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Based on the soil temperature and humidity data of soybean farmland under conservation tillage in Northeast China in the published article, the impact of conservation tillage measures on the soil hydrothermal status of soybean farmland in Northeast China was quantitatively assessed by using conventional tillage (CT) as a control, no-tillage (NT), reduced tillage (RT), straw mulching (SM), and no-till straw mulching (NTSM) as treatments. The results showed: compared with CT, conservation tillage increased the soil volume water content of 0-170cm soil layer in soybean farmland in Northeast China by 9.2%, and reduced the temperature of the shallow soil layer (0-30cm) by 8.2%. Four conservation tillage could increase soil moisture under different climatic conditions; straw mulching could increase soil moisture content throughout the growth period of soybeans, and the effect on soil hydrothermal was greatest during the nutrition period of soybean, and soil temperature increased with the increase of straw mulching; the magnitude of soil temperature reduction by conservation tillage decreases with the decrease of soil clay particles, the magnitude of soil moisture increased by conservation tillage decreases with the increase of soil depth. Among them, NTSM at different soil depths was the most obvious effect of water storage and moisture retention, and the soil moisture in the soil layer of 0-20cm was increased by 32.9%. In summary, conservation tillage could increase soil moisture but reduce soil temperatures. Temperature, precipitation, growth period, straw mulching amount, soil type and soil depth all had an impact on soil hydro-thermality in soybean farmland under conservation tillage. [ABSTRACT FROM AUTHOR]

The effects of irrigation on winter wheat yield and water use efficiency (WUE) were mostly explored based on site-based experiments in North China Plain (NCP) region. However, due to the influences of contrasting environmental factors (e.g. climate and soil properties), these results cannot be accurately cross-compared among different studies, resulting in the difficulty to get the generalizable pattern at regional scale. Here meta-analysis was conducted to comprehensively evaluate the effects of irrigation on winter wheat yield and WUE in NCP region, with the observation data of 1876 pairs from 186 field experimental papers totally. The differences of the irrigation effects in different regions, precipitation year types, soil texture, and nitrogen (N) application levels were explored, and the corresponding optimal irrigation amounts for reaching high yield and WUE were ascertained. Results showed that compared with non-irrigation during the winter wheat growing period, irrigation increased the yield of winter wheat in NCP by 32.0%-38.3%, and reduced the WUE by 27.1%-30.1%. The yield increment due to irrigation in the northwest of NCP (39.6%-53.5%) with total precipitation during the winter wheat growing period below 150mm was higher than that in the southeast of NCP (24.3%-27.1%) with total precipitation during the winter wheat growing period higher than 150mm, while the decrease of WUE due to irrigation in northwest of NCP (32.4%-37.5%) was higher than that in the southeast of NCP (22.0%-24.3%). The optimum irrigation amount for high yield and WUE of winter wheat was 150-180mm in the northwest and 120-150mm in the southeast. Specifically, for different precipitation year types, the optimum irrigation amounts were 120-150mm with 2 times during jointing and flowering stages for dry year, during jointing and heading stages for normal year, and during jointing and booting stages for wet year. For different soil texture, irrigation under loamy soil had the highest increases in yield, while clay soil had the lowest decreases in WUE; the optimum irrigation amounts of winter wheat with four different soil texture of sandy soil, loam, clay loam and clay were 60-90mm, 120-150mm, 180-210mm, and 150-180mm, respectively. For different N application levels, N application of 120-240kg.ha-1 led to the highest yield and WUE under the irrigation amounts of 80-140mm, of which the higher yield was obtained under irrigation amounts of 110-140mm, and the higher WUE was obtained under the irrigation amounts of 80-110mm. Collectively, the NCP region can achieve the goals of high yield and WUE when irrigation amount was 120-150mm with 2 times but at different stages during different precipitation year types (i.e. dry year, normal year and wet year). Meanwhile, the combination of loam conditions with the N application of 120-240kg.ha-1 can synergistically improve the yield and water use efficiency of winter wheat. [ABSTRACT FROM AUTHOR]