Response of soil water, temperature, and maize productivity to different irrigation practices in an arid region

Irrigation combined with plastic film mulch (IPFM) is widely used in arid areas to alleviate water shortages and increase crop yields. However, the mechanisms by which IPFM affected soil water content (SWC) and soil temperature (ST) to promote crop photosynthesis and resources (water, nitrogen and radiation) utilization are unclear. A field experiment was conducted in northwestern China in 2019 and 2020 to evaluate the effects of different irrigation methods combined with transparent film mulching (70% cover) on soil hydrothermal conditions and maize growth, photosynthetic characteristics, yield, and resource use efficiency. The four treatments included border irrigation with no mulching (CK), border irrigation under film mulching (TM), ridge irrigation under film mulching (RM), and drip irrigation under film mulching (DM). Our results showed that TM and RM significantly improved SWC, enhanced photosynthetic rate (Pn), and lowered non-photochemical quenching (NPQ) in maize relative to CK. The DM treatment had wetter soil and lower soil surface temperatures from the V12 to R3 stage, further accelerating maize photosynthesis and resource use relative to the other treatments and thus producing the higher leaf area index and biomass accumulation. The results suggest that DM is an efficient farming strategy, increasing yield by 3.7 - 61.3%, radiation use efficiency for maize grain yield (RUEGY) by 2.8-44.3%, irrigation water use efficiency (IWUE) by 29.7-96.5%, partial factor productivity of nitrogen (PFPN) by 3.7-61.3%, and economic benefit by 12.4-100.0% relative to the other treatments. In addition, the regression function revealed that the increased soil water storage and decreased ST from VT to R3 stages helped increase maize yield. Thus, we recommended DM practice for increasing maize production in arid areas and proposed soil water storage in 0-120 cm profile ranging 342-389 mm and ST ranging from 18.9 degrees to 22.1 degrees C as reference management indicators.