Understanding production potentials and yield gaps in intensive maize production in China

Understanding yield potentials and exploitable gaps in current intensive maize (Zea mays L.) production is essential in order to increase grain yields to meet future food requirements amid strong competition for limited resources. In this study, we used simulations with the Hybrid-Maize Model (http://www.hybridmaize.unl.edu/), highest recorded yields published in the literature, field experiments, and farm survey data to assess yield potentials and gaps in four maize agro-ecological regions of China. In 50 simulations of high-yield sites across China from 1990 to 2009, the yield potential averaged 16.5 Mg ha(-1) for irrigated maize and 13.9 Mg ha(-1) for rainfed maize, respectively. During the same period, the highest recorded yield was 15.4 Mg ha(-1), or 93% of the yield potential of irrigated maize. In comparison, the average farmer's yield was 7.9 Mg ha(-1) based on 5584 farms surveyed in 2007-2008. Consequently, the yield gap between the average farmer's yield and the modeled yield potential (YG(M)) was 8.6 Mg ha(-1) for irrigated maize and 6.0 Mg ha(-1) for rainfed maize and so farmers attained 48-56% of the yield potential. The yield gap between the average farmer's yield and highest recorded yield (YG(R)) was 7.6 Mg ha(-1); so farmers attained 51% of the recorded yield. Because the sites used for simulated and recorded yields possessed the most favorable combinations of soil and crop management, closing the gaps in YG(M) and YG(R) in farmers' fields within a short time frame could be very difficult. The attainable yield was collected from field experiments, which were conducted in farmers' fields by farmers using recommended management practices by local agronomists. The data for attainable yield averaged 12.3 Mg ha(-1) according 137 field experiments across China. The yield gap between the average farmer's yield and the experimental yield (YG(E)) was 4.5 Mg ha(-1), with farmers attaining 64% of the experimental yield. The main factor explaining this gap was inefficient crop management practices, which constrained yield improvements in farmers' fields. In order to narrow this gap, multidisciplinary understanding and cooperation among the disciplines of plant science, agronomy, soil science, agro-ecology and extension, resulting in integrated soil-crop system management, are essential. (C) 2012 Elsevier B.V. All rights reserved.