Zero-tillage as a pathway for sustainable wheat intensification in the Eastern Indo-Gangetic Plains: does it work in farmers’ fields?

Abstract

In controlled-condition field trials across South Asia, zero-tillage (ZT) has demonstrated considerable scope for enhancing wheat productivity in the Indo-Gangetic Plains (IGP) while using less energy and irrigation water. However, studies that quantify the impact of ZT in farmers' fields are scarce, especially in the less productive and densely populated Eastern IGP, an area that the Indian government is targeting for investment to address current and future food insecurity. Furthermore, a recent global meta-analysis has questioned the yield benefits of ZT, especially when permanent soil cover with crop residues is not maintained. To assess the realworld performance of ZT wheat in Eastern India, we quantified the productivity impact of current ZT practices in the State of Bihar, based on a random sample of 1000 wheatgrowing households, stratified by ZT adoption status. CobbDouglas stochastic production frontiers estimated the effect of ZT on wheat output while controlling for potential selection bias between ZT users and non-users regarding crop management. In contrast to the global meta-analysis, we found that the prevailing ZT practices without full residue retention led to a robust yield gain over conventional-tillage wheat across different agro-ecological zones, amounting to 498 kg ha −1 (19 %), on average. The economic benefit from ZT related yield increase and cost savings in wheat production amounted to 6 % of total annual income among sampled households. We conclude that ZT users reap substantial benefits, and that ZT technology could play a major role in making Bihar selfsufficient in wheat. To increase access to the technology among smallholders, an expansion of the network of ZT service providers is essential and can be supported through targeted policies and development interventions.

Growing the service economy for sustainable wheat intensification in the Eastern Indo-Gangetic Plains: lessons from custom hiring services for zero-tillage

“…Sowing wheat until November 15 had become the official recommendation by the Government of Bihar in 2013 (GoB 2013). As Keil et al (2015) show, early sowing of wheat may not be practicable in low-lying areas that are prone to waterlogging during November, but the authors do estimate significant yield gains due to early sowing in well-drained areas. At the same time, they also found that in well-drained environments approximately 38 % of ZT wheat plots and 50 % of CT wheat plots were sown later than November 15 in the 2012/13 rabi season and conclude that the potential of ZT to facilitate earlier sowing should be better harnessed in such areas.…”

“…Based on on-farm trials in Haryana, Mehla et al (2000) estimated a ZT induced yield gain of 15.4 %, which they attributed to timely sowing (9.4 %) and enhanced fertilizer-and water use efficiency, as well as weed suppression (6.0 %). Significant yield increases and cost savings due to ZT wheat have also been confirmed in farmers' fields, both in the Northwestern IGP Krishna and Veettil 2014) and in the Eastern IGP (Keil et al 2015), based on household surveys. For Bihar, Keil et al (2015) estimated a yield gain of 19 % over CT wheat and economic benefits from yield increase and cost savings equivalent to 6 % of the average wheat farmer's annual household income; they concluded that broad-scale adoption of ZT technology could play a major role in making Bihar self-sufficient in wheat.…”

“…For the joint analysis, only ZT SPs residing in the six common districts were considered, reducing their number to 230. Since the primary purpose of the wheat farmer dataset was the estimation of ZT induced yield effects (see Keil et al 2015), the sample was stratified by ZT adoption status, encompassing 400 users of ZT and 600 non-users. To permit sample stratification, a brief census survey was conducted in each of the 40 research villages to elicit households' main occupation, incidence of wheat cultivation (since, in Bihar, ZT is thus far almost exclusively used in wheat), and ZT adoption status.…”

Zero-tillage is a proven technology for sustainable wheat intensification in the Eastern Indo-Gangetic Plains: what determines farmer awareness and adoption?

“…Keil et al (2015) found that the cost savings and yield gain associated with the use of ZT wheat in Bihar led to a combined economic benefit of approximately 110 US$ ha −1 compared to conventionaltillage wheat; for the average ZT wheat adopter in Bihar, the benefits derived from the practice were equivalent to 6% of their total annual household income. ZT-induced wheat yield gains were estimated at 17.4% in the prevailing rice-wheat system with intensive soil puddling in the rice component and only partial retention of rice residues 1 (Keil et al 2015). Despite rich evidence of the economic benefits achieved with ZT wheat, the adoption of the technology has remained slow, with the highest rate estimated at 25% 2 in the Northwestern IGP, and the lowest, 2%, in the East (Singh et al 2012).…”

“…Second, farmers may differ in their access to information about new technologies; in particular, so-called 'progressive' farmers and communities may be targeted by agricultural development projects or have a higher level of connectivity to state extension or private sector input suppliers, leading to earlier exposure and adoption of new technologies (Diagne and Demont 2007). Since smallholder farmers often have limited access to formal 1 Since differences in time of planting and the use of fertilizer, herbicides, and other inputs between ZT and conventional-tillage wheat were controlled for in the analysis, the yield gain was attributed mainly to reduced evaporative losses of soil water under deficit irrigation conditions; see Keil et al (2015) for details. 2 Based on village survey data collected in 2008. sources of agriculture-related information, such as agricultural extension, adoption studies have become more complex by taking dynamic processes of learning by doing and learning from others into consideration (Foster and Rosenzweig 1995).…”