Crop residue returning (CRR) is known to improve the soil environment and thus increase crop production. However, the impacts of CRR on wheat (Triticum aestivum L.) yield have been contrary at times due to the differences in climatic conditions, soil traits, and management practices. These effects were evaluated using 351 paired observations published in 161 papers comprising studies conducted in 19 provinces (autonomous regions) of China. No publication bias or extreme values were found in the data, indicating that the analysis results are highly reliable. Compared with the practice of no crop residue returning (NCRR), the practice of CRR increased wheat yield significantly, on average by 8.29%, and proved more beneficial in Northwest China and in regions with average annual precipitation of 200 to 400 mm, average annual temperatures >11°C, sandy loam soil, and rotation with legumes (soybean [Glycine max (L.) Merr.]–wheat and pea [Pisum sativum L.]–wheat). The following aspects of CRR and crop management conferred greater benefits in yield: continuing the practice for 3 to 6 yr (compared with 1–2, 7–10, and ≥11 yr), using the residues at 3 to 6 t ha−1 (compared with <3, 6–9, and > 9 t ha−1), chopped straw (compared with intact straw), rainfed conditions (compared with irrigated conditions), and applying N at 200 to 300 kg ha−1 (compared with <100, 100–200, and >300 kg ha−1). The yield increase was significantly higher when the residues were returned in the form of mulch (12.56%) and for spring wheat (11.90%) than plowing them back into soil (4.53%) and for winter wheat (7.09%). The meta‐analysis thus confirms the benefits of CRR in higher wheat yields in China and also suggests that the benefits of CRR are site specific.
Measuring the carrying capacity of water resources and identifying obstacle factors are critical prerequisites for the rational allocation of regional water resources and the high-quality development of economic society. This study took Longnan City, a typical city in northwest China with abundant water resources but an underdeveloped economy, as the research object. Based on the DPSR (Driving–Pressure–State–Response), an evaluation indicator system was constructed. TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) and an obstacle model were used to calculate the water resource carrying capacity and main obstacle factors of Longnan City from 2009 to 2019. The results showed that the carrying capacity of water resources in Longnan City had steadily improved, and the comprehensive closeness had increased from 0.44 (2009) to 0.60 (2019). From the perspective of the ruler layer, the carrying capacity of the driving force system increased from 0.05 in 2009 to 1.00 in 2019. The capacity of the state system increased during the change, with the highest value (0.85) appearing in 2013 and the lowest value appearing in 2016. All subsystems, except the pressure system, had a load-carrying capacity of 0.60 or more in 2019. The utilization of unconventional water resources, the proportion of eco-environmental water use, the volume of wastewater discharge, and the per capita urban daily water consumption are the primary factors affecting the water resource carrying capacity of Longnan City. Developing unconventional water sources, improving sewage treatment technology, promoting efficient water-saving technology, and strengthening environmental protection is the key to improving the water resources carrying capacity of Longnan City. This research provides the basis for enhancing the carrying capacity of water resources and sustainable urban development in Longnan City and other cities in China and water scarcity cities in other countries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.