Plastic film mulch in agricultural production becomes essential to maintaining crop yields in arid and semiarid areas. However, the presence of residual film in farmland soil has also drawn much attention. In this study, three experiments were conducted. The first two experimental designs included 0, 450, 1 350, and 2 700 kg ha–1 of residual film pieces of approximately 5 cm side length added to field soil (0–20 cm soil depth) for seven years and added to pots for four years. In the third experiment, 1 350 kg ha^–1 of the residual film with different side lengths (2–5, 5–10, 10–15, and 15–20 cm) was added to field soil for six years to explore the effect of residual film fragment size on soil nutrients, soil microorganisms, crop growth and yields. The residual film had little effect on the soil moisture at a field depth of 0–2 (or 0–1.8) m. There were no significant effects on organic carbon, total nitrogen, inorganic nitrogen, total phosphorus or available phosphorus in the 0–20 cm soil layer. The presence of residual film decreased the richness and diversity of the bacterial community of the surface soil of the residual film, but it had no significant effect on the microbial community of the non-surface soil. The emergence rates of wheat and lentils occasionally decreased significantly with different amounts of residue fragments added to the field. At 450–2 700 kg ha^–1, the residual film reduced the plant height and stem diameter of maize and significantly reduced the shoot biomass of harvested maize by 11–19%. The average yields of maize and potato over the seven years decreased, but there were almost no significant statistical differences among the treatments. These results provide important data for a comprehensive scientific understanding of the effects of residual film on soil and crops in dryland farming systems.

Leaf-mining flies (Diptera: Agromyzidae) are a diverse family of small-bodied insects that feed on living plant tissues as larvae.  Various species in this family are considered globally invasive and have caused great agricultural economic losses.  In China, economically important vegetable crops have been seriously damaged by these pest insects, especially by species of the genus Liriomyza.  However, these species are difficult to differentiate because of their morphological similarities, and the Chinese fauna remains poorly known.  To explore the relevant pest species in China and their phylogeny, agromyzid leafminers were collected from 2016 to 2019, and identified based on morphological characteristics and DNA barcodes.  In total, 27 species from five genera of Agromyzidae were sampled and identified, including 16 species of Liriomyza.  Both mitochondrial and nuclear genes were used to reconstruct their phylogenetic relationships and estimate the divergence time.  Highly congruent and well-supported phylogenetic trees were obtained using the Bayesian inference and maximum-likelihood methods.  This analysis revealed two main clades in Liriomyza, and clade 2 was inferred to have diverged from clade 1 approximately 27.40 million years ago (95% highest posterior density: 23.03–31.52 million years ago) in the Oligocene.  Differences were observed in the distribution patterns and host associations between the Liriomyza clades.  Clade 2 species are distributed in cool, high-latitude environments, suggesting that they may have evolved into a cool-adapted lineage.

The efficacy of integrating green manure in arid irrigation regions to enhance maize yield and nitrogen (N) uptake efficiency has been extensively explored.  However, limited research has delineated the contribution of green manure N versus soil N on crop N utilization efficiency.  This study integrated field experiments with micro-plot experiments to examine green manure (common vetch) management practices for achieving high maize yield and N uptake.  In a micro-plot experiment, ¹⁵N technology was utilized to label green manure crops.  Five treatments were applied in the research methodology: conventional tillage without green manure as the control (CT); tillage with total green manure incorporation (TG); no-tillage with total green manure mulching (NTG); tillage with only root incorporation (T); and no-tillage with removal of above-ground green manure (NT).  The results in the micro-plot experiment were the same in the field, and both demonstrated that the utilization of green manure led to a substantial increase in maize yield and nitrogen uptake efficiency (NU_PE) compared to conventional tillage (CT).  In particular, under NTG, N uptake by maize from green manure was higher than NT and T, accounting for 59.1% of maize N uptake.  Furthermore, the application of NTG boosted the NU_PE of soil N in maize to 50.7%, which is higher than TG by 5.5%.  Meanwhile, it decreased the proportion of soil N in the maize.  The difference between NTG and TG was primarily shown in the maize grains.  For N transport in the soil, NTG decreased N loss while increasing soil N retention.  Also, it facilitated the mineralization of soil organic N before the flowering stage.  In conclusion, the adoption of no-tillage with total green manure mulching not only increased N uptake both from green manure and the soil but also decreased the proportion of soil-derived N in maize. 

Wheat-maize rotation is a widely used planting pattern in oasis irrigated areas in northwest China.  Although this planting pattern has the advantage of breaking the barrier of continuous cropping to some extent, it also has some problems such as large evaporation and prominent soil degradation during fallow period, which seriously restricts the improvement of crop yield.  Planting green manure (GM) after wheat and returning it to field can effectively improve soil physicochemical properties, regulate photosynthetic characteristics of subsequent crops and promote crop yield.  However, the photosynthetic physiological mechanism of crop yield improvement under different green manure return methods (GMRM) is still unclear.  Therefore, by exploring the relationships among soil moisture and temperature environment, maize root structure, photosynthetic characteristics, fluorescence characteristics and yield under different GMRM, this study aims to provide theoretical basis for clarifying the photosynthetic physiological mechanism of GMRM to improve maize yield.  A three-year field experiment was conducted at a research station in the Shiyang River Basin (Gansu, China).  Five treatments were involved in this study: (i) conventional tillage without GM (CT), (ii) no-tillage with total GM mulching (NTG), (iii) no-tillage with removal of aboveground GM (NT), (iv) tillage with total GM incorporation (TG), and (v) tillage with only root incorporation (T).  Results showed that the NTG and TG significantly increased soil water content (SWC) in 0-110 cm soil layer, soil temperature (ST) of maize seedling (V3) to jointing stage (V6), canopy cover (CC), leaf stay-greenness (SG), root length (RL), net photosynthetic rate (P_n), transpiration rate (T_r), actual photochemical efficiency of PSII (ՓPSII), maize biomass and grain yield (GY) compared with CT.  In addition, NTG and TG significantly decreased ST of maize big trumpet stage (V12) to blister stage (R2), and dissipation of excess energy (NPQ) compared with CT.  The GM return to field could improve root structure and canopy coverage of maize mainly by improving soil water content.  The optimization of maize root structure and canopy coverage increased maize chlorophyll content (SPAD) value and promoted P_n.  The increase of P_n inhibits the increase of NPQ, thus promoting ՓPSII.  The increase of ՓPSII promoted the increase of maize biomass, and finally realized the increase of maize GY.