Optimized Ridge–Furrow Ratio to Decrease Greenhouse Gas Emissions and Increase Winter Wheat Yield in Dry Semi-Humid Areas

Abstract

The plastic-mulched ridge–furrow rainwater harvesting (RF) system has been widely adopted worldwide due to its visible economic benefits. However, few and inconclusive studies have focused on greenhouse gas (GHG) emissions. In addition, it is still unknown whether different coverage ratios under RF have an impact on greenhouse gas emissions. Here, we evaluate the effects of various coverage ratios on the soil hydrothermal characteristics, global warming potential (GWP), greenhouse gas intensity (GHGI), and yield productivity in dry semi-humid areas. A control (FP, conventional flat planting without mulching) and three different ridge–furrow ratios (40:40 (RF40), 40:60 (RF60), and 40:80 (RF80)) were tested in 2017–2019. Compared with FP, RF increased the soil temperature and promoted soil moisture in the furrows during the vegetative growth period. However, the soil temperature of the furrows slightly increased with furrow width, whereas the soil moisture obviously decreased under the three RF practices. In a wet year (2017–2018), FP significantly increased the winter wheat yield (43.6%) compared with RF, while the opposite was the case in a normal year (2018–2019). Among the three RF treatments, RF40 and RF80 significantly increased the yield by 13.9% and 17.2%, respectively, compared with RF60. Compared with FP, all of the RF treatments increased the flux of N2O and CO2 emissions but reduced CH4 absorption. Compared with FP, RF with ridge–furrow ratios of 40:40 cm, 40:60 cm, and 40:80 cm increased the GWP by 99.6%, 53.4%, and 31.3%, respectively, and increased the GHGI by 55.8%, 45.3%, and 0.7%, respectively. Therefore, conventional flat planting in wet years and a ridge–furrow ratio of 40:71 cm in normal years can reduce GHG emissions, sustaining crop productivity, and promote the sustainable development of agriculture and the environment.