scholarly journals Effects of percolating water with graduated acidity upon the leaching of nutrients and the changes in some chemical properties of mineral soils

1977 ◽  
Vol 49 (4) ◽  
pp. 250-257
Author(s):  
František Haman
Keyword(s):  
Soil Layer ◽  
Chemical Properties ◽  
Clay Content ◽  
Fine Sand ◽  
Three Solutions ◽  
Clay Particles ◽  
Plastic Bags ◽  
Water Ph ◽  
Mineral Soils ◽  
Basic Cations

Leaching of nutrients and the changes in some chemical properties of surface soil layer treated with solutions of gradual acidity were followed under laboratory conditions. The 25-cm-high columns of three soils, (A – fine sand, B - loam, C - clay loam), placed in plastic tubes were treated with deionized water (pH 6) and with three solutions (pH 5, pH 4, pH 3) of sulphuric acid. The washed out were determined in the leachates collected into plastic bags. The largest amount of nitrogen found in the leachates was in the form of nitrate and this was proportional to the content of organic matter in the soils. The leached amount of NH4-N was considerably lower and like potassium it was negatively dependent upon the clay content in the soils. The concentrations of K, Ca and Mg in the leachates rose in relation to the declining pH of percolating solutions. Especially in soil A, acid solutions of pH 5 (and lower) washed out very effectively the cations. Soils Band C (with a higher content of clay particles) showed a higher resistance to K, Ca and Mg leaching. The acidified water influenced even the pH of the surface layer (0—7,5 cm) of soils in the columns. The most marked decrease in pH values was found in soil A after an application of the solution with pH 3. A decrease in the content of basic cations (Ca and Mg) was parallel to the acidification of the upper layer of the soils.

scholarly journals Calcium, magnesium and potassium in mineral soils from the southern half of Finland

1973 ◽  
Vol 45 (3) ◽  
pp. 254-261
Author(s):  
Armi Kaila
Keyword(s):  
Clay Content ◽  
Total Content ◽  
Fine Sand ◽  
Clay Soils ◽  
Surface Layers ◽  
Surface Soils ◽  
Exchangeable Ca ◽  
Heavy Clay ◽  
Southern Half ◽  
Mineral Soils

210 samples of mineral soils from the southern half of Finland with mainly an acid precambrian bedrock, were analysed for the total contents of Ca, Mg and K, and for the portion of these nutrients which could be exchanged by N NH4OAc (pH 7), dissolved by 0.1 N HCI at room temperature, or released by N HCI at 50° C. The total content of Ca was lowest in samples of heavy clay, 0.78±0.14 % in the surface soils and 0.92±0.10 % in the deeper layers. The mean content in the groups of other soils was at least about 1.1 %. The total content of Mg increased with an increase in the clay content (r = 0.81***). It ranged from 0.6±0.1 % in the sand and fine sand samples to 1.53±0.19 % in the heavy clay soils of the surface layers and to 1.89±0.12 % in those of the deeper layers. Also in the groups of loam and silt soils and of the coarser clay soils, respectively, the Mg content was in the deeper layers higher than in the surface soils. The total content of K also increased with the clay content (r=0.73***) from 1.7±0.1 % in the sand and fine sand soils to 2.74±0.21 % in the heavy clay soils of the surface layers and to 3.10±0.07 % in those of the deeper layers. The portion of exchangeable Ca was relatively high: in the groups of surface soils from more than one tenth to one third of the total amount. The corresponding average amounts released by even the more drastic treatment with acid were not markedly higher. Only a few per cents of total Mg were exchangeable and slightly higher amounts were dissolved by 0.1 N HCI, whereas the treatment with N HCI at 50° C released about half of the total Mg. Exchangeable K and K dissolved by 0,1 N HCI did not exceed 1 % of the total K, except slightly in the heavy clay soils; the average amounts released by N HCI ranged from 5 to 18 % of the total K. The plant availability of these nutrients was discussed.

scholarly journals The properties of river alluviums of the Upper-Dniester alluvial plain

2017 ◽  
pp. 293-303
Author(s):  
Khrystyna Perets ◽  
Oksana Vovk ◽  
Oleh Orlov ◽  
Olena Lutsyshyn
Keyword(s):  
Granulometric Composition ◽  
Alluvial Soil ◽  
Chemical Properties ◽  
Soil Formation ◽  
Hydrological Regime ◽  
Clay Content ◽  
Fine Sand ◽  
Alluvial Plain ◽  
Alluvial Soils ◽  
Floodplain Soil

Alluvial soil formation is a dynamic process, the main prerequisite of which is the regular, periodic flooding of the river floodplain with flood waters, which are enriched with multidispersed organic and mineral particles. During the last century, about 80 % of territory of the Upper-Dniester alluvial plain was transformed by means of hydrotechnical construction: waterproof dams and drainage channels have broken the wide river floodplains into isolated fragments, making impossible the free flow of flood waters, enriched with silt. The results of the study of stratification patterns of the river silt in the riverbed floodplain, depending on the flow velocity, granulometric composition, physical and chemical properties, given its role in the floodplain soil formation are given. The granulometric composition of the Dniester River silt changes downstream from the sandy to the heavy-loamy; In the floodplains of the Stryj and Svicha rivers medium- and heavy-loamy deposits are postponed, respectively. In the upper part of the Upper- Dniester alluvial plain (Chaikovichi 1, 2) accumulates a silt with predominance of the medium and fine sand fraction, which forms a good filtration ability of soils, whereas downstream the physical clay content increases (up to 47.2 %), which makes the river silt an important source of mineral nutrition of plants. The domination (over 40 %)in silt granulometric composition the rough dust fraction (Ustia 1, Zalisky 1) contributes to the improvement of the water-physical properties of alluvial soils and provides optimal conditions for the biota functioning. For the investigated river alluviums an alkaline reaction of the extract (pH (H2O) = 7,44–8,03) and low content of humus (0,54–3,80 %) are characteristic. The amount of nitrogen in the silt varies within 1,47–18,20 mg/100 g of soil. The river alluviums of the Upper-Dniester alluvial plain are an active factor in floodplain soil formation, since it optimizes the water-physical and physical-chemical properties of alluvial soils. But the influence area of silt on the soilsis sharply reduced and is limited only to the space in front of the dams. In the soils outside the dam, to which no fresh alluvial material comes, the hydrological regime is rebuilt and properties change substantially, up to the loss of their typological alluvial features. Key words: river alluviums, silt, floodplain, the Upper-Dniester alluvial plain, alluvial soils, hydrotechnical fragmentation.

scholarly journals Basic exchangeable cations in Finnish mineral soils

1972 ◽  
Vol 44 (3) ◽  
pp. 164-170
Author(s):  
Armi Kaila
Keyword(s):  
Clay Content ◽  
Fine Sand ◽  
Degree Of Saturation ◽  
Clay Soils ◽  
Exchangeable Ca ◽  
Significant Difference ◽  
Heavy Clay ◽  
The Mean ◽  
Mineral Soils ◽  
Plough Layer

The content of exchangeable Ca, Mg, K and Na replaced by neutral ammonium acetate was determined in 470 samples of mineral soils from various parts of Finland, except from Lapland. The amount of all these cations tended to increase with an increase in the clay content, but variation within each textural class was large, and the ranges usually overlapped those of the other classes. The higher acidity of virgin surface soils was connected with a lower average degree of saturation by Ca as compared with the corresponding textural classes of cultivated soils. No significant difference in the respective contents of other cations was detected. The samples of various textural groups from deeper layers were usually poorer in exchangeable Ca and K than the corresponding groups of plough layer. The mean content of exchangeable Mg was equal or even higher in the samples from deeper layers than in the samples from plough layer, except in the group of sand soils. The percentage of Mg of the effective CEC increased, as an average, from 9 in the sand and fine sand soils of plough layer to 30 in the heavy clay soils; in the heavy clay soils from deeper layers its mean value was 38 ± 4 %. In the samples of plough layer, the mean ratio of Ca to Mg in sand and fine sand soils was about 9, in silt and loam soils about 6, in the coarser clay soils about 4, and in heavy clay about 2.

Red soils of different origins from southwest Nigeria: Characteristics, classification, and management considerations

1997 ◽  
Vol 77 (2) ◽  
pp. 295-307 ◽  
Author(s):  
T. A. Okusami ◽  
R. H. Rust ◽  
A. O. Alao
Keyword(s):  
Clay Mineral ◽  
Agricultural Land ◽  
Clay Fraction ◽  
Chemical Properties ◽  
Cropping System ◽  
Clay Content ◽  
Parent Material ◽  
Classification Systems ◽  
Biotite Gneiss ◽  
Variable Charge

Representative profiles of the Owena, Egbeda, Alagba, and Balogun series were studied. The Owena soil is formed in amphibolite whereas Egbeda and Balogun soils are formed in biotite gneiss derived parent materials. The Alagba soil is formed in sandstone parent rock. The main objectives were to characterize the soils and their clay fraction, and to classify and interpret soil properties for agricultural land use. Most soils exhibit 2.5 YR hues in subsurface horizons. A pedon formed in biotite gneiss has the highest dithionite Fe content and Fed/clay ratio. The relationships between clay content and Fed values vary according to parent material origin and, therefore, would have to be interpreted differently for soil weathering processes. Clay coatings were noticeable in some soil horizons of all pedons studied. Soils are generally medium to slightly acid with sandstone-derived soils being the most acid. The clay mineral suite in all soils is dominated by kaolinite with traces of 2:1 and 2:2 clay minerals, goethite, hematite, anatase, maghemite, and rutile. In addition, some soils contain trace amounts of gibbsite. Kandic horizons have been identified in all soils. The low charge properties of the soils reflect the intensely weathered clay mineral suite. The base status is probably influenced by the cropping system and therefore may tend to unnecessarily differentiate highly weathered soils at the order level. The Egbeda and Balogun series were classified as Rhodic Kandiudults, clayey-skeletal, oxidic and Rhodic Kandiudalfs, clayey-skeletal, oxidic, respectively. Others, Owena, and Alagba series, were classified as Typic Kanhaplohumults, clayey, oxidic and Rhodic Kanhaplustults, fine loamy or clayey, oxidic, respectively. In the FAO-Unesco legend, all soils become Rhodic Ferralsols. In addition, the Owena (with its nitic properties) is further classified as niti-rhodic Ferralsol. The two classification systems are at variance for highly weathered (variable charge property) soils and this difference will definitely influence management decisions depending on which system is used at any particular time. Soil attributes favorable for agricultural use include thick sola and favorable structures. Chemical properties suggest minimal fixation of phosphorus. Key words: Dithionite Fe, kandic, oxidic, variable charge, ferralic, exchangeable Al

scholarly journals Effect of termite activity on soil under different land management strategies

2017 ◽  
Vol 38 (1) ◽  
pp. 143
Author(s):  
Liane Barreto Alves Pinheiro ◽  
Rodrigo Camara ◽  
Marcos Gervasio Pereira ◽  
Eduardo Lima ◽  
Maria Elizabeth Fernandes Correia ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Management Strategies ◽  
Chemical Properties ◽  
Clay Content ◽  
Exchange Capacity ◽  
Termite Mounds ◽  
Eucalyptus Plantation ◽  
Exchangeable Acidity ◽  
Calcium And Magnesium ◽  
Surrounding Soil

Mound-building termites are important agents of soil bioperturbation, but these species have not been extensively studied thus far. The present study aimed to evaluate the soil particle-size and the chemical attributes of termite mounds and the surrounding soil under different land use strategies. A one-hectare plot was defined for an unmanaged degraded pasture, planted pasture, and for a eucalyptus Corymbia citriodora plantation. In each plot, the top, center, and base sections of five Cornitermes cumulans mounds, and the surrounding soil at the depths of 0-5; 5-10; 10-20 cm, were sampled in the Pinheiral, Rio de Janeiro state. In the three areas, the center of the mounds contained higher clay content, organic carbon, phosphorous, calcium and magnesium, total bases, and cation exchangeable capacity, when compared to the top, base, and the surrounding soils. However, the center had lower values of exchangeable acidity and potassium, of the three areas. In the eucalyptus plantation, the values of pH, total bases, calcium, and magnesium were lower, whereas aluminum, exchangeable acidity, sodium, and cation exchange capacity were higher both in the mounds and in the surrounding soil, in relation to the pastures. There were no differences among the three areas in terms of organic carbon, potassium, phosphorous, and total bases, in the mounds and adjacent soil. Thus, the termite activity altered the clay content and most of the soil chemical properties in all of the studied areas, but only for the center of the mounds. However, the effect of these organisms was different in the eucalyptus plantation in relation to the pasture areas.

scholarly journals Compositional and industrial assessment of Isua-Akoko, Akure, Ayadi and Lafe (Ode Aye) clay deposits of Ondo state, Nigeria

1970 ◽  
Vol 21 (1) ◽  
pp. 41-49
Author(s):  
O Adegbuyi ◽  
GP Ojo ◽  
AJ Adeola ◽  
MT Alebiosu
Keyword(s):  
Chemical Properties ◽  
Fine Sand ◽  
Coarse Sand ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Medium Sand ◽  
Southwestern Nigeria ◽  
Firing Test ◽  
Clay Deposits ◽  
Ondo State

The physical and chemical properties of clay deposits around Isua-Akoko, Akure, Lafe and Ayadi in Ondo State southwestern Nigeria have been examined. The results have shown that Isua-Akoko, Akure and Lafe Clays are plastic fire clays while Ayadi clay is kaolinite. Grain size analysis reveals that Isua Akoko Clay contains 45% of clay, 18% silt, 12% fine sand,14% medium sand and 11% coarse sand and no gravel; Akure clay contains 42% clay, 14% silt, 13% fine sand, 20% medium sand and 8% coarse sand with 1% gravel. Lafe Clay contains 21% clay, 8% silt, 25% fine sand, 37% medium sand and 8% coarse sand with 1% gravel while Ayadi clay contains 83% clay and 17% silt. The liquid limits of these clay samples range from 41% to 73%% and plastic limits range from 18% to 26% respectively. The chemical analysis reveals that the most abundant mineral is silica (60.97%) and aluminum was next in abundance (23.69%) while other oxides are low. The results show that Isua-Akoko and Akure are residual while Lafe and Ayadi are sedimentary and transported Clays. The firing test, PH, and bleaching tests of the clays are also discussed. The chemical and physical characteristics of the clay deposits are strongly indicative of their industrial importance in the production of ceramics, refractories, paving bricks, paint and pharmaceutical products.KEYWORDS: Kaolinite, fire clay, gravel, ceramics and alumina.

scholarly journals Analyzing rainwater chemistry at the continental GAW station Nagpur

MAUSAM ◽  
2021 ◽  
Vol 57 (4) ◽  
pp. 653-662
Author(s):  
JAYANTA SARKAR ◽  
V. K. SONI ◽  
A. S. GADGIL ◽  
A. K. MUKHERJEE
Keyword(s):  
Acid Rain ◽  
Sea Water ◽  
Monsoon Season ◽  
Dust Particles ◽  
Rainwater Chemistry ◽  
Water Ph ◽  
Marine Influence ◽  
Relationship Of ◽  
Peak Summer ◽  
Basic Cations

lkj & bl 'kks/k i= esa 1981 ls 1996 rd dh vof/k esa ukxiqj esa gqbZ o"kkZ ds ikuh esa jklk;fud rRoksa dh miyC/krk dk v/;;u fd;k x;k gSA bl v/;;u ls ;g irk pyk gS fd ukxiqj esa o"kkZ _rq esa ckj&ckj xtZ ds lkFk vkus okys rwQkuksa ds dkj.k o"kkZ ds ikuh esa Na+ vkSj Cl- ds lkanz.kksa esa leqnz dk izHkko de gSA ;gk¡ ij ekulwu _rq ds vkxeu ls igys ds eghuksa esa vkSj iwjh ekulwu _rq ds nkSjku NO3&  esa cgqr  vf/kd lkanzrk fjdkWMZ dh xbZ gSA ekulwu _rq ds nkSjku K+ dks NksM+dj o"kkZ ds ikuh ds lHkh ?kVdksa dh vxLr rd lkanzrk de gksrh tkrh gSA rFkkfi] flracj esa lHkh ?kVdksa dh lkanzrk esa o`f} ikbZ xbZ gSA Cl- vkSj Na+ ds fu{ksi.k eku rVh; dsanzksa dh rqyuk esa dkQh de ik, x, gSaA SO4&2 ds fu{ksi.k ekuksa dh rqyuk     ;w- ,l- ,l- vkj- ds dqN Hkkxksa esa ik, x, ekuksa ls dh tk ldrh gSA o"kkZ ds ikuh ds fofHkUu ?kVdksa ds chp vuqikrksa dk v/;;u djus vkSj leqnz ds ikuh ds vuqikrksa ds lkFk mudh rqyuk djus ls irk pyk gS fd ukxiqj esa o"kkZ ds ikuh esa Na+ dh vf/kdrk dk dkj.k leqnz ds ikuh ds vykok vU; lzksr Hkh gSaA pH ekuksa esa cgqr vf/kd fofHkUurk ikbZ xbZ gSA ekulwu esa] twu ds ]ckn pH de gksrk tkrk gS vkSj flracj rd cgqr de gks tkrk gSA bldk dkj.k o"kkZ ds ikuh }kjk ewy dSVk;uksa dk i`Fkd djuk ekuk tk ldrk gSA vizSy vkSj ebZ ds lcls rst xehZ ds eghuksa esa pH dh vf/kd ek=k dk dkj.k okrkoj.k esa /kwy d.kksa dh ek=k] ftlesa eq[;r% ewy dSVk;u gksrs gSa] dks ekuk tk ldrk gSA ekulwu _rq ds izR;sd ekg ds pH ds v/;;u ls irk pyk gS fd twu vkSj tqykbZ esa o"kkZ dk Lo:i  lokZf/kd ekSfyd gS tcfd vxLr vkSj flracj esa ukxiqj esa vEyh; o"kkZ dh dqN ?kVuk,¡ ns[kh xbZ gSaA tc ekpZ vkSj fnlcaj ds nks eghuksa esa pH dk eku 5-0 ls uhps fxj tkrk gS rc vEyh; o"kkZ dh leL;k cgqr vf/kd fodV gksrh gSA ekulwu iwoZ _rq ds nkSjku mPp lapkydrk ekuksa dk dkj.k bl vof/k esa okrkoj.k esa /kwy d.kksa dh vf/kd lkanzrk dks ekuk tk ldrk gSA ?kVdksa vkSj o"kkZ ds chp  ds :Ik esa foijhr laca/k ik;k x;k gSA In this paper rainwater chemistry of Nagpur for the period 1981-1996, has been studied. The analysis reveals that at Nagpur rain water there is less marine influence on the concentrations of Na+ and Cl-. Pre-monsoon months, as well as the season as a whole, record higher NO3- concentration which could be attributed to frequent thunderstorm activities in this season. During monsoon months, concentration of all the constituents of rainwater, except K+, goes on decreasing till August. However, in September increase in concentration is observed for all the constituents. Deposition values of Cl- and Na+ are found to be quite low in comparison to that at coastal stations.   SO4-2 deposition value is comparable to the values reported in some parts of USSR. Study of ratios between various constituents and a comparison with sea water ratios reveals that rainwater at Nagpur gets enriched in terms of Na+ from other sources besides sea water. pH values exhibited large variation.  In monsoon, June onwards pH goes on decreasing and lowest value is obtained in September.  This could be attributed to the preferential removal of basic cations by rainwater.  In the peak summer of April and May higher values of pH could be attributed to the abundant prevalence of dust particles in the atmosphere chiefly consisting of basic cations. pH of individual months of monsoon season reveals that in June and July rainfall is predominantly basic in nature while in August and September some instances of acid rain has been observed at Nagpur. Acid rain problem seems to be more acute in the month of March and December when pH in these two months falls below 5.0. High conductivity values during pre-monsoon season could be attributed to higher dust concentrations in the atmosphere during this period. An inverse relationship of form Y = AR-B has been found between the constituents and rainfall.

scholarly journals The hidden ecological resource of andic soils in mountain ecosystems: evidences from Italy

2017 ◽  
Author(s):  
Fabio Terribile ◽  
Michela Iamarino ◽  
Giuliano Langella ◽  
Piero Manna ◽  
Florindo Antonio Mileti ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Chemical Properties ◽  
Organic C ◽  
Mountain Ecosystems ◽  
C Storage ◽  
Mountain Landscapes ◽  
Ecological Importance ◽  
Mineral Soils ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract. Andic soils have unique morphological, physical and chemical properties that induce both considerable soil fertility and great vulnerability to land degradation. Moreover they are the most striking mineral soils in terms of large organic C storage and long C residence time; this is especially related to the presence of poorly crystalline clay minerals and metal-humus complexes. Recognition of these soils is then very important. Here we attempt to show, through the combined analysis of 35 sampling points chosen, throughout the Italian non volcanic mountain landscapes, in accordance to specific physical and vegetation rules, that soils rich in poorly crystalline clay minerals have an utmost ecological importance. More specifically, in various non-volcanic mountain ecosystems (> 700 m) and in low slope gradient locations (

scholarly journals Co-Crystals of Resveratrol and Polydatin with L-Proline: Crystal Structures, Dissolution Properties, and In Vitro Cytotoxicities

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5722
Author(s):  
Yijie Lou ◽  
Kaxi Yu ◽  
Xiajun Wu ◽  
Zhaojun Wang ◽  
Yusheng Cui ◽  
...  
Keyword(s):  
Cell Line ◽  
Chemical Properties ◽  
Cancer Cell Line ◽  
Lung Cancer Cell Line ◽  
Hek 293 ◽  
Dissolution Properties ◽  
Diphenyltetrazolium Bromide ◽  
Water Ph ◽  
Physical And Chemical

Resveratrol (RSV) and polydatin (PD) have been widely used to treat several chronic diseases, such as atherosclerosis, pulmonary fibrosis, and diabetes, among several others. However, their low solubility hinders their further applications. In this work, we show that the solubility of PD can be boosted via its co-crystallization with L-proline (L-Pro). Two different phases of co-crystals, namely the RSV-L-Pro (RSV:L-Pro = 1:2) and PD-L-Pro (PD:L-Pro = 1: 3), have been prepared and characterized. As compared to the pristine RSV and PD, the solubility and dissolution rates of PD-L-Pro in water (pH 7.0) exhibited a 15.8% increase, whereas those of RSV-L-Pro exhibited a 13.8% decrease. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of pristine RSV, PD, RSV-L-Pro, and PD-L-Pro against lung cancer cell line A549 and human embryonic kidney cell line HEK-293 indicated that both compounds showed obvious cytotoxicity against A549, but significantly reduced cytotoxicity against HEK-293, with PD/PD-L-Pro further exhibiting better biological safety than that of RSV/RSV-L-Pro. This work demonstrated that the readily available and biocompatible L-Pro can be a promising adjuvant to optimize the physical and chemical properties of RSV and PD to improve their pharmacokinetics.

Relationships between extractable Al, selected soil properties, pH buffer capacity and lime requirement in some acidic Queensland soils

Soil Research ◽  
1992 ◽  
Vol 30 (2) ◽  
pp. 119 ◽  
Author(s):  
RL Aitken
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Properties ◽  
Buffer Capacity ◽  
Clay Content ◽  
Ph Buffering ◽  
Ph Buffer ◽  
Mineral Soils ◽  
Chloride Salts ◽  
Hydrolysis Of

The objectives of this study were to examine (1) interrelationships between various forms of extractable A1 and selected soil properties, (2) the contribution of extractable A1 to pH buffer capacity, and (3) investigate the use of extractable A1 to predict lime requirement. Aluminium was extracted from each of 60 Queensland soils with a range of chloride salts: 1 M KCl (AlK), 0.5 M CuCl2 (AlCu), 0.33 M LaCl3 (AlLa) and 0.01 M CaCl2 (AlCa). The amounts of A1 extracted were in the order AlCu > AlLa > Alk > AlCa. Little or no A1 was extracted by KC1 or Lac13 in soils with pHw values greater than 5.5 , whereas CuCl2 extracted some A1 irrespective of soil pH. The greater amounts of A1 extracted by CuCl2 were attributed mainly to A1 from organic matter, even though all of the soils were mineral soils (organic carbon 54.7%). Both AlCu and AlLa, were significantly (P < 0.001) correlated with organic carbon, whereas none of the extractable A1 measures was correlated with clay content. AlK and A~L, were poorly correlated to pH buffer capacity. The linear relationship between AlCu and pH buffer capacity (r2 = 0.49) obtained in this study supports the view of previous researchers that the hydrolysis of A1 adsorbed by organic matter is a source of pH buffering in soils. However, the change in CEC with pH accounted for 76% of the variation in pH buffer capacity, indicating that other mechanisms such as deprotonation of organic groups and variable charge minerals are also involved in pH buffering. The ability of CuCl2 and LaCl3extractable Al to estimate lime requirement depended on the target pH. The results suggest that lime requirements based on neutralization of AlLa would be sufficient to raise pHw to around 5.5, whereas requirements based on neutralization of AlCu substantially overestimated the actual lime requirement to pHw 5.5, but gave a reasonable estimation of the lime requirement to pHw 6 5.

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