Identification of Maize Yield Trend Patterns in the North China Plain

Abstract

Yield growth stagnation in grain crops has been reported worldwide over recent decades. To understand this recent crop yield trend and its causes in China, we conducted an analysis of maize (Zea mays L.) in the North China Plain (NCP) as a case study. First, we analyzed the change characteristics of maize yield for the whole region during 1998–2015, then identified trend patterns at county level via an approach based mainly on the Mann–Kendall and Sen’s slope methods, and finally, analyzed the contribution of major causal factors to maize yield changes based on multiple linear regression (MLR) function. The results indicated that regional mean maize yield in the whole NCP increased by 0.02–2.03% per year before 2011, then declined by—0.83% during 2011–2015. Regionally, maize yield in the southern NCP did not improve greatly; in the north, it increased before 2011, then declined or stagnated thereafter. Only 40 counties showed a continuous increasing trend (IN), whereas 180 counties displayed an increasing–stagnating trend (IN-ST); 52 and 40 counties showed trend patterns of stagnating (ST) and decreasing (DE) in yield, respectively. On the whole, the maize yield in 87.8% of the counties tended to stagnate or even decrease. The reason was mainly attributed to the reduced net returns due to the quickly rising costs of labor and production material. To stimulate yield growth, it is essential to increase the profitability of maize by adopting appropriate policy measures to improve production efficiency.