Plastic film mulching stimulates brace root emergence and soil nutrient absorption of maize in an arid environment

Abstract BACKGROUND Root–shoot ratio plays an important role in mulching effects on increases in maize kernel dry weight and grain yield. RESULTS We examined the effects of plastic film mulching with fertigation on soil nitrate, soil Olsen‐P, aboveground and belowground growth, grain filling, and yield of maize. The 2‐year research was conducted in a field with a subsoil sand layer (FSS) and in a field without a subsoil sand layer (FNS) in the Hetao Irrigation District, northwest China. Treatments included two levels of plastic film mulching (FM, fully mulched; PM, partially mulched with a cover ratio of 60%), and a non‐mulched (NM) control. Mulching methods significantly increased soil NO 3 ‐N concentrations (SNCs) in the main root zone in FSS, but not in FNS. Mulching significantly increased root length density in the 0–40 cm soil layer. Mulching increased brace roots emergence by 20.2% under full, and by 9.9% under partial mulching, accelerating soil phosphorus use in the surface soil layer. Mulching increased grain yield in spring maize via enhancing base stem diameter, leaf area, and relative chlorophyll content, decreased the ratio of surface root area to leaf area, and improved kernel dry weight increase. CONCLUSIONS A high proportion of base fertilizer to total fertilizer input resulted in nutrient deficiency during reproductive stage in fertigated maize, therefore, applying a portion of base fertilizer after the maize elongation stage is recommended for a further yield increase of mulched fertigated maize. © 2019 Society of Chemical Industry