The Effect of Climate Change on Spring Maize (Zea mays L.) Suitability across China

Spatio-temporal variations and drought of spring maize in Northeast China between 2002 and 2020

A lot of spring maize is grown in Northeast China (Liaoning, Jilin, and Heilongjiang), an area that is highly susceptible to drought. Here, remote sensing indexes from 2002 to 2020 were studied using the 8-day surface reflectance and land surface temperature of Moderate-resolution Imaging Spectroradiometer data. Spring maize distribution was extracted using a decision tree classification, and the results were compared to the known distribution based on field investigation data and published statistics. The results showed that mixed pixels of spring maize and soybeans had limited influence on the study of spatio-temporal variations of spring maize, and the error was acceptable. The overall accuracy of verifying the spring maize distribution from 2018 to 2020 was above 85%. The stable, fluctuating, and low-frequency planting areas of spring maize accounted for 11.86%, 17.41%, and 34.86% of the study area, respectively. In 2015, the government directed a reduction of the planting area of spring maize in the "Liandaowan" region of Northeast China. The planting area of spring maize was characterized by a continuous increase before this change (2002-2014), exhibited changes and reductions in response to the change (2015-2017), and exhibited optimization and recovery after this change (2018-2020). Compared with the fluctuating and low-frequency planting areas, moderate and severe droughts were higher in stable planting areas. From 2002 to 2020, the most severe droughts occurred in the expanded planting areas. This rapid and large-scale monitoring of spatio-temporal variations and drought of spring maize provides a foundation for improving grain yield. This method could be easily applied to the study of other regions and combined with high-resolution and hyperspectral satellite data to improve monitoring accuracy.

Maize Straw Strip Mulching as a Replacement for Plastic Film Mulching in Maize Production in a Semiarid Region

Straw strip mulching in maize (Zea mays L.) production is showing a positive effect with the increasing negative effects coming from crop straw and plastic film residues. Therefore, it is imperative to develop comprehensive utilization of straw, and promote the green development of agriculture in rainfed regions. A dryland field experiment was conducted in semiarid northwestern China in 2017 and 2018 and included three treatments: maize straw strip mulching with alternating strips of mulched and non-mulched soil (MSSM), and double ridge-furrow fully mulched soil with white or black plastic film (DRWP or DRBP, respectively). The results show that the interaction between mulching treatment and year significantly influenced maize silage yield, grain yield, biomass yield, aboveground plant water content at silage maize harvest stage, ears ha−1, kernels ear−1, and thousand kernel weight (p < 0.001, p = 0.002, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively). For silage, maize growth under straw strip mulching was greater than that of the double ridge mulching system. Silage yield of MSSM was significantly higher than that of DRWP and DRBP, but maize grain and biomass yields under MSSM were significantly lower those under DRWP and DRBP in 2017 and 2018. Compared with the double ridge mulching system, net economic return from silage with MSSM was significantly increased by 28.31% and 20.85% in 2017 and 2018, respectively, and net economic return from grain was 6.67% lower in 2017 and 2.34% higher in 2018. The MSSM treatment exhibited water-temperature coupling; the MSSM treatment significantly reduced soil temperature in the 0–25 cm soil layer by 1.23–2.14 °C and increased soil water storage in the 0–200 cm soil layer by 9.75 and 24.10 mm in 2017 and 2018, respectively, thereby delaying growth development of maize by about 13 days. Therefore, straw mulch can replace plastic film mulch and serve as an environmentally friendly cultivation method for maize in semiarid rainfed regions.

Yield Data Provide New Insight into the Dynamic Evaluation of Maize’s Climate Suitability: A Case Study in Jilin Province, China

Examining the effects of climate change on spring maize, and its suitability under dynamic cultivation patterns, will aid strategic decision-making for future agricultural adaptation. This paper investigates the climate suitability of spring maize, based on daily data from 50 meteorological stations, and statistics on maize yield and area at the county level in Jilin Province, China, between 1986 and 2015. Based on a significant correlation between the cultivation patterns indicator ≥10 °C accumulated temperature (AAT10) and the average yield (R2 = 0.503), the yield data are used to determine suitable thresholds for meteorological factors under the dynamic cultivation pattern, and a fuzzy fitness approach is used to evaluate the climate suitability. The results showed a good agreement between suitability estimates and scaled observed yields (average d = 0.705). Moreover, good consistency between cultivation patterns, climate suitability and yield show that the late-maturing varieties of maize have gradually moved northward and eastward, and the areas of high suitability and high yield have gradually expanded eastward. In addition, drought and chilling hazard factors limit the suitability of climate resources, especially in the eastern and western regions.