A sustainable approach to narrowing the summer maize yield gap experienced by smallholders in the North China Plain

Abstract

CONTEXTThe maize production sector in the North China Plain (NCP) is facing the dual pressures of having to increase its grain yield and improve its environmental sustainability. Evaluating the yield gap and ascertaining the factors that limit the grain yield might suggest new approaches to address these challenges. OBJECTIVEThe objective of this study was to estimate the yield potential and the yield gap associated with smallholdings in the NCP using a hybrid method; to determine the factors driving the grain yield and corresponding sustainability indicators; and to evaluate to what degree the introduction of scientifically developed high-yield and high-efficiency agronomic practices (HH) to smallholders might help to sustainably narrow the exploitable yield gap. METHODSCombined with diagnostic smallholder survey and crop modeling exercise to characterize and decompose yield gaps. With survey data, we assessed the existing variation with respect to various key performance indicators and carried out a number of controlled comparative experiments at farms (HH vs traditional farming practices (FP)) in multiple locations. RESULTS AND CONCLUSIONSOur work revealed the total and exploitable yield gap were 4.3 t ha−1 and 1.8 t ha−1 for rainfed summer maize, and 4.4 t ha−1 and 1.9 t ha−1 for irrigated summer maize across the entire NCP, indicating a large potential for yield improvements. The main factors driving the yield from the entire region were the planting density, the fertilization frequency, and the irrigation frequency. It should be noted that farmers whose yield was in the top 25% bracket of the yield distribution also achieved relatively high utilization efficiencies with respect to N, P, and K fertilizers (15%, 16%, and 16% above the average values, respectively) while their profit was 41% above average. Comparative experiments conducted over several seasons support insights from surveys by demonstrating that major gains in grain yield (+30%), the fertilizer utilization efficiency (+37% in N partial factor productivity, +48% in P partial factor productivity, and + 32% in K partial factor productivity) and economic profit (+62%) are achievable through the adoption of HH. SIGNIFICANCEThrough a hybrid method, our results suggest that agricultural intensification can be achieved in the NCP without having to trade off yield against environmental sustainability. Evidently, smallholders can simultaneously improve their maize grain yield, fertilizer utilization efficiency, and profit by adopting straightforward non-disruptive optimizations of their agronomic practices.