Straw strip mulch improves soil moisture similar to plastic film mulch but with a higher net income

Soil surface mulch is an important measure for conserving more moisture and increasing yield in rainfed agroecosystems. Straw strip mulch (SM) is a new mulching technique for clean production, but the regulation mechanisms of SM on soil moisture and potato yield formation is lack of systematic understanding yet. Therefore, a five-year (2018–2022) consecutive field trial on potato (Solanum tuberosum L.) was conducted in the semiarid rainfed region of Northwest China, using three treatments: full-field black plastic film mulch (PM), SM with 42% of the field area mulched using whole corn stalks, and no mulch as the control (NM). Relative to NM, on average across five growing seasons of potato, SM increased (P < 0.05) the soil moisture in 0–200 cm depth by 6.6%, fresh tuber yield ha−1 by 15.0%, dry tuber yield ha−1 by 23.6%, weight per tuber by 13.3%, net income by 26.3% (8268 ¥ ha−1), and output / input ratio by 10.5%, biomass by 16.5%, water use efficiency 28.5%, but reduced the total water consumption (ET) throughout the potato growth period by 12.9 mm. SM had a similar (P > 0.05) soil moisture in 0–200 cm depth, the total ET, the dry tuber yield and WUE as PM but with a 10.7% (2455 ¥ ha−1) higher net income. Mulching practices not only increased the soil moisture at different growth stages, but also regulated its utilization. Compared with NM, the maximum increase of soil moisture in SM and PM occurred at tuber formation stage. SM and PM decreased water consumptions in early period (sowing to tuber formation) and late period (tuber bulking to maturity), as well as their ratios to total ET, but increased them in middle period (tuber formation to tuber bulking). The increased weight per tuber was the primary yield component that leads to the increased yield in SM and PM. It was concluded that mulching practices improve soil moisture by inhibiting evaporation, increase transpiration ratio to ET, reduce water consumption of early period and its ratio to total ET while increasing them of middle period, resulting in significant increases in biomass and weight per tuber, which were the main mechanisms for yield increases in SM and PM compared to NM. SM is suitable to be popularized in a semiarid rainfed agroecosystem for potato production as an alternative to PM.