Rainfed agriculture is a term used to define agricultural practices that primarily rely on rainfall as the source of water. On closer inspection, it is observed that the majority of the less endowed in developing countries depend on this method for the supply of water. Specifically, more than 95% of farms in sub-Saharan Africa, 90% in Latin America, 75% in the Near East and North Africa; 65% in East Asia, and 60% in South Asia rely on this process as the primary source of water. The huge difference in the topography, relief, soils, and anthropogenic changes makes rainfed agriculture a very unreliable source of water. Due to this unreliability, rainfed agriculture remains a risky, low-input practice. Thus, low investments lead to old agricultural practices, loss of water due to runoff, and water loss caused by fragmentation (Rashid, Hussain, and Khan). This brings a huge water issue to the farmers who may not have any other means of water supply or the existing means may be unreliable. This leads to low yields every time water is insufficient. In addition, poor management of the soils can lead to low production even with an adequate supply of water, since the water may be unable to penetrate into the soil and have high rates of evaporation.
Ways to Manage Water Resources
To minimize the risk of rainfed agriculture, there are ways in which one can manage the water to ensure continuous supply throughout the year. It can be argued that rainfall water management calls for a new era of management of water-focused on the water input and runoff (Molden). This method not only considers the amount of water available but on how efficiently it is used up on the farm. Effective rainwater harvesting, land consolidation, better soil and water conservation, use of the good quality seed, balanced nutrient management, and weed control are some of the ways that can bring about a solution to the issues in rainfed agriculture (Rashid, Hussain, and Khan).
In Situ and Catchment-Based Water Harvesting
The first development in rainfed agriculture is ensuring that water is conserved by the use of better water harvesting techniques in the field. The two most important techniques in this section are in situ and catchment-based water harvesting. In situ water harvesting ensures that as much water as possible is conserved in areas where it falls. For this system, land and soil treatments are involved to ensure water retention of the soils is improved. Catchment-based water harvesting now ensures that water that is in excess of the in situ system is conserved. For water catchment, methods used are contour furrows, terracing, and run-off recycling. Thus, the water level is held up enough for a sufficient amount of time. This method thus basically ensures efficient use of water by crops and is most common in moderate rainfall receiving areas of the world whose rain range between 240 to 400 mm annually. This leads to higher yields due to increased water capacity. For instance, each millimeter of saved water could increase the yield of wheat by an average of about 10 kg ha 1 (Baig, Zia, and Sombathova).
Importance of Water Conservation in Agriculture
Conservation agriculture is also a huge step in water management. This method includes and is not limited to minimum tillage, no-till, direct drill, mulch tillage, stubble mulch, trash farming, and strip tillage. All these methods help to reduce soil erosion. Deep tillage can also be useful in increasing the porosity of soil and breaking the compact cemented layer of soil and thus reducing the permeability of the soil. Thus these practices ensure that the soil is in a condition where it can hold water for a longer amount of time to ensure maximum absorption by the crops. For instance, the use of wheat straw in Pakistan as a mulch was proven to increase soil water retention capacity by 45 percent and pore volume by about 7.5 percent (G.Voss).
Benefits of Rainwater Harvesting
In modern agriculture, it is very common to harvest rainwater and store it in reservoirs, be it dams, dykes, or storage tanks. This usually saves on cost and ensures minimal water wastage. For instance, a dairy farm (which consumes lots of water), could ensure a constant water supply by this method. It could also save up on the bills the farm could have and thus the money could be invested in other ventures. Minidams and dug wells can also be used to harvest water. Water loss due to absorption by the ground or running off counts up to trillions of liters. If dams or dug wells were to be set up, then 50 percent of the water could be saved up by this process. For example, by proper rainfed water management by this process, a dairy farmer in Britain can save up 1 to 2 pounds per cubic meter used (James).
However, developments in rainfed agriculture have been proven to have many setbacks despite their advantages. This is because these modern methods require skill and scientific precision in applying the principle for positive feedback. Improper tillage, for example, leads to soil erosion. Shallow tillage, a method that is seen as positive in its result can lead to the development of a hardpan under the plowed layer. This leads to minimum water absorption and adsorption into the soil and is seen to inhibit root growth in crops according to surveys carried out in America (Hamblin). In addition to this, in situ and end catchment methods may prove disastrous in the case that increasing water capacity in the soil might bring about the habitation of pests in the soil. This may lead to even more losses than initially experienced when using the traditional system. Dams and dug well also inhibit silt deposition in lands of lower altitudes which leads to poor productivity of off-river lands previously highly productive.
In conclusion, rainfall is the most common source of water for agricultural purposes. Thus, its availability directly relates to food production. However, rainfall is unreliable since it depends on a lot of independent uncontrollable factors. Therefore, it is important to set up measures to ensure maximum utilization of rainwater. This is achievable by deviating from the traditional generalistic methods of agriculture to the modern scientific methods thus enabling management of rainwater which leads to improved agricultural capacity. It is however important to exercise caution in the application of these scientific methods as they may lead to disastrous results if done in the wrong manner.
Baig, M.B., et al. Rehabilitation of problem soils through environmental-friendly technologies: Role of Sesbania (Sesbania aculeata) and Farmyard manure. Czech University of Agriculture, Prague. 2005.
G.Voss. Effect of organic amendments on soil properties and rice production. International Rice Research Institute, Terminal Report to IRRI. Los Banos, 1988.
Hamblin, A.P. "The effect of tillage on soil surface properties and the water balance of Xeralific Alfisol." (1984).
James. OASIS Rainwater Harvesting. n.d. 4 March 2016.
Molden. Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture. 2007.
Rashid, A., F. Hussain, and M.I. Khan. Challenges and Strategies for Dryland Agriculture. Crop Science Society of America and American Society of Agronomy, 2004.
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