棉田膜下滴灌年限对土壤盐分累积的影响研究

针对新疆土壤盐碱化开发利用和防治土壤次生盐渍化的问题,以新疆121团不同滴灌年限棉田作为研究对象,通过试验得出棉田在膜下滴灌条件下土壤盐分累积规律.结果表明:滴灌条件下,土壤垂直方向上60～80 cm土壤表现积盐.灌后地表0-5 cm土壤容易返盐;水平方向上土壤盐分随着距滴头距离的增加而增加.土壤盐分在生育期的变化遵循"盐随水动"的规律,膜内土壤与膜间土壤的盐分变化具有明显差别,生育期结束时,膜间0-20 cm土层盐分累积显著.随着膜下滴灌年限的延长,土壤盐分在灌前累积的层次逐渐向地表迁移,吐絮期时土壤垂直剖面各个层次之间盐分差异极显著,呈现表层和底端盐分含量大,中间盐分小的分布特征,滴灌年限相差6～7 a的棉田0-100 cm深度内盐分总量差异达到显著水平,并且土壤盐分随膜下滴灌年限延长呈逐渐累积的趋势.     

莫索湾垦区不同滴灌年限及不同水质灌溉棉田盐分运移规律研究

为分析莫索湾垦区不同滴灌年限及不同水质灌溉棉田膜下滴灌盐分的运移规律,从不同土壤质地、不同生育时期、水平方向不同土层、垂直方向不同土层、总盐含量与产量间关系等5个方面对膜下滴灌盐分的运移进行了分析比对,初步得出:黏土中的盐分积累最重,壤土中次之,砂土积累最少;随着生育时期的推后,各土层含盐量都有不同程度的加大;水平方向露地行中央土层盐分积累最多,滴头处盐分积累最少;垂直方向盐分的积累在0-60cm土层逐渐增加,60-100 cm土层盐分积累受膜下滴灌影响较小;总盐含量越高产量下降越严重;总体来说,井水灌处理要比河水灌各处理积盐多.分析认为,井水与河水轮灌,定期大水漫灌洗盐,恢复排碱渠功能以及合理的轮作是土壤脱盐的必要手段.     

滴灌带布置方式与灌水定额对土壤性状及棉花产量影响

通过田间灌溉试验系统地分析了不同滴灌灌水定额和滴灌带毛管布置方式对土壤性状与棉花产量的影响,旨在筛选出一种适宜新疆北疆棉田棉花栽培的滴灌灌水模式。滴灌灌溉田间试验以棉花品种"ND203"为供试作物,采用当前新疆普遍应用的2种典型滴灌带毛管布置方式(一膜两管六行和一膜三管六行)和3种滴灌灌水定额(常规灌水量,节水15%和节水30%灌水量)进行。结果表明:在滴灌灌水定额相同的条件下,与一膜两管六行相比,一膜三管六行滴灌毛管布置方式淋洗棉花行间0～40 cm土层土壤盐分效果最优,棉花产量增加4%～11%;在滴灌带毛管布置模式相同条件下,灌水定额越大,棉花行间0～40 cm土层土壤总孔隙度越大、容重越小、持水能力越强,棉花单株成铃数越多。因此,可以认为一膜三管六行滴灌带毛管布置方式与节水15%灌水定额(全生育期灌溉定额为3434 m3hm-2)相组合,棉花产量达到最高(6078 kg hm-2),是北疆棉田棉花栽培节水灌溉的首选。     

基于电磁感应的不同膜灌模式下棉田土壤盐分分布研究

选择“1 膜1 管4 行”(114 模式)、“1 膜2 管4 行”(124 模式)以及覆膜漫灌3 种不同膜灌模式下典型棉田地块点位, 同时测定膜上宽行(W)、膜上窄行(N)以及膜间(I)3 个位置不同离地高度的大地表观电导率(EC_a), 建立不同土层深度盐分含量解译模型, 研究不同膜灌方式下盐分的垂直和水平分布特征。研究结果表明: 水平方向上, 0~10 cm土层, 114 模式下膜上窄行盐分含量高于宽行, 124 模式下膜上窄行盐分含量低于宽行,漫灌模式下膜上宽行和窄行盐分含量差异不大; 垂直方向上, 3 种模式下盐分均呈现一定的表聚趋势, 盐分最大值出现在10~20 cm 土层, 80 cm 以下土层土壤盐分含量趋于稳定。基于电磁感应建立的土壤剖面盐分解译模型具有良好精度, 方便快捷, 可实现不同膜灌方式下棉田土壤盐分分布的快速预测, 对指导农业生产具有重要意义。     

干旱区咸水滴灌土壤盐分的分布与积累特征

通过三年咸水灌溉田间试验,探讨了新疆干旱区膜下滴灌条件下,咸水灌溉后土壤中盐分的分布及积累特征。研究结果表明:膜下滴灌棉田持续利用咸水进行灌溉,土壤中盐分逐年增加,积盐程度随灌溉水盐度的增加而加重。地表滴灌土壤盐分的表聚明显;而地下滴灌在滴灌管上部土层盐分含量较高。与地表滴灌相比,地下滴灌的盐分会被淋洗到更深的土层。两种滴灌方式下,0￣100cm土壤平均盐度均逐年增加,且积累程度随灌溉水盐度增加而加重。在干旱区连续进行咸水灌溉,盐分的累积效应非常明显,如果不采取必要的洗盐措施,土壤中盐分最终会累积到危害作物生长的程度。     

不同矿化度咸水膜下滴灌棉花土壤盐分累积规律及其数值模拟

咸水膜下滴灌技术是缓解干旱区灌溉水资源短缺的有效途径之一。该研究基于3 a不同梯度矿化度(2、3、4、5、6 g/L)水源膜下滴灌棉花测坑试验,分析棉花全生育期时段内不同土层盐分累积规律,并基于土壤水分及溶质运动理论构建了咸水滴灌棉田土壤盐分HYDRUS-2D数值模拟模型,分析数值模拟不同咸水矿化度下土壤盐分分布与运移累积特征的可行性。结果表明:1)3、4 g/L矿化度处理下盐分在时间水平上积累量少,且棉花株高、叶绿素、籽棉产量高于5、6 g/L矿化度处理,4 g/L为灌溉水源盐分阈值。2)土壤电导率随灌溉生育期整体呈现出逐渐累加的趋势,至吐絮期达到峰值;滴头位置处电导率随土层深度的增加均呈先增后减趋势,在60～70cm土层达到峰值,该土层各不同矿化度处理土壤电导率分别为3.04、3.18、3.15、3.00、3.12dS/m;3)盐分累积过程中呈锯齿型波动,灌溉水源矿化度越高累积趋势越显著;各土层盐分累积模拟精度以30 cm土层最高、10 cm土层最低,50 cm土层居中,不同土层实测值与模拟值的平均绝对误差小于等于0.168、平均相对误差小于等于15.321、均方根误差小于0.2、决定系数大于0.79,土壤盐分实测值与模拟值具有很好的一致性,说明数值模拟的可行性。研究结果可为干旱区不同矿化度水源膜下滴灌棉花土壤盐分运移机理研究提供依据。     

微咸水膜下滴灌不同灌水量对水盐运移和棉花生长的影响

在新疆巴州水管处重点灌溉试验站进行了不同微咸水灌水量(分别为300mm,337mm,375mm和412.5mm)的棉田膜下滴灌试验,研究了不同微咸水灌水量对棉田不同水平位置和垂直深度处的土壤水盐运移影响,分析了在不同灌水量下棉花生长及产量的变化,以寻求适宜棉花生长的膜下滴灌灌溉制度。结果表明:在棉花生育期内,土壤0—40cm深度宽行土壤含水量随灌水量变化波动较小,窄行及膜间土壤含水量随灌水量变化波动较大,膜间土壤含水量较宽行窄行要小;棉花生育期内滴头下方0—20cm的土壤含盐量均有减小,20—40cm土层的土壤含盐量随灌水的波动较大,灌水量较小的土壤含盐量较大,375mm灌水量对棉花根区土壤盐分淋洗的效果最好;随着灌水量的增加,宽行0—40cm土壤盐分均有一定程度的累积,窄行土壤均表现为脱盐,而膜间土壤由脱盐转变为积盐;种植区总的脱盐率分别为-12.8%,-33.3%,89.0%和94.4%;微咸水灌水量较大的棉花株高和茎粗变化较快,叶片数越多,叶面积越大;在棉花生育期末不同灌水量处理对铃重影响较大,且灌水量越大棉花产量越大,籽棉产量分别为4 681.35,5 052.45,5 006.85,5 817.90kg/hm2。     

灌水处理对漫灌改滴灌红枣土壤盐分时空分布的影响

为确定南疆沙区成龄红枣漫灌改滴灌适宜的滴灌模式,采用双因素组合试验设计,研究了不同灌溉定额(900,1 050,1 200mm)和灌水次数(10,14,18次)对红枣漫灌改滴灌后整个生育期0—200cm土层盐分时空分布及产量的影响。结果表明:水平方向上各处理均表现为距树干越远土壤盐分质量比越高,增大灌溉定额使距树干60cm处0—20cm土层土壤盐分质量比明显增大;增加灌水次数可以显著降低距树干60cm处0—80cm土层土壤盐分质量比。垂直方向上土壤盐分质量比呈"S"形分布,表层土壤有明显积盐现象;不同灌溉定额处理垂直方向上均出现一个低盐带(2g/kg),低盐带深度范围随灌溉定额的增加而增大。漫灌相比改滴灌水平方向上土壤盐分质量比变化不大,且表层土壤也无明显积盐现象。整个生育期内,各处理土壤盐分质量比峰值出现在6月新稍期或7月花期;在0—200cm土层,10次、1 200mm灌水处理和14次、900mm灌水处理的盐分淋洗效果与漫灌CK处理相近,漫灌处理只在0—100cm土层盐分淋洗效果明显优于改滴灌处理。灌水次数对0—200cm土层各时间阶段土壤盐分质量比的影响弱于灌溉定额。漫灌改滴灌不同于连续滴灌,漫灌改滴灌后,过低或过高的灌溉定额均不利于提高红枣的产量,与其他处理相比,18次、1 050mm灌溉定额处理不但具有合理的盐分时空分布,且产量(7 549kg/hm2)和水分利用效率最高,比漫灌增产12.87%,节水30%,可以作为当地节水、高产和高效的红枣漫灌改滴灌灌溉制度。     

海冰水膜下滴灌对棉花产量和水分利用效率的影响

在河北省黄骅中捷农场进行矿化度为3 g/L的海冰水膜下灌溉试验,研究不同灌溉处理对土壤水分含量、盐分积累、棉花生长发育、产量及水分利用效率的影响.结果表明,与井水灌溉相比,海冰水灌溉可以增加土体的中下层土壤含水量.海冰水灌溉会引起土壤表层盐分含量的增加,但经过雨季水分的淋洗作用,盐分会得到很大程度的淋溶,因此,在棉花生长后期2种不同灌溉水源处理,土壤各层次盐分含量无显著差异,井水灌溉棉花产量略高于海冰水灌溉,但二者之间产量及产量构成指标差异不显著.海冰水膜下滴灌与漫灌相比,可以显著提高棉花产量和灌溉水利用效率,其中产量提高22%.研究结果表明,矿化度为3 g/L的海冰水可以用于棉田灌溉,结合膜下滴灌技术可以有效提高灌溉水的利用效率.     

准葛尔盆地南缘不同土壤质地棉田膜下滴灌盐分运移规律研究

为详细分析准葛尔盆地南缘不同土壤质地棉田膜下滴灌盐分的运移规律,主要从不同生育阶段、滴灌年限、水平方向、垂直方向不同土层、总盐含量与产量的线性关系等5个方面对膜下滴灌盐分的运移进行了分析比对,初步得出:随着生育期的推后,各土层含盐量都有不同程度的加大;垂直方向盐分的积累在0-60 cm土层逐渐增加,60-100 cm土层盐分积累受膜下滴灌影响较小;水平方向背行(露地部分)中央土层处盐分积累最多,滴头处盐分积累最少;不同滴灌年限中滴灌年限越长,棉田中的盐分积累就越多,壤土和砂土中的盐分分布较粘土中的呈更规律的变化;分析认为定期大水漫灌洗盐、做好舂复水工作,以及恢复排碱渠功能是土壤脱盐的必要手段.该研究可以为准葛尔盆地南缘不同土壤质地棉田土壤次生盐渍化防治提供理论依据.     

中国华北地区近40年物候春季变化

根据华北地区7个观测站物候资料,分析了华北地区1963-1996年及北京1963-2005年物候春季的变化特征及其与气温的关系。结果表明:华北地区的物候春季有明显提早来临的趋势,而造成这一变化的主要因素是本地区近40 a来冬春季气温的明显上升。其中1963-1996年间华北地区1-3月及4月的平均气温分别上升了2.3℃与1.7℃,物候春季起止日期分别提前了9d和4d,因而使得春季长度也延长了5d;北京1963-2003年间1-3月及4月的平均气温分别上升了3.5℃与2.6℃,物候春季的起止日期分别提前了11d和10d,但春季长度没有明显变化。     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

沈阳市城市表土中微生物区系变化的初步研究

在沈阳市远郊-近郊-市区等不同城市化水平区内选取林地、草地和路边土几种不同利用方式下的表层土壤,对土壤中的微生物状况进行了初步分析。结果表明,随着城市化水平的提高,土壤中微生物的数量表现为明显的减少趋势。其中变化较大的是细菌,而真菌和放线菌的变化不明显。     

Sediment denitrification in waterways in a rice-paddy-dominated watershed in eastern China

Purpose

Rice-paddy-dominated watersheds in eastern China are intensively cultivated, and lands with two crops receive as much as 550–600 kg?ha^–1?year^–1 of nitrogen (N), mainly through the addition of N-based fertilizers. However, stream N concentrations have been found to be relatively low. Waterways in the watersheds are assumed to be effective “sinks” for N, minimizing its downstream movement. We directly measured net sediment denitrification rates in three types of waterways (ponds, streams/rivers, and a reservoir) and determined the key factors that control net sediment denitrification. Such information is essential for evaluating the impact of the agricultural N cycle on the quality of surface water.

Materials and methods

The pond–stream–reservoir continuum was sampled every 2 months at nine sites in an agricultural watershed between November 2010 and December 2011. Net sediment N₂ fluxes/net sediment denitrification rates were determined by membrane inlet mass spectrometry and the N₂/Ar technique. A suite of parameters known to influence denitrification were also measured.

Results and discussion

Net denitrification rates ranged between 28.2?±?18.2 and 674.3?±?314.5 μmol N₂–N?m^–2?h^–1 for the streams, 23.7?±?23.9 and 121.2?±?38.7 μmol N₂–N?m^–2?h^–1 for the ponds, and 41.8?±?17.7 and 239.3?±?49.8 μmol N₂–N?m^–2?h^–1 for the reservoir. The mean net denitrification rate of the stream sites (173.2?±?248.4 μmol N₂–N?m^–2?h^–1) was significantly higher (p?<?0.001) than that of the pond sites (48.3?±?44.5 μmol N₂–N?m^–2?h^–1), and the three types of waterways all had significantly higher (p?<?0.01) mean net denitrification rates in summer than in other seasons. Linear regression and linear mixed effect model analysis showed that nitrate (NO₃ ^?–N) concentration in surface water was the primary controlling factor for net sediment denitrification, followed by water temperature. Using monitoring data on NO₃ ^?–N concentrations and temperature of the surface water of waterways and an established linear mixed effect model, total N removed through net sediment denitrification in the pond–stream–reservoir continuum was estimated at 46.8?±?24.0 t?year^–1 from July 2007 to June 2009, which was comparable with earlier estimates based on the mass balance method (34.3?±?12.7 t?year^–1), and accounted for 83.4 % of the total aquatic N. However, the total aquatic N was only 4.4 % of the total N input to the watershed, and thus most of the surplus N in the watershed was likely to be either denitrified or stored in soil.

Conclusions

High doses of N in a rice-paddy-dominated watershed did not lead to high stream N concentrations due to limited input of N into waterways and the high efficiency of waterways in removing N through denitrification.     

Patterns in trace elements in lichens

Water, Air, & Soil Pollution - Epiphytic lichens were sampled in a Dutch national monitoring survey, which was carried out twice within 5 yr. The samples were analyzed by neutron activation...     

Trace metals in precipitation in Sweden

Trace metals (Cd, Cu, Fe, Mn, Pb, and Zn) concentrations in atmospheric precipitation have been routinely monitored in Sweden since the autumn of 1983. Concentrations are highest in southern Sweden and decrease northward. It is postulated that the long range transport of anthropogenic pollutants from the rest of Europe is the major source of Cd, Pb, and Zn in precipitation. Evidence for this hypothesis is that enrichment factors indicate anthropogenic origin, and Swedish atmospheric emissions of Zn and Cd are 2 to 3 times smaller than deposition fluxes. Also, Cd, Pb, and Zn concentrations are correlated in both space and time and are also well correlated with exSO₄ ⁺, a substance known to be of anthropogenic origin transported long distances.     

Trends in soil science in Switzerland

Phytoremediation is an emerging technology based on the use of green plants to remove, contain, inactivate or destroy harmful environmental pollutants. Recent developments in Europe and the USA show that the approach is somewhat different on both sides of the Atlantic. In Europe, phytoremediation has more basically been research driven and, based on the outcomes, applications have been envisaged. By contrast, the approach in the USA is more application and experience driven. In spite of a growing track record of commercial success, more demonstration projects are needed to prove that phytoremediation is effective in order to rigorously measure its underlying economics, and to expand its applications. More fundamental research is also required to better understand the complex interactions between pollutants, soil, plant roots and micro-organisms at the rhizosphere level, to increase the bioavailability of pollutants, to fully exploit the metabolic diversity of plants and, thus, to successfully implement this new green technology.     

不同种植模式下菜地土壤腐殖质组分特性的动态变化

通过在南京普朗克有机农场开展的9年长期定位监测,研究了有机(露地和大棚)和常规种植模式下蔬菜地耕层土壤有机碳和土壤腐殖质组分特性的动态变化。结果表明,有机露地、有机大棚和常规露地种植土壤有机碳含量分别从11.41、9.29、9.00 g k g-1提高至15.35、20.90、10.00 g kg-1;胡敏酸碳(CHA)分别从1.79、1.23、1.14 g kg-1提高至2.11、3.11、1.31 g kg-1;富里酸碳(CFA)分别从2.19、1.88、1.73 g kg-1提高至2.44、2.68、1.91 g kg-1。两种有机种植模式的土壤有机碳及腐殖质组分含量增加达到显著水平,而常规种植模式下的变化不显著。两种有机种植模式下表征土壤腐殖质品质的胡/富比(CHA/CFA)、胡敏酸占总腐殖物质的比例(PQ值)均高于常规种植模式,土壤富里酸的E4/E6值、色调系数(ΔlogK)值随着种植时间增加的幅度较常规种植模式更大,土壤胡敏酸芳化度呈现先降低后增高的趋势,但在常规种植下变化不明显。说明土壤在长期有机种植模式下不仅更有利于土壤有机碳的积累,而且能促进土壤腐殖化进程。     

Variation in ozone concentration in relation to local climate in south-west Sweden

Ozone (O₃) concentration and air temperature/relative humidity were monitored using diffusive samplers (weekly, 3 m above ground) and Tinytag loggers (10 min sampling, 1 m above ground, self-ventilating radiation shields), respectively, in the forested landscape of south-west Sweden, 40 km north-east of Gothenburg. Two forest sites were included, one at a hilltop (175 m a.s.l.), and one in a nearby (～1 km) valley (110 m a.s.l.). In addition, a valley site (～3 km from the forest sites, 60 m a.s.l.) in an agricultural landscape was included, where ozone was measured using both a UV-based monitor and diffusive sampling. At the agricultural site measurements of temperature and relative humidity were made using a radiation shield with forced ventilation and with Tinytags, as on the forest sites, in addition to observations of wind speed and the vertical temperature gradient. Furthermore, comparison with O₃ concentrations at urban and coastal sites in the region was made. The temperature dependent, systematic error of using a self-ventilating radiation shield was estimated and corrected for. It was found that the elevated forested site experienced higher O₃ concentrations and lower evening cooling rates in calm situations as compared to the forest site in the valley and in particular as compared to the agricultural site. This can be explained by a stronger coupling with the planetary boundary layer at the elevated site and more pronounced night-inversions at the valley sites. The difference in weekly O₃ concentration between the two forested sites was correlated with the difference in average minimum night-time temperature. The coastal site had the highest ozone concentrations, related largely, but not fully, to higher night-time O₃ concentrations. The urban site showed a depression in O₃ concentration associated with the combination of large NO emissions and slow air mixing during the morning traffic rush hours.