Soil water status and root distribution across the rooting zone in maize with plastic film mulching

Knowledge on rooting systems and soil water status across rooting zones is essential in developing effective cropping systems. This study determined (i) the temporal and spatial growth patterns of roots in maize under different film mulching systems, (ii) the effect of film mulching on soil water status at various depths in a semiarid area. We hypothesized that (1) rooting systems and soil water profiles varied with different mulching systems, and (2) full-film mulching on double ridges-furrows increases root growth and improves soil water profile in semiarid areas. Maize (cv. Shengdan 16) was grown in five mulching systems in northwestern China (35°42′N, 107°20′E), in 2008 and 2009. Maize plants rooted to 160 cm deep, but the majority of roots were in the 0-30 cm depth with root volume decreasing substantially with depth. Maize in the full-film mulching (FF) systems had significantly greater root weight density (RWD), root length density (RLD), and root diameter compared to half-film mulching (HF) or the flat planting with unmulched check (CK). Maize in the FF system achieved the greatest RWD in the 30-60 and 90-100 cm depths at the tasselling stage and in the 120-150 cm soil depth at the filling stage. Compared to the CK, the FF treatment significantly improved soil water content in the 0-160 cm depth, and consequently, increased maize grain yield by 81% in 2008 and 92% in 2009. Full-film mulching is an effective, sustainable cropping system for maize production in semiarid areas because of the improved rooting systems, enhanced soil water content at different soil depths, and increased crop productivity.