Pedosphere最新文献

The Institute of Soil Science, Chinese Academy of Sciences (ISSAS) was founded in 1953. The institute aims to solve the problems of agricultural development, ecological conservation, and environmental protection and to promote the development of soil science.

Salt marshes are an important blue carbon ecosystem, with surprisingly fast carbon accumulation rates that are 40 times higher than those of terrestrial forests. In recent decades, salt marshes have suffered great degradation and loss all over the world. The idea to enhance carbon stock in salt marshes (so-called blue carbon) using biochar (so-called black carbon) has recently been proposed. Although experiments and observations remain limited, significant enhancements in soil organic carbon and plant growth have been documented in most case studies. However, due to the limited number of observations and their relatively short time window ranging from months to less than one year, there still exists a knowledge gap regarding the process, mechanism, and effect of biochar in enhancing carbon stock in salt marshes. Future research is urgently needed in the following perspectives: 1) exploring the relationship between carbon stock enhancement efficiency and biochar properties, 2) optimizing the physical and chemical properties of biochar to boost its efficiency, and 3) studying the in-situ responses of complex carbon pools to biochar addition, especially under tidal conditions and over a longer period of time.

Soil phosphorus (P) plays a vital role in both ecological and agricultural ecosystems, where total P (TP) in soil serves as a crucial indicator of soil fertility and quality. Most of the studies covered in the literature employ a single or narrow range of soil databases, which largely overlooks the impact of utilizing multiple mapping scales in estimating soil TP, especially in hilly topographies. In this study, Fujian Province, a subtropical hilly region along China's southeast coast covered by a complex topographic environment, was taken as a case study. The influence of the mapping scale on soil TP storage (TPS) estimation was analyzed using six digital soil databases that were derived from 3 082 unique soil profiles at different mapping scales, i.e., 1:50 000 (S5), 1:200 000 (S20), 1:500 000 (S50), 1:1 000 000 (S100), 1:4 000 000 (S400), and 1:10 000 000 (S1000). The regional TPS in the surface soil (0–20 cm) based on the S5, S20, S50, S100, S400, and S1000 soil maps was 20.72, 22.17, 23.06, 23.05, 22.04, and 23.48 Tg, respectively, and the corresponding TPS at 0–100 cm soil depth was 80.98, 80.71, 85.00, 84.03, 82.96, and 86.72 Tg, respectively. By comparing soil TPS in the S20 to S1000 maps to that in the S5 map, the relative deviations were 6.37%–13.32% for 0–20 cm and 0.33%–7.09% for 0–100 cm. Moreover, since the S20 map had the lowest relative deviation among different mapping scales as compared to S5, it could provide additional soil information and a richer soil environment than other smaller mapping scales. Our results also revealed that many uncertainties in soil TPS estimation originated from the lack of detailed soil information, i.e., representation and spatial variations among different soil types. From the time and labor perspectives, our work provides useful guidelines to identify the appropriate mapping scale for estimating regional soil TPS in areas like Fujian Province in subtropical China or other places with similar complex topographies. Moreover, it is of tremendous importance to accurately estimate soil TPS to ensure ecosystem stability and sustainable agricultural development, especially for regional decision-making and management of phosphate fertilizer application amounts.

For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar, and maize straw biochar (MSB) for an entire growth period of winter wheat. Compared with no biochar control (CK), application of the three types of biochar significantly (P < 0.01) reduced grain PAH concentration, total equivalent concentration (TEC), and incremental lifetime cancer risk (ILCR), indicating that biochar application, especially MSB, reduced the risk of exposure to PAHs in wheat grain. Furthermore, all three types of biochar significantly (P < 0.05) reduced PAH uptake and accumulation in wheat roots and stems, probably because biochar application enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly (P < 0.05) reduced the concentration of PAHs in the rhizosphere soil by 15.9%–33.7%. It was found that the degradation rate of high-molecular-weight (HMW) PAHs (5- and 6-ring PAHs) was significantly (P < 0.05) higher than that of low-molecular-weight (LMW) PAHs (2–4-ring PAHs) regardless of the type of biochar used. Additionally, all three types of biochar significantly increased the relative abundance of the dominant bacterial phyla and genera in soil. Redundancy and correlation analyses also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. This study indicated that biochar effectively reduced the health risk from dietary exposure to PAHs in wheat grains by increasing the abundance of bacteria related to PAH degradation, promoting the biodegradation of PAHs in the rhizosphere soil, and consequently reducing PAH uptake by wheat.

Soil biota play a crucial role in soil ecosystem stability, promoting organic matter decomposition and nutrient cycling. Compared to conventional farming, organic farming is known to improve soil properties such as aggregation. Despite the importance of soil microbial communities in soil biogeochemical processes, our knowledge of their dynamics is rudimentary, especially under different agricultural management practices. Here we studied the effects of vineyard management practices (conventional and organic) and soil aggregate fractions (micro-, meso-, and macroaggregates) on free-living soil nematodes. The abundance, diversity, and ecological indices, such as the Wasilewska index and trophic diversity, of free-living soil nematodes were determined. We found that the abundance of free-living soil nematodes was increased by organic farming. In addition, plant parasites were found to increase in macroaggregates in the organic plot, which may be attributed to the weeds present due to no-tillage and no herbicides. Nematode family network connectivity increased in complexity with increasing aggregate size, highlighting the importance of the interplay between nematodes and soil inter-aggregate pore size and connectivity.

Soil bulk density (BD) is an important physical property and an essential factor for weight-to-volume conversion. However, BD is often missing from soil databases because its direct measurement is labor-intensive, time-consuming, and sometimes impractical, particularly on a large scale. Therefore, pedotransfer functions (PTFs) have been developed over several decades to predict BD. Here, six previously revised PTFs (including five basic functions and stepwise multiple linear regression (SMLR)) and two new PTFs, partial least squares regression (PLSR) and support vector machine regression (SVMR), were used to develop BD-predicting PTFs for coastal soils in East China. Predictor variables included soil organic carbon (SOC) and particle size distribution (PSD). To compare the robustness and reliability of the PTFs used, the calibration and prediction processes were performed 1 000 times using the calibration and validation sets divided by a random sampling algorithm. The results showed that SOC was the most important predictor, and the revised PTFs performed reasonably although only SOC was included. The PSD data were useful for a better prediction of BD, and sand and clay fractions were the second and third most important properties for predicting BD. Compared to the other PTFs, the PLSR was shown to be slightly better for the study area (the average adjusted coefficient of determination for prediction was 0.581). These results suggest that PLSR with SOC and PSD data can be used to fill in the missing BD data in coastal soil databases and provide important information to estimate coastal carbon storage, which will further improve our understanding of sea-land interactions under the conditions of ongoing global warming.

Ammonia-oxidizing archaea (AOA) are important in converting ammonia into nitrate in soils. While many aspects of their community structure have been studied, the relative importance of stochastic versus deterministic processes has poorly been understood. We compared AOA communities across the North China Plain, targeting the amoA gene. A phylogenetic null modelling approach was used to calculate the beta nearest taxon index to quantify the influence of stochastic and deterministic processes. We found that spatial distance between samples predicted the perceived processes involved in community structuring, with stochastic processes dominating at local scales. At greater distances, stochasticity became weaker. However, soil pH, which was also the strongest determinant of AOA community, was a much stronger predictor of community structuring, leaving the distance effect redundant as an explanation of community structuring processes. The communities of AOA differing by less than 1 pH unit differed mainly stochastically in terms of operational taxonomic unit composition. At larger pH differences, deterministic processes based on heterogeneous selection between clades became increasingly dominant. It appears that AOA community composition is largely determined by the environment. However, very similar pH environments are the exception. In environments with very close pH values, stochastic effects dominantly cause differences in community composition, whether spatially near or far.

Halosulfuron methyl is a sulfonylurea herbicide used worldwide for weed control in sugarcane, maize, wheat, and rice production. Considering its environmental impact, this study evaluated the effects of soil type, application rate, and temperature on the dynamics of halosulfuron methyl degradation. Additionally, as soil microbes and enzymes are reliable indicators of the impacts of anthropogenic activities on soil health, the effects of halosulfuron methyl on soil enzymatic and microbial activities were also assessed. The half-life (DT₅₀) of halosulfuron methyl varied from 9.38 to 33.77 d. Increase in temperature accelerated the degradation and DT₅₀ varied from 14.39 to 33.77, 11.05 to 28.94, and 9.38 to 25.41 d at 5, 15, and 25 °C, respectively. The metabolites of halosulfuron methyl, including halosulfuron, methyl 3-chloro-5-((4,6-dimethoxy-2-pyrimidinyl) amino)-1-methyl-1H-pyrazole-4-carboxylate, 4,6-dimethoxy-2-pyrimidinamine, and methyl 3-chloro-1-methyl-5-sulfamoyl-1H-pyrazole-4-carboxylate, were detected in the studied soils, and their appearance and disappearance varied with application rate, soil type, and incubation temperature. Halosulfuron methyl had transitory harmful effects on soil enzymatic and microbial activities depending on its application rate. The results suggest that the application rate of halosulfuron methyl, soil physicochemical parameters, and temperature should be considered together to ensure satisfactory weed control with reduced environmental risk.