海南省胶园土壤肥力质量指标的时空变异特性研究

本文利用海南省现有胶园202个0～20cm土壤混合样与海南省现有胶园相应的自然热带雨林、热带灌木草地的第二次全国土壤普查资料中的土壤剖面资料对海南省胶园土壤pH、有机质和NPK等土壤肥力质量指标的时空变异特性作了分析。分析结果表明,植胶后土壤pH、PK水平在时空方向上发生了显著改变。同时,植胶后各地区土壤pH、有机质含量和NPK水平变异系数均发生了不同程度的改变。     

城市污泥施用对沙地油菜的影响及效果评价

针对京郊沙质土壤贫瘠,植被生长缺乏营养物质等问题,采用盆栽实验研究了污泥添加量对油菜长势及沙质土壤理化性质的影响,测定了油菜长势、营养成分的含量以及重金属的有效浓度,并采用层次分析法构建了污泥改良沙质土壤方案选取分析模型,确立了最佳污泥添加量。结果表明,适量的污泥可有效改善沙质土壤中有机质、全氮和有效磷的含量;且有利于油菜的生长,油菜的发芽率、株高和生物量的增加率分别达到10%、131.55%和58.84%。重金属风险评价结果表明,当污泥浓度低于20%时,土壤处于清洁状态。分析模型评价结果表明3%为污泥的最佳添加量,为今后污泥的资源化利用以及京郊沙质土壤的改良提供了一定的理论依据。     

抓深化改革 求持续发展──对水土保持五大体系建设的一些认识与设想

抓深化改革求持续发展──对水土保持五大体系建设的一些认识与设想刘海峰（甘肃省水利厅水保局,兰州７３００００）中共中央关于建设社会主义市场经济体制的决定和水土保持属于社会公益性基础产业的定性,为水保改革和发展指出了战略方向,带来了前所未有的机遇和挑战。...     

Response of climate-growth relationships and water use efficiency to thinning in a Pinus nigra afforestation

Thinning is the main forestry measure to increase tree growth by reducing stand tree density and competition for resources. A thinning experiment was established in 1993 on a 32-year-old Pinus nigra Arn. stand in central Spain. The response of growth, climate-growth relationships and intrinsic water use efficiency (WUEi) to a stand density reduction were compared between moderate thinned plots and a control plot by a combined analysis of basal area increments (BAI), and C and O stable isotope ratios (δ¹³C_c and δ¹⁸O_c). BAI in the control plot showed a decreasing trend that was avoided by thinning in the thinned plot. Thinning also partially buffered tree-ring response to climate and trees were less sensitive to precipitation although more sensitive to temperature. Δ¹³C_c in the thinned plot was not modified indicating that stomatal conductance (g) and photosynthetic capacity (A) did not change or change in the same direction. However, δ¹⁸O_c decreased in the control plot (unrelated to δ¹⁸O of precipitation) but not in the thinned plot, suggesting a relative increase of temperature and irradiance and/or a decrease of air humidity after reducing the density consistent with an increase in A, g and BAI. As WUEi did not increase in the thinned plot, faster growth in this plot was caused by higher abundance of resources per tree. The trend of WUEi in both plots indicated low-moderate CO₂-induced improvements. Thinning might be a useful adaptation measure against climate change in these plantations reducing their vulnerability to droughts. However, because WUEi was not affected, the positive growth response might be limited if droughts and warming continue and certain thresholds are exceeded.     

海南岛三大流域农业土壤源污染物流失特征研究

采用径流场结合人工模拟降雨方式,研究了海南岛万泉河、南渡江和昌化江三大流域土壤中氮、磷、有机质等营养物质的流失特征。结果表明,三大流域土壤径流系数和泥沙流失速率的大小顺序为：暴雨〉大雨〉中雨;相同雨强条件下,万泉河的径流系数与南渡江相近,昌化江最小;泥沙流失速率大小顺序为：万泉河〉南渡江〉昌化江;雨强对总磷（TP）流失速率的影响达到极显著水平,磷随径流流失以颗粒磷（PP）为主;氮在雨强较小时以可溶氮（DN）流失为主,当达到暴雨时则以颗粒氮（PN）流失为主;雨强越大,地表径流中COD、TN、DN和PN流失速率越高。三大流域区土壤养分随泥沙流失特征相似,不同雨强条件下,三大流域的总氮、总磷和有机质流失速率的规律一致,雨强越大,流失速率越高;在同一雨强条件下,三流域区总氮、总磷和有机质随泥沙流失速率为：昌化江〉万泉河〉南渡江。影响面源流失的主要因素为坡度、雨强、土质等。     

基于水分胁迫系数的枣树园土壤含水率估算

为了实现黄土高原地区滴灌条件下枣树园土壤含水率的小范围快捷监测,根据FAO-56水分胁迫系数的定义和相关计算公式,得到了基于土壤水分胁迫系数的黄土高原地区滴灌条件下枣树根层土壤平均含水率估算公式．2009年4-9月将该公式应用于西北农林科技大学陕西米脂孟岔试验站的枣树试验园,配置了3种不同的土壤含水率控制下限,对枣树2个重要生育期的土壤含水率进行了估算,模拟了水分动态变化过程,并对估算值和实测值进行对比和误差分析．结果表明:采用基于FAO-56水分胁迫系数的计算公式对土壤含水率的动态模拟达到了较高的精度,估算值与实测值之间误差较小:其中开花坐果期各处理(灌水下限为60％,50％,40％的田间持水率)的估算值与实测值之间的相关系数分别为0828 0,0907 3,0935 1;标准误差分别为0055,0093,0068．果实膨大期各处理的相关系数分别为0777 2,0766 7,0905 5;标准误差分别为0057,0092,0079．估算值与实测值之间的相关系数随土壤含水率的增大而减小,随土壤水分胁迫程度的增大而增大,即土壤含水率较高时对公式精度有一定的影响．该方法较适用于黄土高原半干旱地区,对农业用水管理具有一定参考价值．