Environmental consequences of agricultural intensification and their impact on sustainability: insights from a farm-level evaluation of irrigated rice systems in India

The paper aimed at evaluating farm-level experiences of intensive rice systems to address a few key environmental issues such as biodiversity, degradation of soil and water qualities, emergence of pest incidence, etc. based on farm-level data, obtained from 40 intensively rice-growing villages during 1999 crop year; 10 from each state of Andhra Pradesh, and Karnataka (rice-rice system), Punjab and Western Uttar Pradesh (rice-wheat system) representing all major agroecological regions of each state. Results indicate that about 90% of total rice area on sample farms were covered with 45 new cultivars, mostly developed and released in the 1980s. Genealogy of these cultivars shows that many more rice cultivars were present in the form of one or more genes, incorporated in each of these few popular varieties in the process of varietal improvement program over the period. Thus, it is not true that all traditional rice cultivars disappeared due to introduction of HYVs [high yielding varieties] in the irrigated environments. Average farm-level yield was 6.4 t/ha, nearly the same level as scientists reported from research farms. It was found that under existing resource-base with current price structure, rice cultivation is more remunerative. About 50% of the farmers reported increase in rice yield by 0.8 t/ha while 30% expressed that yields declined by 1.2 t/ha especially in wet season over the past 10 years. On the other hand, use of chemical fertilizer has increased rapidly over the period; applied about 40-50 % higher than the recommended levels, implying a significant fall in factor productivity under irrigated environments. Similarly, pesticide applications were increased from 2-3 in 1990 to 4-5 by 1999 while use of labor saving method increased rapidly to cope up peak-season labor scarcity for rice. Yield loss/year over the past one decade due to all biotic and abiotic stresses under intensive rice system was 536 kg/ha, i.e. 8.4% of average yield; 34% and 26% due to insect pests and diseases respectively whereas soil and water-related problems caused rest of 40% of yield loss