ABSTRACT
Green Revolution led to an unprecedented increase in world food production but with a significant carbon footprint raising concerns about its sustainability. With the rising global population and the need to produce more food, the farming systems will have to be sustainable. To identify farming practices that increase yield with minimum environmental cost, it is imperative to quantify the environment footprint of different technologies. The present study quantified the impact of Green Revolution technologies on the carbon footprint of intensive crop production systems, mainly rice-wheat in an agriculturally important region of Indo-Gangetic Plains. The results revealed the overriding importance of groundwater irrigation and fertilizer use in determining the carbon footprint of crop production, and underpin the opportunities for their mitigation. Intensification of agriculture resulted in ~2.5 fold increase in food grain production and 3-fold increase in emission of greenhouse gases (GHGs) during 1980 to 2015. Carbon sustainability of food grain production declined with time indicating that energy use efficiency is decreasing; the greatest decline being in rice followed by wheat and negligible in maize. Options for mitigating environment footprint of food grain production included partially replacing area under rice with other less water requiring crops, improving irrigation water productivity and pumping efficiency, and increasing fertilizer use efficiency. Maize with low global warming potential and high C sustainability appeared a viable option for diversification. The implementation of these mitigation measures can reduce environment footprint by 46%. Preventing crop residue burning will not only offset the associated GHG emissions (6266â¯Ggâ¯yr-1) but can also improve soil health if returned to the soil. Intensification of agriculture has co-benefit of C sequestration in soil, which besides offsetting emissions by ~10% is an important determinant of soil quality and sustainability.
ABSTRACT
A field experiment was conducted for two years to find out best water management practice to mitigate methane emission from the rice-fields. Continuously flooded conditions yielded two major flushes of methane emission and on an average resulted in relatively higher rate of methane emission (2.20 and 1.30 mg m(-2) hr(-1), respectively in 2005 and 2006) during the kharif season. The methane flux was reduced to half (1.02 and 0.47 mg m(-2) hr(-1), respectively in 2005 and 2006) when rice fields were irrigated 2-3 days after infiltration of flood water into the soil. Irrigating the field at 0.15 bar matric potential reduced seasonal methane flux by 60% (0.99 and 0.41 mg m(-2) hr(-1), respectively in 2005 and 2006) as compared to completely flooded conditions, without any decline in grain yield (60 q ha(-1)).
Subject(s)
Agricultural Irrigation , Crops, Agricultural , Methane/analysis , Oryza , SeasonsABSTRACT
A field experiment was conducted for two years on a sandy loam (Typic Ustochrept) soil of Punjab to study the effect of organic materials and rice cultivars on methane emission from rice fields. The methane flux varied between 0.04 and 0.93 mg m(-2) hr(-1) in bare soil and transplanting of rice crop doubled the methane flux (0.07 to 2.06 mg m(-2) hr(-1)). Among rice cultivars, significantly (p < 0.05) higher amount of methane was emitted from Pusa 44 compared to PR 118 and PR 111. Application of organic materials enhanced methane emission from rice fields and resulted in increased soil organic carbon content. The greatest seasonal methane flux was observed in wheat straw amended plots (229.6 kg ha(-1)) followed by farmyard manure (111.6 kg ha(-1)), green manure (85.4 kg ha(-1)) and the least from rice straw compost amended plots (36.9 kg ha(-1)) as compared to control (21.5 kg ha(-1)). The differential effect of organic materials in enhancing methane flux was related to total carbon or C:N ratio of the material. The results showed that incorporation of humified organic matter such as rice straw compost could minimize methane emission from rice fields with co-benefits of increased soil fertility and crop productivity.
