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Background and Aims: Selection effect (SE) and complementarity effect (CE) are often considered as two key indicators to mediate the positive diversity-productivity relationship in the maize-legume intercropping system, as intercropping generally enables crops to use the available resources more efficiently than monoculture. Yet, it is unclear whether soil moisture drives the SE and CE transformation, plant-plant interaction, and accordingly affect the productivity. Methods: A two-year field experiment was conducted to explore the impacts of soil water status (with and without plastic mulching) on interspecific interaction and productivity and its key mechanism in the maize-faba bean intercropping system. Results: Low soil moisture reduced the net effect (NE) and land equivalent ratio (LER) with evident yield loss (NE < 0 and LER = 1.05), whereas the improved soil moisture reversed this trend and resulted in overyielding (NE > 0 and LER = 1.13). Regardless of soil moisture, faba bean was the dominant species and maize was the inferior one. Low soil moisture promoted the contribution of SE to productivity (P < 0.05). In contrast, high moisture turned to lower the competition intensity of faba bean against maize and accordingly promote the transformation of biodiversity effect from SE to CE. The main mechanism was that the water competition imposed by faba bean strips on maize ones decreased the NE through reducing photosynthetic rate and water use efficiency of maize. Conclusion: The adaptive transitions of interspecific relationship and the biodiversity effect were driven by soil water availability. This novel phenomenon should be emphasized in the crop diversity management of intercropping system in the rainfed region. [ABSTRACT FROM AUTHOR]

[Display omitted] • High plastic footprint reduced photosynthetic C storage, regardless of degradability. • C emission intensity increased for elevated C source combined with reduced C sinks. • Decreased soil aggregate stability and net C rhizodeposition reduce soil C sinks. • High plastic footprint deteriorated C footprint for lower permanent C sequestration. Plastic fragments are widely found in the soil profile of terrestrial ecosystems, forming plastic footprint and posing increasing threat to soil functionality and carbon (C) footprint. It is unclear how plastic footprint affects C cycling, and in particularly permanent C sequestration. Integrated field observations (including 13C labelling) were made using polyethylene and polylactic acid plastic fragments (low-, medium- and high-concentrations as intensifying footprint) landfilling in soil, to track C flow along soil–plant-atmosphere continuum (SPAC). The result indicated that increased plastic fragments substantially reduced photosynthetic C assimilation (p < 0.05), regardless of fragment degradability. Besides reducing C sink strength, relative intensity of C emission increased significantly, displaying elevated C source. Moreover, root C fixation declined significantly from 21.95 to 19.2 mg m−2, and simultaneously root length density, root weight density, specific root length and root diameter and surface area were clearly reduced. Similar trends were observed in the two types of plastic fragments (p > 0.05). Particularly, soil aggregate stability was significantly lowered as affected by plastic fragments, which accelerated the decomposition rate of newly sequestered C (p < 0.05). More importantly, net C rhizodeposition declined averagely from 39.77 to 29.41 mg m−2, which directly led to significant decline of permanent C sequestration in soil. Therefore, increasing plastic footprint considerably worsened C footprint regardless of polythene and biodegradable fragments. The findings unveiled the serious effects of plastic residues on permanent C sequestration across SPAC, implying that current C assessment methods clearly overlook plastic footprint and their global impact effects. [ABSTRACT FROM AUTHOR]

Extensive studies have been conducted on the impacts of plastic film residue on crop productivity in dryland agriculture. However, the relevant results were inconsistent or even opposite, which was most probably affected by both the size and concentration of residual films. To clarify this issue, a three-year (2019–2021) field experiment was conducted to examine plastic residue landfill effects on maize productivity using three sizes (0.4 × 0.4 cm2 (small), 4 × 4 cm2 (medium), and 10 × 10 cm2 (large)) under the low and high addition concentrations in an irrigated maize field. The data indicated that medium-sized residues significantly reduced maize yield by 7.3% and 13.8% in low and high addition levels respectively, relative to non-landfill group (CK) (p < 0.05). Large and small-sized residues under low level had no significant impact on yield (p > 0.05), while high amounts of small residues turned to positively influence yield. This trend was closely correlated with soil temperature, soil moisture, key enzyme activities, macroaggregate proportion, soil organic carbon and total nitrogen contents. Structural equation modelling and relative importance analyses demonstrated soil hydrothermal (27.4%), soil nitrogen (22.0%), and physical properties (21.1%) as primary drivers. A general trend was that the sizes of residues showed evidently greater impacts than their addition levels. Moreover, medium residues showed negative effects, while large and small ones had neutral or positive effects. For the first time, our findings confirmed the size- and concentration-dependent effects of plastic residues on crop productivity and provided a novel insight into plastic film pollution assessment & management in agricultural ecosystems. • Medium plastic residues evidently reduced maize yield across the concentrations. • Large and small plastic ones turned to neutrally and positively affect maize yield. • Soil hydrothermal and nutrient status were affected by residue size & concentration. • Residue size showed greater impacts on maize productivity than its concentration. • This study filled knowledge gap in understanding plastic residue production effect. [ABSTRACT FROM AUTHOR]

Reducing the yield loss of inferior crop species is crucial for improving the production of intercropping systems, particularly in drought-prone regions. Yet, the physiological mechanism of yield loss caused by interspecific competition in response to soil water availability is unclear. A two-year (2018–2019) field experiment was conducted to explore the impacts of interspecific competition on yield formation of the inferior crop in the maize-faba bean intercropping system with and without plastic film mulching in a semiarid rainfed region. The plant-water relation, and yield formation in association with nitrogen (N) remobilization were determined and compared. Results indicated that the land equivalent ratio of the intercropping system was greater than 1, regardless of whether treated with plastic mulching. However, the net effect of the intercropping system was significantly greater than 0 only under plastic mulching. Intercropping with faba beans prolonged the anthesis-silking interval of maize by 93.7% (p < 0.05) and the bald tip length by 56.2% (p < 0.05). This trend resulted in insufficient pollination of tassels and an increased kernel abortion rate in maize (p < 0.05). Moreover, the amount of dry matter and N transfer to grain in vegetative organs decreased by 34.0% and 23.2% (p < 0.05), respectively. Physiologically, this brought about yield loss in the intercropped maize. Water competition from faba bean significantly reduced the soil water availability in the intercropped maize strips, regardless of whether treated with plastic mulching. However, plastic mulching alleviated the competition for water between faba bean and maize, and thus kernel abortion in maize was significantly reduced. Our findings reveal the physiological mechanism of yield loss in intercropped inferior species, by connecting kernel formation and remobilization function, in the semi-arid and rainfed intercropping systems. Specific water or nutrient management strategies might be needed for inferior crops to further improve the total productivity of cereal-legume intercropping system in drought-prone environments. [Display omitted] • The yield loss mechanism of inferior crops in legume-based intercropping system is unclear. • Growth loss of maize in cogrowth period cannot be compensated in late seed filling period. • Water competition lowered remobilization function and increased kernel abortion of maize. • Plastic mulching (PM) weakened plant competition and conducive to maize final yield formation. • PM is a promising option to improve the productivity of intercropping system in rainfed regions. [ABSTRACT FROM AUTHOR]