Effects of different mulching technologies on evapotranspiration and summer maize growth

Different mulching techniques, i.e., plastic film, gravel-sand and straw, have been applied in China for many decades, but have not been compared systematically for effects on soil water storage, evapotranspiration, crop growth, yields and water use efficiency (WUE) various crop growth stages. A Two-year summer maize growth experiment was conducted in containers under a rain-shelter to analyze the effects of plastic film, gravel-sand and straw surface mulches on soil water dynamics and crop growth processes. A lysimeter was designed for each container to dynamically measure soil-plant water dynamics. Eight treatments were designed including a control (no mulching - CK), black plastic-film-mulch (BPF0), transparent plastic-film-mulches(TRPF0), 1-mm-straw below black plastic film (BPF1), 1-mm-straw below transparent film (TRPF1), and 69 kg/m2 gravel-sand-mulch (SAND), two straw mulch treatments with chopped-straw-length of 1 mm (ST1) and 100 mm (ST100). The results revealed that, all 7 mulching treatments decreased soil water evaporation during early crop growth stages, which saved water and accelerated maize growth in the middle and later stages. For the 2015 and 2016 growing seasons, average soil water storage during the jointing stage increased 32%, 39%, 48%, 57%, 61%, 62% and 66%, yield increased 13%, 18%, 23%, 28%, 29%, 34% and 29%, and WUE increased 1.4, 2.1, 3.0, 3.2, 3.5, 4.1, and 3.6 kg hm−2 mm−1 compared with the CK treatment, for the ST100, SAND, ST1, TRPF0, TRPF1, BPF0 and BPF1 treatments, respectively. In general, yield and WUE increases were greatest in the BPF0 treatment, followed by TRPF1, BPF1, TRPF0, ST1, SAND and ST100. Yield and WUE increases in the ST100 and SAND treatments were small. This research revealed that plastic mulch had the largest yield and WUE increase, of which, black plastic film was better than transparent plastic film. The yield and WUE increase of gravel-sand-mulching was larger than 100-mm-in-length-straw-mulching but less than 1-mm-in-length-straw-mulching.