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Machine learning algorithms investigate relationships in data to deliver useful outputs. However, past models required complete datasets as a prerequisite. In this study, rough set-based machine learning was applied using real-world incomplete datasets to generate a prediction model of biochar's adsorption capacity based on key attributes. The predictive model consists of if–then rules classifying properties by fulfilling certain conditions. The rules generated from both complete and incomplete datasets exhibit high certainty and coverage, along with scientific coherence. Based on the complete dataset model, optimal pyrolysis conditions, biomass characteristics and adsorption conditions were identified to maximize tetracycline adsorption capacity (> 200 mg/g) by biochar. This study demonstrates the capabilities of rough set-based machine learning using incomplete practical real-world data without compromising key features. The approach can generate valid predictive models even with missing values in datasets. Overall, the preliminary results show promise for applying rough set machine learning to real-world, incomplete data for generating biomass and biochar predictive models. However, further refinement and testing are warranted before practical implementation. Highlights: • It is the first explainable AI-based rough set model to study the tetracycline adsorption capacity of biochar. • Usage of an incomplete Practical dataset through RSML evaded the biasness due to imputations. • Higher accuracy and precision of incomplete Practical datasets revealed the uniqueness of the model. [ABSTRACT FROM AUTHOR]

Biochar has the potential to provide a multitude of benefits when used in soil remediation and increasing soil organic matter enrichment. Nevertheless, the intricated, hydrophobic pores and groups weaken its water-holding capacity in dry, sandy soils in arid lands. In order to combat this issue, starch-carbon-based material (SB), sodium alginate-carbon-based material (SAB), and chitosan-carbon-based material (CB) have been successfully synthesized through the graft-polymerization of biochar (BC). A series of soil column simulations were used to scrutinize the microstructure of the carbon-based material and explore its water absorption properties and its effects on sandy soil water infiltration, water retention, and aggregation. The results indicated that SB, SAB, and CB achieved water maximum absorption rates of 155, 188, and 172 g g−1, respectively. Considering their impact on sandy soils, SB, SAB, and CB lengthened infiltration times by 1920, 3330, and 3880 min, respectively, whilst enhancing the water retention capabilities of the soil by 18%, 25%, and 23% in comparison to solely adding BC. The utilization of these innovative materials notably encouraged the formation of sandy soil aggregates ranging from 2.0 to 0.25 mm, endowing the aggregates with enhanced structural stability. Findings from potting experiments suggested that all three carbon-based materials were conducive to the growth of soybean seeds. Thus, it is evident that the carbon-based materials have been fabricated with success, and they have great potential not only to significantly augment the water retention capacities and structural robustness of sandy soils in arid areas, but also to bolster the development of soil aggregates and crop growth. These materials possess significant application potential for enhancing the quality of sandy soils in arid and semi-arid regions. Highlights: Novel carbon-based materials were prepared using biochar and biodegradable organic matter. The novel materials exhibited excellent water absorption capacity. The novel materials greatly decreased the water infiltration capacity of sandy soil. The novel materials increased the water retention capacity and aggregate size of sandy soils. [ABSTRACT FROM AUTHOR]

Evaluating the lifespan of aged biodegradable mulch films from the perspective of realistic outdoor climate conditions is a challenge. However, it is worthwhile to determine the changes in their structure and stability. In this study, a talc-filled black poly (butylene adipate-co-terephthalate)/polylactide (PBAT/PLA) biodegradable mulch film was designed and mulched with shallow overburden soil to improve the anti-weathering characteristics of winter potatoes grown in southern China. This study focused on the weather resistance properties of biodegradable talc-filled PBAT/PLA-based mulch films. After 4 months of outdoor service, the elongation at break and tensile strength of talc-filled black PBAT/PLA films remained at 360 ± 250% and 15 ± 2.5 Mpa, respectively, with the number average molecular weight decreasing by 21.4% and the gel content increasing to 10%. Combining the results of microstructure analyses, molecular weight changes, thermodynamic properties, and mechanical and structural changes due to accelerated ageing under different indoor conditions, it was concluded that the maintenance of the mechanical properties of the mulch films could be attributed to the inhibition of random chain-breaking and heavy photo-crosslinking in the plastic film system. Our results using biodegradable films based on crop growth characteristics provide an effective strategy for extending the service life of biodegradable plastics and reducing the cost of biodegradable mulch films. [ABSTRACT FROM AUTHOR]

This study aimed to develop a robust predictive model for tetracycline (TC) adsorption onto biochar (BC) by employing machine learning techniques to investigate the underlying driving factors. Four machine learning algorithms, namely Random Forest (RF), Gradient Boosting Decision Tree (GBDT), eXtreme Gradient Boosting (XGBoost) and Artificial Neural Networks (ANN), were used to model the adsorption of TC on BC using the data from 295 adsorption experiments. The analysis revealed that the RF model had the highest predictive accuracy (R2 = 0.9625) compared to ANN (R2 = 0.9410), GBDT (R2 = 0.9152), and XGBoost (R2 = 0.9592) models. This study revealed that BC with a specific surface area (S (BET)) exceeding 380 cm3·g−1 and particle sizes ranging between 2.5 and 14.0 nm displayed the greatest efficiency in TC adsorption. The TC-to-BC ratio was identified as the most influential factor affecting adsorption efficiency, with a weight of 0.595. The concentration gradient between the adsorbate and adsorbent was demonstrated to be the principal driving force behind TC adsorption by BC. A predictive model was successfully developed to estimate the sorption performance of various types of BC for TC based on their properties, thereby facilitating the selection of appropriate BC for TC wastewater treatment. [ABSTRACT FROM AUTHOR]

Combined application of biochar and organic fertilizer improves soil structure and crop yield but may lead to increased loss of phosphorus (P). To reduce the P loss risk in this case, rice straw biochar (BC) and sheep manure (SM) were modified using polyacrylamide (PAM). The effects of using organic amendments (BC, SM, and PAM-modified organic mixtures) and no amendments (CK) on soil total and colloidal P leaching loss from paddy soils were evaluated through soil column leaching experiments. The soil leachate volume was increased by 8.91% with BC treatment and reduced by 15.3% with SM treatment. The total P leaching loss (973.9 μg kg−1) from the BC-treated soil was higher than that from other treatments (541.4–963.5 μg kg−1). However, there was much more colloidal P loss (480.0 μg kg−1) from SM treatment. The optimal conditions for the preparation of BC and SM modified using polyacrylamide (PSB) for reducing P leaching loss were SM/BC = 4:1, 1% PAM, and 100 °C. Molybdate-unreactive P accounts for 58.61–86.89% of the colloidal P in the soil leachate with organic amendments. PSB reduced colloidal P loss (particularly in 10–220 nm range) by ~ 50% compared with BC and SM treatments. The colloidal P concentration in the leaching solutions was significantly correlated with TOC and susceptible to Fe and Al concentrations. Using PAM-modified mixture instead of manure and biochar as a soil amendment can effectively control P leaching from fields. [ABSTRACT FROM AUTHOR]

Anthropogenic activities, such as mining, influence soil bacterial community composition and microbial distributions. In the current study, the patterns in microbial distribution and the environmental drivers shaping the soil bacterial community composition in the alpine mining area of the Tianshan Mountain region, China, were investigated, and the bacterial communities were analyzed using 16S rDNA pyrosequencing. The environmental factors and their relationships with the microbial community composition, structure, and diversity were also assessed. The soil organic carbon (SOC) concentration increased along the elevation gradient, with the highest concentration in the mining area, which increased microbial abundance and species richness. Some metals, like Ca, Cu, Pb, and Zn, accumulated significantly in the tailing area and were negatively correlated with the microbial community structure. Proteobacteria, Acidobacteria, Actinobacteria, and Verrucomicrobia were the dominant phyla; these dominant phyla were more abundant in the areas without mining than in the areas with mining at the same altitude. The relative abundance of Proteobacteria and Verrucomicrobia significantly increased along the elevation gradient, while that of Actinobacteria in the mining camp area was more than twice those in the other areas due to higher soil pH. Soil biomass was the highest in the valley. Collectively, these results elucidate the influence of anthropogenic mining activities on soil microbial communities in alpine mining soils and provide a basis for the future management of heavy metal-contaminated areas using the indigenous dominant bacterial phyla. [ABSTRACT FROM AUTHOR]

Background: Colloid-facilitated phosphorus (P) transport is recognized as an important pathway for the loss of soil P in agricultural systems; however, information regarding soil aggregate-associated colloidal P (Pcoll) is lacking. To elucidate the effects of aggregate size on the potential loss of Pcoll in agricultural systems, soils (0–20 cm depth) from six land-use types were sampled in the Zhejiang Province in the Yangtze River Delta region, China. The aggregate size fractions (2–8 mm, 0.26–2 mm, 0.053–0.26 mm and < 0.053 mm) were separated using the wet sieving method. Colloidal P and other soil parameters in aggregates were analyzed. Results: Our study demonstrated that 0.26–2 mm small macroaggregates had the highest total P (TP) content. In acidic soils, the highest Pcoll content was observed in the 0.26- to 2-mm-sized aggregates, while the lowest was reported in the < 0.053 mm (silt + clay)-sized particles, the opposite of that revealed in alkaline and neutral soils. Paddy soils contained less Pcoll than other land-use types. The proportion of Pcoll in total dissolved P (TDP) was dominated by < 0.053 mm (silt + clay)-sized particles. Aggregate size strongly influenced the loss potential of Pcoll in paddy soils, where Pcoll contributed up to 83% TDP in the silt + clay-sized particles. The Pcoll content was positively correlated with TP, Al, Fe, and the mean weight diameter. Aggregate-associated total carbon (TC), total nitrogen (TN), C/P, and C/N had significant negative effects on the contribution of Pcoll to potential soil P loss. The Pcoll content of the aggregates was controlled by the aggregate-associated TP and Al content, as well as the soil pH value. The potential loss of Pcoll from aggregates was controlled by its organic matter content. Conclusion: We concluded that management practices that increase soil aggregate stability or its organic carbon content will limit Pcoll loss in agricultural systems. [ABSTRACT FROM AUTHOR]

Background: Rice paddy wetlands may serve as a nutrient source or sink in agricultural ecosystems. However, the pattern of nutrient loss on a watershed scale is not clear. A year-round on-site observation study based on 6-h intervals was conducted. Rainfall, temperature, runoff nutrient concentrations, and adjacent stream water samples were automatically monitored to uncover the temporal changes in the runoff losses of the predominant nutrient proxies (total N and total P) from a typical rice-planting area (120 ha) in the Yangtze river delta region of China. Results: A high total N concentration in the rice-planting area was observed during the rice-planting season; however, significant fluctuation in the total P was evident throughout the year. The Δtotal N (drainage minus stream) parameter showed negative values with a mean of −0.25 mg L−1, while Δtotal P showed positive values with a mean of 0.06 mg L−1. The annual average N and P runoff from paddy field were 11.6 kg ha−1 and 1.5 kg ha−1, respectively. The window phases for the total N loss were mainly concentrated in the rice-growing season. However, the window phase for the total P loss was more dispersive throughout the year. No apparent relationships were found between rainfall and N and P concentrations by self-organizing map analysis. Conclusions: The high-resolution monitoring, in this study, suggested that nutrient loss loading rather than nutrient concentration was strongly related to surface runoff Therefore, fertilization before high-intensity rainfall should be avoided to mitigate the nutrient runoff losses and maintain the rice wetland eco-function. [ABSTRACT FROM AUTHOR]

Purpose: Laboratory incubation experiments using 15N stable isotope labeling and acetylene suppression techniques were conducted to compare the autotrophic nitrification and heterotrophic nitrification rates with the addition of swine manure (SW) and swine-manure-derived biochar (SWB) in two paddy soils. Materials and methods: SW and SWB were applied at four N-based amendment levels, namely control (0 mg N kg−1), low (1.1 mg N kg−1), medium (2.2 mg N kg−1), and high (4.4 mg N kg−1). Twenty-five milliliters of C2H2 gas were injected into each storage bottle to inhibit autotrophic nitrification in soil. At the end of the preincubation period, 160 mg kg−1 15N-glycine were added to each storage bottle to stimulate heterotrophic nitrification in soil. Results and discussion: Results showed that SW increased the NH4+-N content by 3.5 to 17.5 mg kg−1 in both soils, while SWB decreased it by 0.1 to 4.7 mg kg−1 compared to control group, regardless of whether autotrophic nitrification was inhibited. Both SW and SWB enhanced NO3−-N accumulation in the two soils compared to control group when autotrophic nitrification was not inhibited; however, NO3−-N concentration in the soil with SWB was up to 24% lower than that with the same level of SW addition. NH3 volatilization rates were elevated at all the SW and SWB amendment levels, although only SW led to higher N2O emission rates. Compared with SW, high level of SWB significantly decreased N2O emissions by 78 to 84% in the loam and clay loam soils. The increase in NH3 volatilization, soil NO3−-N accumulation, and autotrophic nitrification rate were greater with SW than with SWB. Higher rates of soil heterotrophic nitrification were observed in SWB-amended soils than in SW-amended soils with a high (4.4 mg N kg−1) amendment level. Conclusions: Our results suggest that SWB is less likely to increase NO3−-N accumulation in soil and contributes more to the lower soil autotrophic nitrification rate compared with SW. Although SWB can promote heterotrophic nitrification, it generally inhibits the autotrophic nitrification process and slows the increment pace of the gross nitrification in paddy soils. [ABSTRACT FROM AUTHOR]

Purpose: Biogas slurry (BS) is used for soil productivity amendment, but its effect on soil phosphorus (P) form distribution has not been thoroughly examined. The objective of this study was to determine the effect of BS on soil nutrients, phosphomonoesterase activities, and P species distribution. Materials and methods: A 91-day incubation study was carried out for a silt soil which was amended with BS at a rate equivalent to 120 kg N ha−1 and 38 kg P ha−1 and 240 kg N ha−1 and 76 kg P ha−1. The soil with no BS addition was used as control. Solution P-31 nuclear magnetic resonance (31P-NMR) spectroscopy was used to characterize soil P species. Acid phosphomonoesterase (ACP) and alkaline phosphomonoesterase (ALP) activities, pH, cation exchange capacity (CEC), NH4+–N, NO3−–N, and Olsen P were also evaluated. Results and discussion: The results indicated that the application of BS increased pH, CEC, NH4+–N, NO3−–N, and Olsen P contents. Moreover, the addition of BS inhibited ACP activity, but it increased ALP activity. A significant positive correlation was found between ALP and orthophosphates, suggesting ALP activity may play important roles in the release of orthophosphates. The P composition was dominated by inorganic orthophosphate (59.9–76.2% extracted P) and orthophosphate monoesters (23.8–38% extracted P), with smaller concentration of pyrophosphates (1.2–3.6% extracted P), and orthophosphate diesters (less than 1.5% of the extracted P). Conclusions: The P was mainly in the form of inorganic orthophosphates and organic monoesters. The present study shows that BS can be a substitute solution for the supply of essentials nutrients for plants. However, care would be entirely taken with long-term application of BS, since extreme nutrients addition may cause eutrophication of water bodies. [ABSTRACT FROM AUTHOR]

Colloidal phosphorus (CP) as an additional route of P mobilization in soil solution has gained much attention. A batch experiment was conducted to investigate the effect of sheep manure-derived biochar (SMB) on CP release from various land uses (paddy, vegetable, tea, and citrus) at a rate of 0% as a control treatment (CK), 1% as a low (L) level, 2% as a middle (M) level, and 4% as a high (H) level of SMB application. The CP and MRPcoll in the solution increased from 30.58 to 88.97% and from 2.45 to 55.54% of total P (TP), respectively. The SMB enhanced CP release in all the soils and all the treatments (except CK and L levels in tea soil; CK, L, and M levels in vegetable soil; and L and M levels in citrus soil). Multiple linear regression revealed a significant correlation between CP and MRPcoll and between colloidal iron, aluminum, calcium, and total organic carbon (Fecoll, Alcoll, Cacoll, and TOCcoll) and pH, which may play an important role as CP carriers that could depend on the pH. This study suggests that the application of SMB in the soil at an appropriate rate of 1 and 2% for tea and vegetable soils, respectively, could be beneficial to avoid the risk of CP release in water bodies. [ABSTRACT FROM AUTHOR]