Effects of different plastic film mulching on soil hydrothermal conditions and grain-filling process in an arid irrigation district.

Plastic film mulching has been extensively used for spring maize (Zea mays L.) production in the Hetao Irrigation District (HID). Determining whether transparent plastic film mulching results in premature senescence and yield reduction of spring maize still needs to be verified. A two-year field experiment was conducted in the HID that involved planting spring maize under three mulching practices on a flat plot 1) without mulching (control treatment, CK), 2) with black plastic film mulching (BM), 3) with transparent plastic film mulching (TM). The results indicated that TM and BM were superior to CK in terms of effects on soil hydrothermal conditions. Compared with BM, TM produced significantly higher soil temperature at V6, and had no significant temperature effect at V12, R1, R3, and R6. Both TM and BM promoted early seedling emergence and earlier silking, and TM extended the duration of the reproductive stages by 1-2 days compared with BM, and 4-5 days longer than CK. TM and BM produced greater kernel weights and kernel volumes in the superior and middle portions of the ear than CK. TM produced significantly greater total kernel weights per ear than BM at and after 23 days after silking. TM significantly increased grain-filling rate and length of the active grain-filling period compared with BM and CK. Additionally, TM and BM produced significantly higher photosynthetic parameters than CK at the grain-filling stage in the two study years. The net photosynthesis rate for TM was significantly greater than for BM. TM and BM significantly increased grain yields by 28.1% and 15.1%, respectively, in 2019 over CK, and by 24.6% and 21.1% in 2020. Transparent plastic film mulching could serve as a promising adaptive management practice to increase resource use efficiency and to improve maize productivity in the HID.

Is the Taklimakan Desert Highway Shelterbelt Sustainable to Long-Term Drip Irrigation with High Saline Groundwater?

Freshwater resources are scarce in desert regions. Highly saline groundwater of different salinity is being used to drip irrigate the Taklimakan Desert Highway Shelterbelt with a double-branch-pipe system controlling the irrigation cycles. In this study, to evaluate the dynamics of soil moisture and salinity under the current irrigation system, soil samples were collected to a 2-m depth in the shelterbelt planted for different years and irrigated with different groundwater salinities, and soil moisture and salinity were analyzed. The results showed that both depletion of soil moisture and increase of topsoil salinity occurred simultaneously during one irrigation cycle. Soil moisture decreased from 27.4% to 2.4% for a 15-day irrigation cycle and from 26.4% to 2.7% for a 10-day-cycle, respectively. Topsoil electrical conductivity (EC) increased from 0.64 to 3.32 dS/m and 0.70 to 3.99 dS/m for these two irrigation cycles. With increased shelterbelt age, profiled average soil moisture (0-200 cm) reduced from 12.8% (1-year) to 7.1% (10-year); however, soil moisture in 0-20-cm increased, while topsoil salinity decreased. In addition, irrigation salinity mainly affected soil salinity in the 0-20-cm range. We conclude that water supply with the double-branch-pipe is a feasible irrigation method for the Taklimakan Desert Highway Shelterbelt, and our findings provide a model for shelterbelt construction and sustainable management when using highly saline water for irrigation in analogous habitats.