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1.
生物质灰渣与化肥混合对氨挥发的影响   总被引:1,自引:0,他引:1  
黄容  高明  廖燕妮  王丹  邓炜  叶夏依 《土壤学报》2014,51(5):1160-1167
采用室内恒温培养,碱液吸收法测定灰渣-化肥中氮的挥发量,研究了锯木灰、谷壳灰、玉米灰、水稻灰分别与不同化肥配比下,在一定时间内的氨挥发规律。结果表明:四种灰渣在N1、N2、N3水平下,随着时间的增加氨的挥发量和挥发率呈先增大后减小的趋势,各处理的峰值多出现在10~15 d的培养阶段;谷壳灰、玉米灰、水稻灰添加磷酸二氢钾能明显抑制混合物中氨的挥发,而锯木灰添加氯化钾、磷酸二氢钾均能抑制氨的挥发;在四种灰渣中,锯木灰处理的氨挥发率明显高于其他三种灰渣,特别是在N3水平下比同期的其他灰渣处理高5倍。Elovich方程和抛物线扩散方程均能较好拟合氨的挥发量随时间的变化,其相关系数均达到极显著水平。  相似文献   

2.
不同生物质灰渣对磷的吸附解吸动力学特征   总被引:5,自引:0,他引:5  
以锯木灰、谷壳灰、玉米灰、水稻灰4种灰渣为研究对象,采用平衡法研究生物质灰渣对磷的吸附与解析特性。结果表明,灰渣对磷的吸附量随着加入液磷浓度的增加而增加,但增加速率逐渐减缓。与其他生物质灰渣相比,锯木灰在不同浓度下对磷的吸附量和吸附率均较高,吸附量在0.98~11.21g/kg范围内,吸附率均在55%以上,最高可达97.72%。然而,随着加入液磷浓度的增加,吸附态磷解吸率逐渐减小,解吸量逐渐增加,在加入的磷浓度为2 000mg/L时,4种灰渣的解吸量都达到最大值,为最小解吸量的3.5~6.4倍。不同种类的灰渣由于化学组成不同吸附与解吸能力也不同,不同磷浓度对水稻灰、谷壳灰、玉米灰的解吸率影响最大,最高解吸率和最低解吸率差值分别为56.53%,53.67%,44.53%;对锯木灰的影响相对较小,差值仅有12.53%。用Langmuir方程拟合4种灰渣的等温吸附曲线和等温解吸曲线,得到的相关系数都达到显著水平。灰渣对磷的吸附和解吸的动力学特征存在一定的相似性,一般吸附量大的灰渣对磷的解吸量也大;吸附能力强的灰渣对磷的解吸能力也强。锯木灰对磷的吸附解吸能力强于其他3种灰渣。由于灰渣对磷的吸附和解吸能力对土壤中磷的生物有效性有重要影响,因此在选择灰渣种类时需适时适量。  相似文献   

3.
锯木灰渣改良退化菜园紫色土壤的效果研究   总被引:2,自引:0,他引:2  
黄容  高明  吕盛  徐国鑫  黎嘉成 《土壤学报》2018,55(3):695-706
以重庆市九龙坡区白市驿镇蔬菜基地为试验平台,通过大田试验,研究了锯木灰渣不同施用量还田1年后对酸性紫色土改良效果,并进一步分析了锯木灰渣对土壤微生物群落及微生物碳、氮的影响,以期为紫色菜园退化土壤养分和酸化的修复提供合理措施,同时实现循环农业的可持续发展。结果表明:(1)锯木灰渣施用能显著提高蔬菜产量,且随着施用量的增加呈增加趋势,其中锯木灰渣施用量为18 000 kg hm~(-2)时,产量较未施用锯木灰渣(A0)处理显著提高了76.1%~121.9%;(2)经锯木灰渣处理的退化紫色土表层和亚表层的有机质含量和pH提高,尤其是锯木灰渣施用量为18 000 kg hm~(-2)的改良效果较佳,但是过高的锯木灰渣施用量处理对土壤交换性H~+、Al~(3+)效果反而下降,而施用量为12 000~15 000 kg hm~(-2)处理的效果较佳,其中表层土壤交换性H~+、Al~(3+)分别为0.19~0.20,0.63~0.67 cmol kg~(-1);(3)12 000~15 000 kg hm~(-2)的锯木灰渣施用量对土壤碱解氮和速效钾的提升效果较佳,18 000 kg hm~(-2)处理的有效磷含量最大,较A0处理增加了55.3 mg kg~(-1);(4)无论在表层土壤还是亚表层土壤中,细菌的种群数量分布最多,其次为真菌和放线菌,分别在12 000,9 000,6 000 kg hm~(-2)锯木灰渣施用量下的种群数量达到最大值;9 000~12 000 kg hm~(-2)处理对提高表层土壤微生物量碳含量较为明显,较A0显著提高了70.4%~78.7%,18 000 kg hm~(-2)处理的土壤微生物生物量氮(SMBN)含量最大(40.54 mg kg~(-1)),其次为9 000 kg hm~(-2)处理(34.32 mg kg~(-1))。综上,锯木灰渣施用量为12 000~15 000 kg hm~(-2)时对退化紫色土的改良效果较好。  相似文献   

4.
研究了4种土地利用方式下(水田、旱地、林地、菜地)紫色土(紫色湿润雏形土)和紫色水稻土(紫色水耕人为土)NH4+的容量和强度(Q/I)关系。结果表明:紫色土和紫色水稻土NH4+Q/I曲线的曲线部分均出现在NH4+的活度比(ARNH4)较低时,表明土壤存在非交换性NH4+(或专性吸附的NH4+)的释放。紫色土和紫色水稻土NH4+的潜在缓冲容量(PBC)为71.47~203.7 cmol kg-1(mol L-1)-1/2;土壤活性NH4+(-ΔNH40)为0.029 5~0.089 7 cmol kg-1,NH4+的平衡活度比(AR0NH4)为0.187×10-3~1.255×10-3(mol L-1)1/2;土壤专性吸附位点(NH4-sas)为0.010 6~0.118 5 cmol kg-1。相关分析和通径分析表明,土壤小于0.002 mm黏粒含量与NH4+PBC及NH4-sas均呈极显著正相关(p<0.01),小于0.002 mm黏粒对PBC的影响主要是间接作用(间接通径系数为0.585),但对NH4-sas则有强烈的直接作用;有机碳与-ΔNH40和AR0NH4均呈极显著正相关(p<0.01),但是有机碳对-ΔNH40有较大的直接效应(直接通径系数为0.966),而对AR0NH4的影响主要以间接效应为主。土壤-ΔNH40与交换性NH4+数值接近且呈极显著相关(r=0.876 4,n=8,p<0.01),而AR0NH4与交换性NH 4+亦呈极显著相关(r=0.983 7,n=8,p<0.01)。土壤小于0.002 mm黏粒和有机碳的差异是导致不同土地利用方式下紫色土交换性NH4+以及Q/I参数的差异的主要原因,交换性NH4+标志的NH4+有效性指标与由Q/I关系得到的NH4+有效性指标类似。  相似文献   

5.
粉煤灰理化性质与硅素释放规律的研究   总被引:3,自引:0,他引:3  
对粉煤灰理化性质与Si素释放规律的研究结果表明,粉煤灰颗粒以物理性砂粒为主,占44.43%~98.67%,容重较小,pH一般>7.5,可用作土壤改良剂;粉煤灰水溶性硅和有效硅含量与土壤差异不明显,但粉煤灰中Si在100h内释放量比土壤的高3.0~25.0倍,可为水稻等禾本科作物提供相当数量的Si营养。Elovich方程和Freundlich方程可较好地描述粉煤灰和土壤中Si释放量随时间变化的关系,Elovich方程的b值和Freundlich方程的k值反映了Si释放能力,且b、k值越大,Si释放能力越强。  相似文献   

6.
pH和磷的交互作用对稳定化土壤砷释放的影响   总被引:3,自引:0,他引:3  
徐文义  谢爱军  李敏  黄民生 《土壤》2019,51(1):113-120
以3种含Fe材料稳定化土壤(FeSO_4、FeS和Fe~0稳定化土壤)为研究对象,研究了不同pH和P的交互作用对As释放量的影响及其作用机理。结果表明,在pH=3条件下,随着时间的延长能够促进释放的As重新趋于稳定化,而pH=11时3种稳定化土壤中As的释放量显著增加,144 h后分别约为pH=3时的10.5、16和10倍。添加P时,在3种pH条件下都促进了稳定化土壤中As的释放,尤其在酸性条件下,相对于无P体系As的释放量增加最为明显。FeSO_4稳定化土壤中As的释放特征能用Elovich方程较好地描述,而双常数方程拟合FeS和Fe~0稳定化土壤效果更优。在pH=3条件下,3种稳定化土壤中As的释放量与Ca、Mg、Mn的溶出量呈(极)显著相关,而pH=11时FeSO_4和FeS稳定化土壤中As的释放量与SO_4~(2–)的溶出量呈(极)显著相关,表明在酸性条件下,稳定化土壤As的释放主要受Ca、Mg、Mn氧化物结合态As溶解的影响,而碱性条件下,FeSO_4和FeS稳定化土壤中As的释放可能与硫化物的溶解有关。  相似文献   

7.
酸性条件下H+Ca2+在红壤表面反应的能量特征   总被引:5,自引:2,他引:5       下载免费PDF全文
用自行设计的动力学装置研究了酸性条件下H -Ca2 在红壤表面的反应动力学能量特征。结果表明 ,酸性条件下Ca2 吸附分为快反应和慢反应。用一级动力学方程拟合的Ca2 最大吸附量随酸度增加显著下降 ,随温度升高提前达到平衡。用双常数方程描述Ca2 在吸附点位能量分布的不均匀性 ,用扩散速率常数计算的活化能 (Eb )随酸度的增加而增加 ,Ca2 扩散需克服的能障加大 ;ΔH 值为正 ,温度升高可促进Ca2 的扩散 ;ΔS 值均为负 ,说明吸附反应使体系有序度增加。原液pH为 4 .5和 5 .6时 ,流出液的pH急剧下降 ,H 表观释放量用一级动力学和双常数方程拟合为最佳模型 ,其次是Elovich方程、扩散方程和零级方程 ;pH5 .6处理时H 、Al3 扩散进入溶液克服的能障比pH 4 .5处理的小 ,后者质子扩散需热能较大而不易进行 ;H 扩散活化焓变为正 ,其扩散是吸热过程。pH 3.5时流入液比流出液的pH高 ,是由于土壤的缓冲作用、土壤表面质子化和硫酸根专性吸附释放羟基 ;当溶液中H 超过一定数量后 ,向颗粒表面扩散的H 量比向外释放的多 ,反应初期的H 消耗是快反应过程。H 消耗的活化能及热焓比其释放的低 ,更有利于H 的吸附 ,因H 对矿物的溶蚀成为速率控制步骤 ,H 对矿物的溶解可用扩散方程和Elovich方程描述  相似文献   

8.
采用田间试验方法,研究了多菌灵在稻田水、土壤和稻秆中的消解动态,测定了多菌灵在水稻和土壤中的最终残留量。样品采用甲醇和稀盐酸的混合溶液提取,经液-液分配净化,HPLC紫外分析测定。结果表明,田水、土壤、稻秆、谷壳、糙米中多菌灵添加浓度为0.05~1.0mg·kg-1时,平均回收率为83.16%~95.44%,变异系数在1.23%~5.32%之间,方法的最低检测浓度为:田水0.005mg·L-1,土壤0.005mg·kg-1,稻秆0.050mg·kg-1,谷壳0.050mg·kg-1,糙米0.025mg·kg-1。多菌灵在田水、土壤和稻秆中的消解动态均符合一级动力学方程,半衰期分别为2.53~3.41d、6.20~7.27d、3.27~3.91d,原始沉积量与施药量、施药次数密切相关。以231g·hm-2和346.5g·hm-2间隔7d施用多菌灵2次和3次,末次施药21d后多菌灵的最高残留量为:土壤未检出(≤0.005mg·kg-1),稻秆0.524mg·kg-1,谷壳0.528mg·kg-1,糙米未检出(≤0.025mg·kg-1)。多菌灵在稻秆和谷壳中的残留量相对较高,以该稻秆和谷壳作为饲料有一定的风险;多菌灵在糙米中的残留量低于我国和食品法典委员会(CAC)及日本的最大残留限量(MRL)标准。  相似文献   

9.
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   

10.
生物质炭对铵根的吸附解吸影响着土壤的固氮效果,为探讨茶渣生物质炭对茶园土吸附—解吸NH_4~+—N性能的影响,减少土壤中氮素的淋失,提高氮素利用效率,通过模拟培养试验,采用平衡吸附法及HCL解吸法,研究了不同热解温度下制备的茶渣生物质炭在不同添加比例(0.35%,0.70%,1.40%,2.80%)下,茶园土对NH_4~+—N吸附解吸的特性。结果表明:施用生物质炭能有效增强茶园土对NH_4~+—N的吸附,并随生物质炭添加量的增加而增强。同一生物质炭添加量下,4种生物质炭处理下茶园土对NH_4~+—N的吸附量大小表现为BC400BC300BC500BC600。生物质炭的CEC含量是影响土壤吸附NH_4~+—N能力的主要因素。土壤对NH_4~+—N的吸附过程均以Langmuir方程拟合达到显著水平(0.953 7R~20.995 5),以单层吸附为主。施用生物质炭后,土壤产生了解吸滞后,有效降低了茶园土对NH_4~+—N的解吸率,BC400的解吸率最低。茶渣生物质炭能够增强土壤对NH_4~+—N的吸附,降低对NH_4~+—N的解吸,有利于提高土壤对氮素的吸持能力,其中BC400,2.80%处理下效果最佳。  相似文献   

11.
Two varieties of Cucumis melo (Resisto and Arava) were grafted onto three hybrids of Cucurbita maxima and Cucurbita moschata cultivars (Shintoza, RS-841 and Kamel). Ungrafted Cucumis melo var. Resisto and var. Arava plants were used as controls. Plants were grown under controlled greenhouse conditions and were constantly fertilized with macro- and micronutrients, supplied with irrigation water rich in Na+ and Cl- Contents of chlorophylls a and b, carotene pigments, Cl- and total and soluble Na+ and K+ ions were measured in all the scion parts of the plants. The results showed that grafted plants exhibited differences in the leaf content of Na+ and especially Cl- in comparison with ungrafted plants. In addition, yield as well as leaf pigments appeared to be good indicators of Cl- levels in scion parts. It is assumed that grafted plants developed various mechanisms to avoid physiological damage caused by the excessive accumulation of these ions in leaf, including the exclusion of Cl- ion and/or decrease in Cl- absorption by the roots and the replacement or substitution of total K+ by total Na+ in the foliar parts.  相似文献   

12.
Experiments were performed to test the effect of Ca2+ and Mg2+ upon ATPases (E.C. 3.6.1.3) from barley roots (Hordeum distichon L. cv. MULTUM) that had or had not taken up Al3+. Furthermore, the effect of the uptake period was examined. With longer duration of the Al3+ uptake, the activity of the ATPases dropped, independently of whether they were activated by Ca2+ or by Mg2+. Mg2+ stimulated the activity of the ATPases if no Al3+ had been taken up with lacking Ca2+ in the assay. If Al3+ had been taken up no additional activation by Mg2+ to the Ca2+ stimulation could be observed, and in some cases Mg2+ decreased the Ca2+ stimulation.  相似文献   

13.
ABSTRACT

The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg? 1 soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks (‘Sarakhs’ and ‘Qazvini’) were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (ECe) confirmed the above findings. Under 3-d irrigation interval, the ECe required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na+), potassium (K+), and chloride (Cl?) in pistachio. The concentration of Na+, K+ and C1? ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na+, K+, and C1? in the plant tissues, at lowest irrigation intervals ‘Sarakhs’ shows a higher sensitivity to soil salinity than ‘Qazvini’, but with increasing irrigation interval, ‘Sarakhs’ and ‘Qazvini’ can be classified as resistant and sensitive to salinity, respectively.  相似文献   

14.
羟基磷灰石对铅锌矿区土壤吸附Zn2+、Cd2+的影响   总被引:2,自引:0,他引:2  
为探究羟基磷灰石(HAP)对矿区土壤重金属的固化效果,采用吸附试验,研究施加HAP的铅锌矿区土壤对Cd~(2+)、Zn~(2+)的动力学吸附和等温吸附效果。结果表明:土壤对Cd~(2+)、Zn~(2+)的吸附量随Cd~(2+)、Zn~(2+)初始浓度的增加而增加;在酸性条件下,其吸附量随pH上升而上升;准二级动力学方程能很好地描述两者的吸附过程,土壤吸附能力随HAP的添加量增大而增强;在Zn—Cd共存体系中,当初始浓度为20mg/L时,土壤对Zn~(2+)、Cd~(2+)的吸附无明显差异,2种金属离子竞争力度小,随着初始浓度上升,竞争明显,对Zn~(2+)的最大吸附量能达到单一体系中的79%~87%,而Cd~(2+)的最大吸附量只有单一体系中的57%~72%,Zn~(2+)的竞争力优于Cd~(2+),Zn~(2+)对Cd~(2+)吸附产生严重的抑制。综上可知,HAP能提高矿区土壤的吸附性能,在Zn、Cd污染土壤中,更能提升土壤对Zn~(2+)的吸附固持能力。  相似文献   

15.
As a result of Cd treatment, K concentrations decreased in Cd sensItive maize and kidney bean calli (Obata et al. 1994) and in intact roots of kidney bean plants (Obata et al. unpublished). Potassium may be extruded from the roots or the absorption of K may be depressed by the Cd treatment in these Cd sensitive plants. Obata et al. (1996) observed that Cd inhibited both the efflux of H+ and influx of K+ following K+ addition in intact roots of bean. Thus Cd may affect the activity of proteins essential to ion movement., i.e. ioncarriers, channels and ATPase embedded in the membranes and/or may affect the permeability of the lipids of the membrane.  相似文献   

16.
Abstract

An important consideration for milk thistle (Silybum marianum L.) cultivation is regulating development to lengthen the reproductive stage and increase seed yield with high silymarin content. The treatment of milk thistle with foliar fertilizers and growth regulators—thidiazuron (Dropp®), 2,3,5‐triiodobenzoic acid (Tiba®), mepiquat chloride (Pix®), and prohexadione‐Ca (Regalis®)—resulted in an increase in the proportion of mature flower heads. Highest seed yield was observed in plants treated with Pix® and mineral soil fertilization, whereas in plants treated with foliar fertilizers, highest yields were observed with Pix® and Regalis®. The highest content of silymarin was found in plants treated with Dropp® and foliar fertilizer. Generally, treatment of milk thistle with plant‐growth regulators in combination with soil or foliar mineral fertilizers increased the total amount of silymarin by increasing seed yield per hectare.  相似文献   

17.
Introduction

Phosphorus applied on a phosphate deficient soil, by increasing the root development of the plant, or by stimulating the soil microflora especially in the rhizosphere, may increase the amount of phosphorus which the plant takes up from the soil. This present paper is a report on a pot culture investigation of such an effect of added phosphorus.  相似文献   

18.
Mineral regulation of two soybean varieties Jackson and Lee was investigated in long term water culture experiments using saline solutions. The effects of extreme K:Na ratios using chloride and sulfate as counterions were studied in the early stages of salinity.

The growth rates of both varieties were not affected by salinization. A K+ stimulated, intensive acropetal Cl translocation was observed in the salt sensitive variety Jackson. The varieties did not differ in Na+ translocation and in the suppression of Ca2+ and Mg2+ in the leaves. But the effect of the nature of salinization indicates already differences in Na uptake and translocation of the cultivars.

The avoidance of Cl, but also of Ha+, in connection with influences of the resulting ionic imbalance on metabolic pathways are probably the most causative factors for the different tolerance to salinity of the two soybean varieties.  相似文献   

19.
Human activity has increased the amount of N entering terrestrial ecosystems from atmospheric NO3 deposition. High levels of inorganic N are known to suppress the expression of phenol oxidase, an important lignin-degrading enzyme produced by white-rot fungi. We hypothesized that chronic NO3 additions would decrease the flow of C through the heterotrophic soil food web by inhibiting phenol oxidase and the depolymerization of lignocellulose. This would likely reduce the availability of C from lignocellulose for metabolism by the microbial community. We tested this hypothesis in a mature northern hardwood forest in northern Michigan, which has received experimental atmospheric N deposition (30 kg NO3-N ha−1 y−1) for nine years. In a laboratory study, we amended soils with 13C-labeled vanillin, a monophenolic product of lignin depolymerization, and 13C-labeled cellobiose, a disaccharide product of cellulose degradation. We then traced the flow of 13C through the microbial community and into soil organic carbon (SOC), dissolved organic carbon (DOC), and microbial respiration. We simultaneously measured the activity of enzymes responsible for lignin (phenol oxidase and peroxidase) and cellobiose (β-glucosidase) degradation. Nitrogen deposition reduced phenol oxidase activity by 83% and peroxidase activity by 74% when compared to control soils. In addition, soil C increased by 76%, whereas microbial biomass decreased by 68% in NO3 amended soils. 13C cellobiose in bacterial or fungal PLFAs was unaffected by NO3 deposition; however, the incorporation of 13C vanillin in fungal PLFAs extracted from NO3 amended soil was 82% higher than in the control treatment. The recovery of 13C vanillin and 13C cellobiose in SOC, DOC, microbial biomass, and respiration was not different between control and NO3 amended treatments. Chronic NO3 deposition has stemmed the flow of C through the heterotrophic soil food web by inhibiting the activity of ligninolytic enzymes, but it increased the assimilation of vanillin into fungal PLFAs.  相似文献   

20.
红壤交换性钙、镁和钾的分布及施肥对其影响   总被引:1,自引:0,他引:1  
A leaching experiment was Carried out with repacked soil columns in laboratory to study the leaching process of a red soil derived from sandstone as affected by various fertilization practices.The treatments were CK(as a control),CaCO3,CaSO4,MgCO3,Ca(H2PO4)2,Urea,KCl,Multiple(a mixture of the above mentioned fertilizers) and KNO3,The fertilizers were added to the bare surface of the soil columns,and then the columns were leached with 120 mL deionized water daily through perstaltic pumps over a period of 92 days,At the end of leaching process,soils were sampled from different depths of the soil profiles ,i.o.,of 92 days,At the end of leaching process,soils were sampled from different depths of the soil profiles,I.e.0-5cm,5-10cm,10-20cm,20-40cm,and 40-60cm,The results showed when applying Ca,Mg,and K to the bare surface of the soil columns,exchangeable Ca^2 ,Mg^2 ,and K^ in the upper layer of the soil profile increased correspondingly,with an extent depending mainly on the application rates of Ca,Mg,and K and showing a downward trend,CaCO3,CaSO4,MgCO3,and Ca(H2PO4)2 treatments had scarcely and effect on movement of exchangeable K^ ,while CaCO3,and CaSO4 treatments singnificantly promoted the downward movement of exchangealble Mg^2 although these two treatments had no obvious effect on leaching losses of Mg,The fact that under Urea treatment,exchangeable Ca^2 and Mg^2 ,were higher as compared to CK treatment showed urea could prevent leaching of exchangeable Ca^2 and Mg^2 ,the obvious downward movement of exchangeable Ca^2 and Mg^2 was noticed in KCl treatment ,In Multiple treatment,the downward movement of exchangeable Ca^2 and Mg^2 was evident,while that of K^ was less evident,Application of KNO3 strongly promoted the downward movement of exchangeable Ca^2 and Mg^2 in the soil profile.  相似文献   

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