Soil Cation Exchange Capacity Research Articles

Long‐term biochar application promoted soil aggregate‐associated potassium availability and maize potassium uptake

AbstractBiochar is an effective ameliorator for soil quality improvement and nutrient reuse from biomass; however, the effect of biochar application on soil potassium (K) availability, plant K uptake, and the underlying mechanisms have not been well‐elucidated. To address this, the variation in the soil K forms, soil aggregate stability, and aggregate‐associated K concentration, as well as maize K uptake, were investigated in a field experiment after 9 years of biochar amendment. The treatments included no biochar and NPK fertilizer (CK); NPK fertilizer treatment (F); biochar applied annually at the rate of 2.625 t ha−1 (C1), and biochar applied annually at rate of 2.625 t ha−1 with NPK fertilizers (C1F); one‐time biochar applied with NPK fertilizers, with biochar rate of 31.5 (C2F) and 47.25 t ha−1 (C3F). The results showed that after 9 years of field application, biochar inhibited the downward K migration to the deeper layer, thus increasing water‐soluble potassium (WSK), exchangeable potassium (EK), non‐exchangeable potassium (NEK), and total potassium (TK) in 0–20 cm soil, with C1F exhibiting better performance than C2F and C3F. Biochar also increased aggregate‐associated EK, NEK, and TK pools, mainly due to an increase in the macroaggregate proportion (>0.25 mm). Biochar amendment promoted maize K uptake by an average of 35.69%, the path analysis indicated that the positive effect was an outcome of the synergetic effect of the increase in surface soil WSK content and promoted macroaggregate EK pools, which was primarily attributed to biochar improved soil properties, including soil organic carbon, pH, total nitrogen, total phosphorus, and cation exchange capacity. These factors explained 76% of the variance in maize K uptake. In conclusion, biochar is an effective ameliorator for improving soil K content and availability.

Evolving dynamics of insect frass fertilizer for sustainable nematode management and potato production.

Potato production faces major challenges from inadequate soil fertility, and nematode infestation, yet synthetic fertilizers and nematicides are costly and harmful to the environment. This study explored the potential of chitin-fortified black soldier fly-composted organic fertilizer (BSFCOF) as a multipurpose organic fertilizer amendment for enhancing potato yield and suppressing potato cyst nematodes (PCN). The BSFCOF was applied at a rate equivalent to 150 kg N ha-1 and fortified with chitin from black soldier fly pupal exuviae at inclusion rates equivalent to 0.5, 1, 2, 3, 4 and 5% chitin. Data were collected on potato growth characteristics, PCN population densities, and soil chemical properties for two growing cycles. Results showed that chitin fortified BSFCOF significantly improved potato growth parameters, chlorophyll concentration, marketable tuber yield and number of marketable tubers. The marketable tuber yield achieved using chitin-fortified BSFCOF was 70 - 362%, and 69 - 238% higher than the values achieved using unfertilized soil during the first and second growing cycles, respectively. Soil amendment with chitin-fortified BSFCOF significantly reduced the number of cysts per 200 g soil-1, number of eggs and J2 per cyst-1, eggs g-1 soil and reproduction rate by 32 - 87%, 9 - 92%, 31- 98% and 31 - 98%, respectively. The PCN suppression increased with chitin inclusion rates. There were significantly higher values for soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus, calcium, magnesium, potassium, and cation exchange capacity in soil amended with BSFCOF compared to unamended soil. This study demonstrates that BSFCOF fortified with 5% chitin is an effective soil enhancer with multiple benefits, including improved soil fertility, potato performance, and effective management of potato cyst nematodes.

The potential of ferrihydrite-synthetic humic-like acid composite as a soil amendment for metal-contaminated agricultural soil: Immobilization mechanisms by combining abiotic and biotic perspectives

In-situ passivation technique has attracted increasing attention for metal-contaminated agricultural soil remediation. However, metal immobilization mechanisms are mostly illustrated based on metal speciation changes and alterations in soil physicochemical properties from a macroscopic and abiotic perspective. In this study, a ferrihydrite-synthetic humic-like acid composite (FH-SHLA) was fabricated and applied as a passivator for a 90-day soil incubation. The heavy metals immobilization mechanisms of FH-SHLA were investigated by combining both abiotic and biotic perspectives. Effects of FH-SHLA application on soil micro-ecology were also evaluated. The results showed that the 5%FH-SHLA treatment significantly decreased the DTPA-extractable Pb, Cd and Zn by 80.75%, 46.82% and 63.63% after 90 days of incubation (P < 0.05), respectively. Besides, 5% FH-SHLA addition significantly increased soil pH, soil organic matter content and cation exchange capacity (P < 0.05). The SEM, FTIR, and XPS characterizations revealed that the abiotic metal immobilization mechanisms by FH-SHLA included surface complexation, precipitation, electrostatic attraction, and cation-π interactions. For biotic perspective, in-situ microorganisms synergistically participated in the immobilization process via sulfide precipitation and Fe mineral production. FH-SHLA significantly altered the diversity and composition of the soil microbial community, and enhanced the intensity and complexity of the microbial co-occurrence network. Both metal bioavailability and soil physiochemical parameters played a vital role in shaping microbial communities, while the former contributed more. Overall, this study provides new insight into the heavy metal passivation mechanism and demonstrates that FH-SHLA is a promising and environmentally friendly amendment for metal-contaminated soil remediation.

Variation of Geochemical Properties of Soils in Tropical Lowland Rainforests in Sri Lanka

Tropical lowland rainforests (TLRFs) of Sri Lanka are considered as diverse ecosystems which play a vital role in climate change mitigation. In recent years, increasing deforestation leads to diminishing their potential ecosystem roles. For efficient forest conservation, knowledge of both above- and below-ground characteristics of TLRFs is required. Currently, above-ground information on TLRFs is sufficiently available but the details on the below-ground characteristics are limited. Therefore, this study was carried out to investigate pedo-geochemical properties of lowland rain forests of Kanneliya (KDN) and Pitadeniya, (PTD) in Sri Lanka. Four sampling plots with 1 ha in size (KDN1, KDN2, PTD1 and PTD2) were established, selecting altitudes of 117, 174, 509, and 618 m asl, respectively. Five representative near-surface (up to 25 cm) samples were collected from each plot for the investigation. Soil pH, electrical conductivity (EC), and cation exchange capacity (CEC) were measured while soil organic matter (SOM) content was determined by (i) Walkey-Black (WB) and (ii) Loss on ignition (LI) methods. Data were analysed by ANOVA and means were compared using Duncan‘s test. All measured parameters were significantly different (P&lt;0.05) among the sampling plots. Soil pH and EC values were ranged between 3.43– 3.78 and 0.28–0.44 dS m-1, respectively. The highest CEC was recorded in PTD2 (11.09±3.44 cmol(+)/kg) whereas the lowest was in PTD1 (5.31±1.26 cmol(+)/kg). The highest SOM was recorded in PTD1 (17.71±4.42% in WB, 18.04±3.98% in LI) whereas the lowest was noted in PTD2 (5.81±3.07% in WB, 8.21±2.13% in LI). According to the comparison made between WB and LI methods, LI method recorded higher SOM content. The actual SOM and volatilizable water in hygroscopic mineral fractions might be the reason for the higher values in LI method. All acquired data were compared with standard interpretation data and accordingly, soils of the measured TLRFs are acidic, non-saline and non-reduced with sufficient soil aeration. Even though, TLRF vegetation produce high amount of biomass, soil CEC and SOM contents are low in the study area due to rapid microbial decomposition and absorption of dense vegetation. There was no linear relationship between measured parameters and altitude. Overall, measured soil chemical properties can be considered as ideal indicators of TLRFs conservation and therefore, it needs to be correlated with above-ground properties for understanding the behaviour of TLRFs responding to conservation strategies. &#x0D; Keywords: Forest conservation, Soil chemical properties, Soil organic matter content, Tropical lowland rainforest

Influence of sample size, model selection, and land use on prediction accuracy of soil properties

Digital soil mapping (DSM) uses models that integrate field and laboratory data with environmental factors to predict soils and soil properties. The accuracy of predictions depends on the models used, the data collected, and the environmental factors. This study assesses the influence of sampling density and distribution, covariates, and modeling approach on the prediction accuracy of soil organic matter (SOM) and cation exchange capacity (CEC) at three sites in Indiana (ACRE; DPAC; SEPAC) with different management intensity and sampling designs. Ordinary Kriging (OK) and three machine learning models Cubist (CB), Random Forest (RF), and Regression Kriging (RK) were used. The Coefficient of Determination (R2), Root Mean Square Error (RMSE), Mean Square Error (MSE), concordance coefficient (pc), and bias were used for the accuracy assessment.The accuracy of the predictions was influenced by the site, sample density, model type, soil property, and their interactions. Sites were the single largest source of significant variation followed by sampling density and model type for both SOM and CEC. ACRE, with multiple fields and complex management practices, had a higher average RMSE and wider range of RMSE for SOM compared to SEPAC and DPAC with uniform management. At ACRE the RMSE for SOM decreased from 2.75 to 0.85 and from 17.38 to 3.61 for CEC with increasing number of samples from 36 (6 points/ha) to 66 (12points/ha), but did not change with further increases up to 146 samples. At SEPAC and DPAC the RMSE decreased only slightly at sampling densities above 5 points/ha and 1–2 points/ha, respectively (68 and 43 samples, respectively). Based on cross validation, all models performed poorly for SOM with R2 varying from 0.13 to 0.38, while for CEC the model performance varied widely from 0.11 to 0.64. The accuracy predictions for CEC were higher compared to SOM at all sites. Overall, RF performed better while OK performed the worst for both SOM and CEC. The mean R2 values across all sites were 0.35 (SOM) and 0.51 (CEC) for RF and 0.19 (SOM) and 0.17 (CEC) for OK. At ACRE, OK performed worse for both SOM and CEC with only slight differences among the other models, while at SEPAC and DPAC there were only slight differences among all models. Spatial predictions for CB, RF and RK were more detailed and conformed to soil landscape models compared to OK. The spatial differences between sampling densities for predicted SOM and CEC were greater in lower elevation areas compared to higher elevation areas. The results from this study demonstrate that the selection of modeling approach is site-specific, and depends on sampling density, soil properties and their interactions.

Long-Term Organic Manure Retarding Soil Acidity in the Double-Cropping Rice Field of Southern China

ABSTRACT This paper investigates the effects of different long-term (36 years) fertilizer treatments on soil pH, exchangeable acids, exchangeable base cation and cation exchange capacity (CEC) at 0–10 cm and 10–20 cm soil layers in a double-cropping rice field. The following fertilizer treatments were included: chemical fertilizer (MF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without any fertilizer input as a control (CK). This result indicated that soil pH at 0–10 cm layer with RF and OM treatments was higher than that of MF and CK treatments. Soil exchangeable acidity content at 0–10 cm and 10–20 cm layers with RF and OM treatments were decreased by 48.4%, 51.6% and 49.2%, 54.2%, compared with CK treatment, respectively. Soil exchangeable calcium (Ca2+), magnesium (Mg2+) and potassium (K+) contents at 0–10 cm and 10–20 cm layers in paddy field with OM and RF treatments were higher than that of CK treatment. Moreover, compared with CK treatment, soil exchangeable base ion content at 0–10 cm and 10–20 cm layers in paddy field with OM treatment were increased by 54.1% and 42.6%, respectively. Soil CEC and effective cation exchange capacity (ECEC) at 0–10 cm and 10–20 cm layers with OM and RF treatments were significantly higher than that of MF and CK treatments. In conclusion, our results indicated that long-term application of crop residue or organic manure can improve soil exchangeable base ion and exchangeable capacity contents, alleviate soil acidity in a double-cropping paddy field.

Assessing above and belowground recovery from ammonium sulfate addition and wildfire in a lowland heath: mycorrhizal fungi as potential indicators

Atmospheric pollution containing soil‐nitrifying ammonium sulfate ((NH₄)₂SO₄) affects semi‐natural ecosystems worldwide. Long‐term additions of (NH₄)₂SO₄ to nitrogen (N)‐limited habitats, including heathlands, increase climate stress affecting recovery from wildfires. Although heathland vegetation largely depends on ericoid mycorrhizal fungi (ErM) to access soil N, we lack detailed understanding of how prolonged exposure to (NH₄)₂SO₄ may alter ErM community composition and host plants' reliance on fungal partners following wildfire and affect recovery. Simulation of atmospheric pollution ((NH₄)₂SO₄) occurred bi‐weekly for 5 years after a 2006 wildfire in a UK heathland. Ten years after treatments ceased, we measured vegetation structure, lichen and lichen photobiont composition, soil characteristics, ErM colonization, ErM diversity in roots and soil, and assessed ErM potential as novel recovery indicators. Heather height and density, and moss groundcover, were greater in N‐enriched plots. Lichen community indices showed significant treatment effects, but without differences in photobionts. Soil pH and Mg were significantly lower in treated plots while soil cation exchange capacity was significantly higher. There were no detectable differences in ErM composition and keystone ErM taxa between control and treated plots. Soil carbon stock measures were variable. Our results indicate atmospheric pollution following fire can have significant lingering effects above‐ and belowground. ErM diversity and root colonization were not assessed in the original N‐addition experiment; we advocate for their inclusion in future studies as an integral part of the recovery assessment toolkit. We show that mycorrhizal fungi diversity is a viable ecological tool and summarize key steps for ErM identification.

Crude oil pollution effect on agricultural soil properties and germination of bean (&lt;i&gt;Vigna unguiculata(/i) L.) seed

Crude oil pollution affects not only soil properties but also seed germination. The aim of thisresearch is to checkmate the effect crude oil pollution has on soil fertility, seed germinationand microbial activity. Two different agricultural soils from Ibeno and Otuocha collected bycomposite sampling were used to conduct the study. The crude oil for carrying out the research was sterilized with a micron Chromafil CA/S % 45 syringe filters. The physicochemical analysis of the soil and its microbiological enumeration was done. This was followed by the artificial pollution of the soil with fresh crude oil. Soil’s physicochemical properties and microbiological enumeration were analyzed followed by the planting of bean seed son the polluted soil. Unpolluted soils was also planted and served as the control. The artificial pollution of the soils’ increased physicochemical properties like cation exchange capacity, selenium, mercury, arsenic, carbon and phosphorus in both soil. Some physicochemical properties like electrical conductivity, salinity, vanadium, zinc, cadmium, iron, manganese, copper, cobalt, nickel and nitrogen decreased in both soils. Water permeability was positive and became negative after pollution. Soil texture was bound and became loose after pollution. Other soil properties like pH increased in Ibeno soil but decreased in Otuocha soil. The number of microorganisms decreases after pollution. Statistically, cultivated beans germinated faster on unpolluted soil and appear healthier than polluted soil because of slow germination and a wrinkled appearance. This study shows that crude oil pollution has a significant effect on soil fertility, seed germination and microbial activity.

Soil bacterial community is influenced by long‐term integrated soil fertility management practices in a Ferralsol in Western Kenya

AbstractIntroductionSoil bacterial community structure, abundance and diversity, important in biogeochemical cycling, are influenced by several anthropogenic and edaphic factors. Numerous agronomic practices have been promoted to improve soil fertility and crop production in western Kenya, but little is known on their impacts on soil microbial diversity in the region.Materials and MethodsIn this study, conducted in 2019, we assessed the influence of various long‐term (17 years) agronomic management practices, involving application of farmyard manure (FYM) either sole or under different combinations with inorganic nitrogen (N), phosphorus (P) and potassium (K), using 12 treatments, on bacterial community composition, relative abundance and diversity. The bacterial community composition was assessed through amplicon sequencing on an Illumina Miseq platform conducted in MR DNA Laboratory, USA.ResultsThe soil bacterial community composition and diversity were predominantly higher under management practices with application of FYM, either sole or in combination with inorganic fertilisers compared to treatments with either sole NPK fertiliser or no input application. Certain bacterial taxa, involving Proteobacteria, Bacteroidetes, Nitrospirae, Fusobacteria, Nitrospinae and Actinobacteria predominated in management practices where FYM was added either solely or in combination with chemical fertilisers. In addition, several soil chemical parameters showed significant influences on bacterial composition, relative abundance and diversity indices. Soil pH, soil organic carbon (SOC), N, K, Ca, Mg, Cu, Zn, Fe and cation exchange capacity consistently showed strong positive correlation with numerous bacterial phyla. Bacterial phyla were significantly affected by treatments. Some bacterial phyla, like Chloroflexi and Acidobacteria, were mostly dominant in treatments applied with organic inputs but were depressed under carbon‐deficient treatments (no‐input control and sole NPK application treatments).ConclusionThis study revealed that long‐term agricultural management practices that seek to improve SOC content and nutrient availability also stimulated bacterial diversity and shifted bacterial composition.

Salicylic Acid with Humic Acid Addition as Potential Hallmarks for Alleviating Drought Stress in Maize Crop and Enhancing Soil Health

Climate change is the biggest concern to the human kind and threat to agri-food security. Deficiency of water in soil and the ability of plants to uptake water is slowed down due rising temperature and microbial imbalance in soil. Salicylic acid plays an important role in mitigating drought stress and improves the overall production of crop. Humic acid is another amendment to cope against water stress and optimizes the yield. Apart from that, there is little known about their impact on soil geochemistry and that how soil health is altered.&#x0D; To investigate the effect of salicylic acid and humic acid on the drought experiment was conducted at University Research Farm (URF), PMAS Arid Agriculture University, Rawalpindi during summer 2023. The experiment was set up in randomized complete block design in two factorial arrangements with four replications. The first factor was comprised of mitigation strategies; salicylic acid, humic acid and chemical fertilizer, while second factor was water regimes; water stress and irrigation maintaining 60% field capacity.&#x0D; Plant attributes including chlorophyll content (SPAD value), total soluble protein content (mg/g), total free amino acid (mg/g), K+ content (mg/g), Na+ content (mg/g), 1000 grain weight (g) and grain yield (kg/ha) were measured and reported. On the other hand, soil parameters that were estimated are: soil pH, soil organic matter content (%), available N (ppm), available P (ppm), available K (ppm) and cation exchange capacity (cmol/kg).&#x0D; According to the data analysis, all of the features under study had a substantial impact from the mitigation approaches. The increased value of chlorophyll content (49.11 mg/g) was obtained in water stressed condition by the application of salicylic acid. Under water stressed regime and salicylic acid boosted the total soluble protein content (1.67 mg/g) and total free amino acid (31.93 mg/g) while grain yield (9451.7 kg/ha) was also boosted up by the amendment salicylic acid in maize. There was also increase in the values of soil pH (6.78), CEC (54.37 cmol/kg), SOM content (0.87%), available N (3.24 ppm), available P (26.14 ppm) and available K (211.23 ppm) drought conditions with the implementation of salicylic acid.&#x0D; Humic acid also positively impacted the drought stress and improved the maize yield (8436.2 kg/ha) under drought condition. Similarly, soil nutrient retention is also improved to large extent under water stress state; SOM content (0.49%), available N (2.36 ppm), available P (15.67 ppm) and available K (171.94 ppm).&#x0D; Overall, the study showed that amendment of salicylic acid and humic acid, is the greatest strategy to increase crop production and quality while also improving the health of the soil.

Biochar co-pyrolyzed from peanut shells and maize straw improved soil biochemical properties, rice yield, and reduced cadmium mobilization and accumulation by rice: Biogeochemical investigations

Biochar is an eco-friendly amendment for the remediation of soils contaminated with cadmium (Cd). However, little attention has been paid to the influence and underlying mechanisms of the co-pyrolyzed biochar on the bioavailability and uptake of Cd in paddy soils. The current study explored the effects of biochar co-pyrolyzed from peanut shells (P) and maize straw (M) at different mixing ratios (1:0, 1:1, 1:2, 1:3, 0:1, 2:1 and 3:1, w/w), on the bacterial community and Cd fractionation in paddy soil, and its uptake by rice plant. Biochar addition, particularly P1M3 (P/M 1:3), significantly elevated soil pH and cation exchange capacity, transferred the mobile Cd to the residual fraction, and reduced Cd availability in the rhizosphere soil. P1M3 application decreased the concentration of Cd in different rice tissues (root, stem, leaf, and grain) by 30.0%− 49.4%, compared to the control. Also, P1M3 enhanced the microbial diversity indices and relative abundance of iron-oxidizing bacteria in the rhizosphere soil. Moreover, P1M3 was more effective in promoting the formation of iron plaque, increasing the Cd sequestration by iron plaque than other treatments. Consequently, the highest yield and lowest Cd accumulation in rice were observed following P1M3 application. This study revealed the feasibility of applying P1M3 for facilitating paddy soils contaminated with Cd.

Relationship between pH and base saturation associated with soil cation exchange capacity in soils of Mato Grosso do Sul, Brazil

Relationship between pH and base saturation associated with soil cation exchange capacity in soils of Mato Grosso do Sul, Brazil

Predicting soil Cation Exchange Capacity (CEC) from pH, percentage of Clay andOrganic Carbon: A Case Study on Selected Burundi Surface Soils

A statistical linear regression study was performed on surface soil samples collected in four Burundi agro-écological zones (AEZ) of Imbo, Mumirwa, Kirimiro and Moso. The study aimed at evaluating the causal effects of soil pH, % clay and % Organic C (OC) on soil cation exchange capacity (CEC), using simple, two-way and 3-way linear regression models. Soil pH as an explanatory variable of CEC gave poor results, while % OC emerged as the best one-way explanatory variable of CEC (R²=0,40). With 2-way regression analyses, the best fits were obtained in the Kirimiro AEZ with soil pH and % clay (R²=0,63), Imbo AEZ with soil pH and % OC (R²=0.66) and Imbo and Kirimiro AEZ with % clay and % OC (R²=0,63). The 3-way (pH, % clay and % OC) regression analysis gave statistically significant higher R² values ranging from 0.60 (Mumirwa) to 0.76 (Imbo). Linear regression analysis performed on pooled data (256 samples) proved that the 3-way dependent/explanatory variables model is the best fit (R²=0,64). In conclusion, our results outlined that % OC emerges as the key determinant of CEC in highly weathered, kaolinitic Burundi soils.

Effects of Integrated Application of Vermicompost and Inorganic Fertilizers on Selected Soil Characteristics and Productivity of Wheat (Triticum aestivum L.) and Faba Bean (Vicia faba L.) in Dire and Legedadi Watersheds of Ethiopia

The adoption of integrated soil fertility management (ISFM) practices can improve soil quality and sustainably increase crop yield while slowing down the rate of ongoing degradation. This research assessed the effects of selected ISFM practices on soil properties at the Dire and Legedadi watersheds, central highlands of Ethiopia, in the 2021 and 2022 cropping seasons. Eight treatments were selected (sole wheat, sole faba bean, 100% recommended NPS + urea fertilizers, 100% recommended vermicompost (VC), wheat with half dose both NPS + urea and VC, wheat and faba bean intercropping with half dose both NPS + urea and VC, wheat and faba bean intercropping with half‐dose NPS + urea fertilizers, and wheat and faba bean intercropping with 50% VC). The treatments were studied on farmers’ fields using a randomized complete block design with three replications. Analysis of variance showed that soil samples collected from each plot indicated significant differences in soil organic carbon (SOC), total nitrogen (TN), available phosphorus (Pav), exchangeable bases (Ca2+, Na+, and Kexc), and cation exchange capacity (CEC). Soil pH and moisture showed improvement in combined fertilizers application compared to the preplanting soil sample. A combined application of VC and NPS + urea fertilizers significantly (p &lt; 0.05) increased SOC, Pav, K+, Na+, and CEC compared to the control. A combined application of VC and NPS + urea fertilizers improved the soil quality. The highest TN contents of 0.36% at the Dire site and 0.30% at the Legedadi site were obtained with the full dose VC treatment. Additionally, this treatment resulted in the greatest water‐holding capacity and soil carbon stock at both sites. Similarly, the wheat‐faba bean intercropped plots showed a significant (p &lt; 0.05) effect on the soil carbon stock and sequestration over the control in both study sites. Based on the results of the current study, it can be concluded that the combined application of a half dose of each VC and NPS + urea fertilizers improved most soil physicochemical properties at both sites. This suggests that using a combination of VC and NPS + urea fertilizers can help farmers reduce their inorganic fertilizer needs by 50%.

Bioremediation of chlorpyrifos-contaminated soil with biduri plant (Calotropis gigantea), bacteria, and biochar: Soil fertility impact

During the Industrial Revolution, agriculture was linked to environmental issues. One issue is pesticide pollution. Bioremediation is needed because plant diseases and pests cause farmers to use pesticides excessively, polluting and decreasing soil production. This study evaluated soil fertility from bioremediation with biduri plants, bacteria, and biochar on chlorpyrifos-polluted shallot-growing soil in Brebes Regency. This type of research was an experiment in a greenhouse, using a factorial experimental design with a completely randomized design, consisting of two factors, namely bioremediation agent (A0: without bioremediation agent, A1: Atlantibacter hermannii, A2: bacterial consortium) and coconut shell biochar (B0: without biochar, B1: with biochar). There were six treatment combinations, then replicated three times for each treatment, so there were 18 treatment units. The data were statistically analyzed using ANOVA, Duncan Multiple Range Test, and Pearson correlation. The results showed that the best treatments that were able to improve soil fertility after bioremediation were treatments A1B0 (Atlantibacter hermannii + without biochar), A2B0 (bacterial consortium + without biochar), and A2B1 (bacterial consortium + with biochar). The A1B0 treatment (Atlantibacter hermannii + without biochar) increased the pH by 4.97%, and the soil available P was 12 times higher than the initial soil. The A2B0 (bacterial consortium + without biochar) treatment increased soil cation exchange capacity by 99.81% and soil organic C by 116% higher than the initial soil. The A2B1 (bacterial consortium + with biochar) treatment increased soil total N by 37.50% and available K by 38.47%, higher than the initial soil.

Assessing the Impact of Erosion and Farming Practices on the Spatial Distribution of Topsoil Characteristics in a Sloping Vineyard Using an Open-source QGIS Software

Erosion is one of the major threats that negatively affect agricultural soils. Several studies indicated that sloping vineyards are prone to soil erosion due to the soil management method. This study was conducted in a sloping vineyard planted in 2019 (with a slope of 100 and a slope length of 38 m) in Thu Cuc commune, Tan Son district, Phu Tho province, Vietnam. The main objective of the study is to evaluate soil characteristics (pH, particle-size distribution, organic matter, cation exchange capacity (CEC), N, P, and K macronutrients) related to terrain morphology, soil erosion, and farming practices. The open-source QGIS software was used to evaluate the spatial distribution of the soil characteristics. We found that the organic matter content, CEC, and clay content in the soils taken at the footslope zones were higher than those at the top of the hill as a result of soil erosion. In contrast, higher contents of K and silt were observed at the top of the hill compared to the footslope, indicating an unapparent impact of soil erosion on these two factors in the studied vineyard. Phosphorus was evenly distributed throughout the plot and influenced by the soil characteristics. Indeed, a strong correlation between total P content and soil pH, organic matter, and silt content was revealed in our study. On the other hand, cultivation practices exerted a significant impact on the prevailing accumulation of soil organic matter, CEC, total N, and clay particle size at the lower part of the vine rows following the horizontal flow. The vine rows were planted along the contour lines rather than the dominant slope of the vineyard can explain this tendency. In addition, no cover crops sown between the vine rows probably resulted in intense soil erosion at the steepest part of the terrain. Overall, the terrain morphology and farming practices played an essential role in the spatial distribution of soil characteristics. Therefore, integrating geographic information systems into building a digital database and predicting the spatial distribution of soil parameters is necessary to perform soil quality monitoring and serve sustainable land management.&#x0D;

Temporal variation in the soil properties and rice yield of organic rice farming in the tropical monsoon region, Indonesia

One of the organic farming goals is improving soil properties to support sustainable rice production. This study investigated the soil properties and rice yields under temporal variation of organic rice fields. Soil sampling was conducted in organic rice fields with three temporal variations, namely 0, 4, 7, and 10 years in a tropical monsoon region in Central Java, Indonesia. Variables observed included soil organic carbon, soil carbon stock, soil microbes population, dissolved organic carbon, soil liquid limit, soil sticky limit, soil plasticity limit, soil color changing limit, soil friability, soil porosity, soil total nitrogen, soil total phosphorus, soil available sulfur, exchangeable calcium, cation exchange capacity, total potassium, bulk density, base saturation, exchangeable sodium, exchangeable potassium, and rice yield. This study confirms that soil organic carbon increased by 51.63% within 10 years (from 1.84% to 2.79%). Organic farming also improved all the physical, chemical, and biological soil properties, by the increase of soil organic carbon. However, soil organic carbon is mostly determined by soil cation exchange capacity, soil total phosphorus, and soil porosity. The mechanism of rice yield increase in organic rice farming is not affected by soil organic carbon directly but through the synergic increase in soil total nitrogen. The 1% increase of soil organic carbon increases 0.065% of soil total nitrogen hence rice yield increases by 1.66 tons ha&lt;sup&gt;-1&lt;/sup&gt;. This study supports sustainable agriculture by providing evidence of improved soil properties under organic farming.

Changes in Soil Chemical Properties and Rhizosphere Bacterial Community Induced by Soil Amendments Associated with Reduction in Cadmium Accumulation by Rice

Soil amendments have been extensively employed for the purpose of remediating soils contaminated with cadmium (Cd). However, the potential impacts of soil amendments on soil chemical properties, soil Cd bioavailability, total Cd accumulation by rice, and rhizosphere bacterial community in Cd-contaminated paddy fields located in a tropical region is still at its infancy. In this study, a commercial MgO-CaO-SiO2 conditioner (A), biochar (B), and a combination of the commercial MgO-CaO-SiO2 conditioner and biochar with a ratio of 1:1 (C) were applied at two different doses [2250 kg ha−1 (A150, B150, C150), 4500 kg ha−1 (A300, B300, C300)] to investigate their impacts on soil Cd stabilization and total Cd uptake of rice straw and grain in a Cd-contaminated remediation field experiment. Rhizosphere bacterial community diversity and composition were also assessed using high-throughput sequencing based on 16S rRNA genes. Compared with non-amendment treatment (CK), soil pH, cation exchange capacity (CEC), organic matter (OM), total nitrogen (TN), available nitrogen (AN), and nitrate (NO3−) concentrations were significantly elevated, whereas ammonium (NH4+) and soil available Cd concentrations were reduced by soil amendment treatments. Meanwhile, soil amendments significantly decreased concentrations of total Cd in both rice straw and grain, with the lowest Cd concentration in the C300 treatment. Soil pH and CEC were significantly and negatively associated with soil Cd availability and rice straw and grain Cd concentrations, while NH4+ concentration was positively correlated with soil available Cd concentration, and OM, TN, and NO3− concentrations were positively linked with rice grain Cd concentration. Soil amendments significantly increased bacterial Chao 1 and Shannon indexes and altered bacterial community composition in rhizosphere soil, due to changes in the composition of the community primarily influenced by variations in soil pH, CEC, and soil available Cd, NH4+, available phosphorous (AP) and available Potassium (AK) concentrations. Furthermore, the abundant bacterial species (Pseudomonas) and rare bacterial species (Bacillus, Candidatus_Solibacter and Streptomyces) have been up-regulated by different soil amendments, which might be in favour of soil Cd immobilization. A structural equation model also showed that soil amendments could improve bacterial diversity and change soil pH and CEC, which were conducive to hindering the removal and conversion of Cd. Overall, these results indicate that biochar-(MgO-CaO-SiO2) mixed amendments at high dosage exerted better performance compared with single application soil amendment A and B. The changes in soil chemical properties, available Cd content, and rhizosphere bacterial community assembly induced by soil amendments are closely correlated with the decrease in rice’s ability to accumulate Cd.

Influence of azolla, grass, water hyacinth, and peanut residues in amending soil properties

An incubation experiment was undertaken to evaluate the effects of azolla, grass, water hyacinth, and peanut residues for amending some soil properties. The experiment was laid out in pots comprising 7 treatments, viz. T1: Control, T2: Azolla (Azolla pinnata) @ 100 g/pot, T3: Grass (Phleum pretense) @ 100 g/pot, T4: Water hyacinth (Pontederia crassipes) @100 g/pot, T5: Peanut (Arachis hypogaea) @ 100 g/pot, T6: Azolla @ 50 g/pot + Water hyacinth @ 50 g/pot, and T7: Peanut@ 50 g/pot + Grass @ 50 g/pot. The results revealed that peanut treated soils (T5) played an important role in enhancing soil properties significantly (p &lt; 0.05) and the values of soil organic carbon (SOC), pH, nitrogen, moisture content and cation exchange capacity (CEC) reached at an optimum level to support microbial growth over a year. Biodivers. Conserv. Bioresour. Manag. 2023, 9(2): 57-64

Effect of mixed manure on selected chemical properties, and phosphorus adsorption characteristics of Vertisols in Haramaya district, eastern Ethiopia

AbstractThe phosphorus (P) fixing behaviors of Vertisols have been identified as one of the key drivers of crop response to fertilizer application. More than 75% of applied P in tropical soil was found to be inaccessible to crops due to adsorption and precipitation reactions. A pot experiment was carried out to investigate the effect of mixed manure (MM) on P adsorption characteristics and other selected Vertisol properties. The soil was amended with 0, 5, 10, and 15 t ha−1 of MM. Changes in selected soil parameters and P adsorption characteristics were evaluated after a 30‐day incubation period. An analysis of variance was used to analyze the data. The results demonstrated a substantial drop in soil pH and an increase in soil organic carbon, total nitrogen, available P, and cation exchange capacity compared to the control. The overall quantity and efficiency of adsorbed P were drastically reduced as a result of MM rates. Moreover, the interaction effect of MM and added P concentration demonstrated a considerable increase in both the quantity and efficiency of adsorbed P. Both parameters increased with increased rates of added P concentration but decreased with increasing rates of MM. Despite the fact that all treatments fit well to both the Freundlich and Langmuir isotherms, the former was used due to its greater R2 value. When compared with the control, the Freundlich adsorption coefficient and intensity were found substantially lower. As a result, MM treatment boosted P availability by decreasing adsorption and associated Vertisols characteristics.