Potential of conservation agriculture modules for energy conservation and sustainability of rice-based production systems of Indo-Gangetic Plain region

Abstract

Rice-based cropping systems are the most energy-intensive production systems in South Asia. Sustainability of the rice-based cropping systems is nowadays questioned with declining natural resource base, soil degradation, environmental pollution, and declining factor productivity. As a consequence, the search for energy and resource conservation agro-techniques is increasing for sustainable and cleaner production. Conservation agriculture (CA) practices have been recommended for resource conservation, soil health restoration and sustaining crop productivity. The present study aimed to assess the different CA modules in rice-based cropping systems for energy conservation, energy productivity, and to define energy-economic relations. A field experiment consisted of four different tillage-based crop establishment practices (puddled-transplanted rice followed by (fb) conventional-till maize/wheat (CTTPR-CT), non-puddled transplanted rice fb zero-till maize/wheat (NPTPR-ZT), zero-till transplanted rice fb zero-till maize/wheat (ZTTPR-ZT), zero-till direct-seeded rice fb zero-till maize/wheat (ZTDSR-ZT)), with two residue management treatments (residue removal, residue retention) in rice-wheat and rice-maize rotations were evaluated for energy budgeting and energy-economic relations. Conservation-tillage treatments (NPTPR-ZT, ZTTPR-ZT, and ZTDSR-ZT) reduced the energy requirements over conventional tillage treatments, with the greater reduction in ZTTPR-ZT and ZTDSR-ZT treatments. Savings of energy in conservation-tillage treatments were attributed to reduced energy use in land preparation (69-100%) and irrigation (23-27%), which consumed a large amount of fuel energy. Conservation-tillage treatments increased grain and straw/stover yields of crops, eventually increased the output energy (6-16%), net energy (14-26%), energy ratio (25-33%), and energy productivity (23-34%) as compared with CTTPR-CT. For these energy parameters, the treatment order was ZTDSR-ZT ≥ ZTTPR-ZT > NPTPR-ZT > CTTPR-CT (p < 0.05). Crop residue retention reduced net energy, energy ratio, and energy productivity when compared with residue removal. Our results of energy-economic relations favored the "conservative hypothesis," which envisages that energy and monetary investments are not essentially the determinants of crop productivity. Thus, zero tillage-based crop establishments (ZTTPR-ZT, ZTDSR-ZT) in rice-based production systems could be the sustainable alternative to conventional tillage-based agriculture (CTTPR-CT) as they conserved non-renewable energy sources, reduced water requirement, and increased crop productivity.

Keywords: Conservation agriculture; Crop establishment; Crop residue retention; Direct seeded rice; Energy budgeting; Rice/maize/wheat system.

Fig. 1

Monthly rainfall (mm) received during the experimental year 2013–2014 and 2014–2015

Fig. 2

Source-wise input energy (MJ ha⁻¹) components in rainy season rice crop (a), winter season wheat/maize crop (b), and rice–maize/wheat system (c) under different treatments. The values are the mean of 2 years (2013–2014 and 2014–2015)

Fig. 3

Scatter plot of treatments on PCA coordinates and their association with energy parameters (a). Loading value (correlation) of different variables for PC1 and PC2 (b). Heat map and cluster presentation of treatments based on the energy parameters (c). LP energy input for land preparation, RES crop residue energy input, S/T energy input for sowing/transplanting, FERT energy input for fertilizers application, IRR energy input for irrigation management, INT energy input for intercultural operation, HERB energy input for herbicide and its application, PP energy input for plant protection, HAR energy input for harvesting, IE input energy, OE output energy, RGEY system rice equivalent yield, ER energy ratio, EP energy productivity, NE net energy, RW rice–wheat, RM rice–maize, T1 CTTPR-CT, T2 NPTPR-ZT, T3 ZTTPR-ZT, T4 ZTDSR-ZT, R− residue removal, R+ residue retention (for heat map, R stands for residue retention)