The phosphorus export coefficients variability of specific land-use and the threshold response relationship with watershed characteristics in a subtropical hilly region.

The magnitude of land-use phosphorus (P) export in subtropical hilly watersheds is subject to the collective influence of various watershed characteristics. However, the spatiotemporal dynamics of key watershed characteristics and their impacts on P exports remain unclear. Total phosphorus export coefficients (TPECs) can quantify the contribution of different land-use types to P exports.

Freshwater snails (Bellamya aeruginosa) bioturbation to enhance nitrogen removal and associated mechanism in constructed wetlands.

In this study, total nitrogen (TN) removal efficiency of Pontederia cordata and Myriophyllum elatinoides in surface flow constructed wetlands (SFCWs) with Bellamya aeruginosa were 6.43% and 3.54% higher, respectively, than those in non-B.

Contrasting responses of gross N transformation to oxalic acid and glucose supplement in paddy soil.

Labile organic carbon (C) substrates could accelerate microbial transformation of soil N pool by stimulating the decomposition of large molecule organic N. However, it remains unclear how gross N transformation processes (protein depolymerization, amino acid uptake, microbial N mineralization and NH-N uptake rates) in response to individual C substrates. Typical paddy soil was incubated with the supplement of oxalic acid or glucose under simulated field water conditions for 16 days to assess the gross N transformation rates by N pool dilution assays.

Vegetation restoration enhancing soil carbon sequestration in karst rocky desertification ecosystems: A meta-analysis.

Vegetation restoration measures have been increasingly employed to alleviate rocky desertification in karst ecosystems. However, the comprehensive effects of these interventions on soil properties and soil organic carbon (SOC) remain poorly understood. Herein, we gathered 644 paired observations from 68 studies and conducted a meta-analysis to quantify the performance of different vegetation restoration measures including moss (MS), grassland (GL), cash crop (CP), shrub (SH), and secondary forest (SF) through soil properties and SOC.

[Multi-time Scale Variation of Atmospheric Ammonia Concentration and Dry Deposition in a Paddy Rice Region in Subtropical China].

Meteorological factors and anthropogenic activities significantly affect atmospheric ammonia （NH） concentration and its dry deposition. Former studies have examined the spatial and temporal variability in atmospheric NH concentrations at monthly scales. However, the characteristics of atmospheric concentrations at finer time scales such as hourly and daily scales and the influencing factors remain unclear.

Removal efficiency and abundance of nitrogen cycling microorganism in three bio-matrix materials to treat swine wastewater.

A bio-matrix material (BMM) system is used to pretreat swine wastewater and reduce the nitrogen (N) concentration to the tolerance range of plants in constructed wetlands. In this study, rice straw (RS), wheat straw (WS), and corn stalk (CS) were applied to treat pollutants from swine wastewater, respectively. This one year-long field experiment make up for the lack of long-term experiments and mechanistic investigations of BMM.

Rocky desertification succession alters soil microbial communities and survival strategies in the karst context.

Rocky desertification is one of the most ecological problems in the karst context. Although extensive research has been conducted to explore how to restore and protect, the responses of soil fungi and archaea to rocky desertification succession remain limited. Here, four grades of rocky desertification in a karst ecosystem were selected, amplicon sequencing analysis was conducted to investigate fungal and archaeal community adaptation in response to rocky desertification succession.

Response of bacterial and micro-eukaryotic communities to spatio-temporal fluctuations of wastewater in full scale constructed wetlands.

How microbial communities respond to wastewater fluctuations is poorly understood. Full-scale surface flow constructed wetlands (SFCWs) were constructed for investigating microbial communities. Results showed that influent wastewater changed sediment bacterial community composition seasonally, indicating that a single bacterial taxonomic group had low resistance (especially, Actinobacteriota and Gammaproteobacteria).

The deterioration of starch physiochemical and minerals in high-quality indica rice under low-temperature stress during grain filling.

Low temperatures during the grain-filling phase have a detrimental effect on both the yield and quality of rice grains. However, the specific repercussions of low temperatures during this critical growth stage on grain quality and mineral nutrient composition in high-quality hybrid indica rice varieties have remained largely unexplored. The present study address this knowledge gap by subjecting eight high-quality indica rice varieties to two distinct temperature regimes: low temperature (19°C/15°C, day/night) and control temperature (28°C/22°C) during their grain-filling phase, and a comprehensive analysis of various quality traits, with a particular focus on mineral nutrients and their interrelationships were explored.

Intensive N fixation accelerates microbial turnover in cropland soils.

Biological nitrogen fixation (BNF) is strongly affected by the carbon (C) and nitrogen (N) stoichiometry in soil and depends on the input of organic C. Due to the high metabolic costs of nitrogenase activity, however, the response of BNF to organic C input and its impact on microbial turnover remain unclear. To address this knowledge gap, we combined N tracing with high-throughput sequencing by adding glucose or glucose plus mineral N fertilizer for a 12-day incubation in three cropland soils.

Comparative Effects of Heat Stress at Booting and Grain-Filling Stage on Yield and Grain Quality of High-Quality Hybrid Rice.

Rice plants are highly sensitive to high-temperature stress, posing challenges to grain yield and quality. However, the impact of high temperatures on the quality of high-quality hybrid rice during the booting stage, as well as the differing effects of the booting and grain-filling stages on grain quality, are currently not well-known. Therefore, four high-quality hybrid rice were subjected to control (CK) and high-temperature stress during the booting (HT1) and grain-filling stages (HT2).

[Response of Organic Carbon Mineralization to Nitrogen Addition in Micro-aerobic and Anaerobic Layers of Paddy Soil].

In field conditions, a micro-aerobic layer with 1 cm thickness exists on the surface layer of paddy soil owing to the diffusion of dissolved oxygen via flooding water. However, the particularity of carbon and nitrogen transformation in this specific soil layer is not clear. A typical subtropical paddy soil was collected and incubated withC-labelled rice straw for 100 days.

Contrasting change trends in dry and wet nitrogen depositions during 2011 to 2020: Evidence from an agricultural catchment in subtropical Central China.

Over the past decade, China has experienced a decline in atmospheric reactive nitrogen (Nr) emissions. Given that China's subtropical region is a significant nitrogen (N) deposition hotspot, it is essential to accurately quantify the ten-year variations in dry and wet N depositions in the context of reductions in atmospheric Nr emissions. Here, we evaluated the spatiotemporal variation in N deposition on forest, paddy field and tea field ecosystems in a typical subtropical agricultural catchment from 2011 to 2020.

Leaching of soil legacy nitrogen in intact soil columns and significance of soil macropore structure.

Excessive application of chemical fertilizers accumulates nitrogen in soil (soil legacy nitrogen), and its release has a long-term impact on environmental quality. The information regarding leaching of soil legacy nitrogen and role of soil pore structure is scarce. Fifteen undisturbed soil cores with a depth of ~200 mm were collected from five paddy fields in a subtropical area of China, and soil pore structure was characterized with X-ray computed tomography.

Different in root exudates and rhizosphere microorganisms effect on nitrogen removal between three emergent aquatic plants in surface flow constructed wetlands.

Swine wastewater contains high concentration of nitrogen (N), causing pollution of surrounding water bodies. Constructed wetlands (CWs) are considered as an effective ecological treatment measure to remove nitrogen. Some emergent aquatic plants could tolerate high ammonia, and play a crucial part in CWs to treat high concentration N wastewater.

Effect of plant-self debris on nitrogen removal, transformation and microbial community in mesocosm constructed wetlands planted with Myriophyllum aquaticum.

Aquatic macrophytes debris decomposition could release pollutants and nutrients into the water of constructed wetlands (CWs), but their role in nitrogen removal and transformation remains poorly understood. The present study investigated the effects of plant-self debris on nitrogen removal and microbial communities in mesocosm CWs planted with Myriophyllum aquaticum. During the 68-day operation, the plant debris addition did not change the mean removal efficiency of ammonium (NH-N) and total nitrogen (TN) of CWs but showed significant differences over the operation time.

Impacts of organic materials amendment on the soil antibiotic resistome in subtropical paddy fields.

The organic material amendment has been proven to change the soil antibiotic resistance genes (ARGs) profile, which may threaten human health through the food chain, but the effects and mechanisms of different organic materials on ARGs in paddy soils are less explored. In this study, a field experiment was set up with the treatments of conventional chemical fertilization (NPK) and common organic material amendment [rice straw (RS), swine manure (SM), and biochar (BC)] to explore the effects and mechanisms. In total, 84 unique ARGs were found across the soil samples with different organic material amendments, and they conferred resistance to the major antibiotic classes.

Distinct effects of biochar addition on soil macropore characteristics at different depths in a double-rice paddy field.

Soil macropores largely control the water and nutrients transport as well as runoff processes in the soil. Biochar is frequently applied to soils to improve the macropore structure, but the effects remain controversial. To clarify depth-dependent soil macropore characteristics affected by biochar addition, the intact soil cores with a depth of 200 mm were collected from biochar-amended paddy field at addition rates of 0, 24, and 48 t ha (CK, BC1, and BC2, respectively).

[Effects of Chemical Fertilizer Reduction Combined with Straw Application on Diazotrophic Communities in a Double Rice Cropping System].

Based on a three-year field experiment, the effects of reduced chemical fertilizer combined with straw application on paddy yield, soil fertility properties, and community structure of diazotrophs in a double-rice cropping field three years after straw application were examined. Three treatments were applied:conventional fertilizer application (CF), chemical fertilizer reduction combined with a low straw application rate (CFLS, 3 t·hm), and a high straw application rate (CFHS, 6 t·hm). The results showed that CFLS and CFHS did not significantly reduce rice grain yield (>0.

[Annual Nitrogen Removal Efficiency and Change in Abundance of Nitrogen Cycling Microorganisms in Swine Wastewater Treated by Crop Straw Materials].

Based on previous research, using straw material to treat swine wastewater can effectively reduce the concentration of nitrogen (N); however, the annual N-removal efficiency and change in the abundance of N-cycling functional genes remain unclear. In this study, four treatments (wheat straw, rice straw, corn stalk, and CK) were set up, with the aim of studying the annual N-removal efficiency and change in the abundance of functional genes. Our results showed that:① the total nitrogen (TN) removal and NH-N removal efficiency were the best in the first six months and were significantly reduced in the following six months.

Multi-spatial scale effects of multidimensional landscape pattern on stream water nitrogen pollution in a subtropical agricultural watershed.

Multidimensional (coupled land use, soil properties, and topography) landscape effects on stream water nitrogen (N) are complex and scale-dependent. However, studies that identify critical buffer zones that explain large variations in riverine N, and estimate specific thresholds of multidimensional landscape patterns at the class level, result in a sudden changes in riverine N pollution, are still limited. Here, a new multidimensional landscape metric that combined land use, soil properties, and topography effects was applied to various riparian buffer zones and sub-watershed scales, and their relationships to riverine N levels were investigated.

Visualization and quantification of carbon "rusty sink" by rice root iron plaque: Mechanisms, functions, and global implications.

Paddies contain 78% higher organic carbon (C) stocks than adjacent upland soils, and iron (Fe) plaque formation on rice roots is one of the mechanisms that traps C. The process sequence, extent and global relevance of this C stabilization mechanism under oxic/anoxic conditions remains unclear. We quantified and localized the contribution of Fe plaque to organic matter stabilization in a microoxic area (rice rhizosphere) and evaluated roles of this C trap for global C sequestration in paddy soils.

[Effect of Long-term Straw Returning on the Mineralization and Priming Effect of Rice Root-carbon].

Long-term straw returning to the field changes the environmental conditions of rice paddy soil, which affects the mineralization and priming effect of residual rice roots in the soil, but the direction and intensity of its influence is not clear. Therefore, based on a long-term fertilization field experiment, C-CO isotopic labeling technology and laboratorial incubation were used to analyze the characteristics of mineralization of rice roots and native soil organic carbon, the intensity and direction of the priming effect, and the source partitioning of CO emissions in three treatments, consisting of no fertilization (CK), chemical fertilizer (CF), and straw returning with chemical fertilizer (CFS). The results showed that after 120 days of flooding incubation, the root residue (R) increased the cumulative CO emissions by 617.

Glutamine synthetase plays an important role in ammonium tolerance of Myriophyllum aquaticum.

High-strength ammonium (NH), the main characteristic of swine wastewater, poses a significant threat to the rural ecological environment. As a novel phytoremediation technology, Myriophyllum aquaticum wetlands have high tolerance and removal rate of NH. Glutamine synthetase (GS), a pivotal enzyme in nitrogen (N) metabolism, is hypothesized to play an important role in the tolerance of M.