Closing the maize yield gap in the North China Plain
- The gap between yield potential and average farmers' yield measures the capacity for yield improvement with current technology. The North China Plain (NCP) is a major maize producing region of China, and improving maize yield of NCP is essential to food security of the country. Some previous studies have found a substantial maize yield gap in this region (~100% of average yields), whereas others have reported much smaller gaps. In this thesis, multi-year satellite images were used to quantify field-scale maize yield variation in Quzhou County of NCP, and this variation was then analyzed to determine the role of soil type and persistent management factors in explaining yield gaps. The method was then applied to 76 counties in NCP. The aggregated average yield was 8.66 t/ha across county years, and the aggregated yield gap was 0.76t/ha. The weighted average of yield persistence was 25.9% of the average yield gap, or 2.3% of average yield. The results showed tremendous spatial heterogeneity in yield persistence level across NCP, and further analysis within individual counties is required to better prioritize means to shrink the yield gap. In order to further understand the underlying causes to this yield gap, we conducted a case study in Quzhou County, which is typical of NCP such that the average plot size is less than 0.2 ha. First, we identified fields that were either persistently higher or lower yielding according to remote sensing yield estimates, and then conducted detailed field surveys. We found irrigation facility to be a major constraint to yield both in terms of irrigation water quality and farmers' access to wells. In addition, farmers' method of choosing cultivar, which likely relates to their overall knowledge level, significantly explained yield variation. These results inspired possible future research topics in assessing the efficacy of farmer extension programs and the effect of farm size on productivity.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Earth System Science.
|Lambin, Eric F
|Lambin, Eric F
|Statement of responsibility
|Submitted to the Department of Earth System Science.
|Thesis (Ph.D.)--Stanford University, 2016.
- © 2016 by Yi Zhao
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