Mulching improved soil water, root distribution and yield of maize in the Loess Plateau of Northwest China

Knowledge of root systems and soil water status across the root-zone is crucial in developing effective cropping technologies. Mulching improves soil water status and root water transport for increasing grain yield. Therefore, a field experiment with five treatments: (1) plastic film mulching ridge and non-mulching furrow (RF), (2) full plastic mulching with conventional flat cultivation (FPM), (3) straw mulching with conventional flat cultivation (SM), (4) partial plastic mulching with conventional flat cultivation (PPM) and (5) non-mulch with conventional flat cultivation (CK) was conducted during 2018 and 2019 in the eastern Loess Plateau of China. The total root biomass and the grain yield of all treatments were lower in 2019 than that of 2018 because of lower rainfall. However, all the mulching treatments improved root growth in both growing seasons mainly on the top 30 cm soil depth, which led to a distinct effect on grain yield as compared with CK. FPM produced the highest total root parameters in 2018 and at 45 DAS in 2019 due to the highest soil moisture content mainly in 0-30 cm soil depth. However, root biomass of FPM in 30-100 cm soil depth was lower than that of PPM, RF and SM because assimilate at reproductive stage was mostly for plant and seed growth than root growth, thus, there was negative correlation between grain yield and root biomass below 30 cm soil depth especially at grain filling stage. Over two growing seasons, soil moisture content (SMC) under FPM was 8.4 %, 0.6 %, 8.8 % and 11.1 % more than that of RF, SM, PPM and CK. FPM reduced soil evaporation, improved SMC, root distribution and transpiration rate, consequently, increased grain yield and net profit. Therefore FPM is an effective cropping system for improving the synchronization of soil water transport and root water uptake for maize production in rain-fed farming.