Publications

Soil organic matter (SOM) and enzymes are essential for nutrient cycling, and are considered as important indicators of soil quality. The effects of organic and mineral fertilization on soil organic carbon (SOC), total nitrogen (TN) and enzyme activities in bulk soil and particle-size fractions were investigated under a winter wheat/maize cropping system in the North China Plain. The experiment established in 1993 includes three treatments: (1) unfertilized control (CK); (2) mineral fertilizers (MF); and (3) farmyard manure (FYM). Application of FYM significantly increased SOC and TN contents and activities of six enzymes: invertase, β-glucosidase, urease, acid and alkaline phosphatases and dehydrogenase in bulk soil and in all particle-size fractions as compared to those in MF and CK. Highest contents of SOC and TN were found in coarse sand and lowest in the silt fraction. The C/N ratios decreased with decreasing particle-size fractions. β-Glucosidase and acid phosphatase activities predominated in coarse sand fraction, reflecting high substrate availability. The urease activity was highest in clay-size fractions, depending on mineral sorption processes. The SOM and enzyme activities in the coarse sand were the most sensitive to fertilization. The smallest response of SOM in the clay fraction to fertilization confirmed that SOM on clay is the most stable C pool. The 15-year fertilization experiment clearly showed that FYM represented the best management practice for improving soil quality and microbial activity.

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Paddy soils, a type of Hydragric Anthrosol, have much greater soil organic C (SOC) and total N (TN) contents than that in upland soils. However, this fact has never been generalized or mechanistically explained. We conducted a global meta-analysis on the organic C and total N contents and their stocks in continuous paddy soils (578 sites) and compared them with those in adjacent upland soils. Average C stocks up to depths of 35 cm in upland and paddy soils were 31 and 47 Mg C ha−1, respectively. The N stocks in upland and paddy soils were 2.2 and 3.2 Mg N ha−1, respectively. The combined effects of mean annual temperature and precipitation showed that C and N stocks in paddy and upland soils are generally the largest under cool and humid conditions and the smallest in warm and dry climates. Quantitative analysis of climatic, and soil physical and chemical factors showed that 1) climate effects are weakened by management such as puddling and flooding, thereby increasing the importance of soil physico-chemical properties, which control soil organic matter (SOM) stabilization, and 2) climate (e.g., mean annual precipitation) mainly affects C and N stocks in upland soils; the chemical properties (such as pH), on the other hand, primarily affect C and N stocks in paddy soils. Greater C and N stocks in paddy soils are the result of 1) a larger input of organic C by rice than by most upland cereals, 2) slower decomposition of plant residues and SOM under anoxic conditions, and 3) a greater importance of sesquioxides in the biochemical stabilization of SOM. We conclude that these man-made paddy soils store more organic C and N than their upland neighbors despite long-term and intensive management.

The effects of fertilization on activity and composition of soil microbial community depend on nutrient and water availability; however, the combination of these factors on the response of microorganisms was seldom studied. This study investigated the responses of soil microbial community and enzyme activities to changes in moisture along a gradient of soil fertility formed within a long-term (24 years) field experiment. Soils (0–20 cm) were sampled from the plots under four fertilizer treatments: i) unfertilized control (CK), ii) organic manure (M), iii) nitrogen, phosphorus, and potassium fertilizers (NPK), and iv) NPK plus M (NPK + M). The soils were incubated at three moisture levels: constant submergence, five submerging-draining cycles (S-D cycles), and constant moisture content at 40% water-holding capacity (low moisture). Compared with CK, fertilization increased soil organic carbon (SOC) by 30.1%–36.3%, total N by 27.3%–38.4%, available N by 35.9%–56.4%, available P by 61.4%–440.9%, and total P by 28.6%–102.9%. Soil fertility buffered the negative effects of moisture on enzyme activities and microbial community composition. Enzyme activities decreased in response to submergence and S-D cycles versus low moisture. Compared with low moisture, S-D cycles increased total phospholipid fatty acids (PLFAs) and actinomycete, fungal, and bacterial PLFAs. The increased level of PLFAs in the unfertilized soil after five S-D cycles was greater than that in the fertilized soil. Variations in soil microbial properties responding to moisture separated CK from the long-term fertilization treatments. The coefficients of variation of microbial properties were negatively correlated with SOC, total P, and available N. Soils with higher fertility maintained the original microbial properties more stable in response to changes in moisture compared to low-fertility soil.

No abstract is provided for this article.

No abstract is provided for this article.

Deforestation poses a global threat to biodiversity and its capacity to deliver ecosystem services. Yet, the impacts of deforestation on soil biodiversity and its associated ecosystem services remain virtually unknown. We generated a global dataset including 696 paired-site observations to investigate how native forest conversion to other land uses affects soil properties, biodiversity, and functions associated with the delivery of multiple ecosystem services. The conversion of native forests to plantations, grasslands, and croplands resulted in higher bacterial diversity and more homogeneous fungal communities dominated by pathogens and with a lower abundance of symbionts. Such conversions also resulted in significant reductions in carbon storage, nutrient cycling, and soil functional rates related to organic matter decomposition. Responses of the microbial community to deforestation, including bacterial and fungal diversity and fungal guilds, were predominantly regulated by changes in soil pH and total phosphorus. Moreover, we found that soil fungal diversity and functioning in warmer and wetter native forests is especially vulnerable to deforestation. Our work highlights that the loss of native forests to managed ecosystems poses a major global threat to the biodiversity and functioning of soils and their capacity to deliver ecosystem services.

Paddy soils make up the largest anthropogenic wetlands on earth, and are characterized by a prominent potential for organic carbon (C) sequestration. By quantifying the plant- and microbial-derived C in soils across four climate zones, we identified that organic C accrual is achieved via contrasting pathways in paddy and upland soils. Paddies are 39%-127% more efficient in soil organic C (SOC) sequestration than their adjacent upland counterparts, with greater differences in warmer than cooler climates. Upland soils are more replenished by microbial-derived C, whereas paddy soils are enriched with a greater proportion of plant-derived C, because of the retarded microbial decomposition under anaerobic conditions induced by the flooding of paddies. Under both land-use types, the maximal contribution of plant residues to SOC is at intermediate mean annual temperature (15-20°C), neutral soil (pH~7.3), and low clay/sand ratio. By contrast, high temperature (~24°C), low soil pH (~5), and large clay/sand ratio are favorable for strengthening the contribution of microbial necromass. The greater contribution of microbial necromass to SOC in waterlogged paddies in warmer climates is likely due to the fast anabolism from bacteria, whereas fungi are unlikely to be involved as they are aerobic. In the scenario of land-use conversion from paddy to upland, a total of 504 Tg C may be lost as CO

Summary Liquid crystal monomers (LCMs), the integral components in the manufacture of digital displays, have engendered environmental concerns due to extensive utilization and intensive emission. Despite their prevalence and ecotoxicity, the LCM impacts on plant growth and agricultural yield remain inadequately understood. In this study, we investigated the specific response mechanisms of tobacco, a pivotal agricultural crop and model plant, to four representative LCMs (2OdF3B, 5CB, 4PiMeOP, 2BzoCP) through integrative molecular and physiological approaches. The findings reveal specific impacts, with 4PiMeOP exerting the most pronounced effects, followed by 2BzoCP, 5CB, and 2OdF3B. LCM exposure disrupts the photosynthetic apparatus, exacerbating reactive oxygen species (ROS) levels in leaves, which in turn triggers the upregulation of antioxidative enzymes and the synthesis of antioxidant substances. Additionally, LCMs strongly stimulate the expression of genes involved in abscisic acid (ABA) biosynthesis and signalling pathways. The AI‐assisted meta‐analysis implicates ABA as a critical regulator in the tobacco response to LCMs. Notably, exogenous application of ABA alleviates LCM‐induced toxicities, highlighting the pivotal role of ABA in stress amelioration. Our study provides novel insights into the toxicity and tolerance mechanisms of LCMs in plants, shedding light on both their harmful effects on the ecosystems and potential adaptation responses. This is crucial to develop sustainable agricultural systems by reducing the negative environmental impacts caused by emerging organic pollutants.

No abstract is provided for this article.