Refined Climatic Zoning of Spring Soybean in Northeast China

Abstract

The spring soybean in Northeast China is studied, and its climatic zoning index is determined by multi-year relative meteorological yield and meteorological data considering three maturity types of soybeans: Early, medium and late. Considering the influence of temperature, light and water on soybean growth, two suitability evaluation methods, zoning indicator affiliation function and crop response function, are selected to evaluate the climatic suitability of soybean in Northeast China using meteorological data from 1990-2019 after refined interpolation (Anusplin interpolation). The evaluation results are verified using yield indicators. Climatic zoning class thresholds are determined based on the quantitative relationship between yield reduction rate and suitability of soybeans, and refined climatic zoning is conducted for two time periods, 1990-2004 and 2005-2019. The results show that the average temperature in August, cumulative rainfall from May to September and cumulative sunshine hours in July are the main meteorological factors affecting the relative meteorological yield of soybeans. The climatic zoning indexes for soybean in early, medium and late maturity zones are different. Compared with the results of climate suitability evaluation without maturity type, the evaluation results based on different maturity type indicators are more detailed in spatial distribution and better in expressing the distribution of soybean yields and yield stability. When yield data are lacking, the climate zoning results based on crop response functions is a good complement, which can indicate the distribution of soybean yields, but has shortcomings in the description of yield stability. According to the quantitative relationship between climate suitability and yield reduction rate, the evaluation results are classified as four levels: Most suitable (0.76 ≤ S ≤ 1), suitable (0.65 ≤ S < 0.76), sub-suitable (0.49 ≤ S < 0.65) and unsuitable (0 ≤ S < 0.49). The most suitable areas for soybean cultivation in Northeast China are concentrated in the northern part of the Songnen Plain and the south-central part of the Sanjiang Plain. As the climate warms, areas suitable for soybean cultivation expand to higher latitudes and higher altitudes. Refined climatic zoning of soybean in Northeast China is carried out at three levels: Temporal, spatial (1 km by 1 km farmland), and maturity type. The results of the refined climatic zoning can provide scientific basis for the full and rational use of climate resources and optimization of soybean planting structure in Northeast China.

Keywords

• climate suitability
• refined climatic zoning