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1.
华北山前平原典型厚包气带硝态氮分布累积规律 总被引：5，自引：1，他引：4
包气带是连接大气层和含水层水分和养分转换的纽带,也是农田NO_3~–-N分布和累积的重要场所和向含水层淋失的通道,因此研究包气带土壤中NO_3~–-N的分布累积规律对防止地下水NO_3~–-N污染至关重要。本文以中国科学院栾城试验站典型的厚包气带为对象,在无施肥处理(N0)和施氮肥600 kg/(hm~2·a)(N600)两种处理的多年试验田中,利用Geoprobe获取0~10.5 m深度土壤样品,研究厚包气带NO_3~–-N垂向分布、累积规律,并分析其影响因素。结果表明:N0中NO_3~–-N基本保持不变,长年施氮肥600 kg/(hm~2·a)使得NO_3~–-N淋溶至10.5 m,并在深层包气带中形成累积,累积的峰值由土壤的质地和含水量决定;NO_3~–-N的分布和累积主要受水分运移、土壤质地和反硝化作用影响。 相似文献
2.
华北潮土冬小麦-夏玉米轮作包气带氮素淋溶机制 总被引：1，自引：0，他引：1
合理水氮管理可以实现作物目标产量和品质、维持土壤肥力和降低环境污染。然而,自20世纪90年代以来,我国农田过量施氮和大水漫灌等问题突出,引起农业面源污染日趋加重,地下水硝酸盐污染成为一个普遍现象。本文以华北潮土区冬小麦-夏玉米体系为研究对象,采用数据整合和文献分析的方法,阐明了典型农田硝态氮淋溶的时空特征及影响因素,研究了地表裂隙和土壤大孔隙对硝态氮淋溶的影响,定量了氮素在地表-根层-深层包气带-地下水的垂直迁移通量及过程。结果表明,农户常规管理的冬小麦-夏玉米轮作体系氮素盈余较高(299～358kg·hm~(-2)·a~(-1)),导致土壤根区和深层包气带累积了大量的硝态氮。冬小麦季硝态氮的迁移主要受灌溉影响,以非饱和流为主,且迁移距离较短;春季单次灌溉量低于60 mm,可以有效控制水和硝态氮淋溶出根区。冬小麦耕作和灌溉引起的地表裂隙对水氮运移的贡献不大。雨热同期的夏玉米季,土壤水分经常处于饱和状态,再降雨就可以导致硝态氮淋溶出根层进入深层包气带。夏玉米季极易发生硝态氮淋溶事件(占全年总淋溶事件的81%左右),硝态氮淋溶量占全年总淋溶量的80%左右,且单次淋溶事件的淋溶量较高。大孔隙优先流对夏玉米季根区硝态氮淋溶的贡献率在71%左右,这些硝态氮脱离了作物根系吸收范围,反硝化作用对硝态氮去除具有一定作用。在华北气候-土壤条件下,特别应注意冬小麦收获后土壤不应残留过多硝态氮,以避免夏玉米季降雨发生大量淋溶;夏玉米季需要注意施氮与作物需氮的匹配。由于夏玉米追肥困难,生产上提倡一次性施肥措施,控释肥应该能够发挥更大作用。未来气候变化,导致夏季极端高强度降雨事件的频率增加,将会加剧包气带累积硝态氮通过饱和流或优先流向地下水的迁移。合理的水氮管理是从源头上减少硝态氮向深层包气带和地下水迁移的主要措施。 相似文献
3.
RZWQM2模型模拟牛场肥水施用夏玉米土壤硝态氮迁移特征 总被引：1，自引：0，他引：1
为研究华北平原种养结合中养殖肥水的合理施用,减少典型农田水肥施用后土壤氮淋溶对地下水的影响。该研究以河北省徐水区夏玉米为研究对象,应用RZWQM2模型验证牛场肥水施用玉米农田的可行性,对2014—2016年玉米种植前后数据进行模型参数率定与验证。验证结果表明,土壤体积含水率的均方根误差和平均相对误差值分别在0.000 6～0.070 7 cm~3/cm~3和0.21%～21.44%之间变化,土壤硝态氮均方根误差和平均相对误差值分别在0.000 8～2.617 3 mg/kg和0.03%～18.58%之间变化,其中牛场肥水施用土壤中硝态氮主要在0～120 cm土层发生变化,说明RZWQM2模型可以用来模拟华北平原牛场肥水施用对土壤水分、硝态氮含量及玉米产量的动态变化。利用率定和验证后的模型进行了夏玉米农田硝态氮淋溶的验证与预测,表明硝态氮淋溶浓度随肥水氮量的增加而增加。RZWQM2模型可以应用于牛场肥水施用农田的模拟,为预测和评估土壤适宜的肥水施用提供更合适的方法。 相似文献
4.
不同施氮水平对深层包气带土壤氮素淋溶累积的影响 总被引：18，自引：6，他引：12
为研究深层包气带土壤中氮素的迁移规律,采用田间小区试验,研究了不同施氮水平(142.5、285和427.5kg/hm2)对夏玉米种植期间0～500cm包气带土壤中氮素淋溶累积的影响。结果表明,不同施氮水平对NO3--N、NH4+-N和总氮有显著影响,施氮越多,NO3--N、NH4+-N和总氮在土壤中的淋溶累积也就越多,夏玉米生育期间土壤中氮素的淋溶累积含量随着夏玉米生长逐渐减少。在0～200cm土层中,收获后不同施肥水平土壤中NO3--N和总氮累积量随施氮量增加而增多,285kg/hm2施氮水平NH4+-N累积量最多,427.5kg/hm2施氮水平NH4+-N累积量最少,但相差不超过0.1kg/hm2,收获后土壤中氮素累积量有损失。夏玉米生育期间不同施氮水平对土壤NO3--N、NH4+-N和总氮的影响深度主要为0～145cm。粉砂壤土中氮素更易累积,砂质壤土中氮素较易随水分淋溶至下层。142.5kg/hm2施氮水平可有效减少NO3--N在土壤中的淋溶损失,降低土壤中NH4+-N和总氮的含量,对地下水构成的潜在污染风险最小。北京地区地下水埋深较深,NO3--N不易淋溶至地下水,但长期大量施用氮肥、田间土壤大孔隙的存在等会加速NO3--N向深层土壤迁移,对地下水水质构成威胁。 相似文献
5.
为了研究地表水与地下水不同补给关系下硝酸盐氮在傍河农田的迁移规律,选取大沽河河床沙样作为沙槽试验介质,设计地表水与地下水相互补给装置,模拟无补给、地表水补给地下水和地下水补给地表水3种方式下硝酸盐氮在土壤中的迁移,通过测定各取样点硝酸盐氮含量和到达时间,分析了其迁移规律。结果表明:纯淋洗实验中,淋洗强度与沙样颗粒越小,硝酸盐氮在表层沙中的累积越明显,硝酸盐氮的迁移也越慢。地表水与地下水相互补给试验中,补给水位上升,硝酸盐氮的积累量增加、迁移到饱水带的时间缩短;补给水力坡度为0.5时,硝酸盐氮在细沙饱水带中迁移速度约为5.3 cm/min;水力坡度变为0.7时,迁移速度约为9.4 cm/min;补给水力坡度为0.5时,硝酸盐氮在中沙饱水带的迁移速度约为12.3 cm/min。硝酸盐氮在包气带中的积累量随着沙层深度的增加而减少;淋洗强度、水力坡度及沙样颗粒越大,硝酸盐氮在包气带和饱水带中的迁移速度越快;补给水位越高,硝酸盐氮迁移至饱水带的时间越短。 相似文献
6.
再生水灌溉区农田包气带及地下水中硝酸盐分布特征及来源研究 总被引：1，自引：1，他引：0
本文通过对华北平原典型再生水灌溉区(河北省石家庄洨河流域)的包气带土壤、地表水和地下水进行采样分析,对硝酸盐在多种环境介质中的来源与环境行为进行了研究,识别了再生水灌溉区地下水硝酸盐污染来源,明确了不同灌溉条件对包气带土壤中硝酸盐迁移的影响。在受到城市再生水严重影响的洨河流域,地下水中的硝酸盐浓度分布范围在4.0 mg·L?1到156.6 mg·L?1之间,已经形成了距离河道2 km、深度70 m的硝酸盐高值区域,经过计算硝酸盐的垂向扩散速率为每年1～2 m。硝酸盐与氯离子的相关性表明,城市再生水是再生水灌溉区包气带、地表水和地下水中硝酸盐的主要来源。利用Geoprobe获取利用不同灌溉水农田土壤剖面样品,研究再生水对厚包气带NO3?-N垂向分布影响,再生水灌溉区和地下水灌溉区中包气带土壤的NO3?-N的平均含量为137.0 mg·kg-1和107.7 mg·kg-1,最高含量523.2 mg·L?1和725.9 mg·L?1,分别出现1.20 m和0.85 m深度,分布规律有着明显的差别。包气带土壤硝酸盐与氯离子的相关性分析表明,再生水灌溉区土壤硝酸盐主要来源于城市再生水,而地下水灌溉区可能来源于农田氮肥。地下水年龄和硝酸盐之间关系表明,地下水中1975年以前补给的硝酸盐浓度低于1975年以后补给,地下水硝酸盐污染与包气带氮入渗的历史过程密切相关。在华北平原特殊的地质水文背景下,农田面源污染对地下水的影响有限,但再生水灌溉区地下水硝酸盐污染的风险较高。 相似文献
7.
干旱区重度和轻度盐碱地包气带水分运移规律 总被引：2，自引：0，他引：2
为揭示干旱区不同灌溉模式下的包气带水分运移规律,该研究综合使用原位观测、同位素示踪和数值模拟等方法,对跨流域调水背景下,克拉玛依农业开发区重度和轻度盐碱地棉田的土壤水势、土壤含水率和土壤水同位素组成特征,包气带水量平衡以及水分运移规律进行了研究。研究表明,土壤基质势调控的滴灌模式下,重度和轻度盐碱地的灌溉入渗主要影响深度是地表以下0~150 cm,土壤含水率和土壤水势对灌溉和蒸散发动态变化的响应明显,具有前期土壤水和观测期内灌溉入渗水的混合特征。深层(重度盐碱地150~260 cm;轻度盐碱地250~350 cm)受地下水毛细作用影响,土壤水势和土壤含水率对地下水埋深动态变化的响应明显,具有前期土壤水与地下水的混合特征。轻度盐碱地中间层(150~250 cm),几乎不受灌溉入渗和地下水毛细作用的影响,土壤水势和土壤含水率处于动态平衡,主要为前期土壤水的特征。HYDRUS-1D数值模拟结果表明,深层土壤水与地下水之间存在双向交换,地下水对土壤水以补给作用为主,重度和轻度盐碱地地下水补给占包气带水分来源的比例分别为7.9%和15.0%。该灌溉模式对农业开发区地下水补给有一定的抑制作用,但观测期内区域地下水位抬升幅度在50~60 cm之间,说明存在一定的土壤次生盐渍化和地下水咸化的潜在风险。 相似文献
8.
土壤性质对砂土亚表层磷迁移的影响 总被引：5，自引：0，他引：5
ZHANG Ming-Kui 《土壤圈》2008,18(5):599-610
The soil factors influencing the potential migration of dissolved and particulate phosphorus （P） from structurallyweak sandy subsoils were evaluated by means of soil column leaching experiments. Soil colloids were extracted from two types of soils to make the colloid-bound forms of P solution. Eight sandy soils with diverse properties were collected for packing soil columns. The effects of influent solutions varying in concentrations of colloids, P, and electrolyte, on the transport of P and quality of leachates were characterized. P migration in the soils was soil property-dependent. High soil electrical conductivity values retarded the mobility of colloids and transportability of colloid-associated P （particulate P）. Soil electrical conductivity was negatively correlated with colloids and reactive particulate P （RPP） concentrations in the leachates, whereas, the total reactive P （TRP） and dissolved reactive P （DRP） concentrations in the leachates were mainly controlled by the P adsorption capacity and the P levels in the subsoil. The reactive particulate P in the leachates was positively correlated with the colloidal concentration. Increased colloidal concentration in the influent could significantly increase the colloidal concentration in the leachates. Elevated P concentration in the influent had little effect on P recovery in the leachates, but it resulted in significant increases in the absolute P concentration in the leachates. 相似文献
9.
田间施肥后,未挥发和被作物吸收的剩余N素易淋失运移,引起在浅层包气带土壤中的蓄积,且又易再释放进入下层土或地下水中形成污染,并主要受气候、土质结构、微生物作用等的影响。认识和掌握上述规律现象,将有助于研究农田施肥引起地下水污染的治理方法。对田间超量施肥灌溉后,作历时近1年的浅层包气带土壤中N的蓄积试验研究,结果显示:短期内土壤中N的显著蓄积主要发生在土层1.5m以浅部位,随时间、深度及入渗水量的变化而波动。这为探索根治由此引起的地下水污染,提供了较好的应用基础和科学依据。 相似文献
10.
抚仙湖流域砾质土有机及常规肥料淋溶模拟研究 总被引：2，自引：1，他引：1
利用不同高度土柱进行模拟淋溶试验.比较研究了抚仙湖流域砾质土壤有机及常规肥料N、P流失规律及水体污染风险.试验结果表明:随着灌溉次数的增加,有机肥料淋洗液中 TDN (可溶性总N)浓度先升后降,而常规肥料则持续下降;除20 cm高度土柱常规肥料TDP(可溶性总 P )浓度快速下降外,其余各淋洗液中TDP浓度变化幅度很小.有机及常规肥料土壤N、P淋溶均以NO3--N和P04-P形态为主.不同高度土柱TDN、TDP的淋失总量平均值,常规肥料分别为有机肥料的1 57%、52%,可见常规肥料N素淋溶风险大于有机肥料,而P素淋溶风险则相反. 相似文献
11.
Abstract. The efficiency with which fertilizer nitrogen (N) is used in agricultural systems might be improved if the amounts applied at each top dressing were adjusted to avoid the accumulation of mineral-N in the soil profile to levels in excess of the growth requirements of the crop. Such tactical application of fertilizer would be feasible if soil mineral-N could be determined rapidly in the field with sufficient accuracy. This paper describes a rapid field test for both the ammonium and nitrate components of soil mineral-N based on reading paper test strips with a reflectometer, recalibrated for use with KC1 solution. The new test is volumetric and also accounts for the effects of fluctuations in soil water content by means of a standard dilution procedure to provide an absolute measure of soil mineral-N in about one hour. Measurements of ammonium and nitrate in a clay loam soil sampled from grazed pasture were compared with those made by conventional laboratory based methods; they generally differed by less than 5%. The proportion of mineral-N as ammonium averaged about 50% overall and typically exceeded 70% in spring. Ammonium and nitrate were not well correlated. The use of a filter-press to expel soil solution increased the sensitivity of the test five-fold to enable application in studies of soil N transformations in unfertilized and semi-natural environments. 相似文献
12.
小麦根系对水分和氮肥的生理生态反应 总被引：37，自引：4，他引：33
利用模拟土柱研究了不同水分和氮素营养条件下春小麦根系的生理生态反应。结果表明 ,适量施氮 (尿素 60 0kg/hm2)增加了总根重和深层土壤中的根重 ,改善了根系的水分关系 ,提高了细胞膜的稳定性 ,因而有助于提高小麦的抗旱性 ;过量施氮 (尿素 150 0kg/hm2)增加上层根重对抗旱性的意义并不大。严重水分胁迫下 ,过量施氮导致根细胞膜伤害率明显增加 ,根系水分关系恶化 ,根系保水能力下降 ,使小麦抗旱性降低 相似文献
13.
Abstract. Bypass flow and concurrent leaching of nitrogen were studied on a Vertisol in south-western Kenya under rangeland and bare, manually tilled cropland. Showers of 30 mm/hr were simulated, causing bypass flow of 47–62% in rangeland topsoils and 19–49% in cropland topsoils. Volumetric water contents after experimentation increased from 28 to 35% and from 24 to 38%, respectively, for the two land-use types.
In rangeland samples up to 3.4 kg N/ha was found in the leachate of unfertilized soil. With a fertilizer application of 50 kg N/ha, up to 5.7 kg N/ha was lost from a pre-wetted soil, and more than 20 kg N/ha from dry soil. In cropland topsoils up to 2.2 kg N/ha was lost from unfertilized soil, and only up to 2.9 kg N/ha from both dry and prewetted fertilized soil. Although Vertisols are often linked with excess water, the phenomenon of bypass flow can cause water stress to crops in their early growth stages. Nitrogen leaching losses were large from dry grassland, but prewetting helped to decrease them. On intensively cultivated cropland there was little nitrogen leaching; the tilled topsoil was able to retain most of the supplied nitrogen. 相似文献
In rangeland samples up to 3.4 kg N/ha was found in the leachate of unfertilized soil. With a fertilizer application of 50 kg N/ha, up to 5.7 kg N/ha was lost from a pre-wetted soil, and more than 20 kg N/ha from dry soil. In cropland topsoils up to 2.2 kg N/ha was lost from unfertilized soil, and only up to 2.9 kg N/ha from both dry and prewetted fertilized soil. Although Vertisols are often linked with excess water, the phenomenon of bypass flow can cause water stress to crops in their early growth stages. Nitrogen leaching losses were large from dry grassland, but prewetting helped to decrease them. On intensively cultivated cropland there was little nitrogen leaching; the tilled topsoil was able to retain most of the supplied nitrogen. 相似文献
14.
Denitrification in subsoil(to a depth of 12 m) is an important mechanism to reduce nitrate(NO_3~-) leaching into groundwater.However, regulating mechanisms of subsoil denitrification, especially those in the deep subsoil beneath the crop root zone, have not been well documented. In this study, soil columns of 0–12 m depth were collected from intensively farmed fields in the North China Plain. The fields had received long-term nitrogen(N) fertilizer inputs at 0(N0), 200(N200) and 600(N600) kg N ha~(-1) year~(-1). Main soil properties related to denitrification, i.e., soil water content, NO_3~-, dissolved organic carbon(DOC), soil organic carbon(SOC),pH, denitrifying enzyme activity(DEA), and anaerobic denitrification rate(ADR), were determined. Statistical comparisons among the treatments were performed. The results showed that NO_3~- was more heavily accumulated in the entire soil profile of the N600 treatment, compared to the N0 and N200 treatments. The SOC, DOC, and ADR decreased with increasing soil depth in all treatments,whereas considerable DEA was observed throughout the subsoil. The long-term fertilizer rates affected ADR only in the upper 4 m soil layers. The ADRs in the N200 and N600 treatments were significantly correlated with DOC. Multiple regression analysis indicated that DOC rather than DEA was the key factor regulating denitrification beneath the root zone. Additional research is required to determine if carbon addition into subsoil can be a promising approach to enhance NO_3~- denitrification in the subsoil and consequently to mitigate groundwater NO_3~- contamination in the intensive farmlands. 相似文献
15.
Wood Ash Effects on Soil Solution and Nutrient Budgets in A Willow Bioenergy Plantation 总被引：1，自引：0，他引：1
Park Byung Bae Yanai Ruth D. Sahm James M. Ballard Benjamin D. Abrahamson Lawrence P. 《Water, air, and soil pollution》2004,159(1):209-224
The management of wood ash is an important factor in the environmental and economic analysis of wood burning. Wood ash can be applied to energy crops as a fertilizer, which can help replace nutrients removed during harvest. The objectives of this study were to examine the temporal and spatial dynamics of nutrient elements applied in wood ash to an intensively cultured, short-rotation willow bioenergy system. Wood ash was applied at the rates of 10 and 20 Mg ha–1 yr–1 to coppiced willow, Salix purpurea, clone SP3, from 1992 to 1994. The relative abundance of nutrients in applied wood ash was Ca > K > Mg > P > N. There was little effect of wood ash on N or P concentrations in soil solution measured at 20 and 40 cm depth. Soil solution concentrations of base cations were elevated in the last two years of the study by 30 to 90%, depending on the element and treatment, in plots receiving wood ash. Wood ash treatments had little influence on foliar leaching. Wood ash treatment also had few significant effects on willow growth or on the contents of N, P, K, Ca, and Mg in foliage and stems. The addition of P, K, Ca, and Mg in wood ash was more than enough to compensate for harvest removals and leaching losses. This study demonstrated that wood ash can supply most nutrients removed during harvest in willow plantations, with the exception of N, without adverse effects on groundwater or vegetation. 相似文献
16.
华北农区浅层地下水硝酸盐分布特征及其空间差异性 总被引：10，自引：5，他引：5
华北平原地下水硝酸盐污染备受关注,然而受地貌类型、土地利用、土壤结构、含水层水文地质条件等因素差异性的影响,对区域尺度上农区浅层地下水硝酸盐污染程度和特征尚没有统一定论。本文通过综述过去华北平原地下水硝酸盐污染程度的相关研究,并结合近年来对华北平原农业种植区浅层地下水硝酸盐研究所取得的认识,指出补给源区(太行山低山丘陵区)、山前平原和低平原3个典型地貌类型区浅层地下水硝酸盐研究存在的问题:补给源区土地利用变化多样、土壤和含水层渗透性好,要重视对源区氮输入的控制,加强低山丘陵区气候变化对水文过程和氮迁移过程影响机制的研究;山前平原区是农业高产区,地下水埋深较深且包气带厚度大,较高的浅层地下水硝酸盐浓度除了与点源、污水渗漏以及污水灌溉等直接影响因素有关外,农田过量肥料施用对地下水硝酸盐影响的程度、水氮迁移路径以及未来潜在风险是农区地下水硝酸盐研究中亟需关注的问题;低平原区较细的土壤沉积结构减缓了氮向下迁移的速度,但地下水埋深较浅,二者的制约关系决定了地下水硝酸盐浓度,因此应在理解地表水-土壤-地下水转化关系的基础上评估地下水硝酸盐污染的风险。 相似文献
17.
采用盆栽试验方法研究了秸秆填埋对水稻土表层水三氮动态变化的影响。结果表明,施肥后,表层水总氮、铵态氮浓度迅速增加;随时间的推移,表层水氮素浓度下降较快。全氮在施肥后第1d达到峰值,铵态氮在施肥后第2d达到高峰,施肥后7d氮素含量基本与施肥前水平一致。秸秆还田有效地降低了水稻土表层水氮素含量,秸秆深埋处理有利于土壤对氮素吸收,使氮素的流失几率降低（DS处理比N处理表层水全氮浓度平均低10.2%）,流失潜能趋势大大减小。结果显示,施肥后1周内是控制表层水氮素流失的关键时期。 相似文献
18.
Uwe Buczko Luisa Hopp Wolfgang Berger Wolfgang Durner Stefan Peiffer Markus Scheithauer 《植物养料与土壤学杂志》2004,167(3):284-292
Heavy metal contaminations in the top‐soil layers can impose serious threats to groundwater quality. A seepage water prognosis of probable future contaminant entries at the groundwater surface has to take into account the emission characteristics of the source zone and the reactive transport of the contaminated leachate through the unsaturated zone. Here, a possible approach is presented, exemplarily for a site contaminated with chromium, encompassing batch elution experiments, unsaturated soil column leaching experiments with flow interruption, soil monolith lysimeter experiments, and numerical modeling of non‐equilibrium solute transport. The prognosis provides a long‐term prediction of Cr concentrations at the groundwater surface. It must be emphasized, that the modeling results are uncertain, because several of the parameters in the simulations can be determined only with significant errors. Additionally, the approach is not applicable routinely for every hazardous waste site. Our study reveals, however, that reactive contaminants can possibly reach the groundwater at hazardous concentrations within very short time. 相似文献
19.
降雨入渗条件下厚包气带土壤水流通量的模拟与分析 总被引：3，自引：1，他引：2
降雨较少的半干旱半湿润地区大范围的厚包气带中土壤水运动的研究越来越受到关注,其中厚包气带对降雨补给浅层地下水特征的影响是重要的研究问题。探究厚包气带情形下降雨对浅层地下水的补给作用和机理可为分析人类干扰情况下水文循环规律的变化、合理地制定水资源开发利用规划提供理论依据。本文以北京市大兴区新凤河流域采育镇由GEOPROBE钻机获得的9.6m厚包气带土壤样品为研究对象,在室内详细测得土壤特性数据的基础上,运用HYSRUS-1D软件模拟55a降雨入渗条件下的一维土壤水流动态过程,分析土壤水流通量的时空变异特征,探讨用较浅层位(2m深度附近)的土壤水流通量来估算深层土壤水渗漏量的可行性,旨在为野外裸地厚包气带条件下评价降雨入渗对浅层地下水的补给提供简捷实用的方法。研究结果表明:该地区多年自然降雨条件下的平均土壤水分深层渗漏量为131.03mm,多年平均降雨入渗补给系数约为0.21。其中,平水年对应的平均降雨入渗补给系数约为0.18。当模拟时段达到55年时,土壤剖面2m以下的入渗通量几乎不随深度变化而变化。这一实际案例的研究结果对该区域宏观水资源管理和评价具有一定的参考价值。 相似文献
20.
Hong‐mei Yu Zi‐zhong Li Yuan‐shi Gong Ulrich Mack Karl‐Heinz Feger Karl Stahr 《植物养料与土壤学杂志》2006,169(1):47-51
Traditional irrigation and nitrogen (N) fertilization in North China may elevate water drainage and nitrate concentrations in soil and groundwater. A field experiment was conducted in an intensively irrigated vegetable (cauliflower, amaranth, and spinach) field for three consecutive years (1999–2002). The main objective was to test to what extent an improved water and fertilizer management, based on the maintenance of field capacity a defined range of the water content in the 0–50 cm soil layer and an N expert system, could reduce drainage and nitrate leaching without impairing vegetable yield. Rates of water drainage and related nitrate leaching were calculated based on measurements of soil water potential and soil‐water nitrate concentrations. Soil water potential was monitored with tensiometers at depths of 75 cm and 105 cm. Nitrate concentrations were analyzed in soil leachates collected at 90 cm soil depth using ceramic suction cups. The results revealed that the average annual drainage related to the cultivation season for cauliflower, amaranth, and spinach was reduced from 275 mm in the traditional system to 29 mm with improved management practice. The average annual cumulative nitrate leaching during the vegetable‐growing period amounted to 301 kg ha–1 and 13 kg ha–1 in the traditional and improved management practices, respectively. Vegetable yields were not significantly different under the traditional and improved management practices. 相似文献