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1.
Rape (Brassica napus L.) seedling pot experiments were performed with a red soil treated with goethite which had boron (B) either adsorbed (ad-B-goethite) or occluded (oc-B-goethite). Soil acidity, different forms of manganese in the soils and different elements content of the rape seedlings were determined. It was found that the addition of boron-containing goethite to the soils resulted in increased rape growth, elevated soil pH and decreased exchangeable acidity. Compared with the control, boron-containing goethite elevated the content of exchangeable manganese (Mn) (EXC-Mn), organic matter bound Mn (OM-Mn), reducible oxide Mn (RO-Mn) and residual Mn (RES-Mn) which were difficult to use for plant. Low labile organic matter was significantly correlated with easily reducible oxide Mn (ERO-Mn) (P < 0.01) and RO-Mn (P < 0.05). Middle organic matter and soil pH was significantly (P < 0.05) correlated with RES-Mn. Stepwise regression was used to select the combination of variables that best estimates shoot and root dry weight of rape seedling. Among them, soil pH, EXC-Mn, OM-Mn, RO-Mn and RES-Mn significantly influenced the dry weight of rape seedlings. The addition of boron-containing goethite improved the uptake of iron (Fe), calcium (Ca), magnesium (Mg), and copper (Cu) element and decreased the uptake of Mn and zinc (Zn) element in rape seedling. The results suggested that boron-containing goethite could provide a better soil acidity environment for plant growth; it was also an important agent increasing a part of manganese difficult to use for plant and reducing the activity of soil manganese, which was beneficial to altering rape seedling growth.  相似文献   

2.
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.  相似文献   

3.
Boron (B) amelioration of aluminum (Al) toxicity was studied for growth of mungbean (Phaseolus aureus Roxb.) seedlings and cuttings (without roots) in a growth chamber. Mungbean seedlings and cuttings were grown in the solution with combinations of three concentrations of B (0,5, and 50 μM) and three concentrations of Al (0, 2, and 5 mM) in randomized complete block design experiments for 16 days. Results showed that B significantly promoted elongation of epicotyls and hypocotyls, and increased height of seedlings grown under Al stress. Boron also increased fresh weight of seedlings in high Al solution. Treatment of plants grown with high B and Al stress had no apparent effect on fresh and dry weights of seedling roots. Seedling dry weight increased significantly by adding high B to solutions with 2 mM or 5 mM Al. No significant differences were observed between the high B treatment and the control (normal B, 5 μM) in lengths of epicotyls and fresh and dry weights of mungbean cuttings grown under Al stress. High concentrations of B decreased soluble protein and increased chlorophyll in seedlings treated with 2 mM Al. Boron had no amelioration effect on cuttings grown with Al, although Al increased soluble protein. Our results suggested that B alleviation of Al toxicity was related to root function and Al toxicity may possibly be due, in part, to B deficiency.  相似文献   

4.
The purpose of the study was to determine plant availability of boron (B) and relaxation of soil acid to rape seedling exhibited by B-doped goethite in acidic soil. For this purpose, two kinds of B-doped goethite were synthesized: one was goethite with adsorbed B prepared by reacting goethite with borax solution, and the other was goethite with occluded B by synthesizing goethite in the presence of boric acid. The reaction process in soil-like natural minerals of the B-doped goethite was simulated in a rhizobox culture system. Results showed that the B-doped goethite can provide available B for rape growth. Its addition on acidic soil can alleviate soil acidification by increasing soil pH and decreasing soil exchangeable acid. The observation that nutrient uptake was improved supports the view that the B-doped goethite improved soil quality, as also proved by the increase of root morphology and dry weight.  相似文献   

5.
The purpose of the study was to determine the effect of boron (B)-permeated goethite on soil B fractionation and the availability of this B fraction to rape seedlings (Brassica napus L.). For this purpose, goethite and two kinds of B-permeated goethite were synthesized and their processes in soil were simulated. Plant availability of B adsorbed or occluded on goethite was investigated with rape seedling. Results found that both ad-B-goethite and oc-B-goethite significantly increased the water soluble B (WS-B), specifically adsorbed B (SPA-B), B occluded in amorphous iron (Fe) and aluminum (A1) oxides (AMO-B) and crystalline Fe and Al oxides (CRO-B) content in the soil, compared with ordinary goethite. Also the B-permeated goethites improved B content of the rape seedling and therefore enhanced the rape shoot and root dry weight. Correlation analysis demonstrated that water soluble B (WS-B) plays the most important role in rape B uptake and accumulation, moreover the specifically adsorbed B (SPA-B), nonspecifically adsorbed B (NSA-B), amorphous Fe and A1 oxides (AMO-B) was also significant correlated with the B content or B accumulation of the rape.  相似文献   

6.
A stratified subsurface layer of acidic soil can develop in minimally disturbed soil such as no‐till receiving injection of N fertilizer (e.g., anhydrous ammonia). The objective of this study was to evaluate the effectiveness of subsurface band treatments in alleviating soluble Al3+ and Mn2+ toxicities on sorghum growth. Soil columns 40 cm in length were packed with soil (Valentine fine sand mixed mesic Typic Ustipsamment and Thurman loamy sand mixed Mesic Udorhentic Haplustoll) with treatments applied at the 10–18 cm depth to mimic soil pH stratification. The treatments at this depth were: (1) entire layer at soil pH of 3.7; (2) band of soil 6 cm wide at pH of 5.8 with the rest of the soil at pH 3.7; (3) band of soil 6 cm wide at pH of 6.3 with the rest of the soil at pH 3.7; and (4) entire layer at soil pH of 5.8. The soil above and below the 10–18 cm depth was at pH 5.8. Sorghum (Sorghum bicolor L. Moench) was grown in the soil columns under a controlled environment for 6 weeks. High concentration of Al in soil solution was found in soil at soil pH 3.7 which was overcome by either banding to pH 5.8, 6.3, or having the soil layer at pH 5.8. Treatment with pH of 5.8 throughout the soil 10–18 cm depth produced significantly greater top growth, although all other pH or liming strategies performed better than the soil pH 3.7 treatment. The banded treatments at pH 5.8 and 6.3 allowed roots to grow below the 10–18 cm layer of soil, but root growth was still significantly less than in the soil where the entire soil treatment layer was at pH 5.8. The increase in biomass yield with soil pH of 5.8 in the entire treatment layer was higher compared to band treatment at pH 5.8; however, the lime requirement would be 3.4 times more with liming the entire layer compared to banding a portion of the soil to pH 5.8 and would thus be translated into a higher liming cost.  相似文献   

7.
The role of phosphorus (P) in the amelioration of aluminum (Al) toxicity to plants is still unclear. The aim of this study was to examine the amelioration of Al toxicity by P supply. The study involved growing Al-sensitive wheat seedlings for 13 days in an acidic soil [pH 4.5 in calcium chloride (CaCl2)] with increasing added rates of P (0, 20, 40, and 80 mg P kg?1 soil) and Al [0, 50, and 150 mg aluminum chloride (AlCl3) kg?1 soil]. The results indicated that the effects of Al toxicity in this soil could be fully alleviated by the application of P at 50 mg AlCl3 kg?1. The 150 mg kg?1 AlCl3 treatment significantly reduced root growth, but this was partially overcome by the 80 mg kg?1 P treatment. High P significantly reduced the concentration of Al in the apoplast, root, and shoot. It is possible that an insoluble Al-P complex forms in the soil and this decreases Al bound in apoplast as well as uptake into the roots. High P decreased the translocation of Al from root to shoot. This study also concluded that detoxification of Al3+ by P mainly occurs in soil but not within the plant tissue.  相似文献   

8.
Increased Al mobilization and Ca and Mg leaching have been linked to nutritional imbalances in sugar maple across the northeastern US and Canada. The susceptibility of sugar maple fine roots to Al stress is poorly understood, in part because roots respond to Al stress by altering the chemistry of the rhizosphere. AlCl3 was applied to plots of sugar maple at the Hubbard Brook Experimental Forest, NH. After two years of treatment, we sampled fine roots of sugar maple, rhizosphere soil, and bulk soil in the Oa horizon and the upper 10 cm of the mineral soil. AlCl3 treatments resulted in significantly less Ca (21%) and Mg (30%) in fine roots from the organic horizon, but had no significant effect on fine root Al. Fine root (Ca+Mg):Al ratios were 42% lower in AlCl3 plots than in controls, though most roots had ratios above critical toxicity thresholds developed for hydroponically grown sugar maple seedlings. In the mineral horizon, roots differed only in Mg concentration, which was 22% lower in AlCl3 plots. In the AlCl3 treated plots, rhizosphere soil in the organic horizon had 47% greater Al and 29% less Mg than in controls. Combining data from both treatments we found significantly less Al and organically bound Al in rhizosphere soil than in bulk soil, possibly due to leaching of Al from the rhizosphere by organic acids released by roots. These results suggest that increased mobilization of Al in soil lowers (Ca+Mg):Al ratios in sugar maple fine roots, though roots may minimize Al stress by leaching Al from the rhizosphere.  相似文献   

9.
The role of boron (B) fertilization in the vesicular‐arbuscular mycorrhizal (VAM) colonization and growth of container‐grown Citrus seedlings was evaluated. Citrus jambhiri Lush, seedlings inoculated with Glomus fasciculatum, Glomus etunicatum or non‐inoculated were grown in a sandy loam soil for sixteen weeks. Seedlings were fertilized with 25 ug/ml B applied to the foliage as a mist, to the soil as a solution, or to both the foliage and the soil. Boron applied to the foliage or to the soil significantly increased root exudation of reducing sugars and amino acids two weeks after seedling germination. Subsequently, foliar fertilization with B significantly increased VAH colonization of seedlings relative to the controls. Plants inoculated with G. fasciculatum were larger and had greater VAM development than those inoculated with G. etunicatum. The growth of the noninoculated seedlings was not enhanced by B fertilization. The superior VAH colonization and growth of inoculated seedlings fertilized with B suggests that B stimulates the efficacy of plant fungi symbiosis.  相似文献   

10.
利用高寒草甸生荒地进行当归育苗的传统方式造成严重的水土流失。为了探讨农茬口调控土壤特性继而影响后茬当归育苗的效应,在道地产区甘肃省卓尼县熟地培育农作物茬口后进行当归育苗,测定育苗期土壤特性、成苗数和产量。结果表明,农茬口对后茬当归育苗田土壤特性具有显著影响,与休耕茬田比较,马铃薯、油菜、蚕豆茬田土壤电导率极显著降低, pH显著提高,青稞茬田土壤pH和电导率均降低,农茬口极显著提高了后茬土壤阳离子含量,降低了阴离子含量。各茬口土壤K~+含量依次为青稞蚕豆油菜马铃薯休耕, Na~+含量为马铃薯青稞蚕豆油菜和休耕, Cl~-含量为休耕马铃薯青稞油菜蚕豆。随土层加深,紧实度增加,孔隙度减少,含水量随土层和茬口而异。0～15 cm土层的土质疏松且含水量高则有利于保苗。当归成苗数和苗产量与土壤电导率、Cl~-含量均呈显著负相关;苗产量与pH、K~+含量呈显著正相关,与5～10 cm土层容重呈显著负相关;苗数与0～5 cm土层总孔隙度呈显著正相关。各茬口育成苗产量排序与综合评价指数顺序一致,综合评价指数依次为蚕豆(0.986)油菜(0.682)青稞(0.668)马铃薯(0.297)休耕(0.159)。因此,优异的茬口特性可优化当归幼苗赖以生存的农田土壤环境,改善土壤性质,富集营养,促生保苗,蚕豆茬口更为优异。  相似文献   

11.
Root cation exchange capacity (CEC) was analyzed for four cotton cultivars (Pima S‐5, Stoneville 825, Deltapine 41 and Auburn 56) within tvo species (Gossypium barbadense and G. hirsutum) grown in control (O Al) and Al (1.5 mg/l) solution. Pima S‐5, a G. barbadense variety, had significantly (P < 0.10) lower root CEC than G. hirsutum cultivars in control (O Al) solution. Root CEC of Stoneville 825 was numerically but not significantly lower than Auburn 56 and Deltapine Al in control solution. Root CEC was significantly reduced in all cultivars when grown in Al solution. Compared to controls, Pima S‐5 and Stoneville 825 had either numerically or significantly less reduction in root CEC than Auburn 56 or Deltapine 41 in Al solution. Aluminum content of roots after CEC analysis was numerically greater in the former cultivars than the latter.

The lower root CEC of Pima S‐5 and Stoneville 825 in non‐toxic conditions could provide an initially greater Al tolerance when roots grow into marginally Al toxic soil. Under sustained, Al toxic conditions, root CEC becomes altered and is more of an indirect indicator of root growth as affected by as yet undetermined Al tolerance mechanism(s).

The steady‐state technique to determine root CEC virtually eliminated the inherent problems of CO. effects on pH and titrating to an end point in a specific period of time in a dynamic system.  相似文献   


12.
Aluminum toxicity to plants is often responsible for yield reductions under acid soil conditions. Despite the fact that Al becomes insoluble in the slightly acid to neutral pH range, there are indications that it can still be taken up and become toxic to plants. Corn plants were grown in the greenhouse on three highly weathered soils (Oxisol and Ultisols) containing substantial quantities of exchangeable Al. The soils were limed at various rates up to pH values near or above neutrality. On all soils a positive yield response to lime occurred at low pH values while on two of the soils, yields decreased significantly as the pH approached neutrality. Yield and Al content of the tissue were exponentially related irrespective of the level of phosphate applied (r2 = 0.34 and 0.71). The mechanism by which Al becomes increasingly available to the plant as the pH approaches neutrality is not clear and needs further investigation. Strong Al‐Mg and Al‐P antagonisms occur at the high and low pH values. The existance of Al toxicity at near‐neutral pH values can be invoked to explain many of the anomolous results reported in the literature concerning yield depressions previously ascribed a posteriori to such factors as micro‐element or P deficiencies.  相似文献   

13.
Species of Amaranthus are grown extensively as leafy green vegetables in tropical Africa and Asia and as high yielding grain crops in Western South America, Central America, Northern India, Western Nepal, and Pakistan. The crop is often grown on acid, marginal soils, under subsistence conditions, where liming even the soil plow layer may not be economically feasible. Hence, the identification or development of strains with high tolerance to acid soils would be beneficial. Aluminum and Mn toxicities are the most important growth‐limiting factors in many acid soils. The objective of our research was to determine the tolerances of selected Amaranthus strains to high levels of these elements in acid soils.

Fifteen strains, representing five species, were grown in greenhouse pots of an acid, Al‐toxic Tatum soil limed to pH 4.8 and 5.8. Strains differed significantly in tolerance to the acid soil. Relative yields (pH 4.8/pH 5.8%) ranged from 50.1 to 6.3% for tops and from 54.5 to 5.7% for roots. Four strains of A. tricolor L. (vegetable type) were significantly more tolerant than six strains of A. cruentus L. (seed and vegetable type). Strains of A. hypochondriacus L. and A. caudatus L. studied were intermediate in tolerance.

Twelve strains, representing four species, were grown on an acid, Mn‐toxic Zanesville soil at pH 4.6 and 6.3. Strains also differed significantly in tolerance to this acid soil; however, overall growth was better and strain differences were smaller than on Al‐toxic Tatum soil at pH 4.8. On Zanesville soil the relative top yields (pH 4.6/pH 6.3%) ranged from 74.1 to 18.6%. The most tolerant group included three strains of A. tricolor and one strain of A. hypochondriacus, but four strains of A. cruentus were also fairly tolerant. The sensitive end of the scale included one strain of A. cruentus and two strains of A. hypochondriacus.

In general, strains that were most tolerant to the Al‐toxic Tatum soil were also among the most tolerant to the Mn‐toxic Zanesville soil. Likewise, those most sensitive to the high Al soil were most sensitive to the high Mn soil. But some strains that were sensitive to excess Al in Tatum soil were fairly tolerant to high Mn in Zanesville soil.

Results suggest that superior strains of Amaranthus can be selected or developed for use on acid soils.  相似文献   


14.
《Journal of plant nutrition》2013,36(12):2439-2451
Abstract

The aim of the experiment was to examine the effect of boron (B) on biomass production and nutrition of aluminum (Al)‐stressed apple (Malus sp.) rootstocks. The study was carried out under greenhouse conditions on Polish rootstock (P22) and Malling 26 (M.26) planted singly into 1‐L plastic pots filled with perlite and supplied with Hoagland's medium at pH 4.5 without or with Al (100 µM as AlCl3). Boron was added into the Al‐containing medium at 20, 40, or 60 µM whereas into the medium without Al only at 20 µM as boric acid. The results showed that the presence of Al in the medium reduced biomass production of P22 and M.26 rootstocks by 22% and 41%, respectively. Rates of uptake and translocation of phosphorus (P), magnesium (Mg), and calcium (Ca) to aerial plant parts were decreased for Al‐treated rootstocks. Aluminum‐stressed P22 rootstocks grown in nutrient solution at 40 and 60 µM B had higher dry weight of leaves and roots, and also higher ability to take up P, Mg, and Ca and lower Al than those grown in the presence of Al at 20 µM B in the medium. Rates of absorption and transport of B to aerial plant parts corresponded with B level in the medium. These results suggest that on acid soils with high Al availability, supra‐optimal B concentrations in soil solution (40–60 µM) can prevent/alleviate Al toxicity in apple trees grafted on P22 rootstocks.  相似文献   

15.
The objective of this study was to determine whether or not Ca and P in soils from two forested sites at two different stages of acidification were limiting growth of red oak seedlings. The A and E horizons of a Berks soil from Watershed 4 at the Fernow Experimental Forest (cation exchange buffer range) and a Hazelton/Dekalb soil from Pea Vine Hill in Southwestern Pennsylvania (Al buffer range) were placed in pots and utilized as the growth medium for northern red oak seedlings in a greenhouse environment. Soil water NO3-N, Ca, Mg, and K concentrations were significantly higher (α≤0.05) on the Berks soil. Soil exchangeable P and soil solution TP (total phosphorus) were significantly higher (α≤0.10) on the Hazelton/Dekalb soil. Both soils were amended with bone meal (CaPO4) to determine the effects of Ca and P addition on the growth and nutrient uptake of the seedlings. Height growth of the control red oak seedlings was significantly (α≤0.05) greater on the Berks soil after 45 d, but amendment of Hazelton/Dekalb soil with bone meal eliminated this difference. Bone meal addition to the Hazelton/Dekalb soil resulted in significantly greater (α≤0.05) height growth of red oak seedlings when compared to red oak seedlings grown on unamended Hazelton/Dekalb soil, but did not have a similar effect for red oak seedlings grown on Berks soil. Bone meal addition to Hazelton/Dekalb soil resulted in greater (α≤0.05) concentrations of Ca and Mg in red oak leaves. Unfertilized Berks red oak seedling leaves had significantly higher (α≤0.05) concentrations of Ca and K than their Hazelton/Dekalb counterparts. Al/Ca molar ratios were significantly lower on the Berks soil. Red oak height growth was increased significantly by Ca addition to the Hazelton/Dekalb soil.  相似文献   

16.
The modified Tessier’s sequential extraction procedure and rhizobox cultivation were employed to investigate the distribution of aluminum (Al) fractions in the acidic rhizosphere soil of Masson pine (Pinus massoniana lamb) seedlings. The results showed that the Al in soils was fractionated into five operationally defined fractions. Three sets of soil samples used in the rhizoboxes were collected from the three forest sites in the southeast of China: Sichuan, Zhejian, and Jiangsu. At the end of 100-day cultivation, the rhizosphere Al fractions for the original or bulk soils were in the order of residual > iron-manganese (Fe-Mn) oxides > organic > carbonate > exchangeable. However, in rhizosphere soil, the Al fraction follows the order of residual > organic > Fe-Mn oxides > carbonate > exchangeable. On average, the rhizosphere experienced significant increase in organically bound Al and slight decrease in exchangeable Al contents, but had decreases in contents for the other three Al fractions compared to the nonrhizosphere. The correlation analysis indicated that the Al contents accumulated in roots were significantly and positively correlated with exchangeable Al contents in the rhizosphere, and also characterized by the major portion of organically bound Al, which exhibited a bioavailable transformation of Al fractions. Results indicated that decreases in both redox potential and soil pH, as well as increase in dissolved organic carbon (DOC), were observed in the rhizosphere. Exchangeable Al and organic Al fractions were dependent mainly on soil pH (hydrogen ion concentration) and DOC, accordingly. Decreasing rhizosphere pH from 5.93 to 3.42 accelerated the secretion of organic carbon. These data are helpful for understanding the mobility and bioavailability of Al fractions in the acidic rhizosphere soils of Masson pine.  相似文献   

17.
某极度酸化的酸性硫酸盐土壤中可溶性和交换性酸的特征   总被引：4，自引：0，他引：4  
An extremely acidified acid sulfate soil(ASS) was investigated to characterise its soluble and exchangeable acidity,The results showed that soluble acidity of a sample dtermined by titration with a KOH soulution was much significantly greater than that indicated by pH measured using a pH meter,paricularly for the extremely acidic soil samples,This is because the total soluble acidity of the extremely acidic soil samples was mainly composed of various soluble Al and Fe species,possibly in forms of Al sulfate complexes(e.g.,AlSO4^ ) and feerous Fe(Fe^2 )_,It is therefore suggested not to use pH alone as an indicator of soluble acidity in ASS,particularly for extremely acidic ASS,It is also likely that AlSO4^ actively participated in cation exchange reactions.It appears that the possible involvement of this Al sulfate cation in the cation adsorption has significant effect on increasing the amount of acidity being adsorbed by the soils.  相似文献   

18.
Strongly acidic soils (pH < 5.0) are detrimental to tea (Camellia sinensis) production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden soils. A 120-d glasshouse column leaching experiment was conducted using commonly available soil ameliorants. Alkaline slag (AS) and organic residues, pig manure (PM) and rapeseed cake (RC) differing in ash alkalinity and C/N ratio were incorporated alone and in combination into the surface (0--15 cm) of soil columns (10 cm internal diameter × 50 cm long) packed with soil from the acidic soil layer (15--30 cm) of an Ultisol (initial pH = 4.4). During the 120-d experiment, the soil columns were watered (about 127 mm over 9 applications) according to the long-term mean annual rainfall (1 143 mm) and the leachates were collected and analyzed. At the end of the experiment, soil columns were partitioned into various depths and the chemical properties of soil were measured. The PM with a higher C/N ratio increased subsoil pH, whereas the RC with a lower C/N ratio decreased subsoil pH. However, combined amendments had a greater ability to reduce subsoil acidity than either of the amendments alone. The increases in pH of the subsoil were mainly ascribed to decreased base cation concentrations and the decomposition of organic anions present in dissolved organic carbon (DOC) and immobilization of nitrate that had been leached down from the amended layer. A significant (P < 0.05) correlation between alkalinity production (reduced exchangeable acidity -- N-cycle alkalinity) and alkalinity balance (net alkalinity production -- N-cycle alkalinity) was observed at the end of the experiment. Additionally, combined amendments significantly increased (P < 0.05) subsoil cation concentrations and decreased subsoil Al saturation (P < 0.05). Combined applications of AS with organic amendments to surface soils are effective in reducing subsoil acidity in high-rainfall areas. Further investigations under field conditions and over longer timeframes are needed to fully understand their practical effectiveness in ameliorating acidity of deeper soil layers under naturally occurring leaching regimes.  相似文献   

19.
三种植物物料对两种茶园土壤酸度的改良效果   总被引：4，自引：4，他引：4  
王宁  李九玉  徐仁扣 《土壤》2009,41(5):764-771
用室内培养实验研究了稻草、花生秸秆和紫云英在 5、10 和 20 g/kg 的加入量水平下对茶园黄棕壤和茶园红壤酸度的改良效果.结果表明:除了黄棕壤加入紫云英处理会降低土壤的 pH 外,其余所有加入植物物料的处理均使土壤 pH 有不同程度的增加,使土壤交换性酸和交换性Al的数量减小,使土壤交换性盐基阳离子和盐基饱和度增加.有机物料对土壤酸度的改良效果与有机物料灰化碱和N含量有关,灰化碱和有机N的矿化使土壤 pH 升高,NH4+-N的硝化使土壤 pH 降低.3种植物物料中花生秸秆对土壤酸度的改良效果优于紫云英和稻草.加入植物物料使红壤中有毒形态Al的浓度显著减小,说明植物物料能够缓解红壤中Al对植物的毒害.  相似文献   

20.
The relationship between plant‐available silicon (Si) soil concentrations and bark Si concentrations in coniferous species is poorly understood. The objectives of this research were to generate baseline data on Si concentrations in soils and bark of Sitka spruce (Picea sitchensis) seedlings in Ireland and to understand better the relationship between soil and bark Si concentrations. Seedlings were harvested from eight plantation forestry sites and two tree nurseries, and Si concentrations in the bark tissue as well as plant‐available Si concentrations in soils (CaCl2 extractant) were measured. Bark Si concentrations varied significantly between sites and were lowest [mean 790 (± 242 SD) mg kg?1 dry plant tissue] on acidic, organic rich peat soils, while the highest Si concentrations occurred in seedlings [mean 3688 (± 633 SD) mg kg?1 dry plant tissue] grown on soils with low C concentration and higher pH values (≈ 4.5 to 5.5 in H2O). Plant‐available Si soil concentrations were not related to soil C concentrations. There was a negative (but statistically not significant) relationship between plant–soil concentrations and soil pH. A significant negative relationship was observed between plant‐available soil Si concentrations and bark Si concentrations, which may be related to the presence of soil from mixed soil horizons forming the mounds that seedlings were planted on. Uptake and sequestration of Si by seedlings may have been related to the rate of growth of the seedlings, as bark Si concentrations were highest on sites that were expected to have greater seedling growth rates. The negative relationship between bark and plant‐available Si soil concentrations suggest that uptake of Si by Sitka spruce is rejective at higher concentrations.  相似文献   

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