Bo Ma

In arid areas, the combined use of plastic sheeting under gravel-sand mulch on ridge-furrow planting systems is an emerging practice to minimize soil water evaporation and micro-plastic pollution. In this study, we conducted a two-year field experiment near Gobi-Tengger Desert in Ningxia, China, to evaluate the effects of a plastic film underneath a layer of pure sand (MS1), pure gravel (MS2) and mixed gravel-and-sand (MS3) mulch on the soil hydrothermal properties, water use efficiency, yield, and fruit quality of wolfberry, compared to bare soil (CK). The results showed that mulching significantly increased soil temperature and water content in the 0–20 cm surface layer, though the effects varied with soil depth and water availability between a supplemental irrigated year (2022) and a rain-fed year (2023). Mulching markedly altered soil water dynamics, enhancing the capture and retention of light-to-heavy rainfall events. Consequently, all mulches significantly increased seasonal water consumption (ET) and water use efficiency (WUE) compared to CK. The MS1 treatment consistently achieved the highest yield and WUE, and the highest accumulation of beneficial fruit compounds like polysaccharides and flavonoids. However, this treatment also resulted in elevated soil salinity. Our findings demonstrate that combined mulching, especially MS1, is a highly effective strategy for optimizing soil conditions, water productivity, and fruit quality in wolfberry cultivation, although long-term salinity management requires attention.

This study sought to evaluate the potential of mulched gravel to release nutrients in the field by conducting trials with three variations of wet-and-dry cycling of the soil beneath gravel mulch and bare soil. The results revealed that quartz, muscovite, clinochlore, and albite were the most abundant minerals in the gravels. Throughout the whole wet-and-dry cycle, the total content of 30 elements measured in the gravel-mulched soil was higher than in the bare soil treatment, and the content of the total element rose with increasing wet–dry cycle humidity. The enrichment ratio (B_r) of each element in soil under gravel mulch relative to bare soil was in the sequence Mg > Ca > K > Cr > Na > Mn > V > Zn > Fe > Ti > Si > C > N > B> Co > (B_r = 0) > Pb > Cu > Ga > P > Sn > Sr > Al > Be > Li > Mo > Ni > Se > As > S. Under gravel mulch, the elements impacted by the wet–dry cycle are primarily rock-forming, whereas the elements affected under bare soil are primarily trace elements. The wet-and-dry cycles of gravel affected soil nutrients mainly by increasing soil K, Ca, Na, and Mg contents. The differences in soil K and Ca contents significantly affected the growth of jujube trees and the jujube fruit yield. A dry/wet cycle level of 5 L/d per tree under gravel cover conditions can effectively improve soil nutrients and increase the jujube fruit yield without causing environmental problems.

The freezing and thawing process caused soil water and salinity migration from depth to surface that led to massive evaporation and soil salination in spring. Ridges mulching is a very efficient method not only improved soil temperature, restrain evaporation, collected precipitation, but do not affected cultivation. Soil water characteristic curves reveal the relationship of soil water and soil suction, has very important meaning to research soil water migration. The study selected two kinds side mulching methods and one control as objects, the two kinds side mulching methods was weave overlay plastic film and weave, one control was bare soil. van Genuchten (VG) and Brooks and Corey (BC) models were adopted to simulated soil water characteristic curve in the freezing-thawing process. The result showed that VG model has higher simulation accuracy, and the coefficients of determination R² are above 0.9 and nRMSE are less than 10% for BS, W and FW simulation tests except for W and FW conditions of 5 cm. The soil temperature from 0 to 30 cm depth during freezing was highest in FW, second in W, and lowest in BS. Soil water and salinity have migrated during freezing-thawing process, compared with before freezing, soil water increased from 30 cm depth under bare soil conditions and from 15 cm under mulching cover conditions after the end of freezing-thawing, and the same pattern for soil EC, from 15cm depth under mulching conditions soil EC values increased, the EC values at 15cm depth under bare soil conditions still decreasing. The study achievement can provide a reference for the study of water-salinity migration and water characteristic curves during freezing and thawing of soils in arid and cold regions, and also provide a theoretical basis for soil water conservation, suppression of evaporation from farmland and salinity accumulation in topsoil.