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1.
新疆绿洲盐碱地滴灌条件下地下水局部动态对荒地盐分的影响 总被引：1，自引：0，他引：1
为探究新疆绿洲盐碱地应用滴灌技术导致局部地下水位的提升和地下水矿化度的增加是否对附近荒地水分和盐分产生影响。以新疆北部典型绿洲原生盐碱地(下野地灌区)滴灌农田之间荒地为例,于2009—2013年连续5 a进行定位监测,分析土体内不同时期盐分、水分及离子含量的变化。发现荒地0~140 cm土体含盐量和含水率在棉花生育期至冻融期呈"弦式"周期性变化,含盐量在棉花生育期初至生育期末递增,冻融前至消融后递减;含水率的变化趋势与之相反。受滴灌棉田灌溉的影响,棉田地下水位随棉花生育期进程逐步提升,缩短了周边荒地上升毛管水的传导路径,为地下水矿化度的增加提供了相对充足的盐分来源,土体盐分在周边棉花生育期结束后的增加量大于越冬期冻融对其的淋洗量。年际间0~140 cm土体内储盐量以1 179.05 g·a-1的速度递增,盐分的组成离子以Ca~(2+)、Cl~-、Na~+、Mg~(2+)的增加为主。 相似文献
2.
基于HYDRUS-2D的滨海地区膜下滴灌土壤水盐运移模拟研究 总被引：1，自引：0，他引：1
以春玉米“郑单958”为供试作物，采用膜下滴灌灌水方式，设定2种不同灌水定额，分别是单次灌水定额20 mm和10 mm，测定试验区土壤水分、盐分含量，利用HYDRUS-2D模型对土壤水盐运移进行模拟，将模拟值与实测值进行对比分析，探究滨海地区盐碱化土壤水盐运移规律。结果表明：滴灌过程中，水平方向土壤盐分由膜下向膜边运移，膜下土壤淋洗效果好于膜边；竖直方向0~20 cm土壤水分、盐分变化幅度最大，土壤含盐量降低16.1%，淋洗效果明显；下层土壤盐分淋洗效果一般，土壤含盐量降低值仅为9.6%。土壤水分重分布过程中，0~20 cm土层土壤含水率和含盐量变化幅度比20~60 cm土层大。0~20 cm、20~40 cm和40~60 cm土层高灌水定额（20 mm）处理对土壤盐分的抑制作用分别比低灌水定额（10 mm）处理高26%、11%、19%，并且高灌水定额滴灌将土壤盐分淋洗到60 cm土层以下，而低灌水定额滴灌未能将土壤盐分淋洗到60cm土层以下。HYDRUS-2D模拟得到的土壤含水率与含盐量和实测值基本吻合，模型可靠。 相似文献
3.
膜下滴灌棉田冻融期土壤水分盐分变化特征 总被引：2，自引：0，他引：2
通过分析2014年11月—2015年3月北疆地区膜下滴灌棉田冻融期土壤盐分、水分与温度变化,探讨了不同土层水热盐在冻融期的变化和耦合关系。结果表明:冻融期土壤表层和深层含水量较高,中间层含水量较低;土壤剖面盐分在0~80 cm呈现层状分布,浅层土壤发生盐分明显累积,土壤盐分变异系数20 cm土层为0.525、40 cm土层为0.257、80 cm土层为1.041。在冻融期,土壤水分盐分沿剖面分布发生明显变化;土水势梯度、土壤温度梯度是冻融期土壤水分盐分迁移的主要因素,土壤水热盐之间变化具有高度的耦合性。 相似文献
4.
北疆常年膜下滴灌棉田土壤盐分年内及年际变化特征研究 总被引：3，自引：0，他引：3
针对膜下滴灌棉田土壤次生盐渍化问题,从年内变化与年际变化两个方面,分析新疆典型绿洲区膜下滴灌棉田土壤盐分演变特征。研究结果表明:在年内,土壤盐分整体随生育期的顺延而呈下降趋势,其中5月上旬(苗期)、7月中旬(花铃期)、9月中旬(收获期)土壤盐分呈现积盐趋势;膜下滴灌4~12 a的棉田土壤存在稳定积盐层,其深度大约在60~150 cm范围内,其盐分值基本保持在0.6%上下;60 cm以上土层基本处于脱盐状态,其盐分值保持在0.2%~0.4%左右,属于非盐化土壤;膜下滴灌15 a的棉田,土壤盐分随生育阶段变化幅度较大,呈现中度盐化土特征。在年际间,膜下滴灌最初1~6 a,土壤盐分呈现持续脱盐趋势,尤其20 cm以下土层脱盐效果较为明显;实施膜下滴灌6~7 a,土壤盐分变化趋于稳定状态,各棉田出现稳定积盐层,其深度大约在80~100 cm土层,积盐层盐分值大部分保持在0.25%上下,属于非盐化土。 相似文献
5.
采用田间取样、土样实验室分析以及统计分析等方法,对新疆玛纳斯河中游灌区漫灌、滴灌2种灌溉方式下棉田土壤含盐量在棉花全生长季的变化进行定量分析。结果表明:从土层角度分析,漫灌棉田0-100cm整个剖面土层以及各土层土壤平均盐分值低于滴灌棉田;漫灌棉花生长期内土壤盐分主要集中在40-60cm土层,而滴灌棉田土壤盐分主要集中在20-40cm土层;滴灌棉花生长期内各土层土壤盐分分布较漫灌棉田土壤盐分更均匀。从时间角度分析,漫灌棉田0-100cm整个剖面土层以及各土层盐分峰值出现的时间早于滴灌棉田;漫灌棉花生长期内各土层盐分峰值出现在5月或6月份,而滴灌棉田各土层盐分峰值出现在6月或7月份,6月或7月是漫灌、滴灌棉田垂直土层盐分分布比较均匀的时间。研究结论对减缓土壤盐渍化、指导灌溉施肥管理以及改善可持续土地利用的可能措施均有积极意义。 相似文献
6.
膜下长期滴灌土壤盐分的空间分布特征与累积效应 总被引：10，自引：0，他引：10
通过对不同土壤质地和不同滴灌年限两个方面对新疆棉田膜下滴灌盐分的运移与积累规律的研究,结果表明:对于不同土壤质地,壤土中的盐分分布大致呈抛物线型,在40～60 cm处盐分积累量达到最大值.粘土中盐分分布大致呈"S"型,在60～80 cm处土壤盐分积累达到最大值;不同滴灌年限中随着滴灌年限越长,棉田中地表盐分积累越少,而在40～60 cm的盐分积累则越多.分析认为棉田土壤仅通过膜下滴灌淋洗盐分是不够的,必须与一定的灌排水技术相配合才能很好地防止棉田次生盐渍化. 相似文献
7.
膜下滴灌条件下盐荒地土壤盐分变化规律研究 总被引：4，自引：0，他引：4
基于对下野地灌区、金沟河灌区的试验监测,从土壤盐分年内、年际变化及其与地下水埋深的关系两个方面,研究膜下滴灌条件下盐荒地土壤盐分变化规律。研究结果表明:在年际间,下野地灌区、金沟河灌区实施膜下滴灌6～8 a的盐荒地块,深度在60～100 cm的土层土壤含盐率分别保持在0.5%、0.8%上下,形成稳定积盐层,在60cm以上土层土壤盐分基本处于动态平衡;在年内,盐荒地土壤盐分整体上呈现随生育期的推后而降低的趋势,0～60cm土层脱盐效果较为明显,春秋季是两个积盐的高峰期;下野地灌区、金沟河灌区地下水埋深年际均值为3.60、2.26 m,土壤含盐率年际均值为0.49%、0.77%,土壤盐分随地下水埋深的减小而增加,说明石河子垦区土壤含盐量受地下水埋深影响较为明显。 相似文献
8.
长期膜下滴灌对根区土壤盐分及棉花生长影响研究 总被引：2，自引：0，他引：2
通过比较典型灌区内7个(试验设计两个研究区共14块棉田)不同膜下滴灌年限棉田盐分分布,尝试揭示长期膜下滴灌农田根区土壤中盐分演变趋势。两研究区均表现为,应用膜下滴灌技术棉田根区盐分随着该技术应用年限的延长而逐渐降低;且表现为滴灌<6a为迅速脱盐阶段,6~8a为平稳脱盐阶段,>8a为盐分稳定阶段。头年10月至翌年4月,膜下滴灌棉花根层盐分降低显著。滴灌棉田根层盐分的逐年降低,使得棉花根区生境得到改善,应用膜下滴灌技术5~7a内,其对棉花根层生境改良效果较明显,3~7a棉花成活率年均增幅大于26.75%、产量年均增幅超过19.57%。滴灌7~9a以上,棉花根层生境良好,成活率大于82%,产量超过5200.00kg/hm2。 相似文献
9.
冻融期膜下滴灌棉田水盐时空动态特征研究 总被引：1，自引：0，他引：1
利用经典统计学方法,分析了冻融期北疆地区常年滴灌棉田土壤水分、盐分时空动态变化特征。结果表明:在整个冻融期,裸地处理的含水率随时间变异性较覆膜处理大;在最大冻土深度(90 cm土层)附近,土壤盐分随时间变异剧烈,属于强变异性,变异系数高达1.1左右;在深度方向上,土壤含水率呈中等变异性,而土壤含盐率则呈强变异性;在整个冻融过程中,冻结带中盐分随时间和深度的变化幅度较小;冻融期土壤存在稳定盐分累积层,该累积层的深度在120 cm土层,且不受地表覆盖的干扰。覆膜对120 cm土层以下土壤盐分运移影响较小。 相似文献
10.
通过对轻度和中度盐渍化棉田整个生育期土壤水分、盐分含量的动态监测,分析了膜下滴灌棉田土壤水、盐动态变化及其相互作用的关系。结果表明：整个生育期中度盐渍化棉田土壤水分含量要高于轻度盐渍化棉田,土壤水分含量变化规律和土壤盐分含量变化规律相似,均表现出生育前期下降、中期稳定、后期略微增加的趋势;膜下滴灌能够在滴水过程中明显降低土壤中表层0～40 cm盐分含量,下层40～80 cm土壤为盐分聚集区域;以0～20 cm土壤盐
分含量模拟0～40、0～60、0～80、40～80 cm土壤盐分含量,幂函数和线性函数模拟结果较好,模拟0～40、0～60 cm的盐分含量结果达极显著相关,0～80 cm的模拟结果达到显著相关,模拟40～80 cm的土壤盐分变化结果不显著。 相似文献
11.
Allan Walker 《Pest management science》1978,9(4):326-332
[14C]-Labelled methazole was incubated in six soils at 25°C and with soil moisture at field capacity. Under these conditions, methazole was unstable, the concentration declined following first-order kinetics with half-life values in the soils ranging from 2.3 to 5.0 days. The main degradation product was 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) which was more stable than the parent compound. After about 160 days, DCPMU accounted for 30 to 45% of the initial methazole concentration. Degradation of methazole and DCPMU was affected by soil temperature and moisture content. With methazole, half-lives in one soil at field capacity moisture content and temperatures of 25, 15 and 5°C were 3.5, 8.7 and 31.1 days respectively. The half-life at 25°C was increased to 5.0 days at 50% of field capacity and 9.6 days at 25% of field capacity. A proportion of the initial radioactivity added to the soil could not be extracted and this proportion increased with time. After 160 days this unextractable radioactivity accounted for up to 70% of the amount applied. 相似文献
12.
The relationship between the residual phytotoxic activity of pethoxamid (2-chloro- N -[2-ethoxyethyl]- N- [2-methyl-1-phenyl-1-propenyl] acetamide) on rice ( Oryza sativa cv. Kiyohatamochi) seedlings and its behavior in soil was investigated under different moisture conditions. The phytotoxic activity of pethoxamid on the shoot growth of rice seedlings in soil was higher in 80% soil moisture content than in 70% and 60% soil moisture contents. The phytotoxic activity in soil in 70% and 80% soil moisture conditions decreased with the increasing time after application, but the phytotoxic activity was slight in 50% soil moisture conditions at any given time after application. The residues of pethoxamid in soil water, the amount adsorbed on soil solid, and the amount in total soil was reduced with the time after application in a similar manner among these soil moisture conditions. The residual phytotoxic activity of pethoxamid on the shoot growth of rice seedlings in soil was more highly correlated with the concentration in soil water than with the amounts adsorbed on soil solid and in total soil. The partition coefficients between the amounts of pethoxamid adsorbed on soil solid and its concentration in soil water were similar among the soils with different moisture conditions at each day, and the partition coefficient increased with the time after application. These results suggested that the residual phytotoxic activity of pethoxamid in soil depends on the decreasing concentration of pethoxamid in soil water with time, except in low soil-moisture conditions, which were insufficient for seedling growth. 相似文献
13.
关中地区耕作方法与土壤紧实度时空变异及其效应分析 总被引：11，自引：0，他引：11
为了探明关中地区土壤紧实度的基本情况,揭示长期旋耕方法对于土壤紧实度的作用与影响,在关中头道塬设置了旋耕和深翻处理、休闲和种植小麦处理的定位观察试验,在小麦各生育阶段分别监测了0～40 cm剖面范围内土壤紧实度变异情况,分析了影响土壤紧实度的因子等.结果表明:播前施行旋耕土壤紧实度较高,尤其是在15～40 cm表现得较为明显,限制了作物根系伸长;深耕松土的效应在整个小麦生育期间都能得到明显的体现.实验证实了生产上现行的旋耕方法具有明显地导致土壤紧实化的问题.土壤紧实度与含水量明显相关,影响程度随土壤深度的增加而增大;土壤紧实度对含水量的敏感反应意味着土壤干燥化会对作物生长带来干旱和机械双重胁迫;同时随着紧实度的增加土壤内部温度变化幅度也在增大.可见现行旋耕方法使得土壤不良环境缓冲性降低,对于降水或者灌溉的依赖性在增强,土壤已经处于明显疲劳状态. 相似文献
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15.
通过连续6年定位试验，探究较长时间施用生物炭对土壤保水作用的影响，以期为塿土区水土保持和土壤改良提供理论参考。田间试验于2011年开始，设4个生物炭施用梯度：对照，不施生物炭（B0）；5 t·hm-2（B5）；10 t·hm-2（B10）；20 t·hm-2（B20）。在2017年测定了土壤含水量、土壤基础理化性质和水分累积蒸发量等。结果表明：生物炭能够显著减小土壤容重、增加土壤孔隙度、饱和含水量和田间持水量，且随着生物炭施入量的增加，各指标变化幅度也增大，B20与B0处理相比，土壤容重减少了8.28%，毛管孔隙度增加了20.17%，饱和含水量与田间持水量分别增加了22.17%和14.86%；生物炭显著增加了土壤团聚体稳定性，B20与B0处理相比，土壤水稳性团聚体含量增加了19.00%，团聚体破坏率和不稳定团粒指数分别降低了11.34%和9.61%；生物炭还可有效抑制土壤水分的蒸发，B10和B20处理的土壤累积蒸发量分别比B0处理减少了7.45%和10.18%。结合逐步回归分析与通径分析发现，生物炭对土壤结构的改良是其促进土壤持水能力的主要原因。土壤孔隙度和有机碳含量是影响土壤饱和含水量的主要因子，影响土壤毛管持水量的主要因子为有机碳含量和土壤毛管孔隙度，而毛管孔隙度与水稳性团聚体含量则解释了绝大部分土壤田间持水量的变化。研究表明生物炭施用可以显著改良土壤结构，提升塿土持水性能，增加干旱半干旱地区土壤的蓄水保墒能力。 相似文献
16.
17.
Detoxification of glyphosate in soil 总被引：1，自引：0，他引：1
Detoxification of glyphosate in not-autoclaved and autoclaved soils was followed by bioassay with wheat. Comparisons are made with detoxification of MCPA under similar conditions followed by bioassay with spring rape. The well known pattern for microbial metabolism of MCPA with a ‘lag’-phase preceding the rapid degradation was shown. The initial rapid inactivation of glyphosate is by adsorption, but the results also clearly indicate that the further disappearance of activity mainly depends on microbial degradation. Glyphosate does not seem to sustain microbial growth, which indicates that it is degraded by co-metabolism. In autoclaved soil the possibility of a slight chemical degradation or an adsorption that becomes stronger with time could not be excluded. 相似文献
18.
Batch adsorption Koc values of fluroxypyr-methylheptyl ester (20000 1kg?1) and fluroxypyr (74 1kg?1) indicate increased mobility after hydrolysis of the ester to fluroxypyr. After 1 to 2 weeks incubation time in four soils, desorption Koc values of fluroxypyr were 100-200 1kg?1 but increased to 400-700 1kg?1 after 8 weeks. The increase in desorption Koc was related to incubation time and not to concentration, and it was interpreted as an entrapment of the fluroxypyr within the soil organic matter. Similar increases in desorption Koc with incubation time were noticed for pyridinol and methoxypyridine metabolites of fluroxypyr. Koc values also increased along the metabolic sequence fluroxypyr/pyridinol/methoxypyridine, with maximum Koc values of 3000-4000 1 kg?1 for the methoxypyridine metabolite. Hence mobility of the fluroxypyr aromatic ring strongly decreases with increased residence time in the soil. 相似文献
19.
R. G. LEHMANN J. R. MILLER E. L. OLBERDING P. M. TILLOTSON D. A. LASKOWSKI 《Weed Research》1990,30(5):375-382
Fluroxypyr-MHE (methylheptyl ester) was added to four soils and incubated at 26 ± 1°C and approximately 0.1 MPa moisture. After initial rapid hydrolysis of the ester to fluroxypyr, fluroxypyr degraded with half-lives of 12, 12, 23, and 7 days in Barnes loam, Catlin silt loam, Hanford sandy loam, and Mhoon clay soils, respectively. Two metabolites (4-amino-3,5-dichloro-6-fluoro-pyridin-2-ol and 4-amino-3, 5-dichloro - 6 - fluoro - 2 -methoxypyridine) were identified, with the pyridinol at its maximum concentration after 2 to 4 weeks of incubation, and the methoxypyridine after 8 weeks. Degradation rates of fluroxypyr and its pyridinol were not significantly altered by diurnally varying soil temperature (21°C to 32°C) or moisture, nor by the presence of growing grass. Methoxypyridine dissipation was more rapid under greenhouse conditions, suggesting that laboratory studies underestimated the dissipation rate of this metabolite. 相似文献
20.
Dissipation of the fungicide pencycuron was examined under controlled laboratory conditions in clay loam soils from rice cultivated fields of alluvial soil (Typic udifluvent) and coastal saline soil (Typic endoaquept) at field rate, twice the field rate and 10 times the field rate with and without decomposed cow manure maintained at 60% of maximum water-holding capacity (WHC) and waterlogged soil condition. The half-life values depended on the initial concentrations of pencycuron. Pencycuron, in general, degraded fastest in coastal saline soil and in soil amended with decomposed cow manure at 60% of maximum WHC of soil. 相似文献