Ramanjaneyulu and Rajitha
India is a country with a wide diversity in ecological and social situations. Rice being the staple food for more than 65% people, is grown in all possible locations and conditions. This led to the development of rich diversity not only in the varieties but also the way rice is cultivated in different situations. While dry paddy is cultivated in Jharkand, Orissa, Uttaranchal, in West Bengal one can find rice grown in stagnating waters and growing more than 2 m tall. Similarly, Terrace cultivation is practiced in hill tracts of Uttaranchal and Eastern Ghats. Rice is grown in plains with standing water in delta regions of Andhra Pradesh and Tamil Nadu. The green revolution has changed the situation. This major technological change mainly initiated and steered by International Rice Research Institute, Philippines, Indian Council of Agriculture Research and various State Agricultural Universities has introduced improved rice cultivation as using new improved rice varieties mainly drawing genes from IR varieties, grown in ponding conditions, using tractors and chemicals in cultivation.
The productivity oriented extension systems have encouraged excessive monoculture of the crop, varieties and growing practices. India which once had 30,000 varieties of rice; today gets 75% of its rice production from just only 10 varieties (Return to Good Earth, 1990). With construction of dams and after the Green Revolution, rice became predominantly a canal-irrigated crop. Traditional tank systems were totally neglected. The assured procurement with minimum support price made rice cultivation an attractive proposition for all the farmers. Gradually even rainfed areas started cultivating rice under tube well irrigation. This shift has created the most serious economic and ecological damage. The ground waters have exhausted and the governments were forced to discourage rice cultivation under tube wells.
It was in this context, an innovative system of growing rice with less water named ‘System of Rice Intensification’ was initiated in the state of Andhra Pradesh drawing lessons from the experiences of the farmers in Sri Lanka, Madagascar, and in Indian states like Tamil Nadu and Karnataka. In the state, the progressive farmers, NGOs in the state, Acharya NG Ranga Agricultural University and State Department of Agriculture have taken active lead in promoting this model of rice cultivation.
The system of rice intensification (SRI) developed in Madagascar, is showing that by changing the management of rice plants, soil, water and nutrients, it can increase the yields of irrigated rice by 25–50% or more while reducing water requirements by an equivalent percent. This gives farmers incentive to reduce their irrigation water use when growing rice, especially since SRI methods can also reduce farmers’ costs of production which increases their net income per hectare.
Water plays a prominent role in rice production. While many other cropping systems use water mainly for productive purpose (transpiration), the rice cropping system uses water in a wide variety of ways, both beneficial and non-beneficial. One of the major uses being the weed control.
Water requirements of Irrigated Rice
| Purpose | Consumptive use (mm/day) | Remarks | |
| Low | High | ||
| Land preparation | 150 | 250 | Refilling soil moisture, ploughing and puddling |
| Evapotranspiration | 500 | 1200 | Depends on outside temperature |
| Seepage and percolation | 200 | 700 | Maintaining water ponding |
| Mid-season drainage | 50 | 100 | Refilling water basin after drainage |
| Total | 900 | 2250 | |
The field-level control of water for submerged rice growth has led, over the centuries, to the development of specific water management and cultivation practices that produce specific beneficial outcomes. The permanent presence of water on rice fields also generates water percolation and groundwater recharge, which are often beneficial for other water uses. One major advantage of water ponding in rice cultivation is that it prevents weed development, thereby avoiding the use of herbicides or reducing the amount of labour required. The terrace system in mountainous areas is a typical product of the ponding technique and allows cultivation even on steep slopes. This technique is instrumental in preventing soil erosion and landslides. Another advantage of the ponding technique is its capacity for flood control: field bunds have a significant water storage capacity, which reduces peak flows under heavy rains.
There are also arguments that the growing rice under submerged conditions also helps in sustaining soil fertility due to some of the chemical processes in submerged situations.
On the other hand, an acre of rice production in ponding conditions requires about 6 million liters of water which translate to 5000 liters of water for each kilogram of rice production. This shows the burden on the scarce natural resources. Growing rice in ponding conditions also lead to problems like salinity, methane emission etc.
Submerged cultivation also creates hypoxic conditions which leads to (a) the degeneration of plant roots and reduce plant ‘source’ capacity, and (b) shifts in the soil biota, biasing the composition of soil populations toward anaerobic organisms (e.g., practically eliminating fungi, which include the mycorrhizal associations that are so essential for the health and nutrition of most plants). Even on the soil chemistry side, it ignores the fact that under flooded conditions, most of the N available is in NH4 form, rather than NO3 form. Yet IRRI research has shown that rice plants receiving the same amount of N in mixed (50-50) forms rather than all NH4 form will have about 40-70% more yield. This also ignores processes like silicon uptake, which is reduced under hypoxic conditions (more under aerobic conditions), which could explain at least in part why SRI plants are more resistant to lodging and wind and rain damage and also more resistant to insect damage (Norman Uphoff, 2007).
Community Management: Rice being the only cereal that can stand water submergence has the long and diversified linkages with water. This relationship made rice cultivation a collective enterprise, historically. The investment and shaping of the landscape that are needed for the ponding system (flat lands with bunds or terraces) or maintaining a tank or canal required collective organization within the community. This water management also relies on collective interest: crop and water calendars must be organized for large blocks of fields in order to manage water efficiently and organize such work as land preparation, transplantation and drying for harvesting.
Today, the greater challenge is in controlling the irrigation schedules. Given the ‘anarchy’ in the water distribution in the canal irrigated areas (in dams or tanks), practicing SRI is becoming a nightmare for the farmers. The existing systems are built for flood irrigation rather than controlled irrigation. Controlled irrigation should be tried in canal and tank systems at least on an experimental basis to generate experiences in this regard. Unless irrigation systems are controlled, they can not be managed; it makes any attempt at water saving improbable. The command areas also lack proper drainage systems which are essential for better irrigation management. This would help only redesigning the existing irrigation channels with more controlled water management system under canal irrigated areas (in dams or tanks). The management of these canals is also centralized. The farmers cannot plan or manage their cultivation practices. Therefore, there is an urgent need for also decentralizing the management and reviving the community management systems which existed earlier with tanks.
Even in areas under ground water cultivation, the irregular power supplies is forcing the people to go for flooding irrigation so that water can be retained till the next power supply. The power supply needs to be regularized and planned with farming community at least at feeder channel level (Ramanjaneyulu et.al 2007).
The System of Rice Intensification is not just another set of package of practices but a whole paradigm shift in the way rice cultivation is understood and practiced. While the technology was adopted as a way out for the irrigation water crisis, the fundamental contradictions between ponding rice cultivation and SRI remain to be continued. SRI was promoted through demonstrations and subsidy inputs like free electricity and markers and weeders along with the ponding system by the university and extension system. This system which is based on sound ecological and agronomic principles is claimed to not only reduce water utilization by about 40% but the seed quantity required to 2 kg/acre and increases the yields by at least 10%. SRI for the first time after green revolution has brought in several innovations from farmers into mainstream agriculture. SRI also clearly demonstrates the biological potential of soil to support the plant given suitable conditions. The initial experiences show SRI is best suited for the organic production systems.
SRI is yet another case of technology developing from the diverse experiences of the farming community and where practice is preceding theory and formal research. The experiences show the possibilities of SRI in wide situations, provided the support systems are redesigned. The agencies should make a beginning in this direction. Moving to water saving practices like SRI is not an option but a necessity to sustain rice production.
G.V. Ramanjaneyulu, Director;
Rajitha, Consultant
Centre for Sustainable Agriculture, 12-13-445, Street No. 1, Tarnaka, Secunderabad – 500 017, Andhra Pradesh, India
References
Kar S, Varade SB, Subramanyam TK, Ghildyal BP (1974) Nature and growth pattern of rice root system under submerged and unsaturated conditions. Il Riso 23:173–179
Norman Uphoff 2007 personal communication
Ramanjaneyulu GV, Rajitha and Ravindra A (2007) Taking Roots: Experiences of System of Rice Intensification in AP, published by Centre for Sustainable Agriculture and WASSAN
Randriamiharisoa R, Uphoff N (2002) Factorial trials evaluating the separate and combined effects of SRI practices. In: Uphoff N et al (eds) Assessment of the system of rice intensification: proceedings of an international conference, Sanya, China, April 1–4, 2000. Cornell International Institute for Food, Agriculture and Development, Ithaca, pp 40–46
Sahrawat K L (2005) Fertility and organic matter in submerged rice soils, Current Science, Vol. 88, no. 5, 10 March 2005
Uphoff (2003) Higher yields with fewer external inputs? The system of rice intensification and potential contributions to agricultural sustainability. Int J Agric Sustain 1:38–50
