Furrow-Ridge Mulched with Plastic Film Increases Grain Yield in Maize By Allowing Higher Plant Density.

¡¡¡¡Although furrow-ridge mulched with plastic film is widespread in dryland farming areas of NW China, the moisture retained by film mulching may not be used efficiently in maize because of low plant density. Four plant densities (no. of plants per hectare) were tested in the spring of 2014 and 2015 in a semi-arid region: 1) low density of 35000 plants/ha; 2) medium density of 45000 plants/ha; 3) high density of 65000 plants/ha; and 4) extra high density of 72000 plants/ha, to test grain yield effect of planting density in semiarid area of Gansu Province of China. The ridges and furrows were fully covered with transparent polyethylene film as the mulching material. When measured at a depth of 10 cm, soil temperatures were higher in mulched plots than in bare plots by 4.5 ¡ãC in May, 4.3 ¡ãC in June, and 2.5 ¡ãC in July. Moisture content of a 2 m soil layer from June to October was also significantly higher in the mulched plots than the bare plots. And the lower the planting density is, the higher is the moisture content. The higher planting density resulted in the higher plant dry matter and the greater leaf area index. Higher densities also led to significantly higher grain yields, and the highest increase in yield was recorded at high planting density of 65000 plants/ha, being 25% greater than that at medium density in 2014 and 21% in 2015, the corresponding increase in water productivity being 26% and 11%. Therefore, to exploit the moisture saved by film mulching, it is recommended that maize be planted at a density of 65000 plant/ha.