Comparative assessment of energy flow, carbon auditing and eco-efficiency of diverse tillage systems for cleaner and sustainable crop production in eastern India

Abstract

Identification of the appropriate tillage production system having lower energy use and carbon-emission, and better crop productivity is becoming increasingly important to maintain the environmental sustainability. In the present study, a comprehensive system analysis was performed for four consecutive years (2016–2019) in three major agroecosystems of eastern India: eastern Indo-Gangetic plain, coastal agroecosystem and hill & plateau region. Six rice-based production systems with different levels of farm mechanization viz., a) fully mechanized tillage, b) partly mechanized tillage and c) traditional tillage were considered in the analysis. The main aim was to assess the energy flow and carbon-balance of diverse tillage production systems. Among the different sources of total input energy, chemical fertilizer accounted for the highest energy used in partly mechanized tillage (44%) and mechanized tillage (38%) followed by diesel, irrigation water, plant protection chemical, seed and electricity. Seed, human, animal energy and farmyard manure accounted for 21, 20, 16 and 16%, respectively, of the total energy input in traditional tillage. Maximum energy input (52161 MJ ha−1) was noted in mechanized tillage and minimum with traditional tillage (16879 MJ ha−1). Cropping systems followed in eastern Indo-Gangetic plain were more energy-intensive (50908 MJ ha−1) compared to coastal-ecosystem (27459 MJ ha−1). On an average, the total energy output in mechanized tillage (395245 MJ ha−1) were 0.3 and 2.4 times higher over partly mechanized and traditional tillage, respectively. Overall, the present results indicated that partly mechanized tillage and coastal agroecosystem were the most energy-efficient with an energy ratio of 8.88 and 9.81, respectively. Mechanized tillage was 0.24 and 1.66 times more carbon-intensive in comparison to partly mechanized and traditional tillage system. Mechanized tillage had higher carbon efficiency (3.75), carbon-sustainability index (2.75), carbon-footprint in spatial scales (4342 kg CO2eq. ha−1), but had 34% less carbon-footprint in yield scales compared to traditional tillage. Mechanized tillage showed 22 and 73% higher system productivity compared to partly mechanized and traditional tillage, respectively. Partly mechanized tillage had a 23% lower cultivation cost than mechanized tillage. Thus, the present study suggests that partly mechanize tillage was the most appropriate energy and carbon-efficient production system in eastern India.