农业可持续发展模式设计的自然资源评价方法初探

在农业可持续发展模式设计中通过进行以经济价值为表征的自然资源持续性评价，有利于变自然资源的无偿使用为有偿使用，保持农业自然资源的生产能力。对资源经济价值评价理论与方法进行了集中分析，并以资源折旧法对拜泉县试验小区数据进行了运算分析，证实了该方法的有效性。     

农业可持续发展模式设计的自然资源评价方法初探

在农业可持续发展模式设计中通过进行以经济价值为表征的自然资源持续性评价,有利于变自然资源的无偿使用为有偿使用,保持农业自然资源的生产能力。对资源经济价值评价理论与方法进行了集中分析,并以资源折旧法对拜泉县试验小区数据进行了运算分析,证实了该方法的有效性。     

赣县确保项目资金专款专用

赣县狠抓水保专项资金使用“三个环节” ,确保项目资金专款专用 ,项目资金到位率和使用率达到 10 0 %。一是把住项目资金划拨环节 ,由县重点治理工程领导小组根据水保治理规划安排和项目施工进度进行拨款 ;二是把住资金的存取环节 ,项目资金拨款到县水保局后 ,实行专户、专账 ,     

利用多渠道多层次集资开展水土保持工作

近年来各地在多渠道多层次集资方面创造了不少经验。本文研究总结了各地的集资经验,认为增加投入是增强水土保持活力的物质基础,是水土保持工作能够持续稳定发展的关键。文章指出:在当前国民经济治理整顿期间,由于国家每年的水土保持资金不可能增加很多。因此,一要充分注意利用现有资金渠道;二要千方百计开辟和扩大资金渠道;三要改革资金使用办法。使有限的资金发挥更大的效益。     

收回国有土地使用权初探

根据现行的有关法律法规,对收回土地使用权的批准机关关于"转类"审批和"转权"审批进行了探讨。重点对土地使用权的有偿收回与无偿收回问题进行了讨论,"有偿"收回和"无偿"收回的主要区别在于土地增值的归属,"无偿"收回并非绝对的"无偿",应分别不同情形区别对待。     

重庆市南川区加快推进国有林场科学发展

<正>一是按照"不变所有权、放活经营权"的思路,将国有林地经营权统一收归国有林场经营管理,成功收回山王坪林区等近万亩林地,全力保障资产完整性,提高资源利用率,推动国有林场发展转型。二是开展要素流转,促进南川区景观资源与森林资源分离,健全景观资源流转和森林资源抵押管理办法,实行景观资源有偿使用,搭建森林资源融资平台,以市场的办法先后筹集资金近11亿元,促进国     

忠县三举措强化金融支持“三农”发展

<正>一是加大金融政策支持力度。修改完善《忠县银行业金融机构支持县域经济发展考核评比办法》,提高农村"三权"抵押贷款考核权重。研究建立农村产权抵押融资财政贴息和风险分担补偿机制,引导县内金融机构在网点、资金、服务等方面向"三农"倾斜。二是搭建银农对接服务平台。组织县内银行、担保公司深入乡镇调研农业项目融资需求,搭建融资平台。     

忠县三举措强化金融支持“三农”发展

<正>一是加大金融政策支持力度。修改完善《忠县银行业金融机构支持县域经济发展考核评比办法》,提高农村"三权"抵押贷款考核权重。研究建立农村产权抵押融资财政贴息和风险分担补偿机制,引导县内金融机构在网点、资金、服务等方面向"三农"倾斜。二是搭建银农对接服务平台。组织县内银行、担保公司深入乡镇调研农业项目融资需求,搭建融资平台。     

屯留县农业节水浅析

屯留县是一个农业大县,70%的水量用于农业灌溉。全县灌溉水利用系数为0.47,农田水分生产率为0.8~1.0 kg/m3,均低于国家规范要求,农业节水潜力巨大。在农业节水方面应采取的主要对策:一是要建立完善的用水计量体系,核定用水定额,制定合理水价,按用水量收费,超额累进加价;二是要加大宣传力度,强化全民的节水意识;三是多渠道筹措节水工程建设资金,用政策调动社会投资的积极性;四是大力推广普及节水农业新技术。     

2006年全省水土保持工作要抓好十个落实

一是在进一步理清水保工作思路上抓落实,把已出台的10项政策办法落实为实实在在的行动;二是在扶持民营水保工作上抓落实,切实落实扶持资金,在服务民营水保大户、引导新的民营力量投入“四荒”治理上下功夫;三是在水保大示范区建设上抓落实,要按照规划的蓝图,有步骤地、有计划地     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

沈阳市城市表土中微生物区系变化的初步研究

在沈阳市远郊-近郊-市区等不同城市化水平区内选取林地、草地和路边土几种不同利用方式下的表层土壤,对土壤中的微生物状况进行了初步分析。结果表明,随着城市化水平的提高,土壤中微生物的数量表现为明显的减少趋势。其中变化较大的是细菌,而真菌和放线菌的变化不明显。     

Sediment denitrification in waterways in a rice-paddy-dominated watershed in eastern China

Purpose

Rice-paddy-dominated watersheds in eastern China are intensively cultivated, and lands with two crops receive as much as 550–600 kg?ha^–1?year^–1 of nitrogen (N), mainly through the addition of N-based fertilizers. However, stream N concentrations have been found to be relatively low. Waterways in the watersheds are assumed to be effective “sinks” for N, minimizing its downstream movement. We directly measured net sediment denitrification rates in three types of waterways (ponds, streams/rivers, and a reservoir) and determined the key factors that control net sediment denitrification. Such information is essential for evaluating the impact of the agricultural N cycle on the quality of surface water.

Materials and methods

The pond–stream–reservoir continuum was sampled every 2 months at nine sites in an agricultural watershed between November 2010 and December 2011. Net sediment N₂ fluxes/net sediment denitrification rates were determined by membrane inlet mass spectrometry and the N₂/Ar technique. A suite of parameters known to influence denitrification were also measured.

Results and discussion

Net denitrification rates ranged between 28.2?±?18.2 and 674.3?±?314.5 μmol N₂–N?m^–2?h^–1 for the streams, 23.7?±?23.9 and 121.2?±?38.7 μmol N₂–N?m^–2?h^–1 for the ponds, and 41.8?±?17.7 and 239.3?±?49.8 μmol N₂–N?m^–2?h^–1 for the reservoir. The mean net denitrification rate of the stream sites (173.2?±?248.4 μmol N₂–N?m^–2?h^–1) was significantly higher (p?<?0.001) than that of the pond sites (48.3?±?44.5 μmol N₂–N?m^–2?h^–1), and the three types of waterways all had significantly higher (p?<?0.01) mean net denitrification rates in summer than in other seasons. Linear regression and linear mixed effect model analysis showed that nitrate (NO₃ ^?–N) concentration in surface water was the primary controlling factor for net sediment denitrification, followed by water temperature. Using monitoring data on NO₃ ^?–N concentrations and temperature of the surface water of waterways and an established linear mixed effect model, total N removed through net sediment denitrification in the pond–stream–reservoir continuum was estimated at 46.8?±?24.0 t?year^–1 from July 2007 to June 2009, which was comparable with earlier estimates based on the mass balance method (34.3?±?12.7 t?year^–1), and accounted for 83.4 % of the total aquatic N. However, the total aquatic N was only 4.4 % of the total N input to the watershed, and thus most of the surplus N in the watershed was likely to be either denitrified or stored in soil.

Conclusions

High doses of N in a rice-paddy-dominated watershed did not lead to high stream N concentrations due to limited input of N into waterways and the high efficiency of waterways in removing N through denitrification.     

中国华北地区近40年物候春季变化

根据华北地区7个观测站物候资料,分析了华北地区1963-1996年及北京1963-2005年物候春季的变化特征及其与气温的关系。结果表明:华北地区的物候春季有明显提早来临的趋势,而造成这一变化的主要因素是本地区近40 a来冬春季气温的明显上升。其中1963-1996年间华北地区1-3月及4月的平均气温分别上升了2.3℃与1.7℃,物候春季起止日期分别提前了9d和4d,因而使得春季长度也延长了5d;北京1963-2003年间1-3月及4月的平均气温分别上升了3.5℃与2.6℃,物候春季的起止日期分别提前了11d和10d,但春季长度没有明显变化。     

Patterns in trace elements in lichens

Water, Air, & Soil Pollution - Epiphytic lichens were sampled in a Dutch national monitoring survey, which was carried out twice within 5 yr. The samples were analyzed by neutron activation...     

Trace metals in precipitation in Sweden

Trace metals (Cd, Cu, Fe, Mn, Pb, and Zn) concentrations in atmospheric precipitation have been routinely monitored in Sweden since the autumn of 1983. Concentrations are highest in southern Sweden and decrease northward. It is postulated that the long range transport of anthropogenic pollutants from the rest of Europe is the major source of Cd, Pb, and Zn in precipitation. Evidence for this hypothesis is that enrichment factors indicate anthropogenic origin, and Swedish atmospheric emissions of Zn and Cd are 2 to 3 times smaller than deposition fluxes. Also, Cd, Pb, and Zn concentrations are correlated in both space and time and are also well correlated with exSO₄ ⁺, a substance known to be of anthropogenic origin transported long distances.     

Trends in soil science in Switzerland

Phytoremediation is an emerging technology based on the use of green plants to remove, contain, inactivate or destroy harmful environmental pollutants. Recent developments in Europe and the USA show that the approach is somewhat different on both sides of the Atlantic. In Europe, phytoremediation has more basically been research driven and, based on the outcomes, applications have been envisaged. By contrast, the approach in the USA is more application and experience driven. In spite of a growing track record of commercial success, more demonstration projects are needed to prove that phytoremediation is effective in order to rigorously measure its underlying economics, and to expand its applications. More fundamental research is also required to better understand the complex interactions between pollutants, soil, plant roots and micro-organisms at the rhizosphere level, to increase the bioavailability of pollutants, to fully exploit the metabolic diversity of plants and, thus, to successfully implement this new green technology.     

Changes in proteolytic bacteria in paddy soils in response to organic management

Proteolytic bacterial communities, which mineralize organic nitrogen, play a key role in agricultural systems. In this study, alkaline metalloprotease (apr) gene fragments from proteolytic bacteria were investigated in bulk and rhizosphere paddy soil from four fields under organic management (for 2, 3, 5, and 9 years), and from one field under conventional management (for 2 years). We analyzed the abundance and structure of the proteolytic bacterial communities using real-time quantitative PCR and denaturing gradient gel electrophoresis. Our results showed that the abundance of proteolytic bacteria ranged from 1.57?×?10⁸ to 8.02?×?10⁸?copies/g of soil. In addition, the abundance of the proteolytic bacteria in the paddy soils under organic management was significantly higher than those in the paddy soil under conventional management. Moreover, the gene copy numbers in the rhizosphere soils were significantly higher than those in the bulk soils. The abundance of proteolytic bacteria tended to increase with the duration of organic management, with the highest abundance being found in the soil that had been under organic management for 5 years. However, the proteolytic bacteria communities in the paddy soils were not significantly affected by management practices. Phylogeny analysis showed that all gel bands obtained represented genes from Pseudomonas. Additionally, correlation analysis and canonical correspondence analysis showed that C/N, C, and N were important factors that influenced the abundance and community structure of the proteolytic bacteria. These results suggest that proteolytic bacteria are indicators in organic management systems, depolymerize organic N and hence maintain soil sustainability.

Abbreviations: CM: conventional management; OM: organic management; DGGE: denaturing gradient gel electrophoresis; qPCR: real-time quantitative PCR detecting system; COFCC: China organic food certification center; CCA: canonical correspondence analysis