Satellite evidence for yield growth opportunities in Northwest India

Improving crop yields in major agricultural regions is one of the foremost scientific challenges for the next few decades. In Northwest India, the stagnation of wheat yields over the past decade presents a distressing contrast to the tremendous yield gains achieved during the Green Revolution. One commonly proposed way to raise yields is to reduce the often considerable gap between yield potential and average yields realized in farmers' fields, yet the likely effectiveness of different strategies to close this gap has been poorly known. Here we use a unique, decade long satellite-based dataset on wheat yields to examine various options for closing the yield gap in the south of Punjab. Persistent spatial differences in sowing dates and distance from canal are found to be significant sources of yield variation, with the latter factor suggesting the importance of reliable access to irrigation water for yield improvement in this region. However, the total yield gains achievable by addressing persistent factors are only a small fraction of yield losses in farmers' fields. The majority of the yield gap is found to arise from factors unrelated to field location, such as interactions between management and weather. Technologies that improve farmers' ability to anticipate or adjust to weather variations, or that improve stability of genotype performance across different weather conditions, therefore appear crucial if average crop yields are to approach their genetic potential. (C) 2010 Elsevier B.V. All rights reserved.