黄土高原半干旱地区土地利用变化对土壤养分、酶活性的影响研究

对黄土高原半干旱地区土地利用变化进行了土壤养分、酶活性及相关性研究。结果表明，过氧化氢酶活性可表征人工草地苜蓿地的速效磷、速效钾，撂荒地的有机质、全氮和碱解氮的正向转化状况，及沙棘林土壤速效磷负向转化进程，但不能用过氧化氢酶活性表征精细耕作的土壤肥力状况。多酚氧化酶活性可表征农田土壤有机质、全氮正向转化进程及菜园土和果园土有机质、全氮负向转化进程，不能表征自然土壤腐殖质转化状况。转化酶活性可表征农田、菜园土、果园、苜蓿地和撂荒地的碱解氮正向转化进程以及沙棘林碱解氮的负向转化进程，可全面表征撂荒地的速效磷负向转化进程及其它养分的正向转化进程。脲酶活性可表征果园地、菜园土的全氮、碱解氮和有机质的肥力水平。磷酸酶活性可表征果园土、农田和撂荒地的速效磷正向转化状况，不能表征其它土地利用类型的磷素转化状况。     

中国东南部红壤地区不同植被对土壤侵蚀和土壤养分的影响

The effect of different vegetation systems including bamboo plantation (BP), forest ecosystem (CF), citrus orchard (Ctr) and farmland (FL) on erosion and nutrients of red soil were investigated in hilly region of southeastern China to find effective control measures for soil erosion. The results showed that all the vegetation systems could significantly reduce soil erosion and nutrient losses compared to bare land (Br). The ability of different vegetation systems to conserve soil and water was in the order of Ctr > BP > CF > FL > Br. Vegetation could also improve soil fertility. The soil organic matter, total N and total P contents were much higher in all the vegetation systems than in bare land, especially for the top soils. Vegetation systems improved soil physical properties remarkably. Compared to the bare land, soil organic matter, TP, TK and available K, especially soil microbial biomass C, N and P, increased under all the vegetation covers. However, they were still much lower than expected, thus these biological measurements are still needed to be carried out continuously.     

低丘红壤南酸枣-花生复合系统物种间水肥光竞争的研究--Ⅰ.南酸枣与花生生育性状及产量研究

低丘红壤实施南酸枣与花生农林复合种植模式可促进南酸枣生长,花生单作产量及其复合经营总平均单产随土壤熟化而逐年提高,但复合种植花生生育性状在第2年后受南酸枣影响而发生变化,其产量和生物量呈递减趋势。     

红酵母RS1的高耐铝能力与增厚的细胞壁有关而不来自体外铝离子的螯合作用

Aluminum (Al) is very toxic to many living organisms, including plants, animals and microorganisms. However, despite many studies on Al tolerance in plants, little has been reported concerning these mechanisms in microorganisms. In this study, a red yeast, which could tolerate Al 3+ concentrations as high as 200 mmol L-1 , was isolated from acidic soils, identified as Rhodotorula sp. and designated as RS1. As the medium compositions can greatly affect the responses of microorganisms to Al, two culture mediums, glucose medium (GM) and lysogeny broth medium containing soil extract (S-LBM), were used. During growth of RS1, the pH of medium decreased in GM but increased in S-LBM. These changes in the pH of the media were not induced by Al addition. No or little secretion of organic acids was observed in RS1 growth media. Importantly, the thickness of the cell walls and the ratio of cell wall to biomass of RS1 significantly increased in GM with high Al 3+ concentrations. In the presence of 100 mmol Al L-1 , 78.0% of the total Al of whole cells was present in the thickened cell walls. The Al in cell walls was mostly bound to OH, amide and CO groups of polysaccharides. These results suggest that thickening of the cell wall in response to the high Al 3+ concentrations may play an important role in the high tolerance of RS1 to Al and that pH increase of the medium and chelation of Al ions are not involved in Al tolerance of this organism.     

我国农业面源污染治理技术研究进展

随着我国经济社会的进一步发展,农业面源污染已经成为造成我国环境污染尤其是水环境污染的主要因素,农业面源污染治理技术的研究也越来越得到政府和科技工作者的重视。本文重点介绍了当前我国农业面源污染的状况、农业面源污染的成因及特征,并从农村生活污水的治理技术、农村生活垃圾的处理处置技术、农田径流生态拦截技术以及包括化肥减量化技术和农药减量化与残留控制技术为主的农业化学品减量使用技术等方面介绍了我国农业面源污染治理研究的发展现状,提出未来我国农业面源污染治理的系统控制思想和相关技术研究的趋势,包括系统控制与区域治理结合、技术研发与工程示范结合、面源污染控制与管理结合及建立健全国家级农业面源污染监测评价与预警体系等。     

横坡和顺坡耕作对紫色土土壤团聚体稳定性的影响

通过径流小区试验,分析探讨了紫色土横坡和顺坡两种耕作模式下表层(0~20 cm)土壤水稳性团聚体及有机碳含量的特征,为紫色土区坡耕地的有效改造和综合利用提供科学依据。试验结果表明,横坡耕作下土壤水稳性指数K值比顺坡耕作高38.99%,而土壤分散性D值为顺坡耕作的1.64倍,横坡耕作抗蚀性大于顺坡耕作。横坡耕作>0.25 mm水稳性团聚体含量比顺坡耕作增加3.62%,>5 mm、5~3 mm、3~2 mm水稳性团聚体含量横坡耕作均高于顺坡耕作,横坡耕作显著提高>2 mm水稳性团聚体含量。横坡耕作下团聚体结构体破坏率较顺坡耕作减少3.05%,团聚体平均重量直径为顺坡耕作的1.39倍。2种耕作模式下0.5~2 mm团聚体有机碳含量均最高,>0.25 mm不同粒级团聚体有机碳含量百分数均随粒径的减小而减小,均在0.5~0.25 mm粒级下达到最小。横坡和顺坡耕作模式下2~1 mm团聚体有机碳含量无显著差异。横坡耕作较顺坡耕作能够显著增加紫色土>2 mm水稳性团聚体含量,且对有机碳的固持作用更好,有利于土壤结构的改善。     

不同丘陵地柑橘采后生理变化与活性氧代谢的关系研究

试验研究不同丘陵地柑橘果园锦橙果实采后生理变化与活性氧代谢的关系结果表明 ,2个试点柑橘果实采后活性氧均呈先升后降趋势 ,超氧化物歧化酶活性升高峰值滞后于活性氧 ,低温贮藏活性氧与几种膜保护酶活性均明显下降 ,但超氧化物歧化酶与过氧化氢酶活性相对值较高。活性氧代谢还与植物内源激素、丙二醛含量和电解质渗漏率及果实品质变化有密切关系。     

生态系统健康理论与评价方法探析

阐述了生态系统健康理论的形成与发展以及评价生态系统健康的方法和指标 ,并简介了我国生态系统健康理论在温室生态系统的应用。     

长期定位施肥对砂姜黑土肥力及生产力的影响研究

长期定位试验研究化肥与有机肥配施对砂姜黑土土壤肥力和作物产量的影响结果表明 ,长期施肥可提高土壤碱解氮、速效磷及有机质含量 ,不同肥料组合间差异较大 ,以有机肥与化肥配施处理效果最佳 (但同时必须重视K素的投入 ) ,土壤速效钾仅全部施用有机肥处理有所增加 ,单施N、P化肥处理下降最多 ,至 15年后下降2 5 .8%。长期未施肥处理 (对照 )碱解氮变化最大 ,较试验前下降 2 6 .5 % ,其他养分指标变化较小。有机肥与化肥配施处理产量前期不及单施化肥处理 ,中后期则反之。砂姜黑土基本生产力随种植时间延长而渐降 ,土壤对秋粮大豆或玉米的供肥能力高于小麦。     

不同腐殖酸复合肥施用量对辣椒产量及其养分利用率的影响

试验研究不同腐殖酸复合肥施用量对辣椒产量及其养分利用率的影响结果表明 ,随施肥量的增加而辣椒叶片N、P、K累积量逐渐增大 ,果实N、P、K累积量呈二次抛物线趋势变化 ,且施肥量过大时不利于营养元素向果实中的转移。肥料生产效率及N、P、K养分利用率均随施肥量的增大而降低 ,肥料对辣椒产量的贡献率以及辣椒产量随施肥量的变化与辣椒果实营养元素累积量变化趋势相一致