Core Ideas: Transparent film mulching increased the soil water storage more than black film mulching. The mulching treatment only markedly increased the soil temperature in the maize seeding growth stage. Higher plant density decreased the root surface area, root volume, root length, and root diameter. Plastic mulch in combination with high plant density is a common agronomic technique in rainfed maize ( Zea mays L.) production. However, the effects of combining colored film mulching and plant density on soil temperature, soil water storage, the maize roots, and yield have not been thoroughly elucidated to date. Thus, a field experiment to explore the effects of colored film mulching and plant density on soil temperature and water, maize roots, and yield was conducted on main plots with three types of mulching (non‐mulching, transparent film mulching, and black plastic film mulching), which were divided into three subplots with three plant densities (60,000, 75,000, and 90,000 plants ha ⁻¹ ). The results were as follows: The mulching increased the soil water storage during the entire period of maize growth, and transparent film mulching increased soil water storage more than black film mulching. The mulching only markedly increased soil temperature in the maize seeding and jointing stages compared with the non‐mulching treatment, but the plant density augmented the soil temperature after the seeding stage. Compared with the non‐mulching treatment, the mulching treatments significantly increased root length, root length density, and root diameter by 17.0, 21.4, and 11.6%, respectively, during the heading stage and by 65.2, 70, and 11.6%, respectively, during the mature stage. As plant density increased, root surface area, root volume, root length, and root diameter decreased. The best combination, which attained higher yield and profit than other treatments, was the combination of a plant density of 90,000 plants ha ⁻¹ and black film mulching.

As the main organic materials, straw and manure play a critical role in soil organic carbon (SOC) sequestration and crop yield in China. This meta-analysis evaluated the impact of straw and manure amendments, both individually and combined, on crop yield, SOC, and soil nutrients in China by collecting 173 studies. The findings of this study revealed that straw return and manure application increased crop yields by 14.4% and 70.4%, respectively, overall. Combined straw and manure application gained a better improvement effect than straw alone but was less effective than manure alone. Regarding the straw return results, rice straw and a 3000–6000 kg ha⁻¹ returning quantity improved crop yield, SOC, available phosphorus (AP), available potassium (AK), and total nitrogen (TN) the most; regarding the straw return form, straw incorporated into soil and biochar increased crop yield and SOC more, respectively; and <5 years and ≥5 years of straw return treatment increased crop yield and TN more, respectively. Regarding manure application, pig and chicken manure increased crop yield and TN more, respectively; a 50–80% substitution ratio and 10–20 years of duration were best for improving crop yield, SOC, AP, AK, and TN. This study highlights the importance of optimal organic amendment through straw or manure applications to achieve a win–win between crop yield and soil fertility under the requirement of sustainable agriculture.