Cation Exchange Capacity Content Research Articles

Soil Acidification Can Be Improved under Different Long-Term Fertilization Regimes in a Sweetpotato-Wheat Rotation System.

Soil acidification is a significant form of agricultural soil degradation, which is accelerated by irrational fertilizer application. Sweetpotato and wheat rotation has emerged as an important rotation system and an effective strategy to optimize nutrient cycling and enhance soil fertility in hilly areas, which is also a good option to improve soil acidification and raise soil quality. Studying the effects of different fertilization regimes on soil acidification provides crucial data for managing it effectively. An eight-year field experiment explored seven fertilizer treatments: without fertilization (CK), phosphorus (P) and potassium (K) fertilization (PK), nitrogen (N) and K fertilization (NK), NP fertilization (NP), NP with K chloride fertilization (NPK1), NP with K sulfate fertilization (NPK2), and NPK combined with organic fertilization (NPKM). This study focused on the soil acidity, buffering capacity, and related indicators. After eight years of continuous fertilization in the sweetpotato-wheat rotation, all the treatments accelerated the soil acidification. Notably, N fertilization reduced the soil pH by 1.30-1.84, whereas N-deficient soil showed minimal change. Organic fertilizer addition resulted in the slowest pH reduction among the N treatments. Both N-deficient (PK) and organic fertilizer addition (NPKM) significantly increased the soil cation exchange capacity (CEC) by 8.83% and 6.55%, respectively, compared to CK. Similar trends were observed for the soil-buffering capacity (pHBC). NPK2 increased the soil K+ content more effectively than NPK1. NPKM reduced the sodium and magnesium content compared to CK, with the highest magnesium content among the treatments at 1.60 cmol·kg-1. Regression tree analysis identified the N input and soil magnesium and calcium content as the primary factors influencing the pHBC changes. Structural equation modeling showed that the soil pH is mainly influenced by the soil ammonium N content and pHBC, with coefficients of -0.28 and 0.29, respectively. Changes in the soil pH in the sweetpotato-wheat rotation were primarily associated with the pHBC and N input, where the CEC content emerged as the main factor, modulated by magnesium and calcium. Long-term organic fertilization enhances the soil pHBC and CEC, slowing the magnesium reduction and mitigating soil acidification in agricultural settings.

SEBARAN NILAI KAPASITAS TUKAR KATION (KTK) DAN KEMASAMAN (pH) TANAH DI TANAH VERTISOL KECAMATAN SAKRA KABUPATEN LOMBOK TIMUR

Abstract : this study aims to determine the distribution of Cation Exchange Capacity (CEC) and Acidity (pH) values ​​of soil. This research was conducted in December 2021 - January 2022. The location for taking soil samples was in Sakra District, East Lombok Regency, West Nusa Tenggara. Soil analysis was carried out in January 2021 at the Soil Chemistry Laboratory, Faculty of Agriculture, University of Mataram. The approach used in this study is the land unit (land unit). Soil samples in this study were taken by random sampling technique. The random sampling method is the process of taking samples using a random method. The sample points that will be used are 35 points representing vertisol soils in Sakra District. Soil sample data from the field is analyzed or tested in the laboratory. This laboratory test aims to determine the value of Cation Exchange Capacity (CEC) and Soil Acidity (pH). Utilization of Geographic Information Systems (GIS) in this research is by using the Arcgis application which is used to make maps. Maps are made by processing data that has been analyzed so that it can be entered and overlaid in the application. The results of the study showed that the CEC content analysis of this soil was classified as high, with medium to very high categories. Soil CEC at the study site ranged from 19.73 me/100gr to 69.62 me/100gr. Meanwhile, the results of the analysis of soil pH levels were classified as neutral, with a slightly acidic to slightly alkaline category. The pH level at the study site ranged from 6 to 8.4. Based on the results of research that has been done, this soil has a fairly good level of fertility, but it is necessary to add organic matter as a soil conditioner in order to maintain and increase soil fertility.

Determination of useful boron content of the soils of Kırıkhan-Kumlu region of Hatay province and their relationship with some soil properties

In this study, it was aimed to determine the useful boron content of the soils of Kırıkhan-Kumlu region of Hatay province and its relationships with some physical and chemical properties. For this purpose, a total of 60 soil samples were taken from 0-20 and 20-40 cm depths and from 30 different points to represent the study area. The pH, total salt, composition, cation exchange capacity (CEC), lime, organic matter and useful boron contents of the soils were determined. According to the results of the research; pH contents of the soils were 7.95-8.43; total salt contents 0.009-0.115 %; clay contents 18.88-74.16 %; sand contents 7.12-59.84 %; silt contents 15.28-52.72 %; lime contents 0.47-26.59 %; organic matter contents 1.16-6.08 %; CEC contents 22.26-72.83 me/100 g and useful boron contents 0.10-1.25 mg/kg. In terms of useful boron content of Kırıkhan-Kumlu soils of Hatay province, it was determined that 50.00 % of them were very low, 40.00 % were low and 10.00 % were sufficient at 0-20 cm depth and 50.00 % of them were very low, 43.34 % were low and 6.66 % were sufficient at 20-40 cm depth. While a positive significant relationship was determined between useful boron and salt, clay, lime and CEC contents of soils, a negative significant relationship was determined between useful boron and sand content. Positive significant relationships were determined between salt and clay, lime and CEC contents of the soils, while negative significant relationships were determined between salt and pH and sand contents. Positive significant relationships were determined between clay and organic matter and CEC contents of the study area soils, while negative significant relationships were determined between clay and sand and silt contents. Significant negative relationships were determined between sand and organic matter and CEC contents of the soils. At the same time, while negative significant relationships were determined between silt and CEC and lime and organic matter contents of the soils, positive significant relationships were determined between organic matter and CEC. As a result, it was seen that the useful boron content of the soils in the study area was determined at low and very low levels above 92 % in all soils of the study area and it was seen that the useful boron content of the soils was insufficient and therefore boron fertilization should be done.

Fertilizer application and chemical fertility of a lixisol in a crop rotation system in the southern Sudanian zone of Burkina Faso

The lack of organic matter in soils and the high cost of mineral fertilizers are constraints to the intensification of agricultural production in Burkina Faso. The aim of this study is to evaluate the effects of the joint application of organic and mineral matter on soil fertility under crop rotation conditions. The study was carried out at the research station in Farakoba, from 2018 to 2020. The system was a 4x4 split-plot factorial with 3 replications. The 4 treatments corresponded to 4 crop rotations used as the main factor and 4 manures as the secondary factor. We used 4 rotation sequences: Sorghum-Fonio, Soya-Fonio, Mung bean-fonio, Sorghum-Mung bean. The four secondary treatments corresponded to four fertilizers: control with no fertilizer application; NPK and urea; Compost+poultry manure; Compost+poultry manure+Burkina phosphate). Results showed that legume-cereal rotations resulted in a 2.3% drop in C/N ratio, while the total exchangeable base (TEB) and the cation exchange capacity (CEC) increased by 82.53% and 24.08% respectively compared to the soil at the start of cultivation. Compared to the soil at the beginning of the crop, the soya-fonio rotation resulted in CEC and TEB increases of 26.87% and 86.55% respectively. The Compost+poultry manure treatment recorded significantly higher TEB and CEC contents, followed by the Compost+poultry manure+Burkina Phosphate and Compost+NPK+Urea treatments. Compared to the Compost+NPK+Urea treatment, the Compost+Poultry manure +Burkina Phosphate treatment resulted in TEB and CEC increases of 18.7% and 5.06% respectively. The results showed a negative and non-significant correlation between C/N and the parameters Ca, Na, Mg, TEB, CEC and saturation level. On the other hand, the correlation between C/N and K was positive and non-significant (r=0.036). In a context of high mineral fertilizer costs, fertilization techniques and productivity of systems can therefore be improved by combining local fertilizing resources such as poultry manure, Burkina phosphate and legume rotations.

Distribution characteristics of organic carbon (nitrogen) content, cation exchange capacity, and specific surface area in different soil particle sizes

Understanding the distribution of soil organic carbon and nitrogen (OC(N)) content, cation exchange capacity (CEC), and specific surface area (SSA) in different soil particle sizes is crucial for studying soil fertility and properties. In this study, we investigated the distribution characteristics of the OC(N), CECand SSA in different particles of yellow–brown soil under different methods. The result revealed that as the particle size decreased, the soil OC(N), SSA and CEC content gradually increase. The content of OC and ON different soil particles ranged from 1.50–28.16 g·kg−1 to 0.18–3.78 g·kg−1, respectively, and exhibited significant differences between different particles. We observed good linear relationships between OC and ON in different particle sizes of yellow–brown soil under different utilization methods, with correlation coefficients ranging from 0.86 to 0.98, reaching a very significant level (n = 12, p < 0.01). The ranges of SSA and CEC in different particles of the four soils were 0.30–94.70 m2·g−1 and 0.70–62.91 cmol·kg−1, respectively. Additionally, we found logarithmic relationships between SSA (CEC) and the equivalent diameter for the four soils, with correlation coefficients (r2) higher than 0.91. Furthermore, there was an extremely significant linear relationship between CEC and SSA of the four soils, with correlation coefficients (r2) of 0.92–0.97 (n = 12, p < 0.01). These results highlight the close relationship between soil particle size and soil OC(N), SSA, and CEC. The conclusions drawn from this study provide valuable data support and a theoretical basis for further understanding soil properties.

Sorption of Perfluorooctane Sulfonic Acid Including Its Isomers to Soils: Effects of pH, Natural Organic Matter and Na2SO4

Perfluorooctane sulfonic acid (PFOS) has been produced in large quantities for the use in various applications. As a consequence, PFOS is ubiquitous in the environment. Managing transportation of PFOS requires a clear understanding of PFOS mobilization in soils and their interactions with different soil components. The current study investigated a pH-dependent sorption of PFOS isomers onto soil and the effect of dissolved humic substances and Na2SO4. Sorption experiments of PFOS isomers was conducted on top and subsoils to assess their capacity to retain PFOS. Topsoil and subsoil samples were sampled from two areas in Kvarntorp, Kumla, Sweden. Sorption experiments were performed by shaking a mixture of soil and soil solutions spiked with PFOS isomers. One way ANOVA showed that linear PFOS (L-PFOS) and branched PFOS (Br-PFOS) isomers showed different sorption behavior onto soils. Calculated logarithmic partition coefficients revealed that L-PFOS is readily sorbed onto soils sampled at area 1) at very low pH (&amp;lt;4.5) whereas it was the least sorbed onto soils collected at area 2) under the studied pH range. Electrostatic interactions governed the sorption of PFOS isomers during acidic conditions whereas other mechanism controlled the sorption during neutral to alkaline conditions. The presence of humic acid enhanced the sorption of all PFOS isomers whereas fulvic acid inhibited their sorption onto soil. Sorption results revealed that the topsoil had a high capacity to sorb all PFOS isomers compared to the subsoil from the same area. For soils collected from an area covered by young oak trees, a high sorption on the topsoil was attributed to a high organic content [measured as loss on ignition (LOI)] and cation exchange capacity (CEC). However, there was no correlation between sorption capacity and LOI or CEC content for soil collected from another area covered by spruce forest. This suggested that the sorption on latter soils was controlled by other physicochemical properties.

DETERMINATION OF THE RELATIONSHIP WITH THE AVAILABLE BORON CONTENT AND SOME SOIL PROPERTIES OF THE SOILS OF HATAY PROVINCE REYHANLI-KUMLU REGION

In this study, it was aimed to determine the useful boron content of the soils of Hatay province Reyhanlı-Kumlu region and its relations with some physical and chemical properties. For this purpose, a total of 80 soil samples were taken from 0-20 and 20-40 cm depths and 40 different points to represent the study area. The pH, total salt, texture, cation exchange capacity (CEC), lime, organic matter and useful boron contents of the soils were determined in the samples taken. According to the research results; the pH contents of soils were found to be between 6.86-8.44; total salt contents 0.007-0.070%; clay contents of 15.84-76.56%; sand contents 0.72-51.44%; silt contents 16.72-47.28%; lime contents 2.71-64.23%; organic matter contents 0.40-2.89%; the CEC contents between 26.43-91.13 me/100 g and the available boron contents between 0.07-1.76 mg/kg. In terms of the available boron content of Hatay province Reyhanlı-Kumlu soils, at 0-20 cm depth 22.50% is very low, 50.00% is less and 27.50% is sufficient, and at 20-40 cm depth 37.50% is very low, 40.00% were low and 22.50% were sufficient. While a significant positive relationship was determined between the available boron and clay content of the soils, a significant negative relationship was determined between the available boron and silt content. In addition, negative significant relationships were determined between soil pH and salt and sand content, while very significant positive relationships were determined between soil pH and clay with CEC contents. At the same time, a significant positive relationship was determined between the lime and organic matter content of the soils, while a significant negative relationship was determined between lime and CEC. As a result, the available boron content in the soils of the study area was determined at a low or very low level in over 77% of all the soils of the study area, and it was observed that the available boron content of the soils was insufficient and therefore boron fertilization was required.

SIFAT KIMIA TANAH PASCA KEBAKARAN LAHAN DI KEBUN KELAPA SAWIT DI KABUPATEN TULANG BAWANG PROVINSI LAMPUNG

Fire is a serious problem that must be faced in the management of forest or plantation areas. Land fires have caused huge losses of soil nutrient. Lampung is one of the provinces in Indonesia having a problem related to land fires. The purpose of this study was to analyze the impact of land fires on the soil base cations (K, Mg, Ca, Na) and cation exchange capacity (CEC) in three different planting zones (i.e. fertilization, harvesting path, and frond stack areas) within oil palm plantations between land with low fire intensity and land with high fire intensity. Observations were made using a survey method in three zones of oil palm plantations, including fertilization area, harvesting path, and frond stack area. Soil samples were collected by using a soil drill at two depths, namely 0-10 cm and 10-30 cm from the soil surface. The study showed that at depth 0-10 cm, land A (land with low fire intensity) had higher K, Na, and Ca contents, as well as higher CEC as compared to land B (land with high fire intensity). At depth 10-30 cm, field A had higher K and CEC content, and lower Mg content than land B. comparing among different zones of oil palm plantations also showed that soil exchangeable K and Mg were significantly different, especially at depths of 10-30 cm. This was due to differences in land management (i.e. fertilization and liming).

Co-Composting of Khat-Derived Biochar with Municipal Solid Waste: A Sustainable Practice of Waste Management

Biochar is a way to improve the performance of the composting process and the quality of compost. This study was aimed to investigate the optimum ratio of khat straw (Catha edulis) biochar and organic municipal solid waste mixtures to improve the quality of the resulting co-composts. Khat-derived biochar during pyrolysis at 350 °C was added to organic municipal solid waste mix and four co-composting treatments were prepared with the compositions (% w/w): control compost (no biochar) and 5%, 15%, and 25% co-composted biochar in three replicates. The total organic carbon, organic matter, total nitrogen, available phosphorus, and potassium values ranged as 16.76–21.45%, 30.77–40.26%, 0.97–1.68%, 0.58–0.76%, and 12.72–15.29%, respectively. The results confirmed that 5% and 15% co-composted khat biochars had significantly reduced (p &lt; 0.05) organic matter loss and increased the contents of cation exchange capacity, pH, phosphorous, potassium, calcium, magnesium, and zinc compared to the control compost, while some heavy metals (Fe, Cu, and Mn) and EC values in co-composted biochars are lower than the control compost. Khat-derived biochar could be added to municipal organic waste mix at 5–15% (w/w) in order to get better quality of compost, which can be used as biofertilizer.

Hatay İli Kırıkhan-Reyhanlı Tarım Topraklarının pH, Kireç, Organik Madde ve KDK İçeriklerinin Belirlenmesi

Bu çalışmada Hatay ili Kırıkhan-Reyhanlı tarım topraklarının pH, kireç, organik madde ve katyon değişim kapasitesi (KDK) içeriklerinin belirlenmesi amaçlanmıştır. Bu amaç için çalışma alanı topraklarını temsil edecek şekilde iki farklı derinlikten (0-20 ve 20-40 cm) ve 30 ayrı noktadan olmak üzere toplamda 60 toprak örneği alınmıştır. Örneklerde tarım topraklarının pH, kireç, organik madde ve KDK içerikleri belirlenmiştir. Araştırma sonuçlarına göre; çalışma alanı toprakların pH içerikleri 7.57-8.36 arasında değişmekte olup toprak örneklerinin pH’larının tüm bölgede hafif alkalin özellikte olduğu görülmüştür. Kırıkhan-Reyhanlı tarım topraklarının kireç içerikleri % 5.66-51.14 olup kireç içerikleri orta kireçli ile çok fazla kireçli arasında değişmekle birlikte, toprakların % 28.33’ü orta kireçli, % 35.00’i fazla kireçli ve % 36.67’si ise çok fazla kireçli görülmüştür. Çalışma alanı tarım topraklarının organik madde içerikleri % 1.42-4.10 arasında olup toprak örneklerinin organik maddeleri az ile yüksek organik madde arasında değişmekle birlikte, toprakların % 23.33’ü az, % 48.34’ü orta, % 25.00’i iyi ve % 3.33’ü ise yüksek oranda organik madde görülmüştür. Kırıkhan-Reyhanlı tarım topraklarının KDK içerikleri 16.89-42.10 me/100 gr arasında değişmekte olduğu belirlenmiştir. Toprakların pH içeriği ile KDK içeriği arasında pozitif önemli ilişki belirlenir iken, kireç içeriği ile KDK içeriği arasında ise negatif önemli ilişkisi olduğu ortaya konulmuştur.

Komposisi Fraksi Pasir dan Sifat Kimia Tanah Pada Areal Revegetasi Lahan Bekas Tambang Batubara

The purpose of this research were to determine the composition of sand fraction and chemical properties at revegetation area. The research was conducted from April to October 2019 . The mineralogical Compositions of sand fraction were analyzed using a Polarizing Microscope (PM) at the laboratory of Mineral BB Litbang SDLP, Bogor. The results showed that the composition of sand fractionof soil at revegetation area was dominatd by quartz,with small amounts of opaque, zircon,weathered mineral, rock fragment, and tourmaline.Chemical properties indicated that the soil at revegetation area showed pH from 6,05 to 6,49, had low content of cation exchange capacity in the whole layers, very high content of base saturation, very low to low organic carbon. Exchangeable K and Na are low in the whole layers, the moderate content of potential potassium. Both exchangeable Ca and Mg were lot to moderate. Potentioal P content in soil varies from moderate to high.Soil management in revegetation area should be focused on Maintaining soil fertility through application of liming, and fertilizers

Apply biochar to ameliorate soda saline-alkali land, improve soil function and increase corn nutrient availability in the Songnen Plain

Soda saline-alkali soils are characterized by high concentration of sodium cations on the exchange complex or in soil-water resulting in soils which are physically as well as nutritionally challenging for crop production. Biochar application has received growing interest as a sustainable technology to improve physicochemical properties in non-saline and non-alkali soils. However, information is inadequate regarding potential of using corn straw derived biochar as an organic material to reduce soda saline-alkali stress. Based on the established model of corn straw biochar-soda saline alkali soil-corn system, soil and plant samples were collected from long-term field experiment in soda saline-alkali land with different addition rates of corn straw biochar (CK: control, T5: 5 ton ha−1, T10: 10 ton ha−1, T15: 15 ton ha−1, T20: 20 ton ha−1, T25: 25 ton ha−1, T30: 30 ton ha−1). In the seedling and harvest period, addition of corn straw biochar enhanced the contents of cation exchange capacity (CEC), organic matter, and nutrients of 0–20 cm and 20–40 cm saline-alkali soil layers and the above ground and underground parts of corn. However, the results were contrary as far as pH, salt, and Na+ were concerned, and the effect of T20 was the most significant. Principal component analysis showed that CEC, pH, salinity, and organic matter could be used as indicators to evaluate the improvement effect of biochar on soda saline-alkali soil. Irrespective of the application of biochar, pH, salt content, Na+, and nutrients concentrations at seedling stage were higher than those at harvest stage, indicating that planting corn could improve soda saline-alkali soil. It may be concluded that corn straw biochar can be used as an organic amendment for reducing adverse effects of salinity and alkalinity on soil functions governed by their rates of addition.

Interaction between Fusarium Head Blight and Crown Rot Disease Incidence and Environmental Factors and Soil Physiochemical Analysis on Wheat in the South of Iraq, Basra Province

This study was conducted to evaluate the interaction between disease incidence of both Fusarium head blight (FHB) and crown rot (FCR) and physiochemical parameters for soil samples and environmental factors in 14 selected wheat fields in the North of Basra province. The results showed that both diseases were occurred in all surveyed fields. The level of FCR incidence was higher than FHB. The incidence of both diseases was increased with favourable weather conditions (high humidity and temperature ˃15 °C), reaching the highest levels in crucial periods before and during the ripening stage. The percentage of disease incidence ranged between 6 to 71% and 3 to 54% for FCR and FHB, respectively. Nine physiochemical parameters of soil were examined in this study, but only soil organic carbon (SOC) (P< 0.0000), soil organic matter (SOM) (P< 0.0000) and Cation exchange capacity (CEC) (P< 0.0008) and (P< 0.0002) had highly significant differences among the selected wheat fields in the occurrence of disease incidence for FHB and FCR respectively. The values were ranged between 0.33-1.27% for SOC, 0.66-2.54% for SOM and 10.08-20.59 mg/100g for CEC. Favourable weather conditions and poor soils with SOM, SOC and CEC contents were found to be great factors for encouraging both diseases during this study.

Impact of Land Use Types and Soil Depths on the Distribution of Soil Physical and Chemical Properties in Soils of Aboy Gara Watershed, at Gidan District, North Wollo Zone, Ethiopia

The study was conducted at the degraded land soils of the Abuhoy Gara Catchment, which is located in the Gidan District of North Wello Zone, Ethiopia to determine the impact of land use type and soil depth on the distribution of soil physical and chemical properties. Soil samples were collected from representative locations with four replications at two depths, surface (0-15 cm) and subsurface (15-30 cm) of cultivated, grazing and bush land use types. One hundred eighty soil samples were collected from the depths of 0-15 and 15-30 cm each in a radial sampling scheme using an auger. Totally, twelve composite soil samples were collected using flexible grid survey method of 1:30,000 scales. The collected samples were air-dried, homogenized and sieved to pass a 2 mm mesh sieve for the standard physical and chemical analyses. Results showed that the soil physical and chemical properties were significantly affected by the interaction of land uses and soil depths. Silt content decreases while clay content increases across depth from surface to subsurface soils. The lowest pH-H2O was registered at the subsurface soils of the grazing lands, while the highest was recorded at the surface soils of the bush land. The interaction effect of land use by soil depth on the variability of soil organic matter was significantly higher at surface layer of the grazing land and lower at surface layer of cultivated land. Similarly, soil total nitrogen was highest in surface layer of the grazing land, while it was lowest in subsurface layer of the bush land. Exchangeable bases were highest in surface soils of the bush land and lowest in the surface soils of cultivated land. The contents of both exchangeable bases were decreasing with soil depth in all land uses except the bush land. Significant difference in cation exchange capacity contents was observed as highest in surface soil layer of the bush land and lowest in surface soil layer of the cultivated land. From the results of the study, it can be concluded that the interaction of land use with soil depth showed negative effects especially disturbance of soil nutrient status on cultivated land in surface soils. In general, the spatial variability of soil properties indicates the soil conditions were strongly affected by inappropriate land use and soil management practices including soil depth. Therefore, reducing intensity of cultivation, adopting integrated soil fertility management and application of organic fertilizers could maintain the existing soil condition and replenish degraded soil properties.

Long-term effects of residual sewage sludge application in tropical soils under Eucalyptus plantations

Studies regarding the residual effects of sewage sludge in soil several years after the first and only application are still scarce, especially for tropical areas under forestry management. In these soils, the residual effects can represent a neglected phenomenon, since silvicultural management experiences a longer crop rotation cycle compared to most common agricultural cycles. Consequently, under forestry management, sewage sludge applications can represent an event occurring just once over cycles of several years. This study aimed to evaluate the long-term effects of residual sewage sludge application in infertile tropical soils under Eucalyptus plantations in terms of both the main chemical features (pH, soil organic matter, N, P, S, K, Ca, Mg, and cation-exchange capacity) and the potentially toxic elements (As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Se, and Zn) concentrations/behaviors of soil. Residual effects were evaluated in four areas (São Paulo State, Brazil) after 10.0, 12.2, 12.4, and 17.2 years from the first and only application, respectively. Differences in terms of treatments were evaluated by analysis of variance; correlations and similarity analyzed by principal component and cluster analysis, respectively. The results showed that soil organic matter, main macronutrients (N and P), and cation-exchange capacity contents were generally higher in sewage sludge-treated soils while potentially toxic element contents tended to increase at increasing sewage sludge doses. In most of the investigated treatments, the potentially toxic element concentrations were usually below both the soil natural background concentrations and quality reference values. Principal component and cluster analysis revealed that differences among areas were primary due to differences in applied sewage sludge type and amount. The effects of residual sewage sludge application on soil, in terms of both the pros and cons, can be detected even many years after the first and only application. Studies on the long-term effects of sewage sludge should be mandatory for both monitoring the pedoenvironment and for guiding policymakers and producers on the best practices for their reuse and management.

Effect of land use pattern change from paddy soil to vegetable soil on the adsorption-desorption of cadmium by soil aggregates.

The influence of land use change from paddy soil to vegetable soil on the adsorption-desorption behavior of Cd in soil aggregates and the variation in soil properties were investigated. The vegetable soil was characterized by lower pH, organic matter content, cation exchange capacity (CEC), free iron oxides, manganese oxides, and catalase activity and higher urease activity compared with the paddy soil. In the isothermal adsorption and desorption experiments, the adsorption characteristics of Cd of the two soils could be well described by Langmuir and Freundlich equations. The adsorption capacity of vegetable soil decreased 22.72%, and the desorption rate increased 35% with respect to paddy soil. Therefore, conversion from paddy to vegetable field can reduce the adsorption ability to Cd of the soil to a certain extent. Both the two soils reached the maximum adsorption capacity and the minimum desorption rate in the <0.002-mm faction. The adsorption capacity of Cd in paddy and vegetable soils exhibited great reliance on the content of CEC. Desorption rate was negatively correlated with the four indicators: organic matter, CEC, free iron oxides, and manganese oxides, and specific adsorption was primarily controlled by soil organic matter and manganese oxides.

Evaluation of Spatial Variability of Soil Physico-Chemical Characteristics on Rhodic Ferralsol at the Syferkuil Experimental Farm of University of Limpopo, South Africa

&lt;p&gt;Spatial variability among selected soil physical and chemical properties in twelve profiles dug across the research block of the University of Limpopo experimental farm was investigated. The soils were moderately shallow to deep, contain variable textural classes and classified as Rhodic ferralsol. Over 90% of the samples were considered as slightly alkaline based on the water-measured pHvalues but decreased to marginally over 27% when measured in KCl. The electrical conductivity of the soils revealed a generally non-saline field. Bray P1, EC, exchangeable cations, extractable Zn and effective cation exchange capacity contents differed significantly (p &amp;lt; 0.05) with depth while K, Mg, Ca, Mn, organic carbon and ECEC differed significantly (p &amp;lt; 0.05) across profiles. Semi-variograms for the measured variables had low values indicating the existence of considerable level of spatial variability. Spatial dependence among top and subsoil pH, EC, organic carbon, sand, silt clay and bulk density ranged between weak and strong. Results revealed a significant spatial variability of the characterized parameters across the research block because to differences in tillage, cropping pattern and nutrient specific application over the years.&lt;/p&gt;

Influence of soil factors on the soil enzyme inhibition by Cd

A comparative study was conducted on the toxicity of Cd to alkaline phosphatase activity (ALP) and dehydrogenase activity (DHA) in 18 top soils with contrasting soil properties representative of 14 major soil types in China. Soil pH and carbonate content, soil organic matter, and cation exchange capacity (CEC) largely affected the Cd toxicity on two enzyme activities; with the soil pH having only minor effect on the median ecological dose values based on total Cd concentrations (ED50 T). The values of ED50 T/ED50 W (based on water-soluble Cd content) of alkaline phosphatase and dehydrogenase were strongly influenced by pH and CEC contents, which explained up to 71% of the variation for alkaline phosphatase, 82% of the variation for dehydrogenase, and also were significantly correlated with the parameter KF derived from Freundlich adsorption isotherms. This study suggests that the values of ED50 T/ED50 W could be useful to evaluate the buffer capacity of soils which protects soil enzymes from harmful effects of heavy metal.

안산천에서 이탈리안 라이그라스 혼파조합이 사초생산성과 토양 특성에 미치는 영향

This experiment was carried out to order to determine the forage production and soil characteristics in mixtures of Italian ryegrass (IRG) and annual legumes at the riverbed. The IRG and hairy vetch mixture had the highest in fresh, dry matter (DM) as well as total digestible nutrients (TDN) yields among the forage mixtures. Further IRG and hairy vetch mixture had the highest in DM content. The crude protein (CP) content of IRG and hairy vetch mixture was the highest, Whereas non-fiber carbohydrate (NFC) and TDN contents were lower compared to other mixtures. The total nitrogen (TN) of IRG and hairy vetch mixture was the highest due to high nitrogen fixation in the riverbed soil. The IRG and rape mixture was the highest in organic matter (OM) of soil. Moreover, the available P2O5 of soil in IRG and crimson clover mixtures was higher compared to other mixtures. Further, the IRG and hairy vetch mixture was the highest in cation exchange capacity (CEC) content. Therefore IRG and hairy vetch mixture is more suitable in forage mixtures due to high forage production and protein as well as high soil CEC content at the riverbed. (

Effects of combined amendments on heavy metal accumulation in rice (Oryza sativa L.) planted on contaminated paddy soil

Stabilization of heavy metals in situ was investigated. Two combined amendments (LS, limestone+sepiolite; HZ, hydroxyhistidine+zeolite) were applied at ratios of 0.2%, 0.4%, and 0.8% (w/w) to paddy soil with multi-metal (Pb, Cd, Cu, and Zn) contamination. The effects of these two combined amendments on heavy metal bioavailability in soil, and on uptake and accumulation of heavy metals in rice plants were investigated. Application of LS and HZ significantly increased soil pH values and cation exchange capacity contents, and resulted in a reduction in exchangeable fraction of metals and in extract metal concentrations of amended soils through toxicity characteristic leaching procedure (TCLP). LS and HZ obviously inhibited uptake and accumulation of Pb, Cd, Cu, and Zn in rice plants. Compared with the control soil, concentrations of Pb, Cd, Cu, and Zn in brown rice were decreased by 10.6–31.8%, 16.7–25.5%, 11.5–22.1%, and 11.7–16.3%, respectively, as a result of 0.2% to 0.8% addition of LS, and decreased by 5.1–40.8%, 16.7–20.0%, 8.1–16.2%, and 13.3–21.7%, respectively, as a result of 0.2–0.8% addition of HZ. Significant positive linear correlations were found between heavy metal concentrations in TCLP extracts and those in rice tissues except for Pb. Extracting heavy metals with TCLP was a more suitable method for estimating heavy metal bioavailability concentrations of amended soil than exchangeable fraction of heavy metals, because the latter underestimated heavy metal bioavailability. These results demonstrate that LS and HZ could be effective in reducing heavy metal bioavailability and accumulation in rice grown on multi-metal-contaminated soils.