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1.
紫色土K+吸附解吸动力学研究   总被引：7，自引：0，他引：7       下载免费PDF全文
从国家紫色土肥力与肥料效益监测基地定位试验上 ,在第 10年水稻收获后从 0～ 30cm土层采取土壤样品 ,研究土壤K 吸附、解吸动力学过程。结果表明 ,不同施肥处理土壤K 吸附、解吸反应分别在2 4～ 32min和 4 6～ 6 4min达到平衡 ,吸附、解吸平衡量分别为 14 1～ 19 2cmolkg-1和 11 6～ 17 5cmolkg-1。相关分析说明 ,土壤阳离子交换量 (CEC)及粘粒含量是影响吸附平衡时间、吸附平衡量的重要因素 ;CEC、交换钾量是影响解吸平衡时间、解吸平衡量的重要因素。由此可见 ,长期不同施肥对土壤CEC、粘粒及交换钾量产生影响 ,从而影响了紫色土K 吸附、解吸平衡时间及吸附、解吸平衡量。平衡前钾离子的吸附、解吸速度及吸附、解吸率与反应时间lnt间存在良好的线性关系。其中反应速度直线和解吸率直线的斜率、初始反应速度及初始吸附率均与CEC、粘粒含量密切相关。Elovich方程和一级扩散方程分别为描述紫色土K 吸附、解吸反应的最优与最差模型 ,指数方程和抛物线扩散方程拟合性介于Elovich方程和一级扩散方程之间。由此可见 ,紫色土K 吸附、解吸过程不是一个单纯的过程 ,而是一个包括土体膨胀、吸附位活化、表面扩散等诸多因素的复杂过程。  相似文献   

2.
草酸/草酸盐对森林暗棕壤的磷释放效应   总被引：6，自引：0，他引：6       下载免费PDF全文
崔晓阳  宋金凤 《土壤学报》2005,42(6):977-984
模拟森林凋落物淋洗液中的草酸/草酸盐浓度范围,设计了不同浓度草酸/草酸盐溶液一次性浸提和多次连续浸提系列实验,其中的草酸(阴离子)载荷量为0~200 mmol kg-1。结果表明,草酸能显著促进暗棕壤A1层(腐殖质层)磷的释放,土壤磷溶出量随草酸溶液浓度升高而线性增加;但对B层土壤磷的释放效应相对较弱,草酸浓度低于5mmol L-1时B层磷的释放不明显。pH 5.16草酸钠溶液比相同浓度的草酸溶液具有更高的解磷效率,在设置二者浓度为0.5~20.0 mmol L-1时,前者的解磷量是后者的1.51~2.98倍,推断草酸盐溶液或凋落物淋洗液中草酸(盐)类物质促进暗棕壤磷释放的主要机理在于草酸阴离子(C2O42-)配位反应。草酸盐对暗棕壤磷的释放效应具有一定累加性,土壤磷释放量主要由草酸阴离子累积载荷量决定,而与其加入方式(多次或一次性)关系不大;当以pH5.16草酸钠溶液加入时,土壤磷释放量Y(mgkg-1)与草酸阴离子累积载荷量X(mmol kg-1)间的回归方程为Y=-0.000 4X2 0.176 6X 0.425 3,R2=0.990 2。仅以凋落物层溶出的草酸(阴离子)量进行估计,由此增加的A1层土壤磷释放量达2.40 kg hm-2a-1,大约相当于中龄林年吸收磷量的1/3~1/5,因此其实际作用是不可忽视的。  相似文献   

3.
设施蔬菜土壤剖面氮磷钾积累及对地下水的影响   总被引：16，自引：2，他引：14  
针对设施栽培中传统施肥灌溉带来的养分浪费和环境污染问题,采集河北省定州市设施蔬菜、农田土样及相应的地下水样品,分析了不同设施蔬菜种植年限土壤剖面中速效养分的累积规律及地下水受硝酸盐污染的程度。结果表明:0～200cm和0～400cm设施土壤的速效养分累积均高于对照农田。低龄棚硝态氮、速效磷、速效钾及水溶性磷含量分别为377.2mg·kg-1、448.8mg·kg-1、1405.6mg·kg-1、30.6mg·kg-1,分别是对照农田的4.7倍、4.6倍、1.4倍和11.5倍;老龄棚硝态氮、速效磷、速效钾及水溶性磷含量分别为629.1mg·kg-1、555.0mg·kg-1、2567.1mg·kg-1、35.2mg·kg-1,分别为对照农田的6.4倍、16.3倍、2.7倍和12.0倍。设施土壤速效养分深层累积比例随棚龄增加而增加。设施蔬菜栽培区表层地下水(地下饮用水,20m)受硝态氮污染严重,超标率和严重超标率为39.3%和7.1%;而深层地下水(农田和大棚灌溉水,40m)硝态氮含量7.4mg·L-1和9.6mg·L-1,超标率分别为25.0%和37.5%,无严重超标水样。  相似文献   

4.
ABSTRACT

Orchard efficiency (OE) is one of the indices of evaluating the sustainability in production behavior of citrus orchards. A wide range of soil properties broadly categorized into particle size distribution, water soluble and exchangeable cations, and soil available nutrients were investigated in relation to efficiency of Nagpur mandarin (Citrus reticulata Blanco) orchards established on smectite rich three soil orders (Entisols, Inceptisols, and Vertisols) representing 18 locations of central India. The soil properties, viz., free calcium carbonate (CaCO3), clay content, water soluble- and exchangeable-calcium (Ca2 +), available nitrogen (N), phosphorus (P), and zinc (Zn) contributed significantly towards variation in OE. The threshold limit of these limiting soil properties was further established using multivariate quadratic regression models as: 132.1 g kg? 1 free CaCO3, 418.1 g kg? 1 clay, 149.9 mg L? 1 water soluble Ca2 +, 25.9 cmol(p+) kg? 1 exchangeable Ca2 +, 114.6 mg kg? 1 available N, 12.8 mg kg? 1 available P, and 0.96 mg kg? 1 available Zn in relation to optimum OE of 82.1%. These reference values were very close to those obtained from best fit models, and could be effectively utilized in addressing soil related production constraints for precision-aided citriculture.  相似文献   

5.
A study was conducted to examine the impact of land use on soil fertility in an Entisol in the Jalpaiguri District of humid subtropical India. The natural forest served as a control against which changes in soil properties were compared. Soil samples were collected from four different depths (0–25, 25–50, 50–75, and 75–100 cm) of soil from four land uses (viz. forest, home garden, arecanut plantation, and agriculture) and examined for pH, organic carbon (OC), electrical conductivity (EC), cation exchange capacity, available nitrogen (N), phosphorus (P), exchangeable calcium (Ca), magnesium (Mg), potassium (K), aluminum (Al), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and dehydrogenase activity (DHA). Soil pH (5.7), OC (2.29%), N (386 kg ha?1), and P (22.54 kg ha?1) were greatest in forest soil, followed by soil from arecanut plantation, agriculture, and home garden. The greatest Ca (0.892 cmol kg?1), Mg (0.527 cmol kg?1), and Al (1.86 cmol kg?1) were found in the arecanut plantation, whereas K (0.211 cmol kg?1) was greatest in forest. The greatest content of diethylenetriaminepentaacetic acid–extractable copper, zinc, manganese, and iron (2.25, 1.66, 4.86, and 7.65 ppm, respectively) were found in forest. MBC (558 mg kg?1), MBN (26.67 mg kg?1), and DHA (33.03 μg TPF 24 h?1 g?1) was greatest in forest soil. Soil fertility index varied from 13.13 in arecanut plantation to 18.49 in forest. The soil evaluation factor ranged from 5.32 in agriculture to 6.56 in forest. Pearson's correlation matrix revealed strongly significant positive correlation of soil fertility index and soil evaluation factor with soil properties.  相似文献   

6.
Temporal changes in soil chemical and nutritional properties were evaluated in a long-term experiment conducted on Alfisols in West Africa. Effects of land use and cropping duration on soil chemical properties at 0–5 cm and 5–10 cm depths were evaluated for five treatments: (1) alley cropping with Leucaena leucocephala established on the contour at 4-m intervals; (2) mucuna (Mucuna utilis) fallowing for 1 year followed by maize (Zea mays)-cowpea (Vigna unguiculata) cultivation for 2 years on severely degraded land; (3) fallowing with mucuna on moderately degraded soils; (4) ley farming involving growing improved pastures for 1 year, grazing for the second year, and growing maize-cowpea for the third year on severely degraded land; (5) ley farming on moderately degraded soils. Soil chemical properties were measured once every year from 1982 through 1986 during the dry season, and included pH, soil organic carbon (SOC), total soil nitrogen (TSN), Bray-P, exchangeable cations, and effective cation exchange capacity (CEC). Regardless of the cropping system treatments, soil chemical quality decreased with cultivation time. The rate of decrease at 0–5 cm depth was 0·23 units year−1 for pH, 0·05 per cent year−1 for SOC, 0·012 per cent year−1 for TSN, 0·49 cmol kg−1 year−1 for Ca2+, 0·03 cmol kg−1 year−1 for Mg2+, 0·018 cmol kg−1 year−1 for K+, and 0·48 cmol kg−1 year−1 for CEC. Although there was also a general decrease in soil chemical quality at 5–10 cm depth, the trends were not clearly defined. In contrast to the decrease in soil properties given above, there was an increase in concentration at 0–5 cm depth of total acidity with cultivation time at the rate of 0·62 cmol kg−1 year−1, and of Mn3+ concentration at the rate of 0·081 cmol kg−1 year−1. Continuous cropping also increased the concentration of Bray-P at 0–5 cm depth due to application of phosphatic fertilizer. Trends in soil chemical properties were not clearly defined with regards to cropping system treatments. In general, however, soil chemical properties were relatively favorable in ley farming and mucuna fallowing treatments imposed on moderately degraded soils. Results are discussed in terms of recommended rates of fertilizer use, in view of soil test values, expected yields, and critical limits of soil properties.  相似文献   

7.
模拟土柱条件下黑土中肥料氮素的迁移转化特征   总被引：3，自引：0，他引：3  
为明确肥料氮素在土壤中的迁移转化动态特征,利用模拟土柱方法,研究了3倍常规施肥量条件下不同肥料处理(尿素、硫铵)黑土的矿质氮变化。结果表明:不同氮肥处理的氮素养分迁移转化特征有明显差异。对照处理(不施肥)土柱内各层次间NH4+-N和NO3--N含量差异不明显;施用尿素或硫铵后,表层0~50mm土层的NH4+-N和NO3--N含量比不施肥对照分别升高100.8~3408.1mg·kg-1、113.4~388.0mg·kg-1和126.7~4671.1mg·kg-1、51.4~63.3mg·kg-1,且在培养前14d内变化最大。在整个培养期内,施用硫铵处理各层次NH4+-N平均含量比尿素处理高2.54~1423.7mg·kg-1,NO3--N平均含量低4.38~335.1mg·kg-1;而尿素处理各层次的硝化率是硫铵处理的0.79~9.12倍。表明肥料氮素的迁移与转化集中在0~50mm土层内,尿素处理的氮素转化速率较硫铵处理高。  相似文献   

8.
Termites are reported to improve soil physicochemical properties thereby enhance soil fertility of their mound and foraging areas. Empirical study pertaining to these effects is missing in Southwest Ethiopia. For this study, soil samples affected by termite activities were collected at 1 m interval within 0–3 m distance from the base of six termite mounds on gently sloping and sloping land and analyzed for physicochemical parameters. The result of the analysis depicted that soil bulk density (1.38–1.15 g cm?3) and moisture content (21.1–9.9%) decreased with increased distance from the mound base. While clay content decreased with increased distance from the mound base from72.0% to 45.5%, sand and silt contents increased from 8.0% to 21.3% and 19.3% to 28.5%, respectively. PH (6.23), organic carbon (3.85%), total nitrogen (0.4%), cation exchange capacity CEC (30.43 cmol kg?1), exchangeable Ca (13.73 cmol kg?1), Mg (3.15 cmol kg?1), and PBS (56.8%) were higher on termite mounds. While, electrical conductivity (0.03 dS m?1–0.06 dS m?1), exchangeable K (0.52–0.93 cmol kg?1) and Na (0.02–0.03 cmol kg?1) showed increasing trend with the distance from the mound base. Our results indicated that termite mounds are important sinks of organic matter and mineral nutrients, and hence contribute to the enhancement of soil fertility. Thus, for subsistent farmers the uses of termite mounds as a fertilizer present an opportunity to improve agricultural production.  相似文献   

9.
Flooding an extremely alkaline（pH 10.6） saline soil of the former Lake Texcoco to reduce salinity will affect the soil carbon（C）and nitrogen（N） dynamics.A laboratory incubation experiment was done to investigate how decreasing soil salt content affected dynamics of C and N in an extremely alkaline saline soil.Sieved soil with electrical conductivity（EC） of 59.2 dS m-1 was packed in columns,and then flooded with tap water,drained freely and conditioned aerobically at 50%water holding capacity for a month.This process of flooding-drainage-conditioning was repeated eight times.The original soil and the soil that had undergone one,two,four and eight flooding-drainage-conditioning cycles were amended with 1000 mg glucose-14C kg-1 soil and 200 mg NH4+-N kg-1soil,and then incubated for 28 d.The CO2 emissions,soil microbial biomass,and soil ammonium（NE4+）,nitrite（NO2-） and nitrate（NO3-） were monitored in the aerobic incubation of 28 d.The soil EC decreased from 59.2 to 1.0 dS m1 after eight floodings,and soil pH decreased from 10.6 to 9.6.Of the added 14C-labelled glucose,only 8%was mineralized in the original soil,while 24%in the soil flooded eight times during the 28-d incubation.The priming effect was on average 278 mg C kg-1 soil after the 28-d incubation.Soil microbial biomass C(mean 66 mg C kg-1 soil) did not change with flooding times in the unamended soil,and increased 1.4 times in the glucose-NH4+-amended soil.Ammonium immobilization and NO2- concentration in the aerobically incubated soil decreased with increasing flooding times,while NO3- concentration increased.It was found that flooding the Texcoco soil decreased the EC sharply,increased mineralization of glucose,stimulated nitrification,and reduced immobilization of inorganic N,but did not affect soil microbial biomass C.  相似文献   

10.
人为活动对云南纳帕海湿地土壤碳氮变化的影响   总被引：22，自引：0，他引：22       下载免费PDF全文
以纳帕海湿地原生沼泽作为参照 ,选择人为干扰下的沼泽化草甸 ,草甸和排干湿地开垦的耕地作为研究对象 ,研究人为干扰对纳帕海湿地土壤碳氮变化的影响。两年的定位研究结果表明 :沼泽土壤C/N值较高 ;人为干扰下纳帕海湿地土壤空间结构上土壤有机质 0～ 2 0cm表层与 2 0～ 4 0cm下层相差 4倍 ,水平分布上则随人为干扰加强、沼泽化过程减弱而降低 ,下降幅度高达 2 2 .92 %～ 6 9.6 4 %;土壤全氮及其空间分布呈现与有机质相同趋势 ,两者相关系数r=0 .98;NH 4 N、NO-3 N与全氮和水解氮相关系数分别为r=- 0 .74、r=- 0 .6 5 ,r=- 0 .81、r=- 0 .76。表明了纳帕海湿地沼泽土壤较低的矿化量和对碳的固定及较大的氮累积量 ,以及人为活动干扰后湿地土壤碳氮养分的释放变化。  相似文献   

11.
红壤水稻土肥力性状的演变特征   总被引：23，自引：0，他引：23  
大田条件下 ,通过选点采样分析 ,研究了不同利用年限红壤水稻土的物理、化学和生物学性质的动态变化特征。荒地红壤水耕利用后 ,土壤颗粒组成呈现规律性变化 ,粘粒 (<0 0 0 2mm)含量从荒地红壤的 3 9%下降到 80a稻田土壤的 1 7% ,而粉砂 (0 0 2～ 0 0 0 2mm)含量升高。土壤pH一般增加 0 5～ 1个单位 ;0～ 1 0cm土壤有机碳和全氮含量从荒地红壤的 4 5 8gkg- 1和 0 3 9gkg- 1增加到 3 0a红壤稻田的1 9 6gkg- 1和 1 62gkg- 1,其后 ,即使利用时间长达 80a ,土壤有机碳和全氮含量并没有显著差异 ;土壤全磷含量 ,经 3a水耕利用后可从荒地红壤的 0 5gkg- 1提高到 1 3gkg- 1,表明通过施肥可使红壤磷素快速积累 ;而在水耕利用过程中 ,红壤稻田土壤的钾素含量呈下降趋势 ,经 80a利用的红壤稻田 ,0～ 1 0cm土壤钾素含量仅为荒地红壤的 80 % ;全铁和游离铁的含量也呈下降趋势。随着水耕熟化过程 ,细菌数量和脲酶活性也明显升高。不同利用年限红壤稻田土壤的各项性状指标的变化结果还表明 ,荒地红壤水耕利用后要达到高度熟化的稻田土壤肥力水平 ,需要经过 3 0a的时间  相似文献   

12.
Biochar has the potential to decrease salinity and nutrient loss of saline soil. We investigated the effects of biochar amendment (0–10 g kg−1) on salinity of saline soil (2.8‰ salt) in NaCl leaching and nutrient retention by conducting column leaching experiments. The biochar was produced in situ from Salix fragilis L. via a fire-water coupled process. The soil columns irrigated with 15 cm of water showed that biochar amendment (4 g kg−1) decreased the concentration Na+ by 25.55% in the first irrigation and to 60.30% for the second irrigation in sandy loam layer over the corresponding control (CK). Meanwhile, the sodium adsorption ratio (SAR) of soil after the first and second irrigation was 1.62 and 0.54, respectively, which were 15.2% and 49.5% lower than CK. The marked increase in saturated hydraulic conductivity (Ks) from 0.15 × 10–5 cm s−1 for CK to 0.39 × 10–5 cm s−1, following 4 g kg−1 of biochar addition, was conducive to salt leaching. Besides, biochar use (4 g kg−1) increased NH4+-N and Olsen-P by 63.63% and 62.50% over the CK, but accelerated NO3–-N leaching. Since 15 cm hydrostatic pressure would result in salt accumulation of root zone, we would recommend using 4 g kg−1 of biochar, 30 cm of water to ease the problem of salt leaching from the surface horizon to the subsoil. This study would provide a guidance to remediate the saline soil in the Yellow River Delta by judicious application of biochar and irrigation.  相似文献   

13.
Tillage and soil management effects on soil physical and chemical qualities were monitored for eight years from 1979 through 1987 in a long-term experiment involving 17 consecutive crops of maize. Effects of no-till and plow-till methods of seedbed preparation were compared at two levels of residue management (residue removed versus residue returned) and two levels of fertilizer application (without fertilizer versus recommended fertilizer). Soil chemical quality was better for no-till compared with plow-till methods. Mean soil chemical properties of 0–5 cm depth for no-till and plow-till treatments respectively were 18·6 g kg−1 versus 12·2 g kg−1 for soil organic carbon content, 1·9 g kg−1 versus 1·1 g kg−1 for total soil nitrogen, 0·14 units yr−1 versus 0·18 units yr−1 rate of decline in soil pH, 63·1 mg kg−1 versus 31·8 mg kg−1 for Bray-P, and 6·0 cmol kg−1 versus 2·3 cmol kg−1 for Ca+2. Soil chemical quality consistently declined, although the rate of decline differed among tillage and fertilizer treatments. There were also differences in soil physical quality. Soil bulk density increased with cultivation duration in both tillage methods, and use of furadan in no-till plots drastically increased soil bulk density. Infiltration rate and soil moisture retention at all suctions was consistently more for no-till than plow-till treatments. Decline in soil quality with cultivation was reflected in decrease in crop yields. © 1998 John Wiley & Sons, Ltd.  相似文献   

14.
为探讨双季稻田控释尿素施用对养分在土壤剖面的垂直分布与迁移的影响,通过长期田间定位试验,研究比较普通尿素(U)和控释尿素(CRU)减施稻田剖面的养分累积和分布。结果表明:随着土层深度的增加,土壤全氮、NO_3~-—N、有机质、全磷、速效磷和全钾含量呈下降趋势,NH_4~+—N含量先下降后升高,速效钾含量呈上升趋势,土壤pH升高且趋于稳定。施肥会降低0—20cm土层pH和速效钾含量。与U处理相比,0—20cm土层CRU处理全氮含量提高7.72%~19.45%,且随着施N量的增加呈上升趋势;40—60cm土层CRU处理NH_4~+—N含量降低6.99%~19.23%。施用CRU可以有效降低土层NH_4~+—N向下淋溶,提高0—40cm土层全氮和NO_3~-—N含量,避免土壤N素流失。施用CRU对不同深度土层有机质、速效磷、全磷、速效钾、全钾和pH的影响不显著,但减量过大会导致有机质降低。CRU减量10%~20%处理显著提高双季稻成熟期N、P、K的吸收量。相关分析表明,不同用量控释尿素处理早、晚稻成熟期N、P、K吸收量与籽粒产量均呈显著正相关。总之,CRU处理有效地控制N素向下淋溶,减少因N肥施用带来的潜在面源污染,而CRU减施可更好地维持和提高土壤的养分水平和肥力,促进养分累积,实现生态与经济效益的双赢。  相似文献   

15.
Batch acid addition experiments were carried out to determine the acid buffer capacities (amount of acid required to lower soil pH by one unit) of forest soils. Samples of O, E, B (or BC), and C horizons taken from 29 podzolic profiles in southern Finland were used in the experiments. Subsamples of soil were equilibrated for 24 h with NaCl solution containing additions of HCl acid. Cation exchange, mineral dissolution (weathering), and the protonation of organic matter all appeared to have been involved in the buffering of the acid additions. For the O horizon samples, most of the cations released in response to the acid additions were base cations. For the mineral soil samples, most of the cations released were Al3+ ions. With the exception of a few samples, the added acid was not fully neutralised and pH was lowered even with the lowest addition treatment. However, the acid addition treatments corresponded to many times the regional annual acid deposition load (1.6–2.0 cmol(c) m?2). Calculated acid buffer capacities (cmol(c) kg?1 pH?1) ranged from 9.8 to 40.8 for O horizon soil samples and from 0.1 (C horizon) to 5.2 (E horizon) for the mineral soil samples. Total acid buffer capacities for a profile (to a depth of 50 cm) ranged from 500 to 2349, with a mean value of 1091 cmol(c) m?2 pH?1. It is concluded that, in addition to CEC and base saturation, acid buffer capacity is a useful measure to describe the ecological effects of acid deposition on soil.  相似文献   

16.
应用Multi-Langmuir模型评价土壤的表面电荷特性   总被引：2，自引：1，他引：1  
用返滴定技术测定土壤的可变电荷量(Qv),应用Muti-Langmuir模型评价土壤的表面电荷特性。结果表明,黄壤和黄棕壤可变电荷量的变化范围在0～45cmolkg-1,红壤为0～21cmolkg-1,砖红壤和赤红壤为0～14cmolkg-1。可变电荷量(Qv)依赖土壤悬液的pH,3点位模型能很好地描述6种土壤的可变电荷量随pH的变化关系;黄壤、黄棕壤、湖南红壤、江西红壤、赤红壤和砖红壤的pK1分别为4.45、4.46、4.76、4.62、4.66和4.74,可变电荷量Qv1分别为11.7、9.64、9.31、7.14、4.86和5.95cmolkg-1。黄壤和黄棕壤pK1较红壤、砖红壤和赤红壤约低0.3。pK1与ZPC呈现极显著的线性关系,可变电荷量(Qv(i))与有机质含量呈极显著的正相关。  相似文献   

17.
Burying a straw layer and applying flue gas desulphurization(FGD)gypsum are effective practices to ameliorate soil salinization or alkalization and to increase crop yield;however,little information exists on the effects of such integration in saline-alkali soils.A soil column experiment was conducted to investigate the effects of a straw layer plus FGD gypsum on soil salinity and alkalinity.We placed a straw layer(5 cm thick)at a depth of 30 cm and mixed FGD gypsum into the 0–20 cm soil layer at application rates of 7.5,15.0,22.5,and 30.0 t ha^-1,with no straw layer and FGD gypsum as a control(CK).The soil water content in the 0–30 cm soil layer was significantly higher(>7.8%)in the treated soil profiles after infiltration than in the CK,but decreased after evaporation.The electrical conductivity(EC)of the 10–30 cm soil layer was 230.2%and 104.9%higher in the treated soil profiles than in the CK after infiltration and evaporation,respectively,and increased with increasing rates of FGD gypsum application,with Ca^2+and SO4^2-being the main dissolved salts.Compared to those in the CK,the concentrations of Na^+,Cl^-,and HCO3-decreased in the treated soil profiles at depths above 55 cm,but the other soluble ions increased,after infiltration.A similar trend occurred after evaporation for all soluble ions except for HCO3-.The p H and exchangeable sodium percentage in the treated soil profiles were significantly lower than those in the CK over the entire profile,and decreased with increasing FGD gypsum application rates.Therefore,the incorporation of a straw layer plus FGD gypsum can reduce salinity and alkalinity,but the quantity of FGD gypsum should be controlled in saline-alkali soils.  相似文献   

18.
This study analyzes effects of soil and water conservation (SWC) on soil quality and implications to climate change adaptation and mitigation in the Upper Blue Nile River Basin of Ethiopia by using the Anjeni watershed as a case study site. Disturbed and undisturbed soil samples were collected from two sub‐watersheds of Anjeni: the Minchet sub‐watershed (with SWC measures) and the Zikrie sub‐watershed (without SWC measures). Soil samples were taken from 30‐cm depth from five representative landscape positions and analyzed following the standard soil lab analysis procedures. The results show that soils from the conserved sub‐watershed had improved quality indicators compared with those from the non‐conserved site. Significant improvement due to SWC measures was observed in the soil hydrological [total moisture content (+5·43%), field capacity (+5·35%), and available water capacity (+4·18%)] and chemical [cation exchange capacity (+4·40 cmol(+) kg−1), Mg2+ (+1·90 cmol(+) kg−1), Na+ (+0·10 cmol(+) kg−1)] properties. SWC interventions significantly reduced soil erosion by 57–81% and surface runoff by 19–50% in the conserved sub‐watershed. Reduction in soil erosion can maintain the soil organic carbon stock, reduce the land degradation risks, and enhance the C sequestration potential of soils. Therefore, adoption of SWC measures can increase farmers' ability to offset emissions and adapt to climate change. However, SWC measures that are both protective and sufficiently productive have not yet been implemented in the conserved sub‐watershed. Therefore, it is important that SWC structures be supplemented with other biological and agronomic measures in conjunction with soil fertility amendments appropriate to site‐specific conditions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

19.
Shrinking of Lake Chany in W Siberia exposed 10,000 km2 of former lakebed. On this new land we studied a chronosequence of young soils. The fraction of microbial C in total organic C had stabilized at 3% after 30 to 40 y. Concentration of organic C increased within the first 50 to 100 y to 4–5% in the first 10 cm, and to 2–3% at 10–20 cm depth. The amount of sequestered C is equivalent to about 2.5 d of current anthropogenic CO2 emissions.  相似文献   

20.
日光温室土壤剖面矿质态氮的含量、累积及其分布特性   总被引：11，自引：0，他引：11  
测定了西安郊区和杨凌地区日光温室栽培番茄生长期间及收获后土壤剖面矿质态氮(铵态氮及硝态氮)的含量,分析了不同形态氮素在土壤剖面的累积及分布情况。结果表明,随着番茄的生长,土壤剖面硝态氮含量逐渐降低,降低的幅度因土壤层次不同而异;土壤剖面铵态氮以3月份含量最高,11月份与5月份相近。番茄收获后土壤剖面残留矿质氮以硝态氮为主,约占土壤剖面矿质氮的比例为80%～90%;残留的铵态氮在土壤剖面的分布相对较为一致。蔬菜生长期间及收获时日光温室土壤剖面硝态氮累积量均表现出在土壤表层相对累积现象,且温室土壤剖面硝态氮的残留量仍高于露地及高产农田。为减少硝态氮淋失带来的环境问题,除合理施用氮肥外,如何减少日光温室蔬菜作物收获后残留硝态氮的淋溶是值得进一步研究的问题。  相似文献   

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