共查询到20条相似文献，搜索用时 15 毫秒
1.
以博斯腾湖西岸湖滨绿洲为研究区,采用Pearson相关分析与主成分分析方法,探究研究区土壤盐分特征。研究结果表明:(1)土壤表层盐分类型主要为氯化物-硫酸盐类型,其占比大于60.00%;土壤全盐量、Na~++K~+、Ca~(2+)、SO_4~(2-)和C1~-的变异系数均大于100.00%,呈强变异性,HCO_3~-的变异系数大于90.00%,小于100.00%,呈中等变异性;Mg~(2+)在0～10与10～30 cm土壤层中分别呈强变异性与中等变异性,变异系数分别为132.85%与93.30%;(2)土壤全盐量与主要土壤盐分离子均存在极显著正相关(P0.01),与土壤全盐量相关性最强的土壤盐分离子为Na~++K~+,相关系数为0.99,相关性最低的土壤盐分离子为Mg~(2+),相关系数为0.37;(3)在不同土地利用类型中,土壤全盐量由高至低依次为未利用地(11.82 g·kg~(-1))林地(5.98 g·kg~(-1))草地(4.89 g·kg~(-1))耕地(2.50 g·kg~(-1)),土壤全盐量变异系数依次为耕地草地林地未利用地,变异系数最大为176.31%,变异系数最小为87.97%;(4)土壤盐分状况的特征因子为Na~++K~+、HCO_3~-、SO_4~(2-),其主成分综合得分模型Y=0.09(HCO_3~-)+0.30(Cl~-)+0.10(SO_4~(2-))+0.17(Ca~(2+))+0.18(Mg~(2+))+0.09(Na~++K~+),综合得分的平均值为0.58,变异系数为122.00%,呈强变异性。 相似文献
2.
《土壤通报》2020,(4)
探明张掖盆地北部地下水溢出带土壤含盐量、盐分组成及盐分离子的空间分布特征,为当地土壤盐渍化防治和土地资源管理及其可持续利用提供理论依据。土壤盐分数据分析使用了描述性统计、Kriging插值、相关性分析及主成分分析方法。结果表明:研究区土壤以强碱性为主,其阴离子以SO_4~(2-)为主,阳离子以K~++Na~+为主,全盐含量和盐分离子含量具有较强的空间变异性;研究区北部土壤大多数属于非盐渍化等级,而中部及西南部土壤以硫酸盐型轻盐渍化等级为主;SO_4~(2-)、Cl~-、Mg~(2+)、K~++Na~+、Ca~(2+)是引起全盐含量变化的主导因素,盐分离子间具有相关性,且以SO_4~(2-)与Mg~(2+)相关性最高,而Cl~-与K~++Na~+相关性最高;全盐含量、SO_4~(2-)、Cl~-、Mg~(2+)、K~++Na~+、Ca~(2+)是表征研究区土壤盐渍化现象的特征因子;土壤盐渍化的盐分主要是以镁盐为主的硫酸盐和以钠盐、钾盐为主的氯化物。 相似文献
3.
以库车绿洲为例,探讨了星载雷达影像对表征土壤盐渍化微观离子的响应情况.选取春、秋两季的Radarsat影像数据,野外采集土壤剖面0-10 cm和0-50cm处土样,室内测定其8大粒子含量(Na~+,K~+,Mg~(2+),Ca~(2+),Cl~-,SO_4~(2-),HCO_3~--,CO_3~(2-))以及pH值、电导率、矿化度、含盐量.采用GPS定位技术,记录每一采样点位的经纬度坐标和雷达影像进行匹配,采用灰色关联分析法分析了Radarsat C波段HH极化对微观粒子在春、秋季节0-10 cm和0-50 cm土壤剖面的响应.结果表明,春季雷达影像对pH值响应强烈,对含盐量响应不稳定,对电导率、矿化度响应一般.就阳离子而言,对Ca~(2+)响应最为显著;就阴离子而言,对HCO_3~-响应最为显著.10月份雷达影像对pH值、电导率响应强烈,对含盐量响应不稳定,对矿化度响应一般.就阳离子而言,无明显规律.就阴离子而言Cl~-响应最为显著,SO_4(2-),HCO_3~-无明显规律. 相似文献
4.
双河洞小流域主要离子化学特征及其来源分析 总被引：2，自引：0，他引：2
为探究岩溶地表水和地下水水化学特征及其各种盐类对主要离子的贡献,以喀斯特小流域为研究尺度,对贵州绥阳双河洞区域地表水和地下水水化学进行野外监测、采样和室内实验,并运用SPSS统计软件对水样点进行主成分分析研究。结果表明:(1)双河洞水化学阳离子主要以Ca~(2+)、Mg~(2+)为主,阴离子以HCO_3~-和SO_4~(2-)为主。水化学类型主要为Ca~(2+)·Mg~(2+)—HCO_3~-型水,而石膏洞为Ca~(2+)·Mg~(2+)—SO_4~(2-)型水。大多数离子的含量随采样点、季节和水体类型的不同而呈显著性差异;(2)岩石风化对流域离子组成影响显著,阴离子主要来自碳酸盐、蒸发盐或岩盐的溶解和风化,蒸发盐溶解是阳离子的主要控制机制,硅酸盐风化侵蚀作用对区域离子变化存在一定影响;(3)主成分分析法得出对区域离子化学组成的影响程度按碳酸盐、蒸发盐和硅酸盐递减,其中H_2CO_3风化碳酸盐岩的影响显著,但在个别地下水主要受H_2SO_4风化碳酸盐岩的影响显著,此外农业活动和居民生活也有一定影响。研究结果对双河洞洞区水资源的保护和开发利用及岩溶碳循环研究具有重要意义。 相似文献
5.
为研究土壤中盐分离子对小白菜Pb含量的影响,采取正交试验L_(16)4~5和盆栽试验方法,分析了5种阳离子(Ca~(2+)、Mg~(2+)、K~+、Na~+、Pb~(2+))和3种阴离子(SO_4~(2-)、Cl~-、NO_3~-)对小白菜地上部和根系中Pb含量的影响。结果表明,试验条件下小白菜地上部Pb含量为0.215~0.930 mg·kg~(-1),根系中Pb含量为1.648~24.33 mg·kg~(-1),可食用部分超标率达81.3%。土壤盐分离子对小白菜地上部Pb含量影响顺序为:Ca~(2+)Mg~(2+)Na~+Pb~(2+)K~+。根据相关性分析,土壤中Ca~(2+)与小白菜地上部Pb含量呈显著负相关(r=-0.540 3,P0.05),Na~+和Pb~(2+)呈正相关但不显著。Mg~(2+)和K~+呈负相关,也不显著。Cl~-和NO_3~-与小白菜地上部Pb含量呈显著负相关(r=-0.540,P0.05),SO_4~(2-)呈正相关,但不显著。对小白菜根系Pb含量影响顺序为:Pb~(2+)K~+Na~+Ca~(2+)Mg~(2+),土壤中Pb~(2+)对小白菜根系Pb的含量呈显著正相关(r=0.483,P0.05),Ca~(2+)、Mg~(2+)、K~+、Na~+、SO_4~(2-)、Cl~-和NO_3~-相关性不显著。乌鲁木齐土壤中固有的盐分离子对小白菜可食用部分Pb的吸收没有抑制作用。 相似文献
6.
为探明宁夏环香山压砂区盐碱地表层土壤离子分布主要影响因素及盐分类型,研究选取覆盖状况、地面倾角和海拔3个因素,对0～20 cm表层土壤离子分布、盐分存在形式及钠吸附比(SAR)进行研究。结果表明:(1)覆盖状况对土壤表层离子含量有显著影响,地面倾角对HCO_3~-影响显著,海拔对Mg~(2+)有显著影响,裸地Ca~(2+)、Mg~(2+)、K~+、Na~+、Cl~-和SO_4~(2-)含量依次比压砂地高0%～284.21%、100%～130.53%、33.33%～48.94%、18.01%～182.26%、111.94%～468.72%和102.74%～118.82%,而CO_3~(2-)、HCO_3~-含量压砂覆盖比裸地分别高77.08%～400%和24.52%～48.09%;(2)阳离子之间除K~+与Ca~(2+)、Mg~(2+)具有显著正相关外其余都极显著正相关,阴离子Cl~-和SO_4~(2-),CO_3~(2-)和HCO_3~-呈极显著正相关,其余都呈负相关或不显著正相关,阳离子与Cl~-均呈极显著正相关,与SO_4~(2-)除K~+外其余均呈极显著正相关,阳离子与CO_3~(2-)和HCO_3~-呈负相关或不显著正相关;(3)该区域表层土壤盐分主要以NaCl、KCl、CaCl_2、MgCl_2、Ca SO_4、MgSO_4和Na_2SO_4的形式存在,按照摩尔量计,盐分含量排序为:Na~+盐Mg~(2+)盐Ca~(2+)盐K~+盐;(4)覆盖状况对土壤表层SAR影响显著,地面倾角随海拔变化对土壤SAR没有显著影响,压砂地SAR为3.99(mol/kg)~(0.5),裸地为10.73(mol/kg)~(0.5)。宁夏环香山压砂区0～20 cm埋深土壤离子分布主要受到覆盖状况和地面倾角的影响,除K~+外,其他离子受海拔的影响不明显,盐分主要是Na~+盐,其次是Mg~(2+)盐,K~+盐含量最少。 相似文献
7.
中天山典型内陆河流域水化学时空特征分析 总被引：2，自引：0，他引：2
基于2011—2013年不同季节乌鲁木齐河流域6个站点52组地表水化学的测试结果,结合流域气象水文资料,利用水化学分析方法和SPSS统计软件分析了乌鲁木齐河流域地表水化学时空变化特征、地表水各离子间相关性以及流域水化学特征的控制因素。结果表明:(1)乌鲁木齐河流域地表水总体矿化度较低,水体呈弱碱性。(2)流域地表水化学具有明显的季节变化趋势即早春融雪季、春末夏初季和秋季融雪季TDS值偏高,夏季TDS值低;同时也表现出较明显的年际差异性:多雨的年份地表水TDS值较低,少雨的年份地表水TDS值较高。(3)控制地表水体的主要离子为HCO_3~-,Ca~(2+),SO_4~(2-),离子质量浓度大小依次为HCO_3~-Ca~(2+)SO_4~(2-)Cl-Na+Mg~(2+)K+CO_3~(2-);不同季节控制水体的主要离子具有差异性:枯水期河水呈Ca~(2+)-HCO_3~-型;丰水期河流离子浓度受降水、冰川水的稀释影响离子浓度低,呈Ca~(2+)-HCO_3~--SO_4~(2-)型。(4)站点1到站点2河水中SO_4~(2-)浓度突然升高,主要是由于此段河水的含水层中分布有石膏夹层,石膏夹层释放了大量硫酸和氯酸。(5)通过对地表水水化学过程的分析显示控制流域地表水化学过程的主要影响因素为水岩交互运动。 相似文献
8.
《水土保持学报》2015,(6)
以西藏林周县江夏湿地为研究区域,对其水体全年主要离子进行季节监测,分析了该湿地水体水化学特征和主要离子时空变化规律,探讨了主要离子的初步来源,并对湿地不同季节水体灌溉效用进行了评价。结果表明:湿地水体pH值在7.8~8.3之间,为弱碱性水,HCO_3~-在阴离子中占绝对优势,阳离子中春季Na~+占优势,夏秋季节Ca~(2+)、Mg~(2+)占优势,冬季Mg~(2+)占优势。TDS均1g/L,为淡水水体。依据舒卡列夫分类法,江夏湿地水体化学类型为春季HCO_3—Na型水;夏季、秋季HCO_3—Ca、Mg型水;冬季HCO_3—Mg型水。阴离子中除了SO_4~(2-)之外,其余HCO_3~-、Cl~-、NO_3~-含量均为出水口大于进水口。从同一离子不同空间位置来看,Cl~-空间变异系数最大,其次是Mg~(2+),Na~+最小;而从同一空间位置来看,3个位置离子浓度总体变化程度不大。根据离子间相关性分析和Gibbs分类法表明,江夏湿地水体离子来源主要是受拉萨河流域岩石风化的影响,枯水期(春、冬季)伴随一定程度的蒸发—结晶作用影响,大气降水影响不明显。灌溉效用评价结果显示,江夏湿地春季水体不适用于灌溉,而其他3个季节水体均可用于农业灌溉。 相似文献
9.
不同形态氮肥对设施土壤盐分含量和离子组成的影响 总被引：2，自引：0，他引：2
通过室内模拟培养实验,研究了尿素、碳酸氢铵和硝酸钙对设施土壤盐分含量和离子组成的影响.结果表明:(1)随着培养时间延长,不同形态氮肥处理土壤含盐量总体呈先升高后降低再升高的趋势.施肥处理的土壤含盐量较对照(CK)明显增加,但不同氮肥处理与未施氮肥处理(N0)间的土壤含盐量在整个培养期间内总体差异不显著.且氮肥用量对含盐量的影响也不显著.(2)设施土壤中尿素和碳酸氢铵处理的电导率与含盐量呈极显著正相关,硝酸钙处理电导率与含盐量呈显著正相关.且随培养时间的延长呈波浪状变化.其电导率显著高于相同氮用量时的其他两种氮肥处理;电导率与氮肥用量呈极显著正相关.(3)不同形态氮肥处理的土壤盐分离子组成相近,均以阴离子为主.设施土壤阴离子占盐分总量的76.29%～93.81%,露地土壤为75.16%～96.63%,以SO_4~(2-)含量最高,分别占67.37%和67.28%,NO_3~-含量次之;土壤中阳离子含量较少,以Ca~(2+)为主,K~+,Na~+,Ca~(2+),Mg~(2+)的含量随氮肥用量的增加而增加.(4)土壤电导率受阳离子的影响较大.阴离子的影响较小.设施土壤的电导率与Ca~(2+),Mg~(2+),K~+.NO_3~-含量呈极显著正相关,与Cl~-1呈显著正相关.露地土壤电导率与Ca~(2+),Mg~(2+)含量呈极显著正相关,与HCO_3~-呈显著负相关. 相似文献
10.
新疆伊犁察南灌区土壤盐分特征 总被引：2，自引：0，他引：2
以察南灌区土壤为研究对象,对不同含盐量土壤进行盐化程度分级,并对该地区土壤盐分特征进行相关分析和主成分分析,以及对土壤盐分因子区域影响因素进行探讨。结果表明:察南灌区以碱性土壤为主,HCO_3~–是影响该灌区土壤p H最强的因子;对灌区0~100 cm土体土壤的分析表明,灌区盐化土面积约为总灌溉面积的1/4,盐渍化风险较大;相关性分析显示,HCO–3、Cl~–、SO_4~(2-)、Ca~(2~+)、Mg~(2~+)、Na~+、K~+为盐分主要组成离子,总盐分与各离子之间均呈正相关关系,与总盐分相关性最强的阴离子为SO_4~(2-),相关性最强的阳离子为Mg~(2~+);主成分分析显示,HCO_3~–、Cl~–、K~+为影响该灌区土壤盐分特征的主导因子;通过盐分因子区域影响因素定性分析可知,除HCO_3~–和pH是由河流以及地下水综合作用影响外,其他盐分因子均主要受河流影响。 相似文献
11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响 总被引：2，自引：2，他引：0
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。 相似文献
12.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions. 相似文献
13.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing. 相似文献
14.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization
and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition
with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the
decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots
with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass,
soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration,
N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially
(<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation
in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils,
indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but
the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation
for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community
performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea. 相似文献
15.
《中国生态农业学报》2014,(6)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
16.
《中国生态农业学报》2014,(7)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
17.
I.L. Boyd 《Biological conservation》2010,143(7):1664-1674
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options. 相似文献
18.
Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage 总被引：1，自引：0，他引：1
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate. 相似文献
19.
《中国生态农业学报》2014,(8)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
20.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils. 相似文献