Z James Kikon
SMS (Soil Sc.). KVK Dimapur
Drought is a condition under which crops fail to grow and mature because of moisture deficiency. It is the result of imbalance between soil moisture and evapo-transpiration need of crops resulting in damage of standing crops and yield loss. Occurrence of drought is mainly due to late onset of monsoon, prolonged dry spells during the crop period, inadequate rainfall and erratic distribution of rainfall, early cessation of monsoon and improper soil and crop management practices.
In India, as per Irrigation Commission of Government of India as well as India Meteorological Department, drought years have been defined as those years for which annual rainfall is less than or equal to 75% of the normal. Based on long period data, if such drought occurs in certain areas on more than 20% of year, that are is designated as a drought prone area, provided that area does not have provisions of adequate irrigation facilities.
Drought in general can be classified into permanent, seasonal, contingent and invisible droughts. Permanent drought that is characteristic of the driest climate where sparse vegetation growing is adapted to drought and agriculture is possible only by irrigation during the entire crop seasons. Seasonal drought is found in climate regions that have well defined rainy and dry seasons. Natural vegetation is made up of plants that produce seeds during the rainy season and die, and of those plants that remain alive throughout the year but became dormant in dry season. Contingent drought is dependent on the irregularity of rainfall and so is not regular to occur in any definite season. Invisible drought is that drought that can occur even when there is frequent rainfall in an area. When rains do not supply enough water to counteract the water loss by evapotranspiration, a borderline water deficiency in soil occurs, resulting in less than optimum crop yields. This usually occurs in humid zone.
Effect of drought in crop production: Drought does not affect all aspects of plant growth and development equally. Some processes are highly susceptible while others are far less affected. Final yield of the crop is the integrated result of these effects of stress on water relations, photosynthesis respiration, nutrition, growth and development.
Water relations: Drought causes several changes in the plants. It alters the water status of plants through its influence on the physiological processes viz, absorption, translocation and transpiration. Increase in transpiration due to atmospheric dryness results in the loss of turgor, which leads to poor crop growth and development. Photosynthesis: Moisture stress reduces the rate of photosynthesis, chlorophyll content and leaf area. Increase in assimilate saturation in leaves results due to lack of translocation.
Respiration: Respiration increases during mild drought however; severe drought lowers the water content and respiration.
Anatomical changes: Periodical drought leads to anatomical changes which affect growth and development of crops through its influence on decrease in size of the cells and intercellular spaces, thicker cell wall due to greater development of mechanical tissue which increases in the number of stomata per unit leaf. Metabolic reactions: Deficit in water affects almost all metabolic reactions. Severe water deficits cause decrease in enzymatic activities.
Hormonal relationships: Activity of growth promoting hormones like cytokinin, gibberlic acid (GA) and indole acetic acid (IAA) decreases under drought conditions whereas, growth retarding hormones like abscissic acid (ABA) ethylene etc increases. This alteration of hormones in plants affects growth and development.
Nutrition: Drought affects the fixation, uptake and assimilation of nitrogen. Moisture stress may or may not reduce nutrient content but it reduces dry matter production considerably. As a result the uptake of nitrogen, phosphorus and potassium (NPK) are also reduced.
Growth and Development: Moisture stress decreases the growth of leaves, stems and fruits. It also affects germination, leaf area. Leaf expansion and root development however, maturity is delayed if drought occurs before flowering while it advances if drought occurs after flowering.
Reproduction and Grain growth: Drought at flowering and grain development determines the number of fruits and individual grain weight respectively. However, vegetative and grain filling stages are less sensitive to moisture stress. Yield: Yield depends on the influence of drought on growth, flowering, and fruit set etc. moisture stress at critical stages of crop reduces the yield drastically.
Drought management, and food and nutritional security
Drought occurrence is common in the rainfed areas where only Watershed Development Projects are taken up. Presently a special dispensation is not made to mitigate effects of drought. Earlier a drought used to lead to famine, causing deaths. Today we have moved to a situation where we are able to manage drought.
In nineteenth century Col. Baird Smith described Indian famines as famine of work and not of food. He pointed out that when there was no work, there was no money, and consequently adequate food was not available. This situation is as relevant even today as it was 150 years ago. Presently food for work and other employment- generation Programme have received greater attention in the management of drought, the latest being of NREGA.
However to tackle drought, a two- pronged strategy is needed, a short term as well as a long term. The issues needing attention are seed for ensuing season after drought, and food, fodder, nutritional and drinking as well as irrigation water security along with compensatory programme to ensure improved access to food grains, generation of employment and crop insurance. Diversification and tree- based farming also needs our attention. Some details are discussed here.
Seed
Short term: Work for the next year’s requirements, particularly of bold seeds (e.g. groundnut, soybean) under protective irrigation on the priority basis.
Long term: Develop seed banks to cover at least 30% in low- rainfall zones, 15% in medium- rainfall zones and 10% in high- rainfall zones. If the season is normal, these seeds may be sold as grains and the difference in costs is underwritten in budget. Encourage in-village seed production to make seed availability timely and so on assured quality basis. It would also be cheaper.
Food grains
Short term: Generate employment and create money in hands of the poor. Food for work (FFW) had been one of the venues. Now NREGA is put in place to ensure money in the hands of the needy poor. Long term: Capitalize on good rainfall years. Develop local grain storage at the habitat level. Aim at high productivity with a proper blend of soil and crop husbandry.
Fodder
Short term: Transport of fodder from available areas should be the first task. This should be followed by green-fodder production under protective irrigation. Increase use efficiency of fodder through chaff cutter. Long term: Improve silvi-pasture system. Allow grazing on charge. Develop fodder banks. Process alternative feeds and fodders. Develop silage system for daily cattle.
Nutrition
Short term: Care for children and pregnant and lactating women. Provide mineral mixture to livestock. Long term: Develop homestead farming to include leafy vegetables, other vegetables, fruits, small poultry unit (Giriraja, Vanaraja) and small dairy unit (improved breeds).
Drinking water
Short term: Reserve wells or bore- wells for drinking water. Consider the needs of livestock. Long term: Evolve exclusive water-bodies for the purpose.
Irrigation
Short term: Research and Development should encourage adoption of methods to enhance water-use efficiency, e.g. proper lining of channels, use of micro-sprinklers and drip systems. Provide irrigation to match critical phonological stages in crop growth.
Long term: Develop use of water from various water-bodies by mutual agreement. The cropping patterns should match available water in any given season, wherever feasible, recycling of waste-water must be encouraged.
Compensatory programme
Short term: Stress on rabi protection systems. Also work in favorable areas (receiving normally more rainfall and which are better endowed). Long term: Work on good-weather code. Develop local (in-village) storage of food grains.
Generate employment
Short term: NREGA, which is now under implementation in the entire district, need to be streamlined as social audit has shown inadequacies in quite a few instances. Avoid contractorship and machinery. Long term: Evolve shelf of projects to create permanent assets. Also as per NREGA schedule 1, the poor may be helped to generate assets for livelihood support on a sustainable basis.
Crop insurance
Short term: The proposal is to compensate on rainfall distribution with reference to its distribution and phenology of crops. This pilot project needs further coverage. Compensate tillers and not owners (if they are not the tiller). The NAIS, now under implementation, needs fine tuning with reference to coverage of different crops, yield indices, timely payment of compensation; the livestock insurance needs further expansion. Long term: Let insurance companies take over crop insurance scheme. Evolve achievable yield isoline to pay compensation.
Diversification
Short term: Diversify production systems. Long term: Encourage product processing and value addition. Maintain biodiversity (Locals are more tolerant to drought).
Tree-based farming system
Short term: Develop tree farming in homesteads to cover lean periods for earning money in crisis periods. Long term: Ensure biomass production through Multi Purpose Tree species in crop production systems. The tree should not only yield fodder, fuel, manure and fruits, but also be useful as botanicals in managing pests. Thus the four-bank concept of Swaminathan must be encouraged for community food, fodder and water security to humans and livestock. Then fodder, seed, water and grain banks should be included in the system.
