Organic Phosphorus Content Research Articles

A Systematic Review and Meta-Analysis of the Sustainable Impact of Sewage Sludge Application on Soil Organic Matter and Nutrient Content

The increasing scarcity of natural resources makes the linear production model unsustainable, highlighting the need for more sustainable practices under the umbrella of circular economic principles. Sewage sludge emerges as a promising solution to provide soil organic matter (SOM) and nutrients. This meta-analysis evaluated the impacts of three levels of sludge application (low, medium, and high) on organic matter (OM), nitrogen (N), phosphorus (P), copper (Cu), and zinc (Zn) contents, considering different areas and experimental conditions worldwide. The analysis included 37 studies and 355 comparisons, after screening 7625 records, following the 2020 PRISMA protocol. The effects of sludge concentrations, continents, and types of experiment (field or greenhouse) were evaluated. Sewage sludge application significantly increased OM, N, Cu, and Zn levels, mainly at medium and high rates. The largest effects were observed in greenhouses, suggesting variation by location and environment. Moderators explained a part of the variation in the results, but the residual heterogeneity test revealed that there is still unexplained variability.

Reseeding increased plant biomass production and soil fertility, but not plant species diversity in degraded grasslands in China

Reseeding is a primary measure to restore degraded grasslands. Numerous studies have conducted experiments to investigate how the properties of grassland ecosystems respond to reseeding in China. However, there is a lack of summary of the results of these studies. Here, we conducted a hierarchical random-effects meta-analysis on the effects of reseeding on plant, soil, and microbial properties. We collected 19 variables, including plant biomass, species diversity and richness, soil organic carbon content, soil total and available nutrients, soil water content, soil microbial biomass and diversity, and enzyme activity, from a dataset of 1363 paired observations (degraded vs. reseeded) from 75 publications. The results showed that reseeding increased aboveground and belowground plant biomass by 70.2% and 68.0% on average, respectively. Reseeding increased soil organic carbon, phosphorus, and potassium contents, but did not affect soil nitrogen levels. Reseeding increased soil microbial nitrogen under conditions of tillage and fertilization. Reseeding age was found to have a positive correlation with species richness, while planting type, fertilization, and tillage did not have a significant impact on the species richness and diversity. Under the treatments of fertilization, non-tillage, and mix-planting, the response ratio of aboveground biomass to reseeding was positively correlated with the response ratio of species diversity to reseeding. Our results concluded that current reseeding practices can significantly improve plant biomass production and soil fertility but have minor effects on plant species diversity. These findings indicate that the preservation of biodiversity should receive greater attention from both researchers and practitioners in grassland remediation in China.

Application of SWAT to assess peatland forestry impacts on water quality

ABSTRACT Peatland drainage can affect the natural state of hydrological conditions and nutrient loading but is rarely included in catchment-scale models. To understand the gap, we aimed to use the soil and water assessment tool (SWAT) model to observe drained peatlands and their properties to predict nutrients and suspended solids (SS) in the peatland-dominated Simojoki catchment. We integrated drainage networks in SWAT to (i) identify the parameters for the drainage; (ii) determine annual loads and mean concentrations of SS, organic phosphorus (Org-P), total phosphorus (TP), organic nitrogen (Org-N), and total nitrogen (TN); (iii) understand spatial variation of nutrients and SS; and (iv) investigate the uncertainty ranges for the estimates. The calibrated SWAT model showed a 9.6% PBIAS between the simulated flow and the observations with low to medium loading variations for the water quality parameters. For Org-N and TN, the highest loading per year was at the downstream outlet, whereas for SS, Org-P, and TP, it was higher at the upstream outlet of the catchment. This approach of representing the drained peatland in SWAT indicated a maximum spatial distributed load in the peat soil in the clear-cut area and it can be beneficial in future hydrological modelling efforts in identifying the status of nutrients or SS.

Soil Nutrients Inversion in Open‐Pit Coal Mine Reclamation Area of Loess Plateau, China: A Study Based on ZhuHai‐1 Hyperspectral Remote Sensing

ABSTRACTSoil nutrients are crucial to assess land reclamation quality, and the use of various types of remote sensing data for soil nutrient inversion has been a key focus for soil monitoring. However, fewer studies have been conducted using satellite‐based hyperspectral remote sensing. To explore the potential of satellite‐based hyperspectral remote sensing in soil nutrient monitoring, this study selected soil organic matter, total nitrogen, available phosphorus, and available potassium content data from 83 sample sites using ZhuHai‐1 hyperspectral data. After spectral transformation and feature extraction, various inversion models were constructed, including partial least squares regression, support vector machine, recurrent neural network, and random forest. After verification by accuracy, the best spectral‐model combination was used for inversion. The results showed that the R‐squared range of the inversion models was 0.67748–0.78115. High content areas of soil organic matter and available potassium exhibited concentrated and contiguous features, while high content areas of total nitrogen and available phosphorus were more fragmented and fine‐grained. Alfalfa grassland plays a vital role in improving reconstructed soil in the early reclamation stage, and agricultural activities have differential impacts on soil nutrient accumulation. This study provides a theoretical basis for verifying the application capability of ZhuHai‐1 hyperspectral satellite data in soil monitoring.

Importance of dissolved organic nutrients on nutrient stoichiometry in the Yellow Sea and the East China Sea

We investigated seasonal variations in the dissolved nutrients and organic matter (DOM) in the Yellow Sea and the East China Sea shelf waters from 2017 to 2021. Dissolved organic nitrogen and phosphorus (DON and DOP) concentrations were the highest in the upper layer (<30 m) during the time of spring and autumn bloom and were the lowest in summer. In spring, DON and DOP contributed up to approximately 90% and 80% of the total dissolved nitrogen (TDN) and phosphorus (TDP), respectively. The C:N:P stoichiometry of the DOM pool in spring and autumn indicates that freshly in-situ produced DOM is N-rich compared to the DOM observed in summer and winter, resulting in a dissolved inorganic nitrogen (DIN)-limited environment in the upper layer of seawater during spring and autumn. Conversely, in summer, the highest C:N ratios (∼27) of the DOM pool revealed the DOM remained after the degradation and formation of the refractory pool by marine bacteria. In winter, all nutrients were vertically uniform due to active vertical mixing. This study highlights notable seasonal variations in the cycling of DON and DOP, leading to changes in their bioavailability and subsequent ecosystem responses in the shelf sea.

Nutrient Potential Mapping of Soils for Tea Plants Through Laboratory and Geostatistical Approaches

&lt;p&gt;The assessment of nutrient potential is crucial for enhancing tea production and achieving sustainable agricultural goals. Thus, the present study was carried out to assess and map the soil nutrient potential for tea plants through laboratory and geostatistical methods. A total of 74 random soil samples with 3 replications were collected from 0 to 9 cm (topsoil) and 9 to 18 cm (subsoil) depths from Oodaleah Tea Garden (OTG) which belongs to Fatikchhari Upazila of Chattogram District in Bangladesh. All the laboratory analyses were done following standard procedures and maps of individual soil indices were prepared through the Inverse Distance Weighted (IDW) interpolation technique using ArcGIS 10.7 software. The integration of maps for nutrient potential was performed following the Analytic Hierarchy Process (AHP). The mean concentrations of organic matter (OM), total nitrogen (TN), available phosphorus (AvP), available potassium (AvK), and available calcium (AvCa) were found higher at 0 to 9 cm compared to 9 to 18 cm soil depth with significant (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.05) difference among the sampling sites. The maps of individual soil parameters revealed distinct spatial differences at 0 to 9 cm and 9 to 18 cm soil depths. The total study area covered 5.99 km&lt;sup&gt;2&lt;/sup&gt;. Integrated nutrient potential mapping showed that moderately suitable (44.15%) accounted for the largest proportion, followed by highly suitable (26.03%), generally suitable (21.67%), marginally suitable (7.06%), and unsuitable area (1.08%) of the tea plantation suitability evaluation. The integrated map of nutrient potential will aid in better management of the tea soils.&lt;/p&gt;

Effect of potassium fulvate on continuous tobacco cropping soils and crop growth.

Long-term continuous cropping of tobacco causes dysbiosis of soil microbial communities, the imbalance of soil nutrients, and the increase of pathogenic bacteria, which will slow the growth and development of tobacco plants, reduce the production quality, and cause significant losses to tobacco production and tobacco farmers. The application of Potassium fulvic acid can not only provide nutrients, but also inhibit the propagation of pathogens in soil along with raising the amount of organic matter in the soil, which is an effective way to improve soil health. In this experiment, Tobacco variety SNT60 was used as the test material, and 6 treatments were set up by pot test, they were: no fertilisation control group (CK), tobacco special fertiliser (NPK), 3.45 g/kg of potassium fulvic acid fertiliser (T1), 4.65 g/kg of potassium fulvic acid fertiliser (T2), 5.85 g/kg of potassium fulvic acid fertiliser (T3), 7.05 g/kg of potassium fulvic acid fertiliser (T4), Ten replications were set up for each treatment and the soil and fertiliser were mixed and potted before transplanting, 70% as basal fertiliser and 30% as supplementary fertiliser. We also analyzed soil properties, soil microorganisms and agronomic traits of tobacco plants in different treatments to provide reference for mitigating tobacco succession barrier. The test results are as follows: 4.65 g/kg of potassium fulvic acid fertiliser (T2) treatment was the best, soil organic matter, quick nitrogen, phosphorus, potassium, pH, soil catalase, soil sucrase, and soil urease content, compared to CK control, increased by 22.04%, 43.12%, 96.21%, 381.79%, 25.43%, 91.69%, 262.07% and 93.16%. In terms of microbial community, application of potassium fulvic acid fertiliser significantly increased the relative abundance of Ascomycetes, Chlorobacterium, Bacillus, Proteobacteria and Tephritobacterium in the soil. Meanwhile, 4.65 g/kg of potassium fulvic acid fertiliser (T2) promoted the growth of tobacco plants, improved leaf photosynthetic capacity, and enhanced plant disease resistance. This experiment provides practical measures to improve the microbial community of tobacco continuous cropping soils and to reduce the incidence of diseases.

The Influence of Microalgae Fertilizer on Soil Water Conservation and Soil Improvement: Yield and Quality of Potted Tomatoes

We aim to study the impact of microalgae fertilizer on soil nutrients, water conservation and crop yield and quality while also determining the optimal ratio of microalgae fertilizer to chemical fertilizer. Using “Xinoufen No.9” tomatoes as the test subject, we conducted pot experiments with four different treatments: control with 100% chemical fertilizer (CK), T1 (25% microalgae fertilizer + 75% regular chemical fertilizer), T2 (75% microalgae fertilizer + 25% regular chemical fertilizer) and T3 (100% microalgae fertilizer). The results show that an increased application of microalgae fertilizer enhanced the soil organic matter, ammonium nitrogen, available phosphorus and potassium content. T3 showed the most improvement followed by T2. The co-application of microalgae fertilizer with chemical fertilizer can significantly increase the stem girth, plant height and yield of tomatoes. At the same time, microalgae fertilizer effectively regulates leaf stomatal conductance, promoting tomato leaf respiration. As the stomatal conductance increases, the transpiration rate and net photosynthesis rate of all treatments improve, followed by a decline in intercellular CO2 concentration, with T2 exhibiting the best performance. Among all treatments, T2 treatment yielded the highest per-plant production (0.630 kg), followed by T3 (0.521 kg). This is because the microalgae fertilizer promotes the distribution of photosynthetic products to the fruit, enhancing the yield and quality of tomatoes. Additionally, the microalgae fertilizer also increases the content of soluble sugars, soluble protein, vitamin C and lycopene in the fruit while reducing the nitrate content. Compared to the control group CK, T2 increases the content of soluble sugars, vitamins and lycopene by 26.74%, 39.29% and 158.31%, respectively. Microalgae fertilizer also helps to improve soil water and thermal conditions, enhancing the water-use efficiency of tomatoes. Compared to CK, the water-use efficiency of T2 treatment increased by 54.05%. Correlation analysis indicates that water and fertilizer factors significantly affect tomato yield, with a correlation exceeding 70%. The net photosynthesis and transpiration rates significantly influence fruit quality, with correlations above 80%. By applying microalgae fertilizer, the efficiency of water and fertilizer use can be effectively improved, thus achieving the goal of water conservation and quality enhancement. Therefore, through comprehensive analysis, using the membership function method of indicators such as soil environment, crop yield, fruit quality and water-use efficiency, it is concluded that T2 is the optimal fertilization treatment. This study provides theoretical support for the application of microalgae biofertilizer technology in the cultivation of tomatoes and other vegetables in the northern, cold and arid regions.

Long-term contamination of decabromodiphenyl ether reduces sediment multifunctionality: Insights from nutrient cycling, microbial ecological clusters, and microbial co-occurrence patterns

Despite the widespread detection of polybrominated diphenyl ethers in aquatic ecosystems, their long-term effects on sediment multifunctionality remain unclear. Herein, a 360-day microcosm experiment was conducted to investigate how decabromodiphenyl ether (BDE-209) contamination at different levels (0.2, 2, and 20 mg/kg dry weight) affects sediment multifunctionality, focusing on carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling. Results showed that BDE-209 significantly increased sediment total organic carbon, nitrate, ammonium, available phosphorus, and sulfide concentrations, but decreased sulfate. Additionally, BDE-209 significantly altered key enzyme activities related to nutrient cycling. Bacterial community dissimilarity was positively correlated with nutrient variability. Long-term BDE-209 exposure inhibited C degradation, P transport and regulation, and most N metabolic pathways, but enhanced C fixation, methanogenesis, organic P mineralization, inorganic P solubilization, and dissimilatory sulfate reduction pathways. These changes were mainly regulated by microbial ecological clusters and keystone taxa. Overall, sediment multifunctionality declined under BDE-209 stress, primarily related to microbial co-occurrence network complexity and ecological cluster diversity. Interestingly, sediment C and N cycling had greater impacts on multifunctionality than P and S cycling. This study provides crucial insights into the key factors altering multifunctionality in contaminated sediments, which will aid pollution control and mitigation in aquatic ecosystems.

Spatial Distribution Characteristics of Plant Community and the Identification of Driving Factors in Riparian Zone of the Three-River Headwaters Region, China

The unique geographical and climatic conditions in the Three-River Headwaters Region gave birth to distinctive plant species and vegetation types. To reveal the spatial distribution of plant communities and soil habitats along the riparian zone of the Sanjiangyuan Region and their influencing mechanisms, 14 survey plots were set up （ten from the Yangtze River source, two from the Lancang River source, and two from the Yellow River source）, and the effects of soil nutrient characteristics （especially soil phosphorus morphology）, climate factors, and river topography on plant community characteristics were quantitatively analyzed. The results showed that the plant community composition in the riparian zone of the source of the three rivers was dominated by perennial herbs （72.2%）, followed by annual herbs （20.4%） and shrubs （7.4%）. The dominant plants were Stipa purpurea, Polygonum orbiculatum, Carex parvula, Potentilla anserina, and Gentiana straminea. The average plant coverage, Shannon-Wiener index, and Pielou index were （64.4% ±23.6%）, （1.31 ±0.42）, and （0.84 ±0.08）, respectively. The plant community diversity index was the highest in the Yangtze River source, followed by that in the Lancang River source, and the lowest in the Yellow River source. The soil pH of the riparian zone of the Yangtze River source was significantly higher than that of the Lancang River source, whereas the mean contents of organic matter, total nitrogen, and Fe-Al combined phosphorus were significantly lower than those of the Lancang River source. The calcium and magnesium-combined phosphorus was the main form of phosphorus in riparian soil （63.89%）. Temperature, soil organic phosphorus content, and pH had significant effects on plant composition in the riparian zone of the Three-River Headwaters Region, whereas soil calcium and magnesium-combined phosphorus content had significant effects on plant community diversities. These results may deepen the scientific understanding of the evolution trend and genetic mechanism of plant communities in the riparian zone of the Three-River Headwaters Region.

Building microbial consortia to enhance straw degradation, phosphorus solubilization, and soil fertility for rice growth

Straw pollution and the increasing scarcity of phosphorus resources in many regions of China have had severe impacts on the growing conditions for crop plants. Using microbial methods to enhance straw decomposition rate and phosphorus utilization offers effective solutions to address these problems. In this study, a microbial consortium 6 + 1 (consisting of a straw-degrading bacterium and a phosphate-solubilizing bacterium) was formulated based on their performance in straw degradation and phosphorus solubilization. The degradation rate of straw by 6 + 1 microbial consortium reached 48.3% within 7 days (The degradation ability was 7% higher than that of single bacteria), and the phosphorus dissolution rate of insoluble phosphorus reached 117.54 mg·L− 1 (The phosphorus solubilization ability was 29.81% higher than that of single bacteria). In addition, the activity of lignocellulosic degrading enzyme system was significantly increased, the activities of endoglucanase, β-glucosidase and xylanase in the microbial consortium were significantly higher than those in the single strain (23.16%, 28.02% and 28.86%, respectively). Then the microbial consortium was processed into microbial agents and tested in rice pots. The results showed that the microbial agent significantly increased the content of organic matter, available phosphorus and available nitrogen in the soil. Ongoing research focuses on the determination of the effects and mechanisms of a functional hybrid system of straw degradation and phosphorus removal. The characteristics of the two strains are as follows: Straw-degrading bacteria can efficiently degrade straw to produce glucose-based carbon sources when only straw is used as a carbon source. Phosphate-solubilizing bacteria can efficiently use glucose as a carbon source, produce organic acids to dissolve insoluble phosphorus and consume glucose at an extremely fast rate. The analysis suggests that the microbial consortium 6 + 1 outperformed individual strains in terms of both performance and application effects. The two strains within the microbial consortium promote each other during their growth processes, resulting in a significantly higher rate of carbon source consumption compared to the individual strains in isolation. This increased demand for carbon sources within the growth system facilitates the degradation of straw by the strains. At the same time, the substantial carbon consumption during the metabolic process generated a large number of organic acids, leading to the solubilization of insoluble phosphorus. It also provides a basis for the construction of this type of microbial consortium.

The effect of combined application of biochar and phosphate fertilizers on phosphorus transformation in saline-alkali soil and its microbiological mechanism

This study investigated the effects of combining Phragmites australis-based biochar, prepared at 400 °C, with various types of phosphate fertilizers—soluble, insoluble, and organic—on the content and transformation of phosphorus fractions in saline-alkali soil. Additionally, we explored microbiological mechanisms driving these transformations. The results showed that this combination significantly increased the concentrations of dicalcium phosphate (Ca2P), octacalcium phosphate (Ca8P), aluminum phosphate (AlP), moderately labile organic phosphorus (MLOP), and resistant organic phosphorus (MROP) in soil. Conversely, the levels of hydroxyapatite (Ca10P) and highly resistant organic phosphorus (HROP) decreased. The increase in labile organic phosphorus (LOP) content or decrease in iron phosphate (FeP) was found to effectively enhance the availability of Olsen phosphorus (Olsen-P) in soil. Furthermore, the study revealed that biochar mixed with organic phosphate fertilizers increased the activity of soil acid phosphatase (ACP) and neutral phosphatase (NEP), while reducing alkaline phosphatase (ALP) activity. In contrast, biochar combined with soluble and insoluble phosphate fertilizers decreased the activity of ACP (22.59 % and 28.57 %, respectively) and NEP (62.50 % and 11.11 %, respectively), with the combination with insoluble fertilizers also reducing ALP activity by 55.84 %, whereas the soluble combination increased it by 190.34 %. Additionally, the co-application of biochar and phosphate fertilizers altered the composition and abundance of the gene phoD-harboring microbial community, enhancing the abundance of Proteobacteria and reducing that of Actinobacteria. Correlation analysis between phoD-functional microbial species and various phosphorus fractions showed that Rhodopseudomonas was significantly associated with several phosphorus components, exhibiting a positive correlation with Ca2P, Ca8P, AlP, LOP, MLOP, and MROP, but a negative relationship with Ca10P. These findings suggest that the combined application of biochar and phosphate fertilizers could change the abundance of Rhodopseudomonas, potentially influencing phosphorus cycling in the soil. This research provides a strong scientific foundation for the efficient combined use of biochar and phosphate fertilizers in managing saline-alkali soil.

Soil pH and organic matter: Key edaphic factors in sustaining optimum yield and quality of pomelo fruit

Identifying the soil properties associated with crop yield and quality variation is crucial for developing sustainable agronomic strategies. However, such information on pomelo production is scarce. Hence, forty independent sites in the primary pomelo production areas of Pinghe County were selected to investigate the influence of soil properties on pomelo yield and quality, and to provide reference for future soil management strategies. The results showed positive correlations between pomelo yield and soil pH, along with exchangeable calcium and magnesium, but this comes at the expense of fruit flavor quality. Meanwhile, soil organic matter positively influenced fruit flavor quality. Furthermore, a significant positive effect on fruit nutritional quality was noted across various soil properties, except for organic matter and available phosphorus concentration. A random forest model was used to predict pomelo yield, flavor quality, and nutritional quality based on soil properties and yielded R2 values of 0.50, 0.60, and 0.50, respectively. Partial least squares regression and structural equation modeling identified soil pH and organic matter as pivotal pomelo yield and quality determinants. The categorization of samples into four groups based on differences in pH and organic matter highlighted that integrating soil acidification remediation with organic matter increased is essential for sustainable pomelo production. Overall, this study offers comprehensive insights into the effects of holistic soil management on achieving both high yield and quality in pomelo cultivation. Furthermore, these findings serve as valuable reference for advancing sustainable production practices across large fruit types beyond the pomelo.

Effects of different afforestation years on soil moisture and nutrient content in Maxian Mountain of the Loess Plateau

In the area of “returning farmland to forest” on the Loess Plateau in China, it is difficult to cultivate artificially planted trees into forests. In the current study, abandoned cultivated land after 10 years of natural restoration served as controls (CK), while the treatments included afforestation periods of 2, 4, 6, 8, and 10 years. Soil samples were collected from various depths: 0–20, 20–40, 40–60, 60–80, to 80–100 cm. The findings revealed that with increasing years of artificial afforestation, soil pH gradually increased, and soil moisture content rose in the 0–20 cm layer while declining in deeper layers (20–100 cm) in the Maxian Mountain region of the Loess Plateau. Moreover, the total carbon, nitrogen, phosphorus, and potassium content initially increased and then decreased with the duration of artificial afforestation, reaching peak values after 8 years. Contents of organic matter, ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium in the same soil layer increased with each year of afforestation. However, upon reaching 10 years of artificial afforestation, the effective nutrient content in the 60–80 and 80–100 cm soil layers exhibited a decrease. The values of Integrated Fertility Index (IFI) in different afforestation years were ranked as follows: 8 years > 6 years > 10 years > 4 years > 2 year, but all of them were significantly smaller than those of natural restoration plot CK (P < 0.05). Overall, soil fertility in the Maxian Mountain area of the Loess Plateau increases with each additional year of artificial afforestation. However, when the artificial afforestation period is 10 years, soil fertility decreases and marking a shift from enhancement to decline beyond this duration.

Implication of the root growth and soil macropores distribution on sugarcane yield in Takalar, Indonesia

This study examined the relationship between the decline in sugarcane productivity and the distribution of macropores and depth of root penetration in sugarcane plantations in Takalar during one planting period (October 2021-September 2022). There were five observation points (P1, P2, P3, P4, and P5) in one hectare of land to measure the distribution of soil macropores using methylene blue solution. Cross-sections of the soil were made to observe the presence of plant roots at a depth of 0-40 cm with a width of 60 cm. In each plot, disturbed soil samples were collected to measure soil texture, soil organic matter (SOM), nitrogen (N), phosphorus (P), and potassium (K) contents. Other measurement parameters were the infiltration rate and plant productivity. The results indicated that SOM and NPK levels at the research location were deficient, serving as the first indicators of problematic soil. Macropore observations revealed that macropores were distributed only at a less than 10 cm soil depth. This distribution limited the penetration of plant roots to a depth of 0-40 cm. The root length density (RLD) value indicated the absence of roots at depths of 30-40 cm in plots P2 and P3. The field findings explained why sugarcane production in Takalar only achieved 50%, around 40 t ha-1 from the first ratoon sugarcane harvest, instead of the expected 70-80 t ha-1.

Cover crop grazing effects on soil properties in no-tillage dryland cropping systems in the central Great Plains

Integrating ruminant livestock such as beef cattle (Bos taurus L.) to graze cover crops (CCs) could balance goals of short-term profitability and long-term environmental sustainability when CCs are grown in water-limited environments like the central Great Plains (CGP), USA. However, little information currently exists about the effects of CC grazing on soil properties in no-tillage (NT) dryland cropping systems, especially after multiple cycles of grazing. This study was conducted from 2018 to 2021 to evaluate the effects of beef cattle grazing CCs on residue return, soil bulk density (BD) and penetration resistance (PR), water stable aggregates (WSA) and wind-erodible fraction (WEF), as well as soil pH and nutrient concentrations on three producer fields in central and western Kansas. Across sites, CC biomass left as residue post-grazing was similar to pre-grazing and was 60 % of the ungrazed CCs (3704 kg ha−1) because of CC regrowth after the 30–40 day grazing period. Soil BD, PR, WSA, WEF, pH, particulate organic carbon, nitrate-nitrogen, and phosphorus concentration were not different between grazed and ungrazed CCs. However, soil organic carbon (SOC) stocks and potassium concentrations were greater with grazed CCs compared to ungrazed CCs possibly due to substantial CC residue retention following grazing coupled with manure and urine deposition. Regression and correlation analyses showed that increased SOC was associated with decreased soil BD and increased WSA, which suggests decreased soil erosion potential as well as possible improvements in water infiltration and underscores the importance of SOC for overall soil health in this water-limited environment. Based on these results, we conclude that grazing of CCs is a viable management option for producers to intensify NT dryland cropping systems to improve soil health and maintain or increase overall system profitability in the CGP. Longer (>3 years) grazing studies are needed, and results are likely to vary based on grazing animal stocking rate, categories, duration of grazing, and available CC biomass for grazing.

Effects of Soil Conditioner (Volcanic Ash) on Yield Quality and Rhizosphere Soil Characteristics of Melon.

In this study, the effects of soil conditioners on the growth and development of melons and the rhizosphere soil environment were explored. The optimal amount of added soil conditioner was screened to solve the practical production problems of high-quality and high-yield thin-skinned melon. The melon variety "Da Shetou" was used as the material. Under the conditions of conventional fertilization and cultivation technology management, different soil conditioners were set up for potted melons. The effects of Pastoral soil (CK), 95% Pastoral soil + 5% volcanic ash soil conditioner (KT1), 85% Pastoral soil + 15% volcanic ash soil conditioner (KT2), 75% Pastoral soil + 25% volcanic ash soil conditioner (KT3), 65% Pastoral soil + 35% volcanic ash soil conditioner (KT4), and 55% Pastoral soil + 45% volcanic ash soil conditioner (KT5) on melon yield, quality, and rhizosphere soil characteristics were investigated. The soil microbial community was analyzed using Illumina MiSeq technology. Compared to CK, KT1, KT3, KT4, and KT5, the KT2 treatment could improve the single fruit yield of melon, increasing it by 4.35%, 2.48%, 2.31%, 5.92%, and 2.92%. Meanwhile, the highest contents of soluble protein, soluble solid, and soluble sugar in the KT2 treatment were 1.89 mg·100 g-1, 16.35%, and 46.44 mg·g-1, which were significantly higher than those in the control treatment. The contents of organic matter, total nitrogen, alkali-soluble nitrogen, nitrate nitrogen, ammonium nitrogen, available potassium, and available phosphorus in melon rhizosphere soil were the highest in the KT2 treatment. Through Alpha diversity analysis, it was found that the Chao1 index, Shannon index, and ACE index were significantly higher in the KT1 treatment than in the control, while, among all groups, the Simpson index and coverage were not significantly different. The dominant bacteria in the six treated samples were mainly Actinobacteriota, Proteobacteria, Cyanobacteria, Chloroflexi, Acidobacteria, Bacteroidetes, Myxomycota, Firmicutes, Gemmatimonadota, Verrucomicrobia, and Planctomycetes, which accounted for 96.59~97.63% of the relative abundance of all bacterial groups. Through redundancy analysis (RDA), it was found that the organic matter, electrical conductivity, available phosphorus, and nitrate nitrogen of melon rhizosphere soil were the dominant factors of bacterial community change at the dominant genus level. In summary, 15% ash soil conditioner applied on melon was the selected treatment to provide a theoretical reference for the application of soil conditioner in facility cultivation.

Биологическое загрязнение почв побочными продуктами животноводства

By-products of animal husbandry (BPAH) such as manure, manure effluents (ME) are widely used as organic fertilizers. The main disadvantage of the appropriate fertilizers is the high content of microorganisms (MO) untypical to uncontaminated natural environments, including pathogenic ones. Currently used natural methods of BPAH neutralization can significantly reduce the risks of transferring pathogenic and opportunistic MO into fertilized soil, but do not completely exclude them. The study examined the effects of long-term (more than 7 years) introduction of a neutralized liquid fraction (LF) of pork ME and cattle ME on the chemical composition and sanitary and hygienic condition of the soil of arable fields and wooded areas located at 500 m from the boundaries of the fields. Prolonged application of LF led to an increase in the content of organic matter, mobile phosphorus, potassium and sulfur, an increase in the amount of absorbed bases, a decrease in metabolic acidity in arable land compared with adjacent forest areas. However the sanitary condition of both arable land and adjacent territories deteriorated significantly. A significant increase in the total microbial number (TMN) was revealed in all soil samples in comparison to the normative indicators. Particularly high values of TMN were found in soil fertilized with cattle manure. The corresponding soil was characterized by the highest content of organic matter and neutral reactions of the environment, which provided favorable conditions for the active development of saprophytic microbiota. Fresh faecal contamination was detected in all selected soil samples. Soils are characterized as highly polluted. According to the indicators of the index Escherichia coli, Enterococcus and Clostridium perfringens, the soils of all studied sites are moderately dangerous. Higher values of the corresponding indices were found in arable land fertilized by the LF of pork farms and in the territories adjacent to arable land. In the course of sanitary and bacteriological studies, eggs of helminthes were not found in the soil.

Soil microbial community dynamics in response to Tamarix ramosissima afforestation in desert lands: Metagenomic insights

AbstractUnderstanding the influence of afforestation on soil microorganisms, the major drivers of soil processes, is essential for maintaining soil health and sustainability. However, in a desert‐oasis ecotone, variations in the microbial community along shrub afforestation years remain unclear. We conducted a metagenomic analysis to study the temporal changes in microbial community structure in 0–100 cm soil following 3‐, 7‐, and 10‐year afforestation of Tamarix ramosissima Ledeb. on the southern edge of the Taklimakan Desert. Compared to the unreclaimed desert land, in 3‐year or 7‐year stands, soil organic carbon (SOC), nitrate nitrogen, available phosphorus and potassium (AK) contents significantly increased on average by 60%, 852%, 72%, and 299%, respectively. Soil archaeal and bacterial community composition were significantly affected by afforestation; their α‐diversity increased on average by 5.9% and 11.1%, respectively, after afforestation, showing a unimodal pattern along afforestation years. In contrast, fungal α‐diversity and community composition did not show significant variation over the afforestation period. The influence of AK outweighed that of SOC and other nutrients on soil microbial community composition. These findings suggest that T. ramosissima afforestation in the desert‐oasis ecotone has significant impacts on the community composition and α‐diversity of archaea and bacteria, but not fungi, by modifying soil physicochemical properties. This research provides valuable implications for soil management and microbial processes related to the afforestation of salt‐secreting shrubs.

Paleosurface studies of the remains of a building in the Mikhailovsky Cordon settlement

Pedoarchaeological study of the remains of a building on the territory of the Old Slavic site (the settlement of Mik-hailovsky Cordon — the Slavic Borshevo Culture of the late 1st mil. AD) in the Voronezh region were carried out in order to obtain new data on the layout of the settlement, the type of housing building, life sustainability, economy, and residen-tial use. The main purpose of soil research was the identification of the nature of the use of the building and the recon-struction of the economic activities in the adjacent territory. The determination of organic and mineral forms of phos-phates, urease activity, and the quantity of microorganisms of various trophic groups in the ‘natopt’ (trampled soil) at the bottom of the pit and in the soil outside of the building was carried out. It has been established that the most pro-nounced traces of economic activity have been preserved in the soils to the west of the building where the summer stove was located. In this area, the content of phosphates reached 2 mg P2O5/g soil. The soil to the northeast of the construction pit is characterized by the accumulation of organic matter, which is confirmed not only by a high content of organic phosphorus, but also by rather high quantity of saprotrophic bacteria, indicating organic contamination of the soil, which suggests the ingress of organic substrates into the soil (manure, feces, household waste). The values of many indicators of anthropogenic activity inside the building turned out to be unexpectedly low. As such, the low content of phosphates, saprotrophic bacteria and keratinophilic fungi in the analysed ‘natopt’ in the building at the bottom of the pit indicate a low intensity, or periodic use of the premises.