Effects of organic amendments and ridge–furrow mulching system on soil properties and economic benefits of wolfberry orchards on the Tibetan Plateau

Abstract

Water scarcity and low soil fertility severely constrain crop growth and sustainable agricultural productivity on the Tibetan Plateau. Organic amendments and ridge–furrow mulching system (RFMS) are widely used to improve soil moisture, soil structure, and crop production in arid and semi-arid areas. However, their combined effects on soil physicochemical properties and economic benefits of wolfberry (Lycium barbarum L.) on the Tibetan Plateau remain unclear. A two-year field experiment was undertaken to evaluate the combined effects of organic amendments and RFMS on soil water, soil structure, soil saturated hydraulic conductivity, soil organic carbon (SOC), total nitrogen (TN), and economic benefits on wolfberry. Four cultivation practices were established: traditional flat plot with mulching (FP), traditional flat plot with mulching and organic amendment (FPOA), ridge–furrow planting with mulching (RF), and ridge–furrow planting with mulching and organic amendment (RFOA). The organic amendment and RFMS treatments had higher soil water storage (SWS) and soil desiccation index (SDI) than the FP treatment in both growing seasons, especially at 20–60 cm soil depth. In addition, organic amendment significantly decreased soil bulk density by 6.4% and increased soil saturated hydraulic conductivity by 16.8% in the 0–60 cm soil layer, respectively, and improved the proportion of larger soil aggregates (0.02–2 mm) by 10.8% in the 0–40 cm soil layer. Furthermore, the RFOA treatment significantly improved SOC and TN contents at 0–60 cm soil depth by 47.7% and 19.4%, respectively, relative to FP. The measured soil properties were highly correlated with wolfberry yield and water use efficiency over 2 years. In particular, the RFOA treatment had higher crop yield and economic benefit than the other treatments due to the more favorable soil environment. Therefore, the RFOA treatment could be a sustainable and efficient cultivation practice for alleviating drought stress, improving soil properties, and increasing economic benefit on the Tibetan Plateau.