Jun Fan

Understanding whether soil carbon accumulation coincides with yield benefits is essential for sustainable dryland agriculture. We used a 21-year field experiment on the Loess Plateau to compare conventional tillage (CT) and no-tillage (NT), each combined with no mulching (NM), straw mulching (SM), or plastic-film mulching (PM). Surface-soil carbon fractions, plant and microbial biomarkers, microbial communities, extracellular enzyme activities, and maize grain yield were assessed. Relative to NM, SM increased soil organic carbon (SOC) concentration by 19% under CT and 26% under NT, primarily through particulate organic carbon (POC) accumulation, with no significant increase in mineral-associated organic carbon (MAOC). POC increases co-occurred with lignin-phenol enrichment, while fungal and total microbial necromass carbon increased under NT. No-tillage supported greater bacterial and fungal biomass, and microbial community composition differed among mulching treatments. Enzyme vector angles remained below 45°, consistent with greater relative investment in nitrogen than phosphorus acquisition. Plastic-film mulching increased grain yield under both tillage systems, but decreased SOC by 7% under CT and increased it by 6% under NT. No-tillage with straw mulching maintained the highest SOC concentration and belonged to the highest-yielding group. These findings show that yield benefits can accompany contrasting carbon-pool responses. Sustained straw inputs combined with reduced disturbance favored surface-soil SOC accumulation, mainly through increased POC, while supporting high maize productivity in the sampling year.

Critical soil suctions of plant‐available water (PAW), including the soil water suction at field capacity ( h _FC ), threshold suction ( h _threshold ), tipping suction ( h _tipping ), and permanent wilting point ( h _PWP ). Existing research has confirmed that the hydraulic parameters of different soil textures should not have a single value. Selecting “representative” data to parameterize the deterministic soil critical suction is subjective and biased. Therefore, accurately obtaining the key critical suctions with different textures is crucial for assessing water absorption by crops under drought stress. This study examined soybean responses to progressive drought, focusing on leaf gas exchange and soil water suction. Soybeans were grown until the third pair of true leaves in four soils (heavy sandy, sandy loam, sandy silt, and medium clay) before being subjected to progressive drought. Only h _FC of heavy sandy soil meets 100 cm, and h _PWP of medium clay is approximately 15,000 cm, while all other soils do not conform to the classic values. The h _threshold of medium clay is higher than that of sandy loam and sandy silt. The h _tipping for sandy loam, sandy silt, and medium clay are similar, being two to three times greater than that of heavy sandy soil. The lower threshold ( g _s = 0) for PAW characterizing gas exchange aligns well with the actual permanent wilting point, while the upper threshold ( g _s = 0.9) does not accurately reflect the actual field capacity. The PAW at the four critical soil suctions varies with soil texture. Overall, the assessment of plant stomata response to drought across various soils has clarified the key suctions for different textures.

Understanding how cultivated xerophytic shrubs physiologically regulate canopy water loss under anomalously wet conditions is crucial for predicting ecohydrological responses and for providing practical guidance in landscape restoration under the ongoing warming–wetting trend on the northern Loess Plateau. This study tested hypotheses concerning the hierarchy of atmospheric and soil-water controls on canopy transpiration (E_c), stomatal conductance (g_s), the strength of canopy–atmosphere coupling, and species-specific soil-water sensitivities and water-use strategies in Caragana korshinskii and Salix psammophila. Concurrent measurements of branch-level sap flow, meteorological variables, and soil water content (SWC) at multiple depths were conducted in two adjacent stands during the wet season of a climatically wet year (July–September 2017). Meteorological factors, particularly vapor pressure deficit (VPD), were the dominant drivers of daily E_c and g_s, whereas SWC exerted secondary but species-specific influences. Both shrubs were strongly coupled to the atmosphere, with consistently low decoupling coefficients (Ω ≈ 0.11–0.15) on daily scales. C. korshinskii maintained stable water use through access to deeper soil, whereas S. psammophila responded sensitively to fluctuations in shallow SWC. These contrasting patterns indicate depth-partitioned water-use strategies and a context-dependent continuum between isohydric and anisohydric behavior rather than fixed species traits. The findings support improved parameterization of shrub water use in ecohydrological models, more effective water-use management, and informed species selection and nursery practices for landscape restoration in semi-arid regions experiencing warming–wetting climatic shifts.

Most physicochemical properties of soil organic matter (SOM) enhancement are related to soil structure. In poorly structured sandy soil, modifying the mechanical composition may be a prerequisite for effective SOM management and crop yield improvement. This study investigated the effects of organic materials and introduced clay (Quaternary red clay soil with 38.5% clay) on soil water dynamics, maize growth, root morphology, and water use efficiency (WUE) in a sandy field soil (4.3% clay). The treatments included: control (CK), biochar addition (BC), lignite organic fertilizer addition (LG), and biochar and lignite organic fertilizer combined with introduced clay (BCR, LGR). Compared with CK, organic amendments alone (BC, LG) increased the silt + clay content (SC) and SOM content by 4.3%–5.8% and 5.3–9.2 g kg ⁻¹ in the 0–20 cm soil layer ( p < 0.05), and improved grain yield (GY) and WUE by 19%–37% (1428–3312 kg ha ⁻¹ , p < 0.05) and 19%–41% (3.3–6.8 kg ha ⁻¹ mm ⁻¹ , p < 0.05). The introduced clay (BCR, LGR) showed larger improvements: SC and SOM increased by 19.4%–21.2% and 7.0–11.0 g kg ⁻¹ , and GY and WUE increased by 2385–5016 kg ha ⁻¹ and 4.1–9.5 kg ha ⁻¹ mm ⁻¹ . Additionally, volumetric water content (VWC) was significantly linearly correlated with SC and SOM content ( p < 0.05). Sandy soil with an SC of around 16% exhibited reduced SOM decomposition and stable GY. PLS‐PM analysis indicated that WUE was mediated by VWC as an intermediate variable, whereas organic amendments alone had a limited direct impact on VWC. The synergistic organic‐clay co‐amendment provides a feasible long‐term strategy for the sustainable development of sandy farmland.

Coarse soil has a poor structure and is susceptible to wind and water erosion, thereby making it difficult to maintain the soil organic carbon (SOC) content. Woody peat (WP) is an organic material that can increase the SOC content of the soil, while clay materials can rapidly enhance the capacity for soil aggregate formation. In order to explore the synergistic effects of WP and clay materials (bentonite and red clay) on the aggregate structure and hydro‐physical properties of coarse soil, as well as the mechanism associated with SOC mineralization (ΔSOC), we conducted an incubation study using lou soil (L0) and loessial soil (H0) with three treatments: addition of WP alone (LW, HW), mixture of WP and bentonite (LWB, HWB), and mixture of WP and red clay (LWR, HWR). The three treatments enhanced the proportion of macroaggregate (> 2 mm) and aggregate stability of the two soils, and optimized the water retention and ventilation performance. The highest aggregate stability of LWB and HWB can be attributed to the positive synergistic effect of WP and bentonite, and bentonite was more effective than red clay due to its crystal structure. The results also showed that the ΔSOC values were significantly lower under LWB and HWB than those under WP addition alone and adding the mixture of WP and red clay (p < 0.05). Moreover, partial least squares path modeling analysis showed that the hydro‐physical properties of the two improved soils inhibited SOC mineralization (p > 0.05), whereas particulate organic carbon (POC) content significantly accelerated SOC mineralization (p < 0.01). The synergistic effect of clay materials increased mineral‐associated organic carbon (MAOC), which was beneficial to maintain the long‐term effectiveness of WP. Overall, our results demonstrated that the synergistic use of WP and bentonite enhanced the aggregate stability and hydro‐physical properties of coarse soil and improved SOC storage capacity. These results provide scientific and theoretical guidance to facilitate the rapid improvement of coarse soil through engineering measures in arid and semi‐arid areas with water and fertilizer limitations.

Film mulching and biochar have been applied as effective measures for increasing crop yields in arid and semi‐arid areas for many years. However, the effects of the temporal and spatial distributions of soil hydrothermal properties on crop yields are still unclear under film mulching and biochar addition. Thus, we conducted a field experiment with winter wheat on the Loess Plateau of China for two years (2020–2022) with three treatments: control, film mulching, and biochar. The results demonstrated that film mulching and biochar addition increased the average soil temperature in the 0–50 cm soil depth throughout the whole growth period and the influence depth exceeded 50 cm. Biochar addition only significantly increased soil temperature in the overwintering stage ( p < 0.05). Film mulching increased the maximum and minimum temperatures in the 0–50 cm soil depth at seedling stage. Film mulching and biochar increased average ≥10°C accumulated soil temperature by increasing the ≥10°C accumulated soil temperature in the daytime and nighttime, and the number of days with a daily soil temperature ≥10°C during the whole growth period. Film mulching improved soil water storage in the 0–300 cm soil depth in each growth stage during both years, and also increased the wheat grain yield, aboveground biomass, and water use efficiency. Biochar addition increased the wheat grain yield and aboveground biomass of two years compared with control, but the increases were not significant ( p > 0.05). In addition, correlation analysis showed that adequate temperatures in the 0–50 cm soil depth during the seedling and overwintering stages, and suitable soil moisture conditions in the 0–300 cm soil depth before sowing, jointing, and filling stages were important factors for increasing wheat grain yields under film mulching. In summary, film mulching mainly regulated the soil temperature in the 0–50 cm soil depth and moisture conditions in the 0–300 cm soil depth during different growth stages to increase grain yields. Film mulching has more obvious effects on moisture regulation, temperature regulation, and yield increases than biochar addition. Some environmentally friendly measures (such as conservation agriculture) with the same yield improving effect as mulching are also recommended to explore and promote in theLoess Plateau region.