Narrowing the agronomic yield gap with improved nitrogen use efficiency: a modeling approach

Abstract

Improving nitrogen use efficiency (NUE) in the major cereals is critical for more sustainable nitrogen use in high-input agriculture, but our understanding of the potential for NUE improvement is limited by a paucity of reliable on-farm measurements. Limited on-farm data suggest that agronomic NUE (AE(N)) is lower and more variable than data from trials conducted at research stations, on which much of our understanding of AE(N) has been built. The purpose of this study was to determine the magnitude and causes of variability in AE(N) across an agricultural region, which we refer to as the achievement distribution of AE(N). The distribution of simulated AE(N) in 80 farmers' fields in an irrigated wheat system in the Yaqui Valley, Mexico, was compared with trials at a local research center (International Wheat and Maize Improvement Center; CIMMYT). An agroecosystem simulation model WNMM was used to understand factors controlling yield, AE(N), gaseous N emissions, and nitrate leaching in the region. Simulated AE(N) in the Yaqui Valley was highly variable, and mean on-farm AE(N) was 44% lower than trials with similar fertilization rates at CIMMYT. Variability in residual N supply was the most important factor determining simulated AE(N). Better split applications of N fertilizer led to almost a doubling of AE(N), increased profit, and reduced N pollution, and even larger improvements were possible with technologies that allow for direct measurement of soil N supply and plant N demand, such as site-specific nitrogen management.

Increasing Food Production in Africa by Boosting the Productivity of Understudied Crops

“…Based on the study in Yaqui Valley in Mexico, Ahrens et al [224] indicated that the yield gap in wheat could be minimized by improving nitrogen use efficiency (NUE). According to them, split applications of N fertilizer significantly increased seed yield and profit, and reduced N pollution.…”

Precision Agriculture for Smallholder Nitrogen Management

“…For example, developing sitespecific management zones for N on the basis of yield history, aerial photographs of soil color, soil sampling, topography, and farmer experiences has been shown to increase yields significantly without a concomitant increase in the rates of N application. 10 Better synchronizing N supply and demand in smallholder systems would meet all Climate Smart Agriculture objectives-less excess N could reduce nitrous oxide emissions, one of the most important agricultural greenhouse gases; more targeted N application could increase yields; and reducing farmer N costs via more efficient application techniques would increase both net income and resilience to various shocks, including spikes in fertilizer price. 10 Precision Agriculture for Smallholders To date, PA approaches have been predominantly adopted in large-scale, industrial systems in developed countries.…”

“…10 Better synchronizing N supply and demand in smallholder systems would meet all Climate Smart Agriculture objectives-less excess N could reduce nitrous oxide emissions, one of the most important agricultural greenhouse gases; more targeted N application could increase yields; and reducing farmer N costs via more efficient application techniques would increase both net income and resilience to various shocks, including spikes in fertilizer price. 10 Precision Agriculture for Smallholders To date, PA approaches have been predominantly adopted in large-scale, industrial systems in developed countries. Uptake in developing countries is low and, as in developed countries, concentrated in large-scale systems with high-value crops.…”

Influence of management and environment on Australian wheat: information for sustainable intensification and closing yield gaps

“…These production increases need to occur despite multiple interacting challenges such as the need to adapt to a rapidly changing climate, increased competition for agricultural land from other land uses, and societal demands for environmental stewardship (Godfray et al 2010, Lambin and Meyfroidt 2011, Vermeulen et al 2012. With limited opportunities for the expansion of agricultural land, and with vigilance against local environmental impacts (Licker et al 2010, Bommarco et al 2013, intensification and improvement in resource use efficiency have been identified as two of the most prospective ways to increase agricultural production (Green et al 2005, Ahrens et al 2010, Phalan et al 2011, Tilman et al 2011. Yield gaps-where farms produce less than the maximum currently attainable under ideal management (Mueller et al 2012, van Ittersum et al 2013)-often occur in practice, and closing this gap through the intensification of agricultural management is a global priority for addressing future food security (Neumann et al 2010, Mueller et al 2012.…”