Coupling index of water consumption and soil fertility correlated with winter wheat production in North China Region

Crop production responses to water and soil characteristics is important to understand and manage regional agricultural production. However, the coupling characteristic of these factors was less quantified and it lacks a deep understanding of its effect on the crop production. North China Region (NCR), an important food production region in China but also one of the most water-stressed areas, was selected as the study area. Based on the remote sensing monitoring techniques, region evapotranspiration model, multi-criteria evaluation model, the spatial distribution of winter wheat, actual evapotranspiration (ET), and soil fertility score (SF) was measured in sequence. This study proposed a novel coupling index of water consumption and soil fertility (CWS) to measure the coupling characteristic of ET and SF, and correlated it to the winter wheat yield and area. The results indicated a significant correlation between the CWS and winter wheat production but a non-significant correlation between SF and yield and area. CWS in NCR presented a global pattern of high values in the south but low values in the north, in accordance with that of winter wheat production. Coupling the information of water and soil, the CWS showed a higher correlation to winter wheat yield with the correlation coefficient of 0.588 than solely that of the ET with 0.437. A relative lower correlation of CWS than that of ET implied that ignore of soil fertility but emphasis on the water restrictions would limit the high crop yield and influence the optimal allocation of water and soil resources. Our finding demonstrated the effectiveness of CWS and its higher relation to the winter wheat production in NCR. Information of spatial coupling and mismatching between the winter wheat production and CWS was suggested to be considered as a guide of better spatial optimal allocation of winter wheat.