Effects of pruning and mulching measures on annual soil moisture, yield, and water use efficiency in jujube (Ziziphus jujube Mill.) plantations

Abstract

Soil desiccation and water shortage are major challenges of rain-fed crop production in the semi-arid areas of the Loess Plateau of China. Mulching and pruning were considered effective strategies to improve harvest by reducing soil water evaporation and plant transpiration rates. In the present study, the possible synergistic effects of the combination of mulching and pruning on soil water status, growth, yield, and water use efficiency were explored in the jujube plant. Field experiments were conducted in a typical hilly semi-arid region over three growing seasons and two dormancy seasons in 2015–2017. The three treatments applied to mountain jujube plantations throughout the year were grassland (CK), regular pruning (PR), and pruning and mulching (PM). Soil water storage (0–200 cm) was higher in the PM than the PR treatment but lower than that of the CK in all three growing seasons. Relative to PR and CK, PM significantly decreased soil water loss during the dormancy season. The soil moisture infiltration depths were 300 cm, 160 cm, and 420 cm in 2016 and 420 cm, 280 cm, and 460 cm in 2017 for PM, PR, and CK, respectively. Soil desiccation was substantially reduced under the PM treatment in the deep soil layer but was less effectively mitigated under the PR treatment. In the CK treatment, soil desiccation appeared at 0–200 cm but was alleviated by heavy rainfall. Fresh fruit yield ranged from 6643–11,056 kg ha−1 for the PM treatment in 2015–2017. This range was 1221–2628 kg ha−1 higher than that for the PR treatment. Water use efficiency was 2.28 kg m−3, 2.05 kg m−3, and 2.22 kg m−3 under the PM treatment in 2015, 2016, and 2017, respectively. These rates were 1.27 × , 1.26 × , and 1.39 × higher, respectively, than those for the PR treatment. These results suggest that the combination of mulching and pruning is an alternative strategy for mitigating soil desiccation in the hilly regions of the Loess Plateau of China. This alternative land management system may be critical for the sustainable cultivation of economically important forest trees in the Loess Plateau region and elsewhere. Keywords: Soil desiccation, Soil water storage, Pruning, Crop yield, Water use efficiency