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L. W. Parker N. Z. Elkins E. R. Aldon W. G. Whitford 《Biology and Fertility of Soils》1987,4(3):129-135
Summary We compared soil biota and buried wheat straw decomposition on sites subject to topsoiling plus straw mulch reclamation procedures 1–4 years prior to our study and on an unmined site. Rates of straw decomposition were highest on the unmined site. Decomposition rates were higher on the 1- and 2-year-old sites than on the 3- and 4-year-old reclaimed spoil. Microarthropod population densities and number of taxa were greater from decomposing straw on the unmined site and lowest from straw on the 1- and 2-year-old areas. Soil bacteria, fungi, and protozoan populations on buried straw on the oldest reclaimed sites were generally equal to those on the unmined area. Nematode populations on buried straw in the unmined site and 1- and 2-year-old reclaimed sites were similar. Populations of denitrifying bacteria were larger on recently reclaimed sites than on 3- and 4-year-old sites. Decomposition and nitrogen mineralization varied as a function of the diversity and abundance of soil microarthropods. Soil microfauna can serve as an index of soil development in a disturbed arid soil. 相似文献
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基于土地利用和覆被变化的黄河三角洲土壤质量预警研究 总被引：3，自引：5，他引：3
该文通过1987和2002年黄河三角洲土地利用和覆被变化与土壤肥力变化的对比分析，探讨土地利用和覆被变化对土壤肥力的影响。研究结果表明：土地利用和覆被变化对土壤肥力变化有直接影响，耕地转为林草地、建设用地、盐荒地和沙地，土壤肥力均有下降趋势；林草地转为滩涂的土壤肥力明显下降，转为盐荒地的略有下降；沙地转为耕地的土壤肥力明显提高，转为林草地有下降趋势，转为盐荒地的略有提高或不变；盐荒地转为耕地的土壤肥力有较大的提高，转为林草地的保持不变或稍有下降，转为沙地的稍有提高，转为建设用地的略微下降；滩涂转为盐荒地的土壤肥力保持不变或略微下降，转为林草地的稍有提高。 相似文献
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转Bt基因抗虫棉对中华草蛉发育及繁殖的影响研究 总被引：9，自引：1，他引：9
以2种转Bt基因抗虫棉和1种常规棉上的棉蚜饲喂中华草蛉,试验研究Bt毒蛋白对捕食性天敌的影响结果表明,不同处理间中华草蛉幼虫和茧的死亡率以及成虫获得率无显著差异,用混合棉蚜饲喂的中华草蛉幼虫与饲喂“泗棉3号”和“GK-12”的相比发育历期显著缩短(P<0.01),与用“新棉99B”饲喂的相比其发育历期也明显缩短(P<0.05),而分别以“泗棉3号”、“GK-12”和“新棉99B”上的棉蚜单独饲喂的幼虫发育历期无显著差异。不同处理间中华草蛉茧期、茧重和成虫性比差异不显著,成虫产卵前期和产卵期也无明显差异。而饲喂“新棉99B”的单雌产卵量高于饲喂“泗棉3号”和“GK-12”,且成虫寿命延长。幼虫期饲喂“泗棉3号”、“GK-12”和“新棉99B”上的蚜虫成虫产卵的孵化率无显著差异,而饲喂混合棉蚜时其后代卵的孵化率明显降低。 相似文献
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非硬化路面与原生地面侵蚀水动力参数对比研究 总被引：2，自引：1，他引：1
非硬化路面是神府煤田重要的侵蚀单元,其侵蚀过程和方式与原生地面存在一定差别。通过野外人工模拟降雨试验,对比分析了非硬化路面和原生地面水沙响应的过程和机制。结果表明:(1)非硬化路面径流主要为过渡流,原生地面主要为层流,且均为缓流;(2)非硬化路面水流流速、剪切力、佛汝德数、雷诺数、功率大于原生地面,曼宁系数、达西系数小于原生地面;(3)非硬化路面水力参数随坡度、雨强变化趋势与原生地面不完全一致;(4)非硬化路面产沙量随径流量增大,原生地面产沙量为非硬化路面的0.8%~14%;(5)非硬化路面侵蚀模数对水动力参数响应紧密程度表现为:径流总动能平均水流功率平均水流剪切力。 相似文献
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田块和小区尺度下节水灌溉稻田腾发量差异分析 总被引：2，自引：1，他引：1
为了揭示节水灌溉稻田腾发量在不同尺度间的差异,基于田间实测数据,对比分析了节水灌溉田块尺度与小区尺度间稻田腾发量的差异性。结果表明,节水灌溉水稻整个生育期不同尺度腾发量间存在显著差异,田块尺度的总腾发量比小区尺度小18.7%。各生育期稻田腾发量尺度间差异显著(P0.05),不同时段(旬、候)稻田腾发量尺度间差异极显著(P0.01)。节水灌溉条件下稻田下垫面状况、大气湍流状况、灌溉补水过程、土壤水分状况以及气象因子是造成不同尺度稻田腾发量差异的主要原因。气象因子中空气相对湿度和气温造成了尺度间腾发量差异的变化。稻田腾发量尺度差异的揭示可为稻田腾发量在尺度间的转换提供依据。 相似文献
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The adsorption and binding of amino acids (aspartic acid, cysteine, glycine, proline and arginine), ranging in molecular weight from 115 to 174 and in isoelectric point from pH 2.8 to 10.8, to montmorillonite [M] and kaolinite [K] homoionic to H, Na, Ca, Zn, La or Al were studied in unbuffered suspensions. Aspartic acid was adsorbed and bound on M homoionic to Ca or Zn but only adsorbed to K homoionic to Ca or Zn. Cysteine was only adsorbed on M homoionic to Al and adsorbed and bound on M homoionic to Zn and on K homoionic to H or Zn. Proline was adsorbed and bound on M homoionic to H, Ca or Zn and on K homoionic to H; it was adsorbed but not bound on both M and K homoionic to Al. Arginine was adsorbed and bound on M homoionic to H or Al and only adsorbed on K homoionic to Ca or Zn. Glycine was not bound on any of the clays. The amounts of amino acid adsorbed and bound (measured by the loss of amino acid from solution) and the class (Giles et al., 1974a and b) of both the adsorption and binding isotherms (retention against ultimate washing with water) were dependent on the type of amino acid, the type of clay, the type of cation predominant on the clays and the basicity or the additional function moiety (e.g. carboxyl, thiol, guanido) of the amino acid. The relative values of the non-standard free energy of clay-amino acid complexes that had isotherms of the Giles C-class were dependent on the type and molecular weight of the amino acid and on the exchangeable cation on the clay. 相似文献
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水土资源供需之间的矛盾日趋尖锐，而水资源作为土地农业利用的瓶颈因素，决定着区域的土地利用方向，因而有必要将水土资源结合起来进行优化配置研究。以河北省怀来县为例，应用GIS技术获取水土资源优化配置研究的基础资料；在对怀来县水土资源利用特点与存在问题分析的基础上，以区域生态环境建设和资源利用效益最佳为目标，选择粮食作物、 其它作物、林地、灌木林地、 疏林地、 其它林地、 低覆盖度草地、中覆盖度草地和高覆盖度草地9种土地利用类型作为决策变量，利用灰色线性规划模型，分别针对沙源地基本受到控制、沙源地受到控制和沙源地受到控制且作物类型结构较合理3种状态，在常规用水、单位面积节水10％和单位面积节水20％等3种假设条件下，对水土资源进行优化配置，获得水土资源优化利用方案；最后应用GIS空间分析与管理软件将土地利用优化方案落实到空间地块单元上。 相似文献
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城乡土地利用转型研究进展及展望 总被引：1，自引：0，他引：1
研究区域城乡范围内农用地、建设用地、未利用地的“来龙去脉”及其与社会经济制度政策技术之间“前因后果”驱动和响应的机制机理,是土地利用转型研究的热点,也是我国实施乡村振兴战略,实现区域城乡融合发展的重要抓手。本文从城乡土地利用转型的分析尺度、研究内容、研究对象、研究方法、机理分析等方面系统总结了近年来城乡土地利用转型研究进展,认为已有的研究呈现出3个基本特征:基础性研究向应用性研究转变、研究的社会需求引致性、研究分支更加清晰化和系统化。最后提出结合国家宏观经济发展战略定位、城乡融合发展的战略目标和土地制度改革的方向对区域城乡土地进行“全域全覆盖 + 全地类要素 + 土地利用显隐性转型”的动态综合研究,是今后城乡土地利用转型研究的重点。 相似文献
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由于黄土高原退耕还林工程涉及区域广阔，推进迅速，实施经验欠缺，因此目前存在科学规划、充分论证、有序推进不力，造林成活率低．科技支撑不足等不容忽视的问题。根据黄土高原退耕还林工程的现状及相关调查研究结果，谨提出建议如下：(1)明确退耕还林工程在生态建设中的正确定位；(2)增强退耕区生态环境建设与实施综合治理的政策可操作性；(3)加大配套措施实施力度，确保退耕成果不反弹；(4)国家应明确政策，支持封禁，促进植被自然恢复；(5)重视粮食的风险问题与对策。 相似文献
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分析了激光对植物生长调节效应的研究进展,发现研究明显具有以下特点:早期研究主要集中在激光预处理种子对种子萌发、幼苗生长发育、生理生化效应的影响以及激光处理机制的初步讨论;近年来的研究集中于激光处理对环境胁迫下植物生理生化效应影响,环境胁迫因子涉及增强UV-B辐射、干旱与冷冻,其中多数研究集中于激光对增强UV-B辐射下植物生理生化效应的影响,发现激光能增强植物抗UV-B辐射损伤,提高植物抗干旱逆境及抗冷冻能力,并对其作用机理及机制进行了探讨。今后可围绕全球生态环境变化背景下,激光处理对植物生理生化效应的影响进行研究,并深入研究激光影响的分子生物学机制机理。 相似文献
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城镇近郊区空心村整治农户意愿及影响因素分析——以成都市5个县(市、区)17个村为例 总被引：1，自引：0，他引：1
城镇近郊区空心村整治对于新农村建设以及城乡一体化发展等具有重要意义。以成都市5个县(市、区)17个村419户农户为样本,基于结构方程模型研究影响城镇近郊区空心村整治农户意愿的主要因素,结果显示模型的总体拟合度较好,农户的政策认知程度、生活改变接受度以及整治期望度与整治农户意愿存在正向的相关关系,现有状况满意度与整治农户意愿呈负相关,且满意度对整治农户意愿的影响最大。对满意度潜变量影响最大的为搬迁补偿满意度,对认知度潜变量影响最大的为是否了解空心村整治政策,对接受度潜变量影响最大的为建房投入增加接受度,对期望度潜变量影响最大的为收入增加期望度。因此,对城镇近郊区空心村整治农户意愿影响因素的研究需从农户的满意度出发,提高居民搬迁补偿满意度、加强对空心村整治相关政策的宣传、减轻农民新房投入建设成本以及增加收入来源等方面出发,提升空心村整治推广价值。 相似文献
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水土流失对水环境影响研究进展 总被引：9，自引：2，他引：9
本文在系统整理有关文献的基础上,全面总结了水土流失对水环境影响研究和水土流失对水环境影响模型研究方面的最新进展,提出了研究中存在的问题,并展望了水土流失对水环境影响研究的进一步发展方向。 相似文献
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Chitinase is adsorbed on kaolinite below the isoelectric point of the enzyme, pH 6.8. Maximum adsorption is reached below pH 4.6. The amount of chitinase adsorbed to kaolinite depends on the concentration and on the ratio of enzyme to kaolinite. Adsorption results in reduction of chitinase activity. the extent of which depends on the amount of kaolinite present, on pH, and on the length of exposure time. Upon sorption of chitinase on kaolinite the optimal pH for activity is increased from pH 4.7 to 5.7. 相似文献
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土壤结皮对坡面水分入渗及侵蚀产沙具有重要影响,但其具体作用过程和机理尚存在一定争论。以乌拉山矿山废弃地客土坡面为研究对象,采用原位冲刷试验,研究不同坡长(2,4,6,8,10 m)和产流产沙过程中,土壤结皮对径流泥沙的影响。结果表明：(1)2 m土壤结皮坡面总径流和泥沙量显著增加,分别是对照坡面的2.17,1.56倍;4～10 m土壤结皮坡面总径流量和总泥沙量降低,其中总径流量为对照坡面的67.17%～78.45%,总泥沙量为对照坡面的54.53%～83.56%。(2)土壤结皮坡面与对照坡面产流速率随产流时间变化基本一致,呈现波动稳定或略微提高趋势;产沙速率在对照坡面随产流时间呈下降趋势,而在结皮土壤坡面呈现下降与稳定2种趋势。(3)累积径流量、累积泥沙量与产流时间关系均可用线性函数和幂函数表达。随产流时间变化,土壤结皮坡面对累积径流量的影响可分为全程提高、全程降低、先提高后降低3种类型,对累积泥沙量的影响可分为提高与降低2种类型。因此,土壤结皮对坡面产流产沙过程的抑制或促进作用与坡长和侵蚀发生过程密切相关。 相似文献
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暴雨条件下黄土高原长陡坡耕地细沟侵蚀特征 总被引：5，自引：3，他引：2
细沟侵蚀是黄土高原坡耕地侵蚀的重要形式,已有的坡耕地细沟研究成果主要集中于裸土细沟侵蚀特征及其发生机制的小区或水槽试验,极端暴雨条件下细沟侵蚀观测很少,对于田间细沟侵蚀的预报仍然缺少实用的方法。该研究旨在基于实地测量数据,分析极端暴雨条件下黄土高原长陡坡耕地细沟侵蚀特征。2017年无定河流域"7.26"暴雨后,在暴雨中心附近选择15个样地进行细沟侵蚀测量,结合Google影像和无人机航拍影像,调查分析不同类型坡耕地细沟侵蚀特征。研究结果表明:1)暴雨条件下坡耕地是坡面细沟侵蚀的主要地类。长陡坡裸露坡耕地侵蚀模数为22 478 t/km~2,坡长20 m时,约为种植作物的平作坡耕地的1.5倍,且坡长越长,差异越大。等高垄作能够有效减少细沟侵蚀。撂荒坡耕地细沟侵蚀模数仅为裸露坡耕地的12%,草地未发现细沟侵蚀。2)幂函数可以很好地拟合细沟侵蚀模数与坡长的关系,裸露坡耕地坡长指数为0.831。暴雨强度越大,坡长指数也越大。3)上坡来水在坡耕地上造成了严重的细沟侵蚀,与地块上承接的降水相比,上坡来水对细沟侵蚀的影响更大。坡面浅沟汇水明显减小细沟侵蚀强度,浅沟发育程度越高,细沟侵蚀强度就越小。该研究可为估算黄土高原丘陵区不同类型坡耕地的细沟侵蚀提供重要参考。 相似文献
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《Agricultural and Forest Meteorology》1987,40(1):61-70
Cylindrical surface wetness duration sensors were constructed and tested for use in onions. Their potential for use as wetness sensors in flat-leaved crops was also investigated. Dew deposition on both cylinders and flat plates was shown to depend on sensor size, while drying of simulated raindrops depended on drop size. Despite these similarities, dew typically fell 1–2 h earlier and lasted 2–3 h longer on flat plates than on cylinders of the same size. Drops evaporated faster on cylinders than on flat plates at wind speeds < 1.5 m s−1, but similar rates of drying were observed for drops on both sensor shapes at higher wind speeds. 相似文献
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Experimentation by farmers with conservation agriculture (CA) is increasing in southern Africa, but local longer term data on these new production systems are scarce. This study focuses on CA research at two contrasting on‐farm sites and one on‐station long‐term trial in Zimbabwe. The on‐farm trials were conducted at Chikato village on a sandy soil at Zimuto Communal Area with low rainfall and at Hereford farm near Bindura on a clay‐rich soil in a high rainfall area. The on‐station trial was at Henderson Research Station near Mazowe where more in‐depth soil studies were possible. Results of CA systems from the on‐station site show on average 38 and 65% greater water infiltration on ripline‐seeded (RS) and direct‐seeded CA treatments compared with conventionally ploughed control treatments. Results from on‐farm sites show a 123 and 168% greater aggregate stability at Hereford and 11 and 24% lower dispersion ratio at Chikato on the two CA compared with the conventionally ploughed control treatments. Soil carbon increased by 46% in the first 20 cm on the sandy soils at Chikato in RS and by 104% in direct‐seeded CA treatments in four cropping seasons from 2004 to 2008, while it stayed at low levels on the conventionally tilled control treatment. Yields on CA plots were higher on the sandy soils in dry seasons, but lower in very wet seasons because of waterlogging. Yields on clay soils were less affected by the rainfall season. Crop productivity from CA systems increased at all sites over time owing to better management although significant differences between CA and conventional treatments on the three sites were apparent only after several cropping seasons. Conservation agriculture offers practical solutions to small‐scale farmers threatened by future soil degradation and fertility loss, but its successful use will depend on weed control and adequate application of fertilizers. The results indicate that there is no immediate increase in maize (Zea mays L.) yield when changing from a tilled to a CA system, but there is gradual improvement in some soil quality indicators over time. 相似文献
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影响土壤氮素径流流失的因素探析 总被引：14，自引：0，他引：14
从自然因素和人为因素出发探讨了地形、降雨、土壤理化性质、植被以及施肥、耕作制度等因素对土壤N素流失的影响,并综述了国内外有关研究的最新进展。并认为,基于这些因素相互作用的复杂性,有必要开展以下3方面的内容:一是大量开展多因子交叉实验,定量评价它们之间的关系,这为深入理解土壤N素流失机理和确定流域非点源污染模拟模型参数提供科学依据;二是加强有关土壤N素流失机理的多学科之间的联系,协同攻关建立较完善的理论认识;三是利用微观径流小区开展田间试验,结合遥感和GIS分析等方法,建立宏观大尺度土壤N素流失模型,为环境问题的宏观决策提供支持。 相似文献