Mulching Improves the Yield and Water Use Efficiency of Millet in Northern China: A Meta-Analysis

Abstract

In northern China, the production of millet is constrained by water scarcity, necessitating suitable agronomic measures to realize its yield potential. Mulching effectively conserves soil moisture and increases the yield. However, the yield effect varies with the climatic conditions and field management. A meta-analysis of 751 experimental datasets from 58 peer-reviewed papers explored the impact of mulching on the millet yield, yield composition, and water use efficiency (WUE), considering 11 factors. The results showed that, compared to traditional flat planting without mulching, mulching significantly increased the millet yield and WUE by 30.9% and 27.3%, respectively, and also enhanced the yield composition. For optimal results under mulching, the planting density should be less than 300,000 ha−1, with nitrogen, phosphorus, and potassium fertilizer rates below 60 kg·ha−1. Sites with an average temperature below 10 °C, Huangmian soil, or in the northwest region showed superior yield effects from mulching. The annual rainfall and planting methods had no significant impact on the yield, yield composition, and WUE. The variety “Longgu” exhibited the highest yield increase of 63.9%. Biodegradable plastic film mulch showed the most significant yield increase of 61.7%. Overall, mulching should be adapted to the local conditions, and appropriate field management practices should be selected to promote stable increases in the millet yield and WUE.

Keywords

• water use efficiency
• yield response
• subgroup
• meta-analysis
• soil moisture