by Hari Sankar Nayak, Chiter Mal Parihar, Sreejith Aravindakshan, João Vasco Silva, Timothy J. Krupnik, et al.
In the Northwestern Indo-Gangetic Plain of India, long-standing policies of providing highly subsidized nitrogen fertilizer and electricity for irrigation to farmers have incentivized the excessive use of fertilizer and water for rice production. However, these additional inputs do not always result in a corresponding increase in yield. Such excessive resource use not only results in low resource use efficiency and a high carbon footprint but also creates multiple environmental sustainability issues.
Rice plays a critical role in maintaining food security in India, accounting for over a quarter of the country’s total calorie intake. The Green Revolution of the 1960s transformed India’s rice production landscape through the adoption of high-yielding varieties, greater input use, and the expansion of irrigation and mechanization.
However, rice cultivation is an energy-intensive process, requiring greater inputs compared to other cereal crops. This is due to the intensive puddling and tillage practices in rice paddies, as well as the higher use of agrochemicals. The energy inputs for rice production come from various sources, including diesel-powered tractors for preparatory tillage and puddling, diesel or electric pumps for irrigation, and the use of fertilizers.
On average, 6.4 MJ of energy is required to produce 1.0 kg of rice, with the majority of energy input attributed to irrigation and fertilizer use.
In the North-western Indo-Gangetic Plain (IGP) of India, long-standing policies of providing highly subsidized nitrogen fertilizer and electricity for irrigation to farmers have incentivized the excessive use of fertilizer and water for rice production. However, these additional inputs do not always result in a corresponding increase in yield. Such excessive resource use not only results in low resource use efficiency and a high carbon footprint but also creates multiple environmental sustainability issues.
In the past, increased rice production was achieved through energy-intensive methods, relying heavily on electricity and diesel consumption. The production, transportation, and application of inputs also require energy and carbon from non-renewable sources.
As India faces an energy crisis from non-renewable sectors, the need for sustainable energy use has become imperative to fulfill energy demands without rapidly depleting non-renewable resources.
Agriculture, as a sector, transforms energy inputs such as fertilizers, agrochemicals, machinery, diesel, electricity, and manpower into nutritive energy sources through photosynthesis. Hence, energy inputs in agriculture cannot be avoided and the level of input affects the energy output.
On-farm decisions around the amount and timing of energy inputs vary greatly based on knowledge, technology availability, perceived benefits, and prevailing biophysical conditions, in turn affecting energy output in the form of rice yield and contributing to highly heterogeneous energy use efficiency in the region.
Increased energy use may not always be economically viable, and it can also increase the carbon footprint of farming [8]. A recent study in the Gangetic Plains of India indicates that the energy use efficiency of cereal crops, including rice, is decreasing.
Designing a pathway for judicious use of energy in rice production is the need of the hour, given the huge demand for energy by other non-agricultural sectors and activities and the importance for the sustainability of future rice production.
An inventory of the energy use associated with key management practices like tillage, irrigation, fertilizer application, labor, and agrochemicals; and energy output in rice grain yield is required to compute the energy use efficiency and to estimate its variability among farms.
Although numerous studies estimated the energy use efficiency for rice-wheat cropping systems in Northwestern India, only a few compared and classified farms as efficient and less efficient and identified the key drivers affecting energy use efficiency.
A study concluded energy use efficiency for rice production in Western Punjab was in the range of 0.94–0.97 and that ca. 2200 MJ/ha could be saved with efficient crop management. The latter was also observed in Karnataka where energy use can be reduced by 6% in puddled transplanted conditions.
Yet, the aforementioned studies relied on a limited number of observations and hence, do not capture well the diversity of input-output combinations observed across farms and tend to overestimate the energy use efficiency scores derived from Data Envelopment analysis (DEA).
Thus, our study is novel in employing the bootstrapped meta frontier approach using DEA to classify farms as efficient and less efficient from the inventory of energy use and using a truncated regression to find the drivers of energy use efficiency across a large number of farms. The farm level inventory of energy use pattern is important for policy planning in this region, as the farms in the IGP rely on external inputs.
This study can guide policy planners on targeting inefficient farm clusters and operations. DEA is a benchmarking technique, which provides an efficiency score indicating the extent to which a farm is efficient relative to its most energy-efficient peers (i.e., farms producing a given level of output with the least possible energy).
The use of DEA invites erroneous estimates of efficiency scores if outliers are present near the boundary of the frontier. Therefore, bootstrapped DEA was applied in this study as such approach does not rely on single-most boundary points.
The present study was designed to i) assess the main sources of energy use for rice cultivation and estimate energy input, output, and hence efficiency, ii) benchmark energy use efficiency against the most energy use efficient farms observed in the sample while identifying options to reduce energy input without compromising energy output, i.e., designing a sustainable energy use pathway for rice farms and, iii) identify the determinants of energy use efficiency in the intensive rice production systems in the Northwestern IGP of India.
It was hypothesized that farmers spend additional energy in most of the field operations like tillage, irrigation, fertilizer, and labor, which can be reduced without compromising energy output. Such a study at the regional level involved the analysis of 3,832 fields from 7 different districts and contributes to better understand the sustainability of rice cultivation in India with respect to energy use.
Competition for energy between different economic activities demands efficient energy use in the agricultural sector, particularly in intensive cropping systems. Electricity energy for irrigation and energy input through fertilizers were two major activities accounting for more than 75% of the total energy input used for rice production in the Northwestern IGP of India.
We observed a large disparity among farms in terms of energy use efficiency, and in all the districts surveyed it is possible to reduce the energy input in different operations yet without reducing energy output. It is possible to improve energy use efficiency by at least 42% in the districts of Ambala, Fatehgarh Sahib, and Karnal, whereas in other districts energy use efficiency can be increased by 5-19%.
The timing and amount of irrigation, as well as the timing and amount of fertilizers, deserve particular attention due to their large share of the total energy input and their over-application in the least energy use efficient farms. Least efficient farms opted for the higher number of tillage operations like wet harrowing and intensive puddling, which must be reduced to increase energy-use efficiency.
Further, fine-tuning sowing dates, along with timely pest and weed management can improve energy use efficiency in the future. Precision fertilizer application along with optimizing the irrigation number and tillage practices are the key to improve the energy-use efficiency of rice farms in Northwest India.
The methodology and evidence provided in this study can help formulate district-specific action plans for sustainable intensification of rice production in the Northwestern IGP of India and can be extended to other production systems and performance indicators.
The latter is paramount given the environmental and economic concerns associated with inefficient resource use in the Green Revolution corridor of India. Our study is thus helpful to guide policymakers and researchers in identifying pathways toward sustainable energy use for rice production in the future.
Read the study:
Nayak HS, Parihar CM, Aravindakshan S, Silva JV, Krupnik J, et al (2023) Pathways and determinants of sustainable energy use for rice farms in India, Energy, Volume 272, 126986.
