The influence of acid soil factors on the growth of snapbeans in major appalachian soils

Abstract

Acid soil limitations to plant growth were assessed In 55 horizons of 14 major Appalachian hill land soils. Aluminum sensitive “Romano” and Al‐tolerant “Dade” snapbeans (Phaseolus vulgaris L.) were grown for 5 weeks in limed and unlimed treatments of the 55 horizons. Shoot and root growth was depressed >20% in unlimed relative to limed treatments in approximately 2/3 of the horizons. Dade snapbeans were generally more tolerant of the acid soil conditions and had higher Ca concentrations in the shoots than Romano snapbeans. However, the sensitive‐tolerant snapbean pair could not consistently be used to identify horizons with soil Al problems. Growth of both snapbeans was generally best in A horizons and worst in E horizons. The E horizons in this study were characterized by low Ca saturation (exchangeable Ca x 100/cation exchange capacity) and high Al saturation (exchangeable Al x 100/cation exchange capacity). Exchangeable Ca, soil Ca saturation and total soil solution Ca were positively correlated (p<0.01) with snapbean root and shoot growth. Soil Al saturation, total soil solution Al and soil solution Al reacting in 15 seconds with 8‐hydroxyquinoline were negatively correlated (p<0.01) with growth. The ratio of Ca/Al in soil solution was more closely related to snapbean growth than the soil solution concentration of any individual element. Soil and soil solution Mn were, in general, not significantly correlated with snapbean growth. Many of the horizons in this study had both Al toxicity and Ca deficiency problems and interaction between Ca and Al affected both snapbean growth and Ca uptake. These findings confirm the importance of considering Ca as well as Al when investigating Al phytotoxicity.     

茶叶氟含量与茶园土壤特性的相关性及其影响因素

通过对青岛地区10个典型茶园中的茶叶氟含量和土壤水溶性氟、p H、交换性酸及交换性阳离子等的测定,分析了茶叶氟含量与土壤特性的相关性,并探讨了土壤水溶性氟和交换性酸的主要影响因素。结果表明,茶园土壤水溶性氟和交换性酸含量与茶叶氟含量呈显著正相关性(P0.05),是影响茶叶氟含量的关键因素。土壤交换性H+和交换性Na+与土壤水溶性氟含量呈显著正相关性(P0.05),是影响土壤水溶性氟含量的主要因素。土壤交换性Al3+与交换性酸呈极显著正相关性(P0.01),p H、交换性Ca2+、交换性盐基总量和盐基饱和度与交换性酸含量呈极显著负相关性(P0.01),是土壤交换性酸含量的主要影响因素。研究结果可为茶园土壤改良及降低茶叶氟含量的质量安全风险提供依据。     

Influence of Lime and Gypsum on Yield and Yield Components of Soybean and Changes in Soil Chemical Properties

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 cmol_c kg^?1, Mg 0.66 cmol_c kg^?1, base saturation 53%, Ca saturation 35%, and Mg saturation 13%. Soybean plants tolerated acidity (H + Al) up to 2.26 cmol_c kg^?1 soil. In the case of gypsum, maximum grain yield was obtained at exchangeable Ca content of 2.12 cmol_c kg^?1, base saturation of 56%, and Ca saturation of 41%.     

Critical pH and exchangeable Al of four acidic soils derived from different parent materials for maize crops

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 cmol_ckg^?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.

     

蚌壳用作土壤改良剂：对根际和非根际土壤和草地生产力的影响

Large quantities of mussel shells(66 000-94 000 t year 1),an alkaline material that can be used as a soil amendment,are generated as waste in Galicia,NW Spain.A field trial was carried out by planting different pasture species in a Haplic Umbrisol using a randomized block design with four blocks and six treatments(not amended control or soil amended with lime,finely ground shell,coarsely ground shell,finely ground calcined shell or coarsely ground calcined shell) to compare the effects of lime and mussel shells additions on a soil with a low cation exchange capacity and high Al saturation.The trial was established in March 2007,and samples of plants and soil were collected when plots were harvested in summer 2008(separating the bulk and rhizosphere soil).The soils were analyzed for pH,total C,total N,available P,exchangeable cations,effective cation exchange capacity and available micronutrients.Dry matter yield was measured in all plots and plants were analyzed for nutrients.Application of mussel shells and the commercial lime resulted in an increase in pH and exchangeable Ca and a decrease in exchangeable Al and Al saturation.The stability of pH over time was high.These effects were most noticeable in the rhizosphere.The amendment also had a positive effect on dry matter yield and concentration of Ca in the plant.     

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

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。     

Biomass and Phosphorus Uptake Responses of Maize to Phosphorus Application in Three Acid Soils from Southern Cameroon

Abstract

A phosphorus (P) greenhouse experiment was carried out with maize (Zea Mays L.) using surface horizons of three contrasted acid soils from southern Cameroon. The objectives were (i) to assess causal factors of maize differential growth and P uptake and (ii) to explore plant–soil interactions in acid soils under increasing P supply. Shoot and root dry‐matter yield and P uptake were significantly influenced by soil type and P rate (P<0.000), but the interaction was not significant. Soil properties that significantly (P<0.05) influenced maize growth variables were available P, soil pH, exchangeable bases [calcium (Ca), magnesium (Mg)], and exchangeable aluminium (Al). Data ordination through principal‐component analysis highlighted a four‐component model that accounted for 88.1% of total system variance (TSV) and summarized plant reaction in acid soil condition. The first component, associated with 36.1% of TSV, pointed at increasing root–shoot ratio with increasing soil acidity and exchangeable Al. The second component (24.6% of TSV) highlighted soil labile P pool increase as a function of P rate. The third and fourth components reflected nitrogen (N) accumulation in soils and soil texture variability, respectively.     

西藏酸性土壤的酸度特征

根据西藏7个土类6 6个土壤剖面2 5 7层土样的分析资料,探讨酸性土的酸度特征。西藏酸性土面积约占1/ 5 ,主要为山地湿润森林型和高山灌丛草甸型土壤,集中分布于藏东南地区。土壤pH主要决定于其潜性酸中的交换性酸,特别是其中占优势的交换性Al3 ,而受非交换性酸的影响较小。交换性酸中Al3 的相对比例随交换性酸总量增加而增大,随有机质增加而减小,H 的相对比例则呈相反的变化。非交换性酸主要来源于有机质(腐殖质酸性功能团缔合H和络合Al的解离)。土壤pH与交换性酸、非交换性酸饱和度分别呈近线性、非线性负相关,而与盐基饱和度呈非线性正相关,且主要受优势的交换性Ca2 制约。     

Relationship between chemical and mineralogical properties and the rapid response to acid load of soils in humid Asia: Japan,Thailand and Indonesia

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 (Al_o) 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 Al_o 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 Al_o 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.     

Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao (Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

A survey of clover and Lotus rhizobia in Northern Ireland pasture soils

192 sites covering the main soil types in Northern Ireland were analysed for numbers and effectiveness of clover and Lotus rhizobia, and chemical properties. Peat sites were generally highly acid (pH <5.5) and mineral sites near neutral (pH 5.5–7.8). Clover rhizobia were generally absent from peat sites and present in mineral sites as large populations (> 10⁶ g^?1 dry soil). 79% of isolates were effective on T. repens var. Grasslands Huia. Lotus rhizobia were generally absent from peat sites, less often present than clover rhizobia in mineral sites, and as smaller populations. They were mainly effective on L. pedunculatus var. G4705 and were all of the slow-growing type belonging to the genus Bradyrhizobium. Numbers of clover rhizobia were significantly correlated with soil pH, exchangeable Ca, base saturation and Al saturation, but effectiveness of clover rhizobia and numbers of Lotus rhizobia were not correlated with any soil chemical property.     

Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao ( Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

Soil Acidification in Phyllostachys praecox f. preveynalis Cultivation with Intensive Management

Phyllostachys praecox f. preveynalis (Lei bamboo) cultivation with intensive management has high economic profits. However, soil acidification is a severe problem with bamboo plantations that may influence its sustainability in practice. In this study, soils of two sites with different bamboo cultivation times were collected from Lin-an City of Zhejiang Province, China, to understand bamboo soil acidification through analysis of various soil acidification indicators. Results showed that soil nutrients accumulated significantly within the bamboo plantation, but soil pH dropped dramatically. Soil exchangeable acid increased with increasing bamboo planting times, so did the ratio of exchangeable aluminum (Al) to total soil Al. However, the exchangeable base cation [potassium (K) + sodium (Na) + calcium (Ca) + magnesium (Mg)] content and its saturation decreased greatly. With a simple simulation of first-order decay equation, soil acidification rates differed from soil sites but the final pH was similar, which suggested that intensive management exerted an important effect on soil properties.     

有机肥替代化学氮肥提升红壤抗酸化能力

【目的】长期过量施用化学氮肥加剧了红壤区农田土壤酸化,严重制约着该区域农业的可持续发展。施用石灰和有机肥是防治红壤酸化的主要措施,我们研究了有机无机肥配合提高红壤抗酸化能力的作用与机理。【方法】本研究基于2009年在湖南祁阳中国农业科学院红壤站开展的有机肥替代化学氮肥长期定位试验,其中4个处理分别为单施化肥(由于酸化严重,于2018年底添加石灰改良)、有机肥替代化肥氮20%、40%和60%,供试有机肥为猪粪。采集2018和2020年的土壤样品,分析各施肥处理红壤pH、交换性酸铝、阳离子交换量、有机质、酸缓冲能力等指标的变化及相互关系。【结果】至2018年,单施化肥处理较试验之初土壤pH降低了0.48个单位,交换性酸、铝分别增加了2.74和1.06 cmol/kg;添加石灰改良后,土壤pH升高了0.58个单位,交换性酸、铝分别降低了2.62和1.45 cmol/kg。有机肥替代化肥氮40%和60%处理均可有效防治红壤酸化,其中以替代60%处理效果最佳;至2020年60%有机替代处理土壤pH较初始值提高了0.78个单位,交换性酸和交换性铝分别降低了1.10和1.25 cmol/kg。有机肥...     

Effects of acid deposition on acidity and exchangeable cations in podzols of the Kola Peninsula

Response of soil and soil water of podzols in the Kola Peninsula to acid deposition was estimated under both field and laboratory conditions. A significant increasing trend of exchangeable acidity in organic (O) horizons and exchangeable Al in podzolic (E) horizons of podzols with distance from the nickel smelter was observed. The simulated rain at pH 4.5 did not alter chemical properties of soils and soil solutions. As much as 95–99% of the applied H⁺ ions were retained by soils and appeared in the percolates after a treatment period that depended on acid load and soil thickness. Ca and Mg in soil solutions were highly sensitive to acid loading. Simulated acid rain enhanced the leaching of exchangeable base cations out of root zone. Acid inputs resulted in decreased pH, amount of exchangeable base cations and base saturation, in elevated exchangeable acidity and it's Al fraction in soil solid phase. The most significant changes occurred in O and E horizons. Substantial amounts of both Ca and Mg can be lost from the root zone of podzols in the north-western Kola, subjected to acid deposition, thus leading to forest productivity damage.     

Acid soil tolerances of two wheat cultivars related to soil Ph,KCl‐extractable aluminum and degree of aluminum saturation

Aluminum toxicity, associated with soil acidity, is a major growth‐limiting factor for plants in many parts of the world. More precise criteria are needed for the identification of potential Al toxicity in acid soils. The objective of the current study was to relate the acid soil tolerances of two wheat cultivars to three characteristics of an acid Tatum subsoil (clayey, mixed, thermic, typic Hapludult): pH in a 1:1 soil to water suspension; KCl‐extractable Al; and degree of Al saturation. Aluminum‐tolerant ‘BH 1146’ (Brazil) and Al‐sensitive ‘Sonora 63’ (Mexico) wheat cultivars were grown in greenhouse pots of soil treated with CaCO₃ to establish final soil pH levels of 4.1, 4.6, 4.7, 4.9, 5.2 and 7.3. Soil Al, Ca and Mg were extracted with 1 N KCl, and Al saturation was calculated as KCl‐Al/KCl Al + Ca + Mg%.

Within the soil pH range of 4.1 to 4.9, BH 1146 tops and roots produced significantly more dry matter than did those of Sonora 63; however, at pH 5.2 and 7.3, the top and root yields of the two cultivars were not significantly different. Significant cultivar differences in yield occurred over a range of 36 to 82% saturation of the Tatum soil. Graphs of relative top or root yields against soil pH, KCl‐extractable Al and Al saturation indicated that the two cultivars could be separated for tolerance to Tatum soil under the following conditions: pH less than 5.2 (1:1 soil‐water); KCl‐Al levels greater than 2 c mole kg^‐1 and Al saturations greater than 20%. Results demonstrated that any soil test used to predict Al toxicity in acid soils must take into account the Al tolerances of the plant cultivars involved.     

Effects of lime applications to parts of an upland catchment on soil properties and the chemistry of drainage waters

The liming of soils in the lower part of an upland catchment was found to have a major effect on both soil properties and the chemistry of drainage waters. Exchangeable Al was closely correlated with soil pH and showed a very steep rise from 2.6-4.8 meq 1⁻¹ over the pH range 5.5-4.5. As streams flowed from unimproved through improved land there was an increase in pH and the concentration of all major anions and basic cations. The greatest increase was in Ca (approximately 3.5-fold). The concentrations of all dissolved Al species decreased, with inorganic monomeric Al falling to near zero. Leachates were examined from soils representative of the most acidic and the least acidic. Calcium concentrations differed by almost tenfold. Aluminium was present in leachates from the limed soil, but most was unreactive and none was inorganic monomeric. Most of the Al leached from the acid soil was monomeric.
A model of soil acidification is proposed in which soil Ca is depleted at a rate of 8% of the exchangeable Ca per annum. The model predicts that liming a soil to neutrality would be likely to influence drainage water chemistry for 30-40 years and that the most acidic soils of the catchment show no net loss of Ca to drainage.     

Effects of charcoal production on maize yield,chemical properties and texture of soil

The effects of charcoal production on soil textural and chemical properties were investigated in Ejura, Ghana. The aim was to study the effects of heating and charcoal residue on maize yield, soil texture and soil chemical properties. Composite samples were taken from the 0–10 cm layer of soil at charcoal-making sites and from adjacent fields (control). Twelve sites were randomly selected for the study across the range of the Kotokosu watershed. Maize was planted in four selected locations on charcoal site soils (CSS) and adjacent field soils (AFS) to assess the impact of charcoal production on crop yield. There was a significant increase in soil pH, base saturation, electrical conductivity, exchangeable Ca, Mg, K, Na and available P in the soil at the kiln sites as compared to the adjacent soils. A relative change of up to 329% was observed in K while organic C and total N decreased by 9.8% and 12.8%, respectively. Organic C and total N were highly correlated ( P <0.01) and both parameters significantly ( P <0.05) depended on clay minerals in the soils. Soil texture was also modified with a significantly higher sand content and lower clay fraction in the CSS. The grain and biomass yield of maize increased by 91% and 44%, respectively, on CSS as compared to AFS. Further research to ascertain the long-term effects of charcoal production on the soil environment and the fertility of tropical soils is needed.     

Hybrid ryegrass response to acid soil treatment with calcitic and dolomitic lime

Abstract

Since ryegrass (Lolium sp.) is a widely grown cool‐season forage grass, its magnesium concentration is of special interest to ruminant livestock producers. This study was conducted to investigate the effect of calcitic or dolomitic lime addition on dry matter yield and mineral composition of hybrid ryegrass, Lolium (multiflorum x perenne x perenne) grown in eight acidic soils. Each soil received two levels of calcitic or dolomitic lime, L(C₁) and L(C₂) or L(D₁) and L(D₂), which raised pH to approximately 5.3, and 6.0. Dry matter yield response was obtained only in soils having an initial % Al saturation ≥59, % Mg saturation ≤10 and % Ca saturation ≤21. Only in one soil, which had an initial exchangeable Mg level of 0.05 cmol_c/kg of soil, was response to dolomitic lime higher than that obtained with calcitic lime. Magnesium concentration in dry matter was increased by both levels of dolomitic lime with the increase dependent on the rate used and on the initial level of exchangeable Mg. The average Mg concentration increased from 0.8 to 3.9 g/kg, from 1.6 to 3.6 g/kg, and from 2.6 to 3.9 g/kg, when ryegrass was grown in soils having low, medium, and high initial exchangeable Mg levels, respectively. Mg concentration in the ryegrass tended to be lower in the unlimed soils than when calcitic lime was used, 1.1 vs. 1.4 g/kg, when the soils had low to medium exchangeable Mg levels. The results suggest that if ryegrass is to be grown in acidic soils containing low to medium levels of exchangeable Mg, the use of dolomitic lime is desirable, even if no yield response to applied Mg is expected, to decrease the probability of the Mg deficiency disease, hypomagnesemia, in ruminant animals.     

广东省酸性硫酸盐水稻土作物产量的主要限制因子分析

【目的】酸性硫酸盐水稻土(ASPS,简称反酸田)因强酸严重限制水稻生长,其产量远低于全国平均水平,是我国南方典型中低产田。为了进一步提高反酸田的水稻产量,需要对反酸田土壤的主要限制因子进行分析,以更好地对症下药,有效合理地改良土壤。本研究调查了不同产量水平下酸性硫酸盐水稻田的理化性状,探讨限制水稻生长的关键土壤化学因子,为反酸田的改良提供理论依据。【方法】 根据前期调查结果,选择3种产量水平(4500、 3000、 1500 kg/hm2)的代表性反酸田为研究对象,并以因强酸而撂荒的水稻田作为对照,于2013年6月28日在不同采样点各采集8个耕作层土壤样品,测定其有机质, 酸度, 氮、 磷、 钾养分以及微量元素含量等化学性状指标,比较不同田块间各种化学性状的差异,并通过相关分析、 主成分分析探讨影响反酸田水稻生长的关键土壤化学因子。【结果】反酸田的酸度水平极高,其pH值在3.0~4.0之间,水溶性酸、 交换性酸和吸持性酸含量分别达到0.6~5.6、 2.7~6.3和1.3~14.1 cmol/kg; 不同调查田块的酸度水平差异显著,高产田块的各种形态酸含量均显著低于低产田块,尤以水溶性酸和吸持性酸的差异更明显。随产量水平的降低,反酸田的有效磷、 速效钾含量显著降低,而水溶性硫、 交换性硫、 交换性锰、 交换性铝含量显著提高,交换性钙、 交换性锌、 交换性铜含量差异不显著,反映出缺磷、 缺钾、 硫酸盐含量过高、 铝毒、 锰毒显著限制了反酸田的水稻产量。相关分析表明,土壤有效磷、 速效钾与各种形态酸含量和硫酸盐含量显著负相关,而交换性钙、 锰、 铜、 锌、 铝与各种形态酸含量和硫酸盐含量显著正相关,表明反酸田水稻产量的主要限制化学因子受土壤酸含量及硫酸盐含量的水平影响。主成分分析表明,水溶性硫、 交换性硫、 交换性铝、 交换性酸、 交换性锰、 水溶性酸、 吸持性酸、 pH值、 有效磷、 速效钾等组成一个相对均质的变量群组,概括了64.99%的不同产量水平下反酸田理化性状的总变异度,为影响反酸田产量的主要土壤化学因子。其中水溶性硫、 交换性硫、 交换性铝、 交换性酸、 交换性锰、 水溶性酸、 吸持性酸为影响反酸田产量水平的负效应变量,而pH值、 有效磷、 速效钾为影响反酸田产量水平的正效应变量。【结论】硫酸根含量过高、 铝毒、 锰毒、 酸毒、 缺磷、 缺钾是限制反酸田产量的主要土壤化学因子。酸、 硫酸盐是反酸田的发育产物,是影响广东省反酸田水稻生长的原生及根本性障碍因素,而铝毒、 锰毒、 缺磷、 缺钾等是因土壤中酸、 硫酸盐含量较高时引起的次生障碍因素。因此,在反酸田的改良过程中需以减缓黄铁矿氧化、 促进黄钾铁矾水解,降低耕层土壤酸、 硫酸盐含量为主要目标。