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1.
Losses of phosphorus (P) to water that follow manure applications can be high while water treatment residuals (WTR) have an appreciable capacity to sorb soluble P which is an important risk factor in determining the susceptibility of manure P to run‐off losses. The objective of this study was to assess whether co‐blending WTR with dairy cow manure prior to surface application would reduce P concentrations in run‐off from grassland. An alum‐derived WTR was collected from a water treatment works (WTW), dried and characterized for its phosphorus sorption capacity (PSC) based on oxalate‐extractable Al and Fe. Multipoint P sorption isotherms were used to calculate the Langmuir P sorption maximum (Pmax) and equilibrium P concentration (EPC0). The WTR contained 170 g Alox/kg and 2.2 g Feox/kg with a nominal long‐term PSC of 118 g/kg. Following a 6 day incubation of WTR, the Langmuir Pmax was 82.6 g/kg and the EPC0 of 0.13 mg P/L. Laboratory incubations of manure co‐blended with WTR indicated that 144 g WTR/kg dry matter (DM) manure significantly lowered (P < 0.001) manure WSP by 71.5 ± 16.6% after 108 h, but lower WTR mixing rates of 72 and 36 g WTR/kg had no statistical effect on manure WSP. Results from a field experiment using simulated rain on 0.5‐m2 grassland plots showed no significant effect on run‐off P 2 days after applying 50 m3/ha of 6% DM manure co‐blended WTR at rates of 150 and 250 g WTR/kg.  相似文献   

2.
Twenty‐five pasture soils were sampled from high‐rainfall zones of southeastern Australia to examine relationships between soil properties, and between soil properties and P buffering capacity (PBC) measures. Correlations between PBC values and soil properties were generally poor, with the exception of oxalate‐extractable Al (Alox) (r ≥ 0.97). Predictions of PBC were further improved when clay, as well as Alox, was included in a linear regression model (r2 ≥ 0.98). When Alox and oxalate‐extractable Fe were excluded from the modelling exercise, a more complex three‐term linear regression model, including pHH2O, exchangeable H and cation exchange capacity, adequately fitted both PBC values of the 25 soils examined in this study (r2 ≥ 0.76). However, the Alox, Alox plus clay and the three‐term models gave poor predictions of the PBC values when the models were validated using 28 independent soils. These results emphasize the importance of model validation, because predictive models based on soil properties were not robust when tested across a broader range of soil types. In comparison, direct measures of PBC, such as single‐point P sorption measures, are more practical and robust methods of estimating PBC for Australian soils.  相似文献   

3.
Phosphate sorption was studied in samples (0 - 20 cm depth) of five soils from Egypt (pH 7.4 - 8.7), four soils from Ethiopia (pH 3.9 - 5.3) and six soils from Germany (pH 3.3 - 7.2). Sorption parameters were calculated according to Pagel and Van Huay (1976) and according to Langmuir (Syers et al., 1973). Phosphate sorption parameters and oxalate extractable Fe and Al (Feox, Alox) were related to the phosphate uptake by young rye plants in Neubauer pot experiments. P sorption parameter after Pagel and Van Huay (A) correlated significantly positively with the Feox and Alox content in acid (r = 0.73) as well as in calcareous soils (r = 0.89) if the whole equilibrium concentration range (0 - 14 mg P/L) was considered. The relations calculated after Langmuir (B) were similar. P uptake by rye in acid soils was negatively correlated with the affinity constant n (r = ?0.76, (A)). In calcareous soils, a negative correlation between P uptake and affinity constant was calculated in the lower P equilibrium range (0 - 2.8 mg P/L) only for (B). Thus, P uptake decreased with increasing strength of P bonding to soil. From these results it is concluded that phosphate sorbed to Fe/Al oxides is an important P source for plants in acid and calcareous soils.  相似文献   

4.
As repeatedly reported, soil flooding improves the availability of P to rice. This is in contrast with an increased P sorption in paddy soils. The effects of soil flooding on the transformation of Fe oxides and the adsorption/desorption of P of two paddy soils of Zhejiang Province in Southeast‐China were studied in anaerobic incubation experiments (submerging with water in N2 atmosphere). Soil flooding significantly increased oxalate‐extractable Fe (Feox), mainly at the expense of dithionite‐soluble Fe (FeDCB), as well as oxalate‐extractable P (Pox), but decreased the ratio of Pox/Feox. Flooding largely increased both, P adsorption and the maximum P adsorption capacity. The majority of newly sorbed P in the soils was Pox, but also more newly retained P was found to be not extractable by oxalate. Flooding also changed the characteristics of P desorption in the soils. Due to a decrease of the saturation index of the P sorption capacity, P adsorbed by flooded soils was much less desorbable than that from non‐flooded soils. There are obviously significant differences in the nature of both, the Feox and Pox fractions under non‐flooded and flooded conditions. The degree of the changes in Feox, Pox, P adsorption and P desorption by flooding depended on the contents of amorphous and total Fe oxides in non‐flooded soils. Our results confirm that the adsorption and desorption behavior of P in paddy soils is largely controlled by the transformation of the Fe oxides. The reasons of the often‐reported improved P availability to rice induced by flooding, in spite of the unfavorable effect on P desorbability, are discussed.  相似文献   

5.
Estimation of the phosphorus sorption capacity of acidic soils in Ireland   总被引：4，自引：0，他引：4  
The test for the degree of phosphorus (P) saturation (DPS) of soils is used in northwest Europe to estimate the potential of P loss from soil to water. It expresses the historic sorption of P by soil as a percentage of the soil's P sorption capacity (PSC), which is taken to be α (Alox + Feox), where Alox and Feox are the amounts of aluminium and iron extracted by a single extraction of oxalate. All quantities are measured as mmol kg soil?1, and a value of 0.5 is commonly used for the scaling factor α in this equation. Historic or previously sorbed P is taken to be the quantity of P extracted by oxalate (Pox) so that DPS = Pox/PSC. The relation between PSC and Alox, Feox and Pox was determined for 37 soil samples from Northern Ireland with relatively large clay and organic matter contents. Sorption of P, measured over 252 days, was strongly correlated with the amounts of Alox and Feox extracted, but there was also a negative correlation with Pox. When PSC was calculated as the sum of the measured sorption after 252 days and Pox, the multiple regression of PSC on Alox and Feox gave the equation PSC = 36.6 + 0.61 Alox+ 0.31 Feox with a coefficient of determination (R2) of 0.92. The regression intercept of 36.6 was significantly greater than zero. The 95% confidence limits for the regression coefficients of Alox and Feox did not overlap, indicating a significantly larger regression coefficient of P sorption on Alox than on Feox. When loss on ignition was employed as an additional variable in the multiple regression of PSC on Alox and Feox, it was positively correlated with PSC. Although the regression coefficient for loss on ignition was statistically significant (P < 0.001), the impact of this variable was small as its inclusion in the multiple regression increased R2 by only 0.028. Values of P sorption measured over 252 days were on average 2.75 (range 2.0–3.8) times greater than an overnight index of P sorption. Measures of DPS were less well correlated with water‐soluble P than either the Olsen or Morgan tests for P in soil.  相似文献   

6.
Phosphorus adsorption isotherms are presented for samples from agricultural areas in central Greece. The soils contain montmorillonitic clays, have high exchange capacities and range in pH from 6.8 to 8.1. The amounts of P adsorption are high for surface and subsurface samples and are comparable to the adsorption observed in acid kaolinitic soils. The fit of the Freundlich equation to the experimental data was significantly improved when NaHCO3 extractable P was used as an estimate of the labile soil P to account for P already adsorbed in the soil. No conclusive relationship was established between the Freundlich parameters and selected soil properties though in some cases a values (capacity term) increased with increasing organic carbon content.  相似文献   

7.
High gradient magnetic separation was used to fractionate the clay from some tropical soils. Acid-oxalate-extractable iron (Feox) and aluminium (Alox) and total carbon were measured in the whole clay, the magnetic fraction and the tailings. The magnetic separation resulted in a wider range of concentrations of these elements than in the whole clays. In each of the clays Feox was greater in the magnetic fraction than in the tailings; Alox was more variable. Carbon was also concentrated in the magnetic fraction suggesting that it is associated more with Feox than Alox. The relationships between Feox, Alox and carbon depend on soil classification and soil age.  相似文献   

8.
Abstract

The objective of the present study was to clarify the influence of volcanic ash addition on soil carbon stocks and the carbon accumulation process in brown forest soils (BFS) in Japan. The degree of volcanic ash addition to the soil was estimated according to the acid ammonium oxalate extractable aluminum (Alox) and lithic fragment contents, and their vertical distribution patterns. The BFS was classified in order of increasing volcanic ash influence on the soil into the following types: high Alox content with no gravel (H-Alox-NGv), high Alox with a high gravel content (H-Alox-Gv), moderate Alox (M-Alox), and low Alox (L-Alox), and then analyzed for carbon content, carbon amount, carbon stock, Alox amount and pyrophosphate extractable aluminum (Alpy) amount. The correlation between the carbon and Alpy amounts and the relationship between the Alpy and Alox amounts in the BFS samples indicated that the amount of carbon is determined by Al—humus complex formation, which is defined by the active Al generated from additional volcanic ash in BFS soil samples of BFS. Therefore, soils with thicker horizons and greater amounts of Alox had higher carbon levels in deeper horizons. For this reason, soil carbon stocks at depths of 0–30 cm and 0–100 cm, and in the effective soil depth of BFS, were larger and followed the order H-Alox-NGv = H-Alox-Gv > M-Alox > L-Alox. Furthermore, successive accumulations of volcanic ash on the soil surface promoted soil carbon accumulation as a result of the development of the surface horizon in H-Alox-NGv BFS. Our results suggest that volcanic ash additions control the soil carbon accumulation of forest soil in Japan.  相似文献   

9.
Abstract

The methods used to predict phosphorus (P) fertilizer requirements use extractable P levels. The inclusion of soil P buffer capacity with extractable P levels to improve fertilizer P prediction accuracy should be further investigated for Mediterranean soils. The objectives of this study, were to characterize the P adsorption properties of selected soils and to compare different soil P buffering capacity indices to determine their contribution to predict P fertilizer requirement. Twenty‐one soils were collected and P adsorption isotherms determined. On 11 soils wheat was grown in the greenhouse and P requirement determined. The Langmuir adsorption isotherm described the P adsorption of all soils. The prediction of crop P requirement was improved by the inclusion of a soil P buffer capacity index in the prediction equation. The index proposed by Salmon is easy to determine under routine soil analyses and does not require special analytical equipment. However, clay content can be used to predict the Salmon buffer index for similar soils.  相似文献   

10.
Mixtures of peat and substrate clays are commonly used as growth media for horticultural plant production. A quality protocol for substrate clays defines a threshold value of active manganese (Mnact = sum of exchangeable and easily reducible Mn) in substrate clays of < 500 mg kg–1 to prevent toxic reactions of plants. This threshold value was tested in experiments with peat‐clay blends under various growth conditions, and nutrient solution experiments were additionally conducted to investigate the effects of silicic acid and dissolved organic matter on the occurrence of Mn toxicity. Common bean (Phaseolus vulgaris L.) and hydrangea (Hydrangea macrophylla) plants were cultivated in different peat‐clay substrates and in peat under different moisture and pH levels. The clays varied in their Mnact content from 4–2354 mg kg–1. The results of the substrate experiments reveal that a threshold value for Mn in substrate clays is not justified, as plants grown in all peat‐clay substrates did not develop any Mn toxicity even at high substrate moisture or low pH conditions which are known to increase the Mn availability. The extraction of active Mn did not well reflect the Mn concentrations in plant dry matter and substrate solution. As plants tolerated high Mn concentrations in the substrate solution compared to the nutrient solution without toxicity symptoms, the influence of silicic acid and dissolved organic matter (DOM) on Mn toxicity was characterized in a nutrient‐solution experiment. Manganese toxicity was clearly diminished by silicic acid application, but not by DOM. The former effect probably explains the tolerance of bean plants in peat substrates where high silicon concentrations in the substrate solution were observed. Peat‐clay blends even provided up to five times more silicon to plants than pure peat.  相似文献   

11.
Submerged macrophytes are commonly used for the environmental engineering of the controlling of shallow lake eutrophication, and are also an effective and valid alternative for the remediation of eutrophic water bodies, not only under experimental conditions but also under natural conditions. Therefore, the effects of submerged macrophytes on the improvement of shallow lake water quality have been intensively investigated. But the mechanism was not well understood, especially the mechanism of the effects of submerged macrophytes on the exchange of nutrients at sediment–water interface in shallow lakes. This study selected a familiar submerged macrophyte Hydrilla verticillata in China and evaluated the effects of H. verticillata on the phosphate retention and release at the lake sediment–water interface in a simulated condition. The effects of H. verticillata on the phosphate sorption isotherm, phosphorus (P) availability were investigated and the subsequent kinetics of P release was also measured by repeated extraction with CaCl2 solution. Exchangeable Ca and ammonium oxalate-extractable Fe (Feox) and Al (Alox) of the sediments were also determined. The results show that the contents of organic matter, cationic exchange capacity (CEC), Ca, Fe, Al, exchangeable Ca, Feox and Alox of the sediments with H. verticillata were higher than those of the control sediments, and the contents of total phosphorus (TP), Olsen-P and reactive dissolve phosphorus (RDP) were lower. The sediments with H. verticillata had stronger P sorption ability and weaker ability of P release. H. verticillata did not significantly affect the trends of the sorption isotherms and kinetics of the released P on the sediments. H. verticillata can significantly increase the ability of P sorption, decrease in the ability of P desorption on sediments was one of the mechanism that maintained lower P levels of the overlying water through affecting the contents of organic matter, CEC, Ca, Fe, Al, exchangeable Ca, Feox and Alox in sediments.  相似文献   

12.
Abstract

The advanced classification of brown forest soils (BFS) is based on the specific properties of these soils, including the acid ammonium oxalate extractable aluminum (Alox) and lithic fragment contents, as well as their vertical distributions in the soil profile. In the present study, these properties were used to classify BFS, resulting in four types: (1) H-Alox-NGv BFS, (2) H-Alox-Gv BFS, (3) M-Alox BFS, (4) L-Alox BFS. H-Alox-NGv BFS is derived from volcanic ash characterized by a high Alox content and no lithic fragment, whereas L-Alox BFS is derived from weathered bedrock and has a low Alox content. H-Alox-Gv BFS and M-Alox BFS are derived from mixtures of volcanic ash and weathered bedrock. H-Alox-Gv BFS is characterized by high Alox content and many lithic fragments, whereas M-Alox BFS has moderate Alox content. H-Alox-NGv BFS and black soils (BLS) develop from accumulated volcanic ash, as indicated by declining Alox and clay content with decreasing depth in the surface horizons, as a result of successive additions of less-weathered volcanic ash to the soil surface.  相似文献   

13.
采用硝酸氧化及一次平衡法,研究了硝酸处理对褐煤中的可提取性腐殖酸含量、CEC（阳离子交换量）、E4/E6及其对各种养分离子吸附规律变化的影响。结果表明:一定强度的HNO3能使褐煤中可提取性腐殖酸含量增加45.8%以上,使其阳离子交换能力提高;随硝酸处理时间的不断延长,褐煤中可提取性腐殖酸含量和CEC均呈先增加后减小的趋势,但CEC达到最大值所需时间相对较长;硝酸处理后的褐煤腐殖酸光学性质也发生了很大的变化。经硝酸处理褐煤腐殖酸样品对铵、钾吸附能力分别可提高58.73%和41.53%,其等温吸附式分别符合Freundlich和Langmuir方程。而对磷的吸附能力降低,一定条件下其吸附量仅为处理前的5.33%,其等温吸附式用Langmuir方程描述最佳。上述结果表明,经硝酸处理后,褐煤腐殖酸更适宜作为缓效肥料基质使用。  相似文献   

14.
Phosphate sorption on topsoil and subsoil samples from different soils located in the eastern part of Germany was studied. Two models were fitted to sorption data obtained after 4 and 40 d of gentle shaking. The models differ with respect to the fractions of iron and aluminium (hydr)oxides that are considered and whether the phosphate initially sorbed in the soil is taken into zccount. Oxalate-extractable P, (Pox), appears to be a major part of the total soil P. The total P sorption measured, F, was predominantly related to the amounts of amorphous iron (Feox) and aluminium (Alox). A significant relation between crystalline iron (Fed– Feox) and total P sorption was not found. Reversibly adsorbed phosphate (Pi), measured after 40 d reaction time, was a function of clay content and content of amorphous iron and aluminium (hydr)oxides.  相似文献   

15.
Abstract

An experiment was conducted to assess the suitability of three extractants, water (H2O), 0.005M DTPA, and 0.4M nitric acid (HNO3) for determining plant available copper (Cu) in peat substrates. Cucumber was used as a test crop. Four levels of Cu were compared in two peat substrates, each at two pH levels. There was good correlation between Cu extractable in H2O, DTPA, and HN03 and the Cu content of cucumber leaves, the correlations being 0.88, 0.87, and 0.89, respectively. These correlation coefficients did not differ significantly. It was concluded that all three extractants are suitable for estimating Cu availability in peat substrates.  相似文献   

16.
Zinc (Zn) is a vital plant nutrient that is widely deficient in Thai cultivated calcareous soils. The chemical fractionation and adsorption of Zn are among the most important solid- and liquid-phase interactions that determine the retention of Zn in the soils. This study aimed to investigate the fractionation and adsorption isotherms of Zn in cultivated Thai calcareous soils. The results of sequential extractions showed that Zn is mainly distributed in residual fractions followed by organic-bound, iron and manganese oxides-bound, carbonate-bound, and exchangeable Zn, respectively. Zinc adsorption was well fitted by the Langmuir and Freundlich isotherms. Thai calcareous soils had high Zn adsorption capacity. Soil pH, organic carbon, calcium carbonate, cation exchange capacity, and extractable calcium were the major soil properties that affected the Zn adsorption isotherms in these soils. Zinc hydroxide was the solid precipitate and the Zn hydroxide ion (ZnOH+) was the dominant Zn ion in alkaline equilibrium solution.  相似文献   

17.
The partitioning of dissolved organic carbon (DOC) within mineral soils is primarily controlled by adsorption to soil particle surfaces. We compare the theoretical limitations and modeling accuracy of four isotherm approaches to describe DOC partitioning to soil surfaces. We use 52 mineral soil samples to create linear initial mass (IM), non-linear, and Langmuir isotherms, all relating the initial solution concentration (Xi) to the amount of DOC adsorbed or released from soil surfaces. The Langmuir isotherm is also used with final concentration (Xf). The IM isotherm failed to meet theoretical assumptions and provided poor fits to experimental data. The non-linear and Langmuir Xi approaches had good fits to experimental data, and the Langmuir Xi approach had the most robust estimates of desorption capacity. Both Langmuir Xi and Xf isotherms hold the advantage of estimating the maximum adsorption capacity, yet the Xf isotherm is a better reflection of adsorption processes.  相似文献   

18.
Exchange reactions between 0.0in AlCl3 solutions of different pH and Ca-saturated montmorillonite, vermiculite, illite, and soils from the Park Grass Experiment at Rothamsted and the Deerpark Experiment, Wexford, Ireland, showed that Al3+ and Al(OH)2+ were adsorbed from solutions of pH > 4.0 and Al3+ and H+ from solutions of pH < 3.0. When Al was adsorbed, the cation exchange capacity of Ca-saturated soils and clays increased. Conventional Ca: Al exchange isotherms showed that Al3+ was strongly preferred to Ca2+ on all soils and clays. The equilibrium constant for Ca: Al exchange, K, was identical for soils before and after oxidizing their organic matter and did not vary, for any exchanger, with Al-saturation or the initial pH of the AlCl3 solution. This proved the validity of the procedure used for calculating exchangeable Al3+. K values for Ca:Al exchange favoured Al3+ in the order: vermiculite > Park Grass soil > Deerpark soil > illite > montmorillonite. The influence of surface-charge densities of the clay minerals on this order is discussed and a method proposed and tested for calculating the K value of a soil from its mineralogical composition.  相似文献   

19.
广东主要母质发育水稻土对硅的吸附特性   总被引：3，自引：0，他引：3  
Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silicate fertilizer use in these areas. A correlation analysis showed that silicate adsorption did not obey the Langmuir equation （r = -0.664- 0.301） but did obey the Freundlich and Temkin equations （P〈0.01, r = 0.885-0.990）. When the equilibrium silicate concentration （Ci） was less than 45 mg SiO2 kg^-1, the adsorption capacity was in the following decreasing order of paddy soils： basalt-derived 〉 Pearl River Delta sediment-derived 〉 granite-derived 〉 sand-shale-derived. Stepwise regression and path analysis showed that for the investigated paddy soils amorphous MnO and Al2O3 were the two most important materials that affected silicate adsorption. Moreover, as Ci increased, amorphous Al2O3 tended to play a more important role in silicate adsorption, while the effects of amorphous MnO on silicate adsorption tended to decrease.  相似文献   

20.
Abstract

Calcareous soils often need supplemental manganese (Mn) to support optimum plant growth, but some reports show that the apparent recovery of applied Mn is very low in such soils, i.e., nearly all of the applied Mn is retained in the soil. This experiment was conducted to find the relationship between the retained Mn and selected properties of calcareous soils. Eleven surface (0–20 cm) soil samples with pH ranging from 7.7 to 8.1 and calcium carbonate equivalent (CCE) ranging from 20 to 50% were used in the Mn adsorption study. Two‐gram subsamples of each soil were equilibrated with 20 mL of 0.01M CaCl2 solutions initially containing 10 to 200 mg Mn L‐1. The Mn that disappeared from solution (after 6 h shaking at 25°C) was considered as adsorbed (retained) Mn. The adsorption data showed a highly significant fit to Freundlich and also to the two‐surface Langmuir adsorption isotherms. The coefficients of both isotherms showed significant positive correlations with cation exchange capacity (CEC), organic matter (OM), and CCE of the soils indicating that OM and calcium carbonate are the sites of Mn retention in calcareous soils. Comparison of the adsorption data of this experiment with those of plant Mn uptake of the same soils (published earlier) shows that as the Langmuir second surface adsorption maxima (maximum retention capacity) of the soils increase the plant Mn concentration and uptake decrease.  相似文献   

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