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1.
不同人工造林树种及其配置方式对土壤理化性质影响分析 总被引：3，自引：0，他引：3
人工造林是黄土高原改善生态环境,减少水土流失的重要手段。不同树种及其配置方式下地表植被的生长、土壤理化性质的差异影响着生态水文功能的强弱。以长武王东沟流域8种造林树种和不同配置径流小区为研究对象,采用样方法进行造林地及林下地表植被调查,分层采样测定0—40cm土层土壤容重、孔隙度、有机质含量,分析不同人工造林模式下土壤理化性质,并初步分析了植被特征与土壤理化性质间的关系。结果表明:不同造林方式小区内林下草本层虽然覆盖度区别很大,但物种丰富度、多样性、均匀度指数差异不显著。0—20cm表层土壤理化性质变异性小于20—40cm土层。不同人工造林方式间土壤容重差异显著,且对20—40cm层土壤的毛管孔隙度、总孔隙度有显著性影响。不同造林方式下草本层丰富度、多样性指数与林下土壤毛管孔隙度相关性显著。草本层丰富度、多样性与0—20cm表层土壤的保水作用存在良好的对应关系。相比较而言,0—40cm土壤剖面上,草地和侧柏刺槐混交林地下的土壤孔隙度和有机质等理化性质,以及相关的蓄水性和入渗性等生态水文功能要好于其他造林林种。 相似文献
2.
《Land Degradation \u0026amp; Development》2017,28(3):1005-1015
The patchy distribution of semiarid ecosystems determines productivity and controls the retention of resources within the system. Resource fluxes depend on a number of biophysical and soil variables, besides the amount and intensity of particular rainfall events. At two Mediterranean experimental sites with contrasted composition and spatial vegetation arrangement, we evaluated a straightforward way to simplify some of these processes by using different planting techniques that modify the runoff generation threshold and redirect runoff towards the planting hole (M) and enhance the water infiltration and conservation in it (MDW). Traditional planting technique (H) and M were combined with the addition of composted biosolids. Soil moisture was increased with treatments during drought periods in the first 2 years after planting with mean values of 10·1, 8·9 and 6·9% in MDW, M and H, respectively. Lower landscape organization values at the site resulted in sinks being more efficient at retaining resources, with 3·68‐fold more organic matter accumulation on the soil surface of the planting hole, better growth of the Olea europaea‐planted seedlings and a better response to compost application in MDW than in H. At the site with better landscape organization, planting techniques only showed improvement in seedling survival (+20% in MDW than in H). We discuss ecosystem properties, such as plant composition and spatial arrangement, that determine the effectiveness of these techniques as dryland restoration tools and the hierarchy between water and nutrients as essential resources in these semiarid Mediterranean areas. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
3.
In arid and semiarid Mediterranean areas, Pinus halepensis Mill. is one of the dominant forest species and is widely used in restoration programmes. We collected samples and investigated the understory plant species in an age sequence of 0‐, 5‐, 9‐, and 13‐year‐old P. halepensis plantations to assess the effect of the tree on soil properties and development of plant community. Soil samples were taken from two depths (0–10 and 10–30 cm) under tree canopy and in the associated open spaces. Results showed that tree establishment and development enhanced organic C, total N, and available P accumulation, and improved soil moisture content which increased significantly with increasing plantation age. At the same time, P. halepensis facilitated the colonization and development of understory vegetation. Indeed, the number of plant species, the total plant cover, and the perennial species density were more important under tree canopy and increased with increasing plantation age. The soil dynamic under 13‐year‐old P. halepensis plantations reflected two phase restoration sequence, characterized by nominal changes during tree establishment (0–5 years) and marked and rapid changes associated with the start of canopy closure (5–13 years). Our results provide that the introduction of P. halepensis with afforestation could be an effective and applicable measure to restore arid degraded areas. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
Relationships between soil lightness, soil organic matter (SOM) composition, content of organic C, CaCO3, and texture were studied using 42 top‐soil horizons from different soil types located in southern Germany. SOM composition was determined by CPMAS 13C NMR spectroscopy, soil color was measured by diffuse‐reflectance spectrophotometry and given in the CIE L*a*b* color coordination system (Commission Internationale de l'Eclairage, 1978). Multiple‐regression analysis showed, that soil lightness of top‐soil horizons is principally determined by OC concentration, but CaCO3 and soil texture are also major variables. Soil lightness decreased with increasing OC content. Carbonate content had an important effect on soil lightness even at low concentrations due to its lightening property. Regressions between soil lightness and organic C content were strongly linear, when the soils were differentiated according to texture and CaCO3 content. The aryl‐C content was the only SOM component which correlated significantly with soil lightness (rS = –0.87). In the linear regressions carried out on the different soil groups, soil aryl‐C content was a more significant predictor for soil lightness than total OC content. 相似文献
5.
A. N. Nunes C. O. A. Coelho A. C. de Almeida A. Figueiredo 《Land Degradation \u0026amp; Development》2010,21(3):260-273
This paper analyses the effects of land abandonment on runoff and sediment yield in a central inland area of Portugal. Rainfall simulation experiments were performed in areas of traditional land use (land cultivated with cereals) with various types of soil plant cover associated with the period of abandonment (4–5 years, 15–20 years and 30–40 years) in two different seasons, namely under very dry conditions and after a long wet period. Statistical analysis showed a notable difference between the cultivated soils and those abandoned for a long period of time, which included appreciable vegetation recovery, higher organic matter content and negligible overland flow and soil loss. Cereal cultivation, in particular ploughing, is a very negative land management practice, due to the high runoff and soil loss. Within 4–5 years a crust develops over abandoned soils with sparse herbaceous plant cover, particularly after a dry season, which enhances runoff and sediment yield. In scrubland and oak plots, although marked water repellency was registered at the end of a dry, warm season, its influence seems to be irrelevant in terms of overland flow and erosion yield. The major factor in controlling overland flow and reducing soil erosion rates appears to be the role played by vegetation in protecting the soil surface and supplying organic carbon to the top layer. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
6.
以内蒙古自治区毛乌素沙地飞播造林地为对象,研究了不同植被恢复年限样地土壤酶活性的变化。结果表明:经过17 a的植被恢复,土壤表层（0—10 cm）脲酶、蔗糖酶和磷酸酶显著增加,土壤过氧化氢酶活性在植被恢复初期上升趋势明显;土壤脲酶、蔗糖酶和磷酸酶活性与土壤养分之间有一定的正相关性,而这种相关性在土壤表层（0—10 cm）中要强于中下层（10—40 cm）;土壤表层（0—10 cm）土壤脲酶、蔗糖酶和磷酸酶三种水解酶之间呈极显著相关（p < 0.01）。表明毛乌素沙地飞播造林植被恢复过程中土壤脲酶、蔗糖酶和磷酸酶活性的增强和土壤养分的改善相互促进,土壤酶活性能在一定程度上能反映沙地植被恢复过程中土壤肥力水平,沙地表层土壤中氮素的转化、多糖的转化和有机磷的转化之间关系密切并且相互影响。 相似文献
7.
为明确黄土丘陵区典型人工幼林土壤水分时空变化特征,采用ECH2O土壤水分监测系统,基于标准径流小区坡面土壤水分观测方法,收集土壤水分及气象数据,分析了撂荒地与不同类型人工幼林土壤水分状况及时间稳定性。结果表明：(1)与撂荒地相比,人工幼林土壤含水量整体较低,且具有明显的季节性变化特征,变化趋势基本一致,均随降水量的增加(减少)而升高(降低);(2)不同类型人工林土壤水分垂直分布差异较大,相较于撂荒地,刺槐和油松在50 cm深度土层土壤含水量较低,在80—120 cm深度土层土壤含水量较高,丁香幼林土壤水分整体偏低;(3)油松和撂荒地土壤水分代表深度分别为：120 cm和80 cm,决定系数(R2≥0.9)和纳什系数(NSE≥-0.1)对该结果的评价显示土壤水分代表深度的选择均是可接受的,刺槐和丁香不同深度土层土壤水分差异较大。研究认为,在黄土丘陵区,人工幼林显著影响土壤水分垂直分布规律,土壤含水量整体呈低态势,相较于撂荒地,刺槐和丁香土壤水分变异性较大,油松较为稳定。 相似文献
8.
沈阳地区河岸植被缓冲带对氮、磷的削减效果研究 总被引：4，自引：0，他引：4
为充分了解河岸植被缓冲带对地表径流污染物的去除效果, 本研究选取辽宁省沈阳市两条典型河流——浑河与蒲河为对象, 研究其滨水不同河岸植被缓冲带对地表径流氮、磷污染物的削减效果。结果表明: 在6 种河岸植被带中, 人工林草地对氮的削减效果最好, 对总氮、硝态氮和铵态氮的平均削减率分别为47%、36%和31%; 人工林地对磷的削减效果较好, 平均削减率为74%; 而人工林地对氮以及人工草地对磷的削减效果较差。随长度增加, 河岸植被缓冲带对地表径流污染物的削减效果基本呈增强趋势。以上研究结果说明不同河岸植被缓冲带对地表径流中氮、磷的削减各有优点。在对遭受污染的河流进行生态修复时, 应考虑环境污染特点和地表特征, 以充分发挥河岸植被缓冲带对污染物的削减优势。 相似文献
9.
晋北丘陵风沙区不同植被恢复模式的水土保持效应 总被引：1，自引：1，他引：0
通过对山西右玉贾家窑阳坡退耕还林约20年后的4种植被恢复模式(自然恢复草地、油松林、柠条灌丛和油松—柠条林)土壤水分、理化性质、径流量和侵蚀量的测定,探讨了不同植被恢复模式的水土保持效应。结果表明:(1)4种植被恢复模式0—100cm土层土壤平均含水量无显著差异,油松林和自然恢复草地的土壤容重高于油松—柠条林和柠条灌丛,土壤总孔隙度的变化趋势与容重相反;(2)4种植被恢复模式0—20cm土层土壤粒度组成、pH、有机质、铵态氮和速效磷无显著差异,硝态氮和速效钾差异明显(P0.05);(3)4种植被恢复模式径流量没有明显差异,但土壤侵蚀量自然恢复草地和油松林显著高于柠条灌丛和油松—柠条林(P0.05);(4)覆盖度相似条件下,根系密度、近地表植被盖度和枯枝落叶层厚度是影响林草植被水土保持效应的主要因素。 相似文献
10.
In the past 50 years, large areas of the Horqin sandy land were afforested to prevent desertification. Although the afforestation policy appears successful, many people now doubt whether it is suitable to plant trees with high density on the poor soils in semiarid regions. Little is known about the impacts of afforestation on the sandy soil properties, although the evaluation of these impacts is fundamental to judge the rationality of afforestation policy. Soil phosphorus （P） fractions, acid phosphomonoesterase activities, and other soil chemical properties were compared among five adjoining typical ecosystems on poor sandy soils in southeastern Horqin sandy land. The ecosystems studied are natural elm savanna, degraded grassland, Mongolian pine （Pinus sylvestris var. mongolica） plantation, Chinese pine （Pinus tabulaeformis） plantation, and mixed plantation of Mongolian pine and poplar （Populus simonii）. The results showed that organic P dominated soil P （47%-65%） was the principal source of available P. The degradation of elm savanna to grassland significantly reduced soil pH and resulted in an overall reduction in soil fertility, although slightly increased labile inorganic P. Grassland afforestation had no significant influence on soil pH, organic carbon, and total N but significantly reduced total P. Impacts of grassland afforestation on soil P fractions depended on tree species. Natural elm savanna had higher soil P conserving ability than artificial plantations. Therefore, with the aim of developing a sustainable ecosystem, we suggested that vegetations with low nutrient demand （particularly P） and efficient nutrient cycling would be more suitable for ecosystem restoration in the semiarid region. 相似文献
11.
提高半干旱山地水土保持效果的研究 总被引：2，自引：0，他引：2
半干旱山地水土流失严重,通过生物措施增加山地植被是治理山地水土流失的根本措施。半干旱山地造林成活率低的根本原因是缺水,提出了采取挖水平沟、鱼鳞坑、施用ABT生根粉等措施蓄水保墒,提高造林成活率,增强半干旱山地的水土保持效果。 相似文献
12.
Climate models often predict that more extreme precipitation events will occur in arid and semiarid regions, where C cycling is particularly sensitive to the amount and seasonal distribution of precipitation. Although the effects of precipitation change on soil carbon processes in desert have been studied intensively, how vegetation cover and rain timing co-regulate the responses of soil CO2 efflux to precipitation change is still not well understood. In this study, a field manipulative experiment was conducted with five simulated rain addition treatments (natural rains plus 0%, 25%, 50%, 75%, 100% of local annual mean precipitation) in a desert ecosystem in Northwest China. The rain addition treatments were applied with 16 field rain enrichment systems on the 10th day of each month from May to September, 2009. Soil water content, soil temperature and soil CO2 efflux rates were measured in both bare and vegetated soils before and after the rain addition during a 3-week period for each rain treatment. The response magnitude and duration of soil CO2 efflux to rain addition depended not only on the rain amount but also on the type of vegetation covers and the timing of rain addition treatments. Soil water content responded quickly to the rain addition regardless of rain amount and timing, but soil CO2 efflux increased to rain addition only in May–July but not in late growing season (September). In addition, soil CO2 efflux from the bare and vegetated soils showed similar increase to rain additions in May–July, but they demonstrated distinct responses to rain addition in September. The differences in the responses of soil CO2 efflux to rain addition between the bare and vegetated soils could be explained by the root activities stimulated by added rain water, while the difference in soil CO2 efflux response to rain addition among treatment times could be attributed to soil water condition prior to rain addition and/or soil temperature drop following rain addition. Thus, both vegetation cover and rain timing can co-regulate responses of soil CO2 efflux to future precipitation change in arid desert ecosystems, which should be considered when predicting future carbon balance of desert ecosystems in arid and semiarid regions. 相似文献
13.
Xiao-Yan Li Sergio Contreras Albert Solé-Benet Yolanda Cantón Francisco Domingo Roberto Lázaro Henry Lin Bas Van Wesemael Juan Puigdefábregas 《CATENA》2011
Semiarid karst landscapes represent an important ecosystem surrounding the Mediterranean Basin for which little is known on runoff generation. Knowledge of the sources and patterns of variation in infiltration–runoff processes and their controls is important for understanding and modelling the hydrological functions of such ecosystems. The objectives of this paper are to determine the infiltration rates and their controls in a representative mountain karst area (Sierra de Gádor, SE Spain) at micro-plots and to investigate the integrated response of rainfall on a typical hillslope. Rainfall simulations in micro-plots and natural rainfall-runoff monitoring on a hillslope were carried out complementarily. We investigated the role of soil surface components (vegetation, rock outcrop, fracture, and soil crust), topographic position, antecedent soil moisture, and rainfall characteristics in regulating infiltration–runoff processes. Results of rainfall simulation revealed the importance of vegetation cover and the presence of rock fractures in promoting the infiltration in the limestone karst landscape, while bare patches and rock outcrops acted as sources for runoff. All plots with > 50% vegetation cover had no runoff with up to 55 mm h− 1 of simulated rain. In contrast, nearly all bare plots had runoff under the same simulated rain, with runoff coefficients ranging from 3.1 to 20.6% on dry soil surface conditions, and from 2.0 to 65.4% on wet soil surfaces. Runoff coefficients amounted to 59.0–79.5% for rock outcrops without cracks, but were drastically reduced by the presence of cracks. The surfaces with rock fragments resting on the soil (generally located in the middle of the slopes) prevented more effectively the runoff generation than those surfaces where rock fragments were embedded in the top soil. Antecedent soil moisture had significant impact on runoff generation, with wet soil having doubled runoff coefficient, shortened time to runoff, and increased runoff rate compared to the same but dry soil. Linear regressions indicated that the main controls for constant infiltration rate were the cover percentages of vegetation and litter, plus rainfall intensity; while the major controls for runoff coefficient were the bare soil and vegetation coverage, plus rainfall intensity. High infiltration rates measured at the micro-plots agreed with low intra-event runoff coefficients (mostly below 1%) observed under natural rainfalls at the hillslope. Runoff depth and coefficient at the hillslope was significantly correlated with rainfall depth, maximum hourly rainfall intensity and antecedent precipitation over 20 days (AP20). During the 1.5-year monitoring period from Sep-2003 to Mar-2005, the overall infiltration was 41% of the total rainfall amount and the maximum infiltration rate was almost 94% of the largest single rainfall event. The results from this study contribute to improved understanding of the magnitude and controls of the surface runoff in semiarid karst mountain areas. 相似文献
14.
马莲河流域高效林草建设初探 总被引：4，自引：0，他引：4
通过对马莲河流域世行贷款水土保持项目实施前后人工造林、种草成效的对比分析,认为“高效林草建设”是植被稀疏、地形支离破碎、水土流失严重的黄土高原沟壑区、黄土丘陵沟壑区植物措施治理的最佳途径.其主要措施有:按照“适地适树、适草”的原则,选择适应性强、速生丰产优质的树草(品)种,对位配置;积极推广ABT生根粉蘸根、吸水剂泡根、根宝浸根、径流林业、容器苗造林、营造乔灌混交林、浸水造林等实用造林技术;进行规范化育苗和精细整地,辅以家畜舍饲喂养,缓解林牧矛盾等. 相似文献
15.
With a world‐wide occurrence on about 560 million hectares, sodic soils are characterized by the occurrence of excess sodium (Na+) to levels that can adversely affect crop growth and yield. Amelioration of such soils needs a source of calcium (Ca2+) to replace excess Na+ from the cation exchange sites. In addition, adequate levels of Ca2+ in ameliorated soils play a vital role in improving the structural and functional integrity of plant cell walls and membranes. As a low‐cost and environmentally feasible strategy, phytoremediation of sodic soils — a plant‐based amelioration — has gained increasing interest among scientists and farmers in recent years. Enhanced CO2 partial pressure (PCO2) in the root zone is considered as the principal mechanism contributing to phytoremediation of sodic soils. Aqueous CO2 produces protons (H+) and bicarbonate (HCO3‐). In a subsequent reaction, H+ reacts with native soil calcite (CaCO3) to provide Ca2+ for Na+ Ca2+ exchange at the cation exchange sites. Another source of H+ may occur in such soils if cropped with N2‐fixing plant species because plants capable of fixing N2 release H+ in the root zone. In a lysimeter experiment on a calcareous sodic soil (pHs = 7.4, electrical conductivity of soil saturated paste extract (ECe) = 3.1 dS m‐1, sodium adsorption ratio (SAR) = 28.4, exchangeable sodium percentage (ESP) = 27.6, CaCO3 = 50 g kg‐1), we investigated the phytoremediation ability of alfalfa (Medicago sativa L.). There were two cropped treatments: Alfalfa relying on N2 fixation and alfalfa receiving NH4NO3 as mineral N source, respectively. Other treatments were non‐cropped, including a control (without an amendment or crop), and soil application of gypsum or sulfuric acid. After two months of cropping, all lysimeters were leached by maintaining a water content at 130% waterholding capacity of the soil after every 24±1 h. The treatment efficiency for Na+ removal in drainage water was in the order: sulfuric acid > gypsum = N2‐fixing alfalfa > NH4NO3‐fed alfalfa > control. Both the alfalfa treatments produced statistically similar root and shoot biomass. We attribute better Na+ removal by the N2‐fixing alfalfa treatment to an additional source of H+ in the rhizosphere, which helped to dissolve additional CaCO3 and soil sodicity amelioration. 相似文献
16.
黄土高原生物利用型土壤干层的水文生态效应研究 总被引：25，自引：0，他引：25
对黄土高原高产农、林、草、灌、果5种植被1000cm土层土壤剖面含水量多点测定结果表明,各植被类型均存在不同程度的生物利用型土壤干层,该土壤干层的水文作用表现为增强土壤-植被-大气间垂直水分交换,阻碍入渗降雨转化为地下径流,削弱植被对枯水季节低径流量的补偿能力,其生态效应是恶化植物生长的土壤水分环境,削弱土壤水库对年际干旱的调节能力。 相似文献
17.
F. Curran Cournane R. W. Mcdowell R. P. Littlejohn D. J. Houlbrooke L. M. Condron 《Soil Use and Management》2011,27(3):376-384
Agriculture is a major source of phosphorus (P) and suspended sediment (SS) losses to aquatic ecosystems promoting eutrophication. Mechanical soil loosening equipments such as topsoil looseners or aerators have been reported to improve the physical quality and infiltration of soils susceptible to livestock damage resulting from treading. We hypothesized that soil aeration would significantly decrease the volume of surface runoff and consequent losses of P and SS compared with non‐aerated soil (control) in cattle‐grazed pasture on a poorly structured silt‐loam soil. Hydrologically isolated plots (2 m long × 1 m wide × 0.15 m deep) were installed in aerated and control plots to collect surface runoff following irrigation or rainfall and analysed for P and SS losses for 1 year. Soil physical properties [% macroporosity, bulk density, saturated hydraulic conductivity (Ksat) and unsaturated hydraulic conductivity (Kunsat at ?1kPa)] were measured in the aerated and control treatments and taken before each irrigation event (n = 12). Six months after mechanical aeration was employed, but before cattle grazing commenced, no significant differences in soil physical quality were found between aerated and control treatments, with the exception of a minor increase in Kunsat for the control plots. This lack of treatment difference continued after grazing and was largely attributed to the re‐settling of the poorly structured and dispersive soil. Flow‐weighted mean concentrations and annual loads of dissolved reactive P (DRP) on the mechanically aerated soil (2.24 kg DRP/ha) were approximately double those from the control treatment (1.20 kg DRP/ha). However, no significant differences were observed between treatments for surface runoff volumes and losses of total P and total SS, which may reflect the similar soil physical conditions exhibited between treatments throughout most of the trial. As observed elsewhere, time (days) since grazing or fertilizer application was found to influence P and/or SS losses. We conclude that aeration did not decrease P and SS losses. Any changes in soil physical properties such as macroporosity were short‐lived and therefore unlikely to influence surface runoff and subsequent P and SS losses for this soil type. 相似文献
18.
Soil erosion and runoff in different vegetation patches from semiarid Central Mexico 总被引：2，自引：0，他引：2
Rebeca Vásquez-Méndez Eusebio Ventura-Ramos Klaudia Oleschko Luis Hernández-Sandoval Jean-Francois Parrot Mark A. Nearing 《CATENA》2010
Vegetation patches in arid and semiarid areas are important in the regulation of surface hydrological processes. Canopy and ground covers developed in these fertility islands are a natural cushion against the impact energy of rainfall. Also, greater levels of organic matter improve the soil physicochemical properties, promoting infiltration and reducing runoff and soil erosion in comparison with the open spaces between them. During the 2006 rainy season, four USLE-type plots were installed around representative vegetation patches with predominant individual species of Huisache (Acacia sp), Mesquite (Prosopis sp), Prickly Pear or Nopal (Opuntia sp) and Cardon (Opuntia imbricata), to evaluate soil erosion and runoff, in semiarid Central Mexico. A comparative bare surface condition (Control) was also evaluated. Vegetative canopy and ground cover were computed using digital images. Selected soil parameters were determined. Soil erosion was different for the studied vegetation conditions, decreasing as canopy and ground cover increased. There were not significant differences in runoff and soil erosion between the Control and O.imbricata surfaces. Runoff was reduced by 87%, 87% and 98% and soil loss by 97%, 93%, and 99% for Acacia farnesiana, Prosopis laevigata and Opuntia sp, respectively, as compared to the Control. Soil surface physical conditions were different between the low vegetation cover conditions (Control and O.imbricata surfaces) and the greater vegetation cover conditions (A.farnesiana, P.laevigata and Opuntia sp), indicating a positive effect of vegetation patches on the regulation of surface hydrological processes. 相似文献
19.
Porous hydrated calcium silicate (PS) is a by-product of autoclave light weight concrete and is being used as a silicon fertilizer in Japan. The impacts of this amendment on the yield and cadmium content of rice (Orzya sativa L. var. Kokoromachi), soil pH and the extractability of soil cadmium assessed by 1 M NH4OAc were compared with those of silica gel and CaCO3 by pot experiments. The application of PS at the rate of 2.0% and silica gel at the rate of 1.0% in Andosol and PS at the rate of 0.75% in Alluvial soil significantly increased the grain weight of rice. PS and CaCO3 treatment significantly increased soil pH, decreased the 1 M NH4OAc extractability of cadmium and reduced cadmium content in straw and brown rice in the two soils. However, cadmium content of rice of PS treatments was not significantly different from that of CaCO3 treatments in Andosol, while was significantly lower than that of CaCO3 treatments in Alluvial soil. Soil analysis showed that it was less effective in increasing soil pH and decreasing the extractability of cadmium by 1 M NH4OAc than CaCO3 at the same application rate in Andosol. Soil pH and 1 M NH4OAc extractability of cadmium were not significantly different between 2.0% of PS and CaCO3 treatments in Alluvial soil. The application of silica gel did not improve soil pH nor decrease the extractability of soil cadmium, but resulted in a significant decline of cadmium content in brown rice. These results demonstrate that the supply of silicon together with an increase in soil pH, as obtained by PS application, shows potential to reduce the cadmium content of rice. 相似文献