuable products. This plant is also useful in management of land slide. This has been postulated that bioengineering techniques in soil conservation are more sustainable than civil engineering techniques. Vetiver grass is extremely drought tolerant and it is commonly cultivated as hedge plant. Vetiver is soil-binding grass and is involved in soil and moisture conservation.
There is great potential of growing high value fruit plants under rain-fed conditions. The possibility of growing olive in rain-fed areas of Punjab especially Potohar region, NWFP and Balochistan may be ascertained to increase vegetable oil production. In Gilgit and Baltistan areas there is great prospectus of increase in production of apples, pear, peach and plum, grapes, pomegranates, almond and fig. The climates and soil conditions of Potohar region call for propagation of apple, pear, peach and plum.
Apple is an important fruit of Murree, while apple and citrus are common in Swat area. There is great potential for fruit production in Quetta, Loralai, Zhob, Chaman and other parts of Balochistan province. The apples grapes, cherries and dates are common fruits in this province. Dates production may also be increased in Dera Ismail Khan, Dera Ghazi Khan and Muzaffargarh districts. The potential of coastal arid area for propagation of tropical fruits like oil palm, dates, coconut, papaya, banana and chiku, needs to be explored.
Banana production in Sindh can be increased substantially by adoption of improved production technology. Kelp, a seashore weed can be used as fertiliser material as it contains 1.6 to 3.3 per cent nitrogen, 1-2 per cent P2o5 and 15-20 per cent K2O. In dry areas ber (Ziziphus spp) propagation is other valid possibility.
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