首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 375 毫秒
1.
In a preliminary laboratory experiment, samples from three cultivated and three virgin acid sulphate soils (pH 3.9-4.7) were treated with water or equivalent amounts of Ca(OH)2 or KOH and incubated at about field capacity for three months. Both base treatments (133 meq/kg) similary reduced soil acidity and, thus, the same influence on the pH-dependent biological and chemical reactions was concluded. The liming-induced mineralization of organic S seemed to account for increased extratability of sulphate, being in most soils of the same magnitude in both treatments. Inversely, the solubility of P hardly was affected by the decomposition of organic matter but rather by the reactions of inorganic P. KOH markedly raised water-soluble P, whereas Ca(OH)2 did not. The results of a rapid extraction test suggested that the poorer extractability of P in the soils amended with Ca(OH)2 could partly be ascribed to a higher Ca saturation and its impact on the electrochemical properties of charged surfaces. In addition, a higher base-associated ionic strength created by Ca2+ was of great importance in reducing the P desorption in the Ca(OH)2- treated soils.  相似文献   

2.
Humus horizons of dystric cambisols were sampled six times during 1990–1992 at 66 points along a beech forest transect in Scania, s. Sweden. Cation concentrations of soil solutions obtained by centrifugation of sifted samples at field moisture were related to pH, DOC, exchangeable pools of the cations and soil moisture. Soil solution Al was speciated in free ionic (easily reacting) Alr and organically complexed Alorg. Two or three variables accounted for a large share (70–90 %) of the cation variability between sampling points. Exchangeable soil pools were the most important variables for K, Mg. Ca, and Mn and contributed more when calculated on C. E. C. than on soil dry weight. Some function of pH was also of importance to most cation concentrations. Alr correlated well with both Alorg(+) and pH(-). Soil moisture was positively related to DOC and K, negatively to H-ion concentration. pH measured by different methods were closely correlated (r = 0.93–0.97), pHkcl and pH being ca. 0.5 unit lower, pH ca. 0.3 unit higher than soil solution pH, which varied between 3.5 and 5.6.  相似文献   

3.
Summary A laboratory incubation experiment was carried out over 17 weeks to determine the effect of liming on soil organic matter. The amount of lime as calcium hydroxide [Ca(OH)2] required to completely neutralise exchangeable Al was found to be five times the standard lime requirement. This large amount of lime had a limited overall effect on the short-term stability of soil organic matter, causing the release of 1300 g g-1 of C (1.7% total soil C) above the control during the incubation. Liming may have altered the potential availability of soil organic matter and organic P, as shown by a marked reduction in the extractability of soil organic P with sodium bicarbonate and sodium hydroxide. The latter was unlikely to be due to the formation of calclium-P artefacts, and may be attributed to the combined chemical effects of added calcium hydroxide and precipitation of exchangeable Al on the nature and solubility of soil organic constituents and organomineral complexes. The addition of lime increased the degradation of added oak leaf litter by 50%, from 3.2 to 4.7 mg g-1, as determined by CO2 evolution. The enhanced litter degradation indicated increased microbial activity in limed soil, but this improvement had only minor effects on the stability of native organic matter. This study highlights the need for further research into the relationships between the chemical nature of organic P in soil and the physical, chemical, temporal, and agronomic factors that control its turnover and availability.  相似文献   

4.
Abstract

The acid soils of the western region of Ghana which hitherto have been relegated to forest and tree crops production are becoming increasingly important for agricultural food crop production in the country. However, on account of their strongly acidic properties, there is the need to apply agricultural lime to the soils to improve upon their productivity. At present, however, information on the lime requirement and appropriate liming practice for these soils is lacking. The objective of this study was to compare the suitability of selected chemical methods for the determination of the lime requirement to predict lime needs of these naturally occurring acid soils. The lime requirement of six acid soils were determined by calcium hydroxide [Ca(OH)2] titration, exchangeable aluminum (Al), and Shoemaker, McLean, and Pratt (SMP) buffer methods. Correlation analysis showed that all the methods were highly correlated with one another. The SMP method was found to be somewhat better than either exchangeable Al or Ca(OH)2 titration method for estimating the lime requirement of the soils. Hence, the SMP method is recommended for use as the diagnostic index of lime requirement of these soils because of its speed and simplicity. Regression studies on the lime requirement values by the three methods and selected soil properties showed that exchangeable Al and organic carbon were the most important soil factors contributing to the lime requirement of these soils. Clay content was significantly correlated only with the Ca(OH)2‐based lime requirement values (r = 0.81*).  相似文献   

5.
《Geoderma》2006,130(1-2):26-34
Aluminum–humus complexes are believed to be highly stable under natural conditions in nonallophanic Andosols. However, it has been shown that the aluminum complexed with humus is easily released by acidic buffer solutions and possibly controls the aluminum solubility of these soils. Thus, it is highly probable that Al–humus complexes are easily influenced by rather simple chemical treatments. We examined the effects of liming (CaCO3 treatment) on Al–humus complexes of A and B horizons from Andosols. It was observed that liming reduced the Al release rates from soil samples with pH 3.5 acetate buffer solution and the amounts of the KCl-extractable Al, suggesting the formation of precipitation from easily exchangeable Al. A much larger decrease with liming was also obtained for 0.1 M sodium pyrophosphate-extractable Al (decrease rates of 7–52%) and 0.5 M CuCl2-extractable Al (decrease rates of 9–43%). These results strongly indicate that liming reduces significant amounts of organically complexed Al as well as the exchangeable Al. The increase in the cation exchange capacity of soils at pH 7 after liming further suggested that the carboxyl group of humus complexed with Al was partly liberated from the Al complexation and became to develop negative charges.  相似文献   

6.
Soybean is one of the most important legume crops in the world. Two greenhouse experiments were conducted to determine the influence of liming and gypsum application on yield and yield components of soybean and changes in soil chemical properties of an Oxisol. Lime rates used were 0, 0.71, 1.42, 2.14, 2.85, and 4.28 g kg?1 soil. Gypsum rates applied were 0, 0.28, 0.57, 1.14, 1.71, and 2.28 g kg?1 soil. Lime as well as gypsum significantly increased grain yield in a quadratic fashion. Maximum grain yield was achieved with the application of 1.57 g lime per kg soil, whereas the gypsum requirement for maximum grain yield was 1.43 g per kg of soil. Lime significantly improved soil pH, exchangeable soil calcium (Ca) and magnesium (Mg) contents, base saturation, and effective cation exchange capacity (ECEC). However, lime application significantly decreased total acidity [hydrogen (H) + aluminum (Al)], zinc (Zn), and iron (Fe) contents of the soil. The decrease in these soil properties was associated with increase in soil pH. Gypsum application significantly increased exchangeable soil Ca, base saturation, and ECEC. However, gypsum did not change pH and total acidity (H + Al) significantly. Adequate soil acidity indices established for maximum grain yield with the application of lime were pH 5.5, Ca 1.8 cmolc kg?1, Mg 0.66 cmolc kg?1, base saturation 53%, Ca saturation 35%, and Mg saturation 13%. Soybean plants tolerated acidity (H + Al) up to 2.26 cmolc kg?1 soil. In the case of gypsum, maximum grain yield was obtained at exchangeable Ca content of 2.12 cmolc kg?1, base saturation of 56%, and Ca saturation of 41%.  相似文献   

7.
Cadmium is both readily available and highly toxic to plants and animals. Our objectives were to evaluate the effect of oyster shell as a liming material on reducing plant cadmium (Cd) uptake and to compare oyster shell and Ca(OH)2, a common liming material in Korea. Ground oyster shell and Ca(OH)2 were applied at 0, 2, 4, and 8 Mg Ca per hectare to an upland soil contaminated manually with CdSO4 (total Cd 8.96 mg kg?1). Radish (Raphanus sativa L.) was sown on the contaminated soil. Oyster shell was less effective at increasing soil pH and net negative charge than Ca(OH)2, but more effective at suppressing radish Cd uptake in both roots and shoots. The portion of Cd that is strongly bound to soil (fraction 5) increased more with oyster shell than with Ca(OH)2. Radish plant Cd concentration was positively correlated with 0.1 N HCl-extractable Cd and negatively correlated with the residual Cd fraction (F5), indicating that an increase in the strongly bound Cd fraction played an important role in reducing radish Cd uptake in soil to which oyster shell was applied. The greater potential of oyster shell to decrease Cd extractability in soil and plant Cd uptake compared to Ca(OH)2 might be attributed to the layered morphology of oyster shells. Based on these results, oyster shell could be a very good alternative liming material to reduce Cd phytoavailability in Cd-contaminated soil.  相似文献   

8.
长期施用氮磷钾肥和石灰对红壤性水稻土酸性特征的影响   总被引：16，自引：0，他引：16  
利用34年的长期定位施肥试验,研究不施肥(CK)、施氮磷钾肥(NPK)和氮磷钾化肥配施石灰(NPK+Ca O)对红壤性水稻土不同形态酸、土壤盐基离子及水稻植株阳离子吸收量的影响,探讨土壤交换性H+和Al3+占交换性酸的比例、土壤盐基离子、植株带出阳离子数量与土壤酸度的关系。结果表明,长期NPK处理早、晚稻土壤p H较CK处理分别降低0.2和0.3个单位,交换性酸提高2.3倍和4.2倍,水解性酸提高35.4%和40.0%;NPK+Ca O处理早、晚稻土壤p H较NPK处理分别提高0.5和0.7个单位,较CK处理分别提高0.3和0.4个单位,交换性酸、水解性酸均显著低于NPK和CK处理(p0.05)。土壤交换性H+、Al3+含量高低顺序均为NPK+Ca OCKNPK。土壤交换性盐基离子以交换性Ca2+所占比例最大(81.8%~89.3%),NPK+Ca O处理交换性Ca2+较CK和NPK处理分别提高40.1%和62.9%。交换性Ca2+、交换性盐基离子、盐基饱和度与土壤p H正相关,与交换性酸、水解性酸负相关,交换性Mg2+与交换性酸、水解性酸负相关,交换性Na+与水解性酸负相关。植株移出带走的钙、镁、钾、钠离子量及其总量对土壤p H、交换性酸和水解性酸有一定影响,但其相关性均不显著。研究表明长期施用化肥条件下通过配施石灰可有效缓解稻田土壤的酸化,促进酸性稻田土壤的生态修复与改良。  相似文献   

9.
Purpose

The purpose of this study is to determine the critical soil pH, exchangeable aluminum (Al), and Al saturation of the soils derived from different parent materials for maize.

Materials and methods

An Alfisol derived from loess deposit and three Ultisols derived from Quaternary red earth, granite, and Tertiary red sandstone were used for pot experiment in greenhouse. Ca(OH)2 and Al2(SO4)3 were used to adjust soil pH to target values. The critical soil pH was obtained by two intersected linear lines of maize height, chlorophyll content, and yield of shoot and root dry matter changing with soil pH.

Results and discussion

In low soil pH, Al toxicity significantly decreased plant height, chlorophyll content, and shoot and root dry matter yields of maize crops. The critical values of soil pH, exchangeable Al, and Al saturation varied with soil types. Critical soil pH was 4.46, 4.73, 4.77, and 5.07 for the Alfisol derived from loess deposit and the Ultisol derived from Quaternary red earth, granite, and Tertiary red sandstone, respectively. Critical soil exchangeable Al was 2.74, 1.99, 1.93, and 1.04 cmolckg?1 for the corresponding soils, respectively. Critical Al saturation was 5.63, 12.51, 14.84, and 15.16% for the corresponding soils.

Conclusions

Greater soil cation exchange capacity and exchangeable base cations led to lower critical soil pH and higher critical soil exchangeable Al and Al saturation for maize.

  相似文献   

10.
Acidity in the soil surface and subsurface is of major concern in horticulture, cropping and pasture production systems in southern Australia. Broadcast applications of lime to the surface have proved to be ineffective in ameliorating subsurface acidity in the short term. Two calcium-saturated coal-derived organic products, an ‘oxi-product’ (OXPR) and an ‘oxi-fulvate’ (OXFU), were evaluated for use as liming materials with specific consideration given to amelioration of subsurface acidity. The effects of these two organic products and of lime on the chemical composition of the A1 and A2 horizons of an acid red podzol were investigated in leaching columns, 20 cm long. OXPR and OXFU supplying 80 or 160 g Ca m?2 were compared to 160 g Ca m?2 applied as CaCO3 and a control receiving no amendments. The effects of CaCO3 on exchangeable Al and pH were limited to the surface 2 cm. In contrast, the two organic amendments were effective in decreasing exchangeable Al and increasing pH and exchangeable Ca to depth, the extent being a function of amendment and rate applied. The formation of inorganic and organic complexes were assumed to be responsible for the movement of Al out of the column in the leachate, although significant quantities of Al were precipitated in the column. Significant linear regressions were observed between the ionic strength and Al in the leachate. Significant quantities of Mg and K were displaced by Ca and leached from the column; consequently, this loss must be considered against the benefits of decreased exchangeable Al when assessing fertility for plant production.  相似文献   

11.
In 1990, wetlands in the Røynelandsvatn catchment in Southern Norway were limed with finely ground limestone powder at a rate of 20 t ha–1 to remediate acid discharge. JORDFORSK has investigated changes in the chemical properties of soil over a three year period in a selected limed fen. Calcium (Ca) contents above natural background levels were found in the uppermost 20 cm of the peatsoil. The major part of Ca introduced by liming was in the uppermost 3 cm of the peatsoil. Remaining Ca from liming is roughly estimated to be 2,5–3 t ha–1. Similarly, pH of the uppermost cm of the peatsoil of the limed fen was around 7. Deeper peatsoils (> 20 cm) had pH-values around 3,8–4,9. After liming the dominance of hydrogen (H) — and aluminium (Al) ions in the exchangeable cation pool was replaced by Ca in the uppermost cm of the fensoil. In deeper peatlayers (> 20 cm) the exchangeable cations were still dominated by H+ and Al-ions. A smaller part of organically bound Al in the lime-influenced mire topsoil than in other peatsoil may indicate that Al has changed from an organically bound to a mineral (amorphous) phase. The liming has changed chemical properties of the uppermost part of the soil. This will counteract acidic and Al-rich input The results underline the origin of acid-neutralising effects and stress the importance of hydrology and patterns of water flow in the surface layers of mires.  相似文献   

12.
Abstract

It is essential to determine the relationship between soil chemical and mineralogical properties and soil response to acid load to understand the acid-neutralizing capacity and cation behavior of different ecosystems. For 46 soil samples from a subsurface horizon in humid Asia, that is, Japan, Thailand and Indonesia, exchangeable cations, total bases and oxalate-extractable Al (Alo) were determined, and acid titration was conducted to investigate the rapid soil response to acid load. The acid titration experiment indicated three types of soil response: (1) the release of base cations (particularly Ca and Mg) strongly correlated with exchangeable bases, which dominated the tropical soil samples, (2) the release of Al correlated with Alo content, which dominated the Japanese soil samples, (3) acid and anion adsorption in soil samples with low acid-neutralizing capacity. To gain further information on the source of soil alkalinity, a column experiment with HCl was conducted using eight selected soil samples in which first-order kinetics were assumed to simulate the time-courses of cation release. In the column experiment, the amounts of Ca and Mg released were close to the exchangeable amounts, and Alo dissolved more rapidly than Al in crystalline minerals. The rate constants of cation release were large for Ca and Mg, and small for Al, clearly indicating a difference between the exchange and dissolution reactions. Thus, rapid soil response to acid load differed among the soils. A cation exchange reaction was dominant in the tropical soils. In some tropical soils, Ca and Mg were present in exchangeable forms at a higher ratio in the total amounts and they were considered to be easily utilized by plants, but leached out from the soils. In the Japanese soils, including the Andisols, secondary mineral dissolution was conspicuous, resulting in a large acid-neutralizing capacity. In both the tropical and Japanese soils with low acid-neutralizing capacity, anion adsorption mainly contributed to acid neutralization.  相似文献   

13.
Subsoil acidity is a serious constraint to crop production, and is difficult to correct by conventional liming practices. Thus, a different approach to ameliorating acid subsoils was evaluated. Subsoil material of an acid Ultisol (pH 4.4) was packed into 50-cm long columns, then leached with solutions of CaCl2, CaCO3 (suspension) or Ca fulvates prepared from chicken manure, cowpea green manure, or sewage sludge. The total water applied was 30.26 cm (or 800 ml) in 2 days. Thereafter, the columns were dismantled and cut into 5-cm segments for chemical analysis. The results indicated that only 2% of the added Ca from CaCO3 moved past the 15-cm depth, compared to 68% from CaCl2 and 35–75% from Ca fulvates. Correspondingly, CaCO3 precipitated all KCl-extractable Al in the top 5 cm, but had no effect beyond the 10-cm depth. The CaCl2 displaced a small but significant portion of extractable Al from the top 15 cm and redeposited some of that Al in lower depths. Similar to CaCO3, Ca fulvates from chicken manure and green mamure only decreased extractable Al significantly in the top 10-cm layers, but had little effect beyond that depth. By contrast, the Ca fulvate from sewage sludge decreased Al down to the 45-cm depth. In terms of reducing Al saturation as a percentage of total extractable cations (effective cation exchange capacity), the Ca fulvates were as effective as CaCO3 in the 0-to 5-cm layer, and more effective than CaCl2 in any soil layer because of the increased exchangeable Ca and/or decreased Al. In general, surface application of common organic material-derived Ca fulvates can increase subsoil Ca and decrease the Al saturation percentage. However, Mg depletion and enrichment of unwanted metals (e.g., Na or heavy metals) may be a problem when leaching with these organic sources.  相似文献   

14.
Summary Soil pH, total organic C, total N, exchangeable Al, available P, CO2 evolution, microbial biomass C and N, phosphatase and dehydrogenase activities were determined in acid soils sampled under spruce subjected to acid deposition, before and after liming. A slight decrease in pH values was observed from the edge of a tree canopy to the base of the trunk in acid soils. Liming drastically reduced exchangeable Al and increased CO2 evolution, microbial biomass, and the metabolic quotient. The microbial biomass C to total organic C ratio increased after liming but did not reach 2%, the average value considered valid in soils where the C content is in equilibrium, that is when C inputs are equal to C outputs. The microbial biomass C:N ratio decreased after liming, thus indicating that bacteria became predominant over fungi when soil acidity decreased. Dehydrogenase activity but not phosphatase activity was increased by liming. The decrease in phosphatase activity was not completely related to the increase in available P, but was also dependent on microbial growth and the decrease in acid phosphatase, the predominant component of acid soils.  相似文献   

15.
The decrease in anthropogenic deposition, namely SO42— and SO2, in European forest ecosystems during the last 20 years has raised questions concerning the recovery of forest ecosystems. The aim of this study was to evaluate if the long term data of element concentrations at the Fichtelgebirge (NE‐Bavaria, Germany) monitoring site indicates a relationship between the nutrient content of needles and the state of soil solution acidity. The soil at the site is very acidic and has relatively small pools of exchangeable Ca and Mg. The trees show medium to severe nutrient deficiency symptoms such as needle loss and needle yellowing. The Ca and Mg concentrations in throughfall decreased significantly during the last 12 years parallel to the significant decline in the throughfall of H+ and SO42— concentrations. Soil solution concentrations of SO42—, Ca and Mg generally decreased while the pH value remained stable. Aluminum concentrations decreased slightly, but only at a depth of 90 cm. Simultaneously a decrease in the molar Ca/Al and Mg/Al ratios in the soil solution was observed. Ca and Mg contents in the spruce needles decreased, emphasizing the relevance of soil solution changes for tree nutrition. The reasons for the delay in ecosystem recovery are due to a combination of the following two factors: (1) the continued high concentrations of NO3— and SO42— in the soil solution leading to high Al concentrations and low pH values and, (2) the decreased rates of Ca and Mg deposition cause a correlated decrease in the concentration of Ca and Mg in the soil solution, since little Ca and Mg is present in the soil's exchangeable cation pools. It is our conclusion that detrimental soil conditions with respect to Mg and Ca nutrition as well as to Al stress are not easily reversed by the decreasing deposition of H+ and SO42—. Thus, forest management is still confronted with the necessity of frequent liming to counteract the nutrient depletion in soils and subsequent nutrient deficiencies in trees.  相似文献   

16.
Abstract

The seriousness of soil acidity and the unavailability of “conventional”; liming materials in many developing countries necessitate a search for alternatives. With this goal in mind, the liming potential of two organic manures was investigated. The investigation was conducted in the greenhouse, using a highly weathered, acid Ultisol. Application rates were 0, 5, 10, 20, and 40 g kg‐1 for chicken manure and 20 g kg‐1 for sewage sludge. Treatments of Ca(OH)2 at 2, 4, 6, and 8 cmolckg‐1, were included for comparison.

Based on growth response of Desmodium intortum, a tropical forage legume with a relatively high Ca requirement and low Al tolerance, it was demonstrated that soil acidity can be corrected by either Ca(OH)2 or organic manure additions. Both lime and manures raised soil pH and inactivated Al. In terms of pH increases, 5 and 10 g chicken manure kg‐1 were equivalent to 3.4 and 6.7 cmolckg‐1; and 20 g sludge kg‐1, equivalent to 6.5 cmolckg‐1 as Ca(OH)2. The manures also detoxified soluble Al by organic complexation and enhanced Ca uptake of the Desmodium. The plant's maximum growth required at least 1.0% Ca in leaves, and this growth was reduced by half when leaf Al ≥ 76 mg kg‐1 and soil‐solution Al3+ activity ≥ 4 μM.  相似文献   

17.
  相似文献   

18.
Solution cation concentrations and base cation leaching were simulated for a homogenous soil block and a soil showing five horizons of a podzolic forest soil. The dynamic model ACIDIC simulated water flow, nutrient uptake for tree growth, and cation exchange between H+, Al3+, Ca2+, Mg2+ and K+ in forest soil. In the multi-layer simulations exchangeable base cation concentrations changed most in the O horizon. The subsoil had a decisive effect on the pH of the runoff and base cation leaching from the soil. The one-layer model underestimated Ca and Mg leaching and overestimated H+ and Al concentrations in the runoff. In the eluvial and the top of illuvial horizon the solution Al / (Ca + Mg) ratio exceeded that in one-layer structure more than 10-fold. Cases with the horizon-specific cation exchange coefficient values and mean coefficient values for all layers showed only minor differences in Al / (Ca + Mg) ratio. The vertical variation in the soil chemical properties should be accounted for even if some details of processes and parameters were unavailable.  相似文献   

19.
W.A. Stoop 《Geoderma》1983,31(1):57-69
Factors affecting P solubility were studied for four Hawaiian soils: the Waialua, Wahiawa, Halii and Honokaa series, classified, respectively, as: Haplustoll, Eutrustox, Gibbsihumox and Hydrandept.Phosphate solubility in the oxidic soils depended mainly on salt concentration and cation valency. It was decreased by the accompanying cation according to: K < Mg </ Ca. This cation effect on P solubility decreasedwith increasing contents of layer silicate clay minerals and/or increasing base saturation of the soil. Consequently, it was almost absent in the Haplustoll which contains montmorillonite and kaolinite.The P solubility in all four soils increased greatly when the pH was raised with NaOH. When Ca (OH)2 was used, however, this effect was almost completely eliminated due to the action of Ca ions. This result explains why in many fertility studies of oxidic soils even moderate liming rates were not found to increase the P availability.In a subsequent pot experiment evidence was obtained on the negative effect of the Ca ion on P uptake by Sudangrass from the Gibbsihumox and Eutrustox.  相似文献   

20.
A Typic Palexerult from northern Spain was subjected to acidity correction field tests over a period of 2 years. The experimental crop was a local rye variety and the amendments included gypsum, dolomite, limestone, and sugar foam waste, all at a 6000 kg ha–1 rate as calcium carbonate (CaCO3). General analyses were integrated with specific tests for soluble and easily exchangeable aluminum (Al) forms (Al-CaCl2) in addition to potassium chloride (KCl)–, barium chloride (BaCl2)–, and copper chloride (CuCl2)–extracted Al and adsorbed and amorphous Al. Two types of multiple linear regression models for production each year were established; some encompassed all studied variables and others the six Al forms only. As shown here, Al-KCl, Al-CaCl2, base saturation, and exchangeable Ca were the individual variables most strongly correlated with production, with R 2 = 0.865, within the topmost 12 cm. A principal component analysis exposed a substantial share of pH-dependent charge in organic matter on the cation exchange capacity of the soil.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号