Abstract: The work was conducted over two consecutive years (2015-2016), in dry-farming areas of southern Ningxia for two consecutive years. The potato variety Longshu 3 was used and the research aim was to study the effect of different mulching patterns on soil water temporal and spatial variation patterns, and on potato yield. Three mulching patterns were set up: full mulching of furrow and ridge with plastic film (ridge covered with plastic film, furrow covered with plastic film, DD), dual-mulching of ridge and furrow with plastic film and straw (ridge covered with plastic film, furrow covered with straw, DJ), and traditional flat(CK) was used as control. It was found that compared with CK, the soil water content of the 0-200 cm soil layer was significantly improved in the DJ and DD treatments by 18.4% and 9.1%, respectively, in 2015 and 38.1% and 15.7%, respectively, in 2016, averaged over different potato growth stages. Differences were especially important during the period from 70 to 90 d (days after sowing). During that critical growth period (70-90 d), the soil water coefficient of variation in the 0-60 cm layer was decreased significantly under the DJ and DD treatments by 63.4% and 49.7%, respectively, in 2015 and 56.1% and 25.8%, respectively, in 2016, compared with CK. The DJ treatment increased the water infiltration from the upper soil layer (0-100 cm) to the lower layer (100-200 cm), and the soil water content in the lower layer of the DJ treatment was increased significantly compared with CK treatment (by 10.9% and 37.9%, respectively, in 2015 and 2016). The variation amplitude (K_a) and coefficient of variation (C_v) for soil water in the 0-200 cm soil layer of the different treatments was greater in the upper layer than in the lower layer. K_a and C_v averaged over the DJ and DD treatments had significantly lower values than in the CK treatment and were, respectively, 19.6%, and 14.5% lower than CK in 2015, and 20.8% and 19.0% lower in 2016. In this study, the different mulching treatments altered the duration of the rapid growth period of tubers, and improved potato yield and harvest index. The average duration of the tuber rapid growth period was significantly prolonged (by 12.3 and 8.2 d in 2015 and 2016, respectively); the average tuber yield was increased by 50.8% and 38.5% in 2015 and 2016, respectively, and the average harvest index was improved by 33.6% and 18.1% in 2015 and 2016, respectively. Correlation analysis showed that at the seedling stage (30 d), the correlation between soil water and soil water coefficient of variation and yield was mainly related to the 0-40 cm soil layer, while in the bud, tuber formation and expansion stages (50-90 d), this correlation mainly related to the 0-120 cm soil layer. In summary, the dual-mulching of ridges and furrows with plastic film and straw (DJ) significantly improved the soil water environment during the critical crop growth for potatoes, prolonging the rapid growth period of tuber, and increasing the potato yield and harvest index in dry-farming areas of southern Ningxia.

Key words: dual-mulching with ridge and furrow, soil water content, temporal and spatial change, potato growth, yield