Retention Capacity Of Soils Research Articles

Pedoecological Regularities of Organic Carbon Retention in Estonian Mineral Soils

Soil organic carbon (SOC) retaining capacities of epipedon (EP), subsoil (SS) and soil cover (SC) as a whole, are soil type specific. Depending on individual and sites characteristics, the generalized humus status indices of soil types (EP and SC thickness and SOC stocks) may vary. Land use and land use change primarily influence the properties and fabric of the EP, but the humus status (SOC concentration and stock, fabric of horizons) of the SS remains practically unchangeable. The mean mineral soils SOC stocks, EP quality and SOC distribution in soil profiles depend mainly on the water regime, mineral composition (texture, calcareousness), development of eluvial processes and the land use peculiarities of soils. The mean area weighted SC SOC stock of Estonian mineral soils is 99.9 Mg ha–1, thereby the mean hydromorphic soils SOC retention capacity considerably exceeds the SOC retention capacity of automorphic soils (means are accordingly 127.5 and 78.9 Mg ha–1). The sustainable management of SOC is based on adequate information about actual SOC stocks and theoretically established or optimal humus status levels of soil types. The aggregate of SOC retained in the mineral soils of Estonia (3,235,100 ha) amounts to 323 ± 46 Tg (1 Tg = 1012 g). Approximately 42% of this is sequestered into stabilized humus, 40% into instable raw-humous material and 18% into forest (grassland) floor and shallow peat layers.

The use of hydrogel in afforestation of postindustrial areas

Some areas intended for afforestation are characterised by a lack of moisture and mineral nutrients. One of the approaches to improve water retention capacity of soils is the use of hydrogels (polymer soil conditioners). The presented experiment was performed with 4 different methods of hydrogel applications and control in a postindustrial area – a dumping ground of the Brown Coal Mine Belchatow (Forest District Administration Belchatow). The Aquaterra product (pure hydrogel) and hydrogel with nutrients (TerraVit) produced by TerraGubin company were used in all experiments. From 292 to 306 one-year old seedlings of Pinus sylvestris L. of an average height of 80–101 mm were planted in each plot. The influence of hydrogel application method on successful afforestation and growth of seedling was analyzed after the first vegetation year. Maximum number of survived seedlings (93.3%) was observed for hydrogel applied through roots coating, minimum (72.4%) for hydrogel with fertilizers applied under plants. Results obtained for pure hydrogel surface application (89.1%) and pure hydrogel applied under plants (85.3%) can be compared with results from control plot (89.7%). Mean heights of surviving seedlings were similar (128–130 mm) for root coating, and both methods of hydrogel application under plants, in contrast with surficial hydrogel application (117 mm) and control where they were minimal (111 mm). Mean height increments in surviving seedlings were minimum in control plot (31 mm), and similar (38–40 mm) for root coating and surface application. The best results of height increments (47 mm) were obtained when hydrogel mixed with fertiliser was applied under plants. To sum up, in view of plant survival the best method of polymer soil conditioner (hydrogel) application was root coating; this method gave also satisfactory increments of plant height.

Gravity factor of the formation of the field and capillary water capacities in soils and artificial layered soil-like bodies

The water retention capacity of soils characterizes a quasiequilibrium between the forces retaining and removing the soil water. It has been studied under field and laboratory conditions. It is shown that the gravity factor, as well as the soil particle-size distribution and structure, has an important role in determining the soil water capacity after the outflow of gravitational water. Our study enlarges the traditional notion about the nature of the field water capacity and capillary water capacity. Physically substantiated methods for determining these constants from the soil water retention curves are suggested. The assessment of the amount of perched water in the layers with broken capillary systems, such as in the layered soils and in the artificial soil-like bodies created upon the construction of soil drainage systems, is of particular importance. Regularities of the water retention capacity in such layered soils of different textures with inclusions of gravelly and peat layers have been analyzed. It is shown that the creation of layered soils with gravelly and peat layers may be an efficient method to rise the soil water retention capacity and protect the soil from secondary salinization.

Multi‐scale modelling of land‐use change and river training effects on floods in the Rhine basin

AbstractLand‐use changes effects on floods are investigated by a multi‐scale modelling study, where runoff generation in catchments of different sizes, different land uses and morphological characteristics are simulated in a nested manner. The macro‐scale covers the Rhine basin (excluding the alpine part), the upper meso‐scale covers various tributaries of the Rhine and three lower meso‐scale study areas (100–500 km2) represent different characteristic land‐use patterns. The main innovation is the combination of models at different scales and at different levels of process representation in order to account for the complexity of land‐use change impacts for a large river basin.The results showed that the influence of land‐use on storm runoff generation is stronger for convective storm events with high precipitation intensities than for long advective storms with low intensities. The simulated flood increase at the lower meso‐scale for a scenario of rather strong urbanization is in the order of 0 and 4% for advective rainfall events, and 10–30% for convective rain storms with a return period of 2–10 years.Convective storm events, however, are of hardly any relevance for the formation of floods in the large river basins of Central Europe, because the extent of convective rainstorms is restricted to local occurrence. Due to the dominance of advective precipitation for macro‐scale flooding, limited water retention capacity of antecedent wet soils and superposition of flood waves from different tributaries, the land‐use change effects at the macro‐scale are even smaller, for example at Cologne (catchment area 100 000 km2), land‐use change effects may result in not more than 1–5 cm water level of the Rhine. Water retention measures in polders along the Upper and Lower Rhine yield flood peak attenuation along the Rhine all the way down to the Dutch border between 1 and 15 cm. Copyright © 2007 John Wiley & Sons, Ltd.

Forest site classification of forest ecosystems in Bohemian Karst (Czech Republic)

The study focuses on selected forest site units on water uninfluenced sites on limestone in Bohemian Karst. The species composition of phytocoenoses, their potential production and soil properties were assessed. Studied forest site complexes are correctly determined and they provide important information from the aspect of planning and practical nature conservation management. It is necessary to specify the criteria of categoria calcaria in detail, since it is often difficult to distinguish it from categoria mesotrophica. Water retention capacity of soils, a criterion often neglected so far, presents a useful view of forest site water budget and it is a suitable criterion in forest site classification.

Characterization and Heavy Metal Retention Capacity of Soils in Mangrove Forest of the Niger Delta, Nigeria

Soils under the main mangrove (Rhizophora racemosa and Avicennia germinans) forest in the Niger Delta, Nigeria, were characterized, and their capacities to retain heavy metals were examined by using soil column leaching experiments, using 20 mg L−1 Cu, 50 mg L−1 Zn, 20 mg L−1 Cd, and 100 mg L−1 Mn solutions. At the end of the leaching experiments, soil samples from each column were divided into two layers (0–5 cm and 5–10 cm) and analyzed for total metal retained. The fractionation of heavy metals in the surface soil samples (0–5 cm) was investigated by the sequential extraction technique. The study showed that the soils were influenced by tidal flow and characterized by the presence of very fine textured, thin (0–5 cm) to moderately thick (10–15 cm) layer of alluvium (mud) on the surface. The fibric soil material beneath the surface mud varies in thickness from about 70 to 100 cm, and beyond the histic layer is the plastic, very sticky, massive clay. In situ, the soils were neutral in reaction (pH 7.0–7.2), but became strongly acid (pH 3.3–4.8) upon drying. They are saline, high in soluble salts, highly reduced, with CEC that is low in the fibric layer, but high in the mineral, clayey subsoil horizon. The soils are saturated with water for much more than 30 days in a year and have fiber content that is more than 40 cm thick, with the fibric sphagnum constituting more than three‐fourths by volume to a depth greater than 90 cm. The soils, classified as Typic Sphagnofibrists, sequestered considerable amounts of copper (Cu), zinc (Zn), cadmium (Cd), and manganese (Mn) with most of the metals retained in the surface soils. The anthropogenic heavy metals were mostly adsorbed probably to the negatively charged sites of organics and clay. These loosely bound metals may be desorbed and reenter the aqueous phase, thus becoming a secondary source of metal pollution.

Phosphate Reactivity in Long‐Term Poultry Litter‐Amended Southern Delaware Sandy Soils

Eutrophication caused by dissolved P from poultry litter (PL)‐amended agricultural soils has been a serious environmental concern in the Delaware–Maryland–Virginia Peninsula (Delmarva), USA. To evaluate state and federal nutrient management strategies for reducing the environmental impact of soluble P from long‐term PL‐amended Delaware (DE) soils, we investigated (i) inorganic P speciation; (ii) P adsorption capacity; and (iii) the extent of P desorption. Although the electron microprobe (EMP) analyses showed a strong correlation between P and Al/Fe, crystalline Al/Fe‐P precipitates were not detected by x‐ray diffraction (XRD). Instead, the inorganic P fractionation analyses showed high levels of oxalate extractable P, Al, and Fe fractions (615–858, 1215–1478, and 337–752 mg kg−1, respectively), which were susceptible to slow release during the long‐term (30‐d) P desorption experiments at a moderately acidic soil pHwater The labile P in the short‐term (24‐h) desorption studies was significantly associated with oxalate and F extractable Fe and Al, respectively. This was evident in an 80% reduction maximum in total desorbable P from NH4 oxalate/F pretreated soils. In the adsorption experiments, P was strongly retained in soils at near targeted pH of lime (≈6.0), but P adsorption gradually decreased with decreasing pH near the soil pHwater (≈5.0). The overall findings suggest that P losses from the can be suppressed by an increase in the P retention capacity of soils via (i) an increase in the number of lime applications to maintain soil pHwater at near targeted pH values, and/or (ii) alum/iron sulfate amendments to provide additional Al‐ and Fe‐based adsorbents.

Effects of hydrogel amendment on water storage of sandy loam and loam soils and seedling growth of barley, wheat and chickpea

The hydrogel amendments may improve seedling growth and establishment by increasing water retention capacity of soils and regulating the plants available water supplies, particularly under arid environments. The effects of different levels of a locally prepared hydrogel were studied on the moisture properties of sandy loam and loam soils (fine-loamy, mixed, hyperthermic Typic Haplargids, USDA, Luvic Yermosol, FAO) and on growth response of three plant species, viz. barley (Hordeum vulgare L.), wheat (Triticum aestivum L.) and chickpea (Cicer arietinum L.). Water absorption by gel was rapid and highest in distilled water and was inhibited by an increase in water salinity. The addition of 0.1, 0.2 and 0.3% hydrogel increased the moisture retention (θr) at field capacity linearly (r = 0.988) and thus the amount of plant available water significantly in both sandy loam and loam soils compared to the untreated soils. Seed germination of wheat and barley was not affected but seedling growth of both species was improved by the gel amendment. In loam soil, seed germination of chickpea was higher with 0.2% gel and seedling growth increased with increase in gel level compared with control conditions. The hydrogel amendment caused a delay by 4–5 days in wilting of seedlings grown in both soils compared with control conditions. The hydrogel amendment was effective in improving soil moisture availability and thus increased plant establishment. However, the varied responses of plant species in sandy loam and loam soils warrant further studies on the behaviour of different soil types with gel amendments.

Soil texture and tree coverage influence on organic matter

Soil organic matter (OM) is an important factor for maintaining the productivity and the stability of the so-called Caldenal woodland ecosystem of central Argentina. Little is known about the influence of tree coverage and soil texture on OM accumulation in soils of the study region. The relationships between OM content, silt clay content, and the percent of tree coverage were studied in a 25 × 25 m grid in 2 sites. Results showed that OM was lower (P < 0.05) at Site I (2.86%) than at Site II (6.41%). The OM was positively correlated with the percent of tree coverage in Site I (OM = 0.0156 trees cover 1.97, R2 = 0.29, P < 0.001), but not in Site II. Conversely, a positive correlation with silt clay was observed in Site II (OM = 0.17 silt clay − 6.79, R2 = 0.41, P < 0.05) but not in Site I. A multiple regression analysis [OM = − 16.64 0.71 (silt clay) 0.04 (tree coverage), n = 78, R2 = 0.55, P < 0.001] tended to confirm these results. Although they differed in their relative weight both silt clay and tree coverage affect OM accumulation at both sites. The larger influence of trees on OM variability at Site I was attributed to the lower, but highly variable, tree coverage, and the stronger influence of silt clay on OM variability at Site II can be attributed to the lower variability of tree coverage, and the higher variability of soil texture.According to our results, (a) 41% of OM variability is explained by silt clay content when tree coverage is dense and uniform, and (b) a 29% of OM variability is explained by tree coverage when such coverage is sparse and heterogeneous. The influence of tree canopy on OM distribution could be explained by its effect on the temperature regime. The influence of soil texture on OM could be attributed to its effect on the water retention capacity of soils. While forest clearing increases the maximum temperature and the temperature amplitude of soils, erosion in cleared areas affects soil texture, and consequently, its water retention capacity. The deterioration of both temperature and soil water regimes deteriorates, in turn, the capacity of the soil to accumulate OM.

Soil texture and tree coverage influence on organic matter

Soil organic matter (OM) is an important factor for maintaining the productivity and the stability of the so-called caldénal woodland ecosystem of central Argentina. Little is known about the influence of tree coverage and soil texture on OM accumulation in soils of the study region. The relationships between OM content, silt + clay content, and the percent of tree coverage were studied in a 25 × 25 m grid in 2 sites. Results showed that OM was lower (P &lt; 0.05) at Site I (2.86%) than at Site II (6.41%). The OM was positively correlated with the percent of tree coverage in Site I (OM = 0.0156 trees cover + 1.97, R2 = 0.29, P &lt; 0.001), but not in Site II. Conversely, a positive correlation with silt + clay was observed in Site II (OM = 0.17 silt + clay - 6.79, R2 = 0.41, P &lt; 0.05) but not in Site I. A multiple regression analysis [OM = - 16.64 + 0.71 (silt + clay) + 0.04 (tree coverage), n = 78, R2 = 0.55, P &lt; 0.001] tended to confirm these results. Although they differed in their relative weight both silt + clay and tree coverage affect OM accumulation at both sites. The larger influence of trees on OM variability at Site I was attributed to the lower, but highly variable, tree coverage, and the stronger influence of silt + clay on OM variability at Site II can be attributed to the lower variability of tree coverage, and the higher variability of soil texture. According to our results, (a) 41% of OM variability is explained by silt + clay content when tree coverage is dense and uniform, and (b) a 29% of OM variability is explained by tree coverage when such coverage is sparse and heterogeneous. The influence of tree canopy on OM distribution could be explained by its effect on the temperature regime. The influence of soil texture on OM could be attributed to its effect on the water retention capacity of soils. While forest clearing increases the maximum temperature and the temperature amplitude of soils, erosion in cleared areas affects soil texture, and consequently, its water retention capacity. The deterioration of both temperature and soil water regimes deteriorates, in turn, the capacity of the soil to accumulate OM.

Comparison of high resolution sub-annual records of trace elements in a modern (1911–1992) speleothem with instrumental climate data from southwest Australia

High spatial resolution measurements of Mg, P, U, Sr, Ba and Na using 193-nm excimer laser-ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern Australia. The age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew (1911–1992). This chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content. Eleven laser-ablation transects across a ∼0.5 mm wide section of the speleothem growth axis were measured. Cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record. P and U positively, and Mg inversely, mimic the sudden 20% decrease in annual rainfall experienced by this region since 1965. We argue that P from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil, owing to the low P retention capacity of southwest Australian soils. Both vegetation activity and the transport of vegetation-derived HPO 4 2− are sensitive to rainfall. Groundwater P concentration may also influence the transport of U through the strong affinity between phosphate and uranyl ions. Mg appears to be sensitive to groundwater residence time as this affects drip-water Mg/Ca composition by preferential loss of Ca during drier episodes when calcite precipitates before reaching the stalagmite. The effects of groundwater residence time may also be important for Sr on inter-annual scales. However, the behaviour of Sr on the annual cycle is opposite to Mg but compatible with Ba and Na, which are shown to depend on speleothem growth rate.

Use of Sequential Extraction in the Study of Heavy Metal Retention by Silty Soils

This study focused on the capability of two silty soils (tills) having low clay contents and CEC to retain and release two heavy metals, Pb and Cu. Samples of two non contaminated till deposits from the Eastern Townships region of Quebec, Canada, were artificially contaminated with concentrated solutions of these heavy metals. The latter were later extracted from the various geochemical phases of the soils by using the sequential extraction procedure. The results show that silty soils may have a relatively high heavy metal retention capacity due to the presence of carbonate and that this retention capacity can be comparable in magnitude to the retention capacity of certain clayey soils. This is particularly positive in the context of municipal waste disposal (landfills) in Quebec, where some old sanitary landfill sites are underlain by till deposits. A high buffering capacity is not as desirable in the case a deposit needs to undergo remediation.

The roles of texture and structure in the water retention capacity of burnt Mediterranean soils with varying rainfall

Differences in soil texture, structure and water retention capacity between burnt and unburnt soils were studied in an area affected periodically by forest fires in SE Spain. The burnt and unburnt soils were sampled at altitudes ranging from 100 to 1000 m a.s.l., with slight differences in climate between the sampling sites. Comparisons were made at three levels: all-sites, between-sites and within-site. Between all the burnt and unburnt soils only two significant differences were found: greater aggregate stability and smaller clay content in burnt soils. Slight differences in climate between the locations hide other effects of fire on these already degraded soils. However, at some sites, where the burning was thought to have been more intense, the water retention capacity was greater for unburnt than for burnt soils. Multiple regression equations for certain aggregate sizes (mainly 1 – 0.105 mm), textural classes (mainly coarse silt) and organic matter content predict quite well the soil moisture content of burnt soils at different suction pressures.

Measurement of soil microbial biomass phosphorus by an anion exchange membrane method

A method to measure soil microbial biomass phosphorus (biomass P) in granitic soils and andosols of high P retention capacity is described. Strips of anion exchange membrane (AEM) were shaken with suspensions of soil in (1) distilled water, (2) a mixture of distilled water and alcohol free chloroform (CHCl 3) liquid, and (3) a standard inorganic P solution (2.5 mg KH 2PO 4P1 −1), to estimate the recovery of CHCl 3-released P. After shaking, the AEM strips were rinsed with distilled water to remove the soils from the AEM strips. Phosphorus adsorbed by the AEM strips was then eluted by 0.5 m HCl, and determined colorimetrically. The amount of CHCl 3-released P was calculated from the difference between the amount of inorganic P adsorbed by AEM in unfumigated and fumigated soils. The high P retention capacity of soils, and the dark color of the extracts solution due to humic substances did not interfere with the measurement of P by this method. Biomass P was calculated from: biomass P = Ep Kp × 100 R , where Ep = (inorganic P released by CHCl 3 and extracted by distilled water) minus (inorganic P released from unfumigated soil), Kp = Biomass P released by CHCl 3 and extracted as inorganic P by distilled water (Kp = 0.40 at 25°C), R = percentage recovery (82.0–91.2%) of added P. Compared to the original CHCl 3-fumigation extraction (FE)-method, the AEM-method is simpler, more accurate, and more flexible, allowing assay of biomass P in soils of high P retention capacity, e.g. andosols. The use of AEM allows quick and efficient adsorption of P in the soil suspensions, and is analytically very convenient.

Phosphorus Retention by Wetland Soils used for Treated Wastewater Disposal

AbstractWetlands function as buffers for nutrients loaded from terrestrial ecosystems through drainage and surface discharges. The objectives of our study were to (i) determine the P retention capacity of representative wetland soils being used for disposal of treated wastewater and (ii) relate P retention characteristics to selected physicochemical properties to evaluate likely mechanisms of P removal in the soils. Intact soil cores (0–40 cm) and bulk soil samples (0–15 cm) were collected from a system of natural and constructed wetlands currently being used for disposal of treated wastewater. Floodwater P concentrations of the intact soil cores were monitored over time to determine the rate of P removal. Batch experiments were conducted to determine maximum P retention capacity of the soils. Soil samples were analyzed for inorganic P pool sizes, and selected physicochemical properties. During a 21 d hydraulic retention time, the constructed wetlands (sandy, low organic matter soils) retained 52 to 66% of added P, as compared with 46 to 47% retained by the natural wetlands (high organic matter soils). The P retention maximum, as estimated using the Langmuir model, ranged from 196 to 1821 mg P kg−1 (aerobic incubations) and from 32 to 1415 mg P kg−1 (anaerobic incubations). The P sorption maximum for these soils could be predicted by batch equilibration with a single high P solution. Anaerobic conditions increased P solubility. Organic P pools and the Fe‐Al‐bound fraction seemed to control P chemistry in these natural and constructed wetlands.

Physico-chemical properties and productivity of two tropical soils amended with dehydrated swine waste

With maize ( Zea mays L.) as the productivity indicator crop, the fertilizing value of dehydrated swine waste (DSW) was assessed on two texturally contrasting tropical soils, a sandy Kandic Paleustult (S l) and a clayey Lithic Usorthent (S 2). The treatments were different rates of DSW and inorganic fertilizer (F): 0%; 2·5%; 2·5% + F; 5·0%; 5·0% + F; 7·5%; 7·5% + F; 10·0%; 10·0% + F; and F alone. The F treatment consisted of the locally recommended rates of N, P, K and Mg for maize production. On both soils, high rates of DSW (⩾ 5·0%) delayed maize germination. Maize height and dry-matter yield increased with DSW rates, with the highest yield obtained at the 10·0% + F treatment. On all treatments, yield was consistently better on the more fertile S 2 than on the S 1 soil. All treatments including DSW out-performed the F-alone treatment because of higher nutrient contents of the organic waste-amended soils. The amounts of N, P, K, Ca and Mg released during the study explained individually between 66 and 73% of variation in maize yield on both soils. The C:N ratio of the treatments had an indirect effect on maize performance, explaining between 91 and 95% of the variation in yield. Increasing rates of DSW progressively increased the soil pH, organic carbon, N, P, exchangeable Ca, Mg, K and CEC, and reduced the exchangeable acidity at the end of the experiment. Also, the moisture retention capacity of both soils increased at all matric potentials between 0 and − 1500 kpa following DSW application. Even though the water-dispersible clay increased slightly with high DSW rates (implying reduced stability at the colloidal level), the overall effect of the organic amendment was towards enhanced resistance of the macro aggregates to disruptive water forces. Improvement in these physico-chemical properties was a direct consequence of increased organic matter levels following the DSW application to the soils.

Retention capacity of dry soils for NAPLs.

Retention capacity values were measured in the laboratory for three non-aqueous phase liquids (NAPLs), PCE, TCE and gasoline. The dry soils studied were sandy loam, clay, organic top soil and peat moss. For the conditions tested, it was determined that the retention capacity increased with an increase in the NAPL's density and the soil's porosity and a decrease in the soil bulk density. The largest observed retention capacity was for peat moss and PCE at approximately 7 gg-1. A simple model was developed to correlate the findings and allow estimation of the retention capacity values for different soils and NAPLs. Applications of the retention capacity model are illustrated with typical examples.

Agronomic potential of brewers' spent grains

The agronomic potential of brewers' spent grains (BSG) was evaluated on two texturally contrasting tropical soils, using a split-plot design with three replications. The main plot treatments were the two soils S 1 (Ultisol) and S 2 (Entisol), whereas the subplot treatments were different rates of BSG and complete fertiliser (F): 0%, 2·5%, 2·5% + F, 5·0%, 7·5%, 10·0% and F. Complete fertiliser consisted of 60 ppm N, 15 ppm P, 60 ppm K and 20 ppm Mg. The test crop was maize Zea mays L. On both soils the highest plant height and dry matter yields were obtained at the 2·5% BSG rate. This rate out-performed the F treatment by 293% on S 1 and 46% on S 2. Generally there was higher maize response to BSG on the less fertile S 1 than S 2. Progressively increasing rates of BSG increased the residual organic matter contents, aggregate stability, moisture retention and available water capacity of both soils but did not alter the soils' pH levels. On the two soils a BSG rate of 10% was the best for optimizing these physical conditions. Increase in organic matter contents of these soils following BSG additions accounted for more than 70% of the variability in the stability of the aggregates to water, between 58 and 66% of the variability in the moisture retained at different tensions by S 1, and 51–82% of the variability in the moisture retained at different tensions and total and readily available water capacity in S 2. The improvements in the productivity of these two fragile soils induced by the BSG amendment were due to high contents of N, P, K, Ca, Mg and carbon as well as the low C : N ratio of this waste product.

Method for Evaluating Phosphate Retention Capacity of Soils at Constant Final Phospate Concentration

Method for Evaluating Phosphate Retention Capacity of Soils at Constant Final Phospate Concentration

Some Aspects on the Measurement of Phosphate Retention Capacity of Soils

Some Aspects on the Measurement of Phosphate Retention Capacity of Soils