Biomaterial amendments combined with ridge-furrow mulching improve soil hydrothermal characteristics and wolfberry (Lycium barbarum L.) growth in the Qaidam Basin of China

Droughts, intense soil evaporation, and poor soil structure with low water holding capacity and nutrients restrict agricultural production in the Qaidam Basin on the Tibetan Plateau. Excessive chemical fertilizers have been applied to increase the yields of wolfberry (Lycium barbarum L.), a significant economic crop in northwest China, which has further degraded soils. Biomaterial amendments and ridge-furrow mulching are effective measures for increasing soil water availability, crop yields, and water use efficiency (WUE). However, the combined effects of biomaterial amendments and ridge-furrow mulching on soil hydrothermal conditions, crop growth, and yield in this area are unknown. A field study was undertaken in 2018 and 2019 to investigate their combined influences on soil moisture and temperature, crop growth, yield characteristics, and WUE on the Tibetan Plateau. The experiment comprised four treatments: flat planting with film mulching (FM), flat planting with film mulching and biomaterial amendment (FMBA), ridge-furrow planting with film mulching (RM), and ridge-furrow planting with film mulching and biomaterial amendment (RMBA). The biomaterial amendment and ridge-furrow mulching treatments increased soil water content in the 0-120 cm soil layer, especially at 0-60 cm soil depth at early growth stages, compared with FM. Furthermore, the ridge-furrow mulching treatments had significantly higher soil temperatures than the FM treatment at the sprout stage. The RMBA treatment produced favorable soil hydrothermal properties, which significantly increased mean plant height, ground diameter, and root length density (RLD). The RMBA treatment also produced the highest crop yield, WUE, and berry quality in both growing seasons. Compared with FM, the RMBA treatment increased mean yield and WUE by 23.0% and 28.6%, respectively, across the two growing seasons. We conclude that the RMBA treatment is an effective and prom-ising cultivation pattern for alleviating water scarcity and improving soil hydrothermal conditions, yield, and WUE on the Tibetan Plateau.