Effects of plastic-hole mulching on effective rainfall and readily available soil moisture under soybean (Glycine max) cultivation

Plasticulture is becoming popular to control soil temperature and increase water-use efficiency in rain-fed agriculture. Non-perforated plastic mulching reduces effective rainfall by preventing infiltration, while perforated plastic mulching (plastic-hole mulching) increases effective rainfall by enhancing infiltration; both mulching control soil temperature. The comparative performance of these mulching is not, however, well investigated yet. So, a field experiment was conducted by cultivating soybean (Glycine max) under non-perforated plastic mulching (hereafter denoted by P), plastic-hole mulching (hereafter denoted by PH) and bare soil to investigate soil temperature, effective rainfall, total readily available soil moisture (TRAM), soil-moisture extraction pattern (SMEP) and yield of soybean. The mulching treatments reduced soil temperature by 2 °C at 5 cm depth compared to the bare treatment and created a favorable environment for soybean growth under high air temperature during summer in Japan. The PH treatment increased effective rainfall by as much as 9% of total rainfall compared to the P treatment. The SMEP in the 0- to 30-cm soil profile revealed that soil moisture was consumed, mostly, from the upper soil layer in the bare treatment, while in the P and PH treatments, soil-moisture consumption occurred both from the upper and from the lower soil layers. Consequently, the P and PH treatments provided greater TRAM (57.3 and 54.0 mm) than the bare treatment (48.0 mm), indicating that mulching contributed increasing soil-moisture availability in the root zone. The mulching treatments augmented plant height, number of nodulations per plant, and seed and biomass yields; the PH treatment produced the maximum seed yield.