No-tillage with straw mulching improved grain yield by reducing soil water evaporation in the fallow period: A 12-year study on the Loess Plateau

No-tillage with straw mulching (NTS) during the fallow period is an effective measure for storing precipitation and reducing soil water evaporation on the Loess Plateau of China. However, the duration of this effect of NTS during the fallow period in different cropping systems and different precipitation types is unclear. Therefore, a 12-year field experiment of two tillage methods (NTS; and conventional tillage, CT), in three cropping systems (winter wheat monoculture, WW; spring maize monoculture, MM; and winter wheat-spring maize rotation, WM) were conducted to evaluate the effect of NTS on grain yield, precipitation storage, soil water status, soil evaporation rate and cumulative soil evaporation during the fallow period in different precipitation types. Additionally, the duration for which NTS reduced soil evaporation was calculated using the linear-platform model. Our results showed that compared to CT, NTS increased precipitation storage by 35.3, 47.1 and 53.5 mm under WW, by 31.5, 31.5 and 40.4 mm under MM and by 53.2, 30.2 and 50.3 mm under WM in the wet, normal and dry fallow periods, respectively, at depths of 0–200 cm. As a result, the soil water storage at sowing was higher under NTS than that under CT. The linear-platform model showed that NTS was effective in reducing soil water evaporation for 86, 95 and 126 days under WW, 87, 81 and 110 days under MM, and 95, 104 and 121 days under WM in wet, normal and dry fallow periods, respectively. Additionally, we found that there was a large amount of cumulative soil water evaporation after the abovementioned durations in MM and WM. The path analysis indicated that NTS improved grain yields indirectly by reducing cumulative soil evaporation and increasing the soil water status at the sowing stage. Capturing precipitation when the fallow period is > 125 days may further improve yield. • NT improved grain yield by reducing soil water evaporation in the fallow period. • NT reduced soil water evaporation for 80–125 days in different fallow periods. • Capturing precipitation when the fallow period is > 125 days may further improve yield.