南通市城市土壤铅污染特征研究

对南通市城市五大功能区的土壤进行采样测定,对南通市城市不同功能区的土壤铅含量进行分析和评价。结果表明。南通市城市土壤总体未受到严重的铅污染,但工业区受到中度污染,商业区和老居民区受到轻度污染,风景区和农业区未受到明显污染。说明南通市城市交通运输和工业“三废”是土壤中铅污染的主要来源。     

二氧化氯对剑麻外植体材料消毒的应用研究

为建立高效、环保的剑麻无菌繁殖技术,以H.11648剑麻的珠芽为外植体,以1 000 mg/L HgCl2溶液对外植体材料浸泡消毒灭菌20 min作对照,以不同浓度的ClO2溶液对外植体材料进行不同时间的浸泡消毒灭菌试验。结果表明,500~3 000 mg/L ClO2溶液对剑麻珠芽外植体浸泡消毒20~50 min,可显著降低培养材料的污染率,外植体生长好,腋芽萌动快,腋芽萌发率在14.175%~47.335%,显著高于对照的4.340%,最初3次继代的增殖率为5.685~11.325倍,显著高于对照的3.040倍。剑麻珠芽外植体材料消毒灭菌的最适宜方法是1 000 mg/LClO2溶液浸泡消毒30 min。     

有机肥料施用后潮土中活性有机质组分的动态变化

研究了潮土中加入稻草秸秆或猪粪后,土壤微生物生物量碳、水溶性有机碳和溶解性酚等活性有机质组分的动态变化。有机肥施用后,微生物生物量碳、水溶性有机碳都迅速上升并达到最大值,随着时间的推移都有所下降;而溶解性酚从实验开始时就逐渐下降,最后基本保持稳定。相关性分析表明,微生物生物量碳、水溶性有机碳和溶解性酚相互之间都呈显著性正相关。     

液体地膜覆盖对棉花产量与土壤环境的影响

基于棉田可持续发展的思想,研究了液体地膜覆盖对棉花产量与土壤物理性状的影响。结果表明,适量液体地膜(112.5 kg/hm²)覆盖棉花增产显著,平均增产皮棉21.7%。液体地膜覆盖棉田提高土壤温度和含水量,降低土壤容重。表明液体地膜覆盖棉田对土壤环境无不良影响,利用液体地膜覆盖棉田是一项可行的技术。     

水网平原稻田土壤养分空间变异特性研究

 通过对绍兴独树养分监测村土壤10种养分元素空间变异性的研究,明确了水网平原水稻土养分空间变异规律。各向同性球型、指数型半方差函数较好地描述了土壤养分变异与空间距离的关系,该村土壤N、P、K、Mn、Fe等5种养分具有中等的空间相关性, Ca、Mg、S、Cu、Zn等5种养分具有高度的空间相关性。进一步用各向异性变异模型分析土壤养分空间变异,表明土壤Ca、Mg、K、Cu存在一定的带状异质性。经不同采样距离下Kriging内插十字交叉验证,明确可用土壤养分空间相关距离确定方格取样法确定最大取样距离。     

液体培养研究不同土壤中硝化活性

A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4)2SO4 at the rate of 154 mg N kg-1 dry soil to fresh soil. However, the amounts of nitrifying bacteria in the three soils were not related to soil nitrification capacity. When the soil samples or the isolates of AOB enriched from the corresponding soil were incubated in liquid with pH 5.8, 7.0 and 8.0 buffers and 10 mmol L-1 ammonium nitrogen, there were no significant nitrification differences in the same soil type at each pH. The ability to oxidize ammonia through AOB from different types of soils in a homogeneous culture medium was similar, and the soil nitrification capacity could reflect the inherent properties of a soil. Altering the culture medium pH of individual soil type also showed that acidification of an alkaline fluvo-aquic soil decreased nitrification capacity, whereas alkalinization of the acidic red soil and permeable paddy soil increased their nitrification. For a better insight into factors influencing soil nitrification processes, soil properties including texture and clay composition should be considered.     

海南橡胶园土壤持续利用措施的研究

This research was designed to help solve existing sustainable use problems such as soil nutrient loss and soil fertility decline in natural rubber plantations located in the hilly land of the south central mountainous area of Hainan Island,China. Two different land management practices, sustainable and traditional, were adopted in a four-year experiment.Contour terraced fields and deep ditches for green manure were built in a sustainable way with a balanced, need-based application of complex fertilizer. Results of the four-year experiment showed that these sustainable measures compared to traditional measures improved available P and available K; had a 47.8% less soil erosion (an average of 3663 t km^-2 year^-1) and a 15.9% lower runoff coefficient of 0.53; increased the dry rubber yield by 42.4%; and improved the economic benefit by 2.4 times. The sustainable land management scheme not only improved land utilisation efficiency, hut also helped maintain soil fertility while increasing production in rubber plantations. It thereby offered a reasonable and sustainable use for land resources in the tropical mountainous areas.     

中国亚热带稻田土壤碳氮含量及矿化动态

Dynamics of soil organic matter in a cultivation chronosequence of paddy fields were studied in subtropical China. Mineralization of soil organic matter was determined by measuring CO2 evolution from soil during 20 days of laboratory incubation. In the first 30 years of cultivation, soil organic C and N contents increased rapidly. After 30 years, 0-10 cm soil contained 19.6 g kg^-1 organic C and 1.62 g kg^-1 total N, with the corresponding values of 18.1 g kg^-1 and 1.50 g kg^-1 for 10-20 cm, and then remained stable even after 80 years of rice cultivation. During 20 days incubation the mineralization rates of organic C and N in surface soil （0-10 cm） ranged from 2.2% to 3.3% and from 2.8% to 6.7%, respectively, of organic C and total N contents. Biologically active C size generally increased with increasing soil organic C and N contents. Soil dissolved organic C decreased after cultivation of wasteland to 10 years paddy field and then increased. Soil microbial biomass C increased with number of years under cultivation, while soil microbial biomass N increased during the first 30 years of cultivation and then stabilized. After 30 years of cultivation surface soil （0-10 cm） contained 332.8 mg kg^-1 of microbial biomass C and 23.85 mg kg^-1 of microbial biomass N, which were 111% and 47% higher than those in soil cultivated for 3 years. It was suggested that surface soil with 30 years of rice cultivation in subtropical China would have attained a steady state of organic C content, being about 19 g kg^-1.     

长白山岳桦-暗针叶林过渡带根系呼吸对土壤总呼吸的贡献

Total and root-severed soil respiration rates for five plots set up 50 m apart in a Betula ermanii Cham.-dark coniferous forest ecotone on a north-facing slope of the Changbai Mountains, China, were measured to evaluate the seasonal variations of soil respiration, to assess the effect of soil temperature and water content on soil respiration, and to estimate the relative contributions of root respiration to the total soil respiration. PVC cylinders in each of 5 forest types of a B. ermanii-dark coniferous forest ecotone were used to measure soil respirations both inside and outside of the cylinders. The contribution of roots to the total soil respiration rates ranged from 12.5% to 54.6%. The mean contribution of roots for the different plots varied with the season, increasing from 32.5% on June 26 to 36.6% on August 3 and to 41.8% on October 14.In addition, there existed a significant （P 〈 0.01） logarithmic relationship between total soil respiration rate and soil temperature at 5 cm soil depth. Also, a similar trend was observed for the soil respiration and soil water content at the surface （0-5 cm） during the same period of time.