大渡河干热河谷农业环境资源的开发模式

大渡河干热河谷光、热资源充裕,雨、热同期,主、支流(沟)纵横交错,为农业灌溉提供了水源;经济林木资源优势相对突出,农业环境资源立体层次丰富。因此,本文提出了开发大渡河干热河谷农业环境资源的4种模式。     

清江水布垭水库农村移民安置区环境容量研究

清江是长江流出三峡之后的第一条大支流,发源于鄂西利川市,自西向东流经湖北省的１０个县（市）,于宜都市注入长江,在清江建设水布垭水电站是“流域,梯极,滚动,综合”开发利用清江水利资源的重要决策,将促进区域经济的发展。水布垭水库淹没涉及巴东,鹤峰,建始,宣恩,恩施５县（市）的陆地面积５５．４ｋｍ＾２,其中耕园地１１４７．８ｈｍ＾２。     

白色农业:21世纪养活16亿中国人的重大工程

白色农业是我国新的农业科技革命的重要组成部分。发展白色农业既可以满足我国２１ 世纪对食品数量增加、质量改善和安全性的需求,又能有效地提高动、植物资源利用率,改善和保护生态环境。白色农业是我国２１ 世纪养活１６ 亿人的强有力保证。     

Embarking on the Second Green Revolution for Sustainable Agriculture in India: A Judicious Mix of Traditional Wisdom and Modern Knowledge in Ecological Farming

The Green Revolution in India which was heralded in the 1960‘s was a mixed blessing. Ambitious use of agro-chemicals boosted food production but also destroyed the agricultural ecosystem. Of late Indian farmers and agricultural scientists have realized this and are anxious to find alternatives – perhaps a non-chemical agriculture – and have even revived their age-old traditional techniques of natural farming. Scientists are working to find economically cheaper and ecologically safer alternatives to agro-chemicals. Blue-Green Algae Biofertilizers, Earthworm Vermicomposts (Vermiculture), biological control of pests and herbal biopesticides are showing promise. Saline agriculture and sewage farming are also being promoted in India to augment food production in the face of water scarcity. There is a move to search for alternative foods, which are more nutritious, cheaper and have shorter harvest cycles. Farm and food policy in India has to change its outlook before there can be a second green revolution. This revised version was published online in August 2006 with corrections to the Cover Date.     

NONPOINT SOURCE DISCHARGES OF NUTRIENTS FROM PIEDMONT WATERSHEDS OF CHESAPEAKE BAY1

ABSTRACT: We measured annual discharges of water, sediments, and nutrients from 10 watersheds with differing proportions of agricultural lands in the Piedmont physiographic province of the Chesapeake Bay drainage. Flow-weighted mean concentrations of total N, nitrate, and dissolved silicate in watershed discharges were correlated with the proportion of cropland in the watershed. In contrast, concentrations of P species did not correlate with cropland. Organic P and C correlated with the concentration of suspended particles, which differed among watersheds. Thus, the ratio of N:P:Si in discharges differed greatly among watersheds, potentially affecting N, P or Si limitation of phytoplankton growth in the receiving waters. Simple regression models of N discharge versus the percentage of cropland suggest that croplands discharge 29–42 kg N ha^-1 yr^-1 and other lands discharge 1.2–5.8 kg N ha^-1 yr^-1. We estimated net anthropogenic input of N to croplands and other lands using county level data on agriculture and N deposition from the atmosphere. For most of the study watersheds, N discharge amounted to less than half of the net anthropogenic N.     

Conservation practices in U.S. agriculture and their impact on carbon sequestration

Increase in the use of conservation practices byagriculture in the United States will enhance soilorganic carbon and potentially increase carbonsequestration. This, in turn, will decrease the netemission of carbon dioxide. A number of studies existthat calibrate the contribution of various individual,site-specific conservation practices on changes insoil organic carbon. There is a general absence,however, of a comprehensive effort to measureobjectively the contribution of these practicesincluding conservation tillage, the ConservationReserve Program, and conservation buffer strips to anchange in soil organic carbon. This paper fills thatvoid. After recounting the evolution of the use ofthe various conservation practices, it is estimatedthat organic carbon in the soil in 1998 in the UnitedStates attributable to these practices was about 12.2million metric tons. By 2008, there will be anincrease of about 25%. Given that there is asignificant potential for conservation practices tolead to an increase in carbon sequestration, there area number of policy options that can be pursued.     

生物炭对华北农田土壤N2O通量及相关功能基因丰度的影响

为了探寻施用生物炭对农田土壤氧化亚氮(N_2O)的减排效果和机制,于2015年3月27日至6月5日,利用盆栽实验研究了施用生物炭(CK,C1:5%,C2:10%,C3:15%,C4:30%)(质量分数)对华北农田土壤N_2O通量、氨单加氧酶(amo A)、亚硝酸盐还原酶(nir S、nir K)以及氧化亚氮还原酶(nos Z)基因丰度的影响.结果表明:(1)施用低量生物炭(5%)能够促进N_2O排放,施用中、高量生物炭可以起到抑制N_2O排放的效果,且生物炭用量为15%时减排效果最佳.(2)实验初期,施用生物炭对土壤硝化反硝化基因丰度影响较大,AOA和nir S基因丰度与生物炭施用量呈极显著正相关关系,nir K基因丰度与生物炭施用量呈显著正相关关系,AOB和nos Z基因丰度与生物炭施用量呈显著负相关关系;实验末期,AOA丰度与生物炭施用量表现为显著负相关关系,AOB丰度与生物炭施用量表现为显著正相关关系.(3)实验初期,N_2O排放通量与AOA、nir S基因呈现极显著的负相关关系,说明在土壤含水量较高的条件下,N_2O的产生受AOA、nir S基因丰度控制调节;实验末期,N_2O排放通量与nos Z基因呈现极显著正相关关系,说明在土壤含水量较低的条件下,N_2O的产生受nos Z基因丰度控制调节.本研究结果表明施用生物炭能够增加硝化反硝化功能基因丰度,并降低N_2O的排放,为华北农田合理施用生物炭提供了一定的理论依据.     

秦皇岛市气候变化对农业气象灾害的影响

40多年来秦皇岛市气候发生了明显的变化，致使农业气象灾害增加：第一，冬暖、倒春寒、春末高温等灾害频次增多，冬季低温冻害频次和程度减少；第二，冬旱、春旱、秋旱、秋冬连旱、冬春连旱增多，伏旱次数明显减少，盛夏洪涝频次减少；第三，低温连阴雨、高温干旱、干热风等灾害在频次和程度上均发生明显变化。因此，秦皇岛农业生产防灾减灾的重点和方法也适当调整。     

我国农业自然灾害保险市场分析及其合理模式

萎靡的农业自然灾害保险市场不利于我国农村经济的发展。从产品特性、风险和费率设定三方面分析了农业自然灾害保险市场的特征，通过对农业自然灾害保险市场进行经济学分析，找出其衰退的原因，提出了适合我国国情的发展模式。     

ECONOMIC ANALYSIS OF WETLAND RESTORATION ALONG THE ILLINOIS RIVER1

Creating and restoring wetland and riparian ecosystems between farms and adjacent streams and rivers in the Upper Mississippi River Basin would reduce nitrogen loads and hypoxia in the Gulf of Mexico and increase local environmental benefits. Economic efficiency and economic impacts of the Hennepin and Hopper Lakes Restoration Project in Illinois were evaluated. The project converted 999 ha of cropland to bottomland forest, backwater lakes, and flood‐plain wetland habitat. Project benefits were estimated by summing the economic values of wetlands estimated in other studies. Project costs were estimated by the loss in the gross value of agricultural production from the conversion of corn and soybean acreage to wetlands. Estimated annual net benefit of wetland restoration in the project area amounted to US$1,827 per ha of restored wetland or US$1.83 million for the project area, indicating that the project is economically efficient. Impacts of the project on the regional economy were estimated (using IMPLAN) in terms of changes in total output, household income, and employment. The project is estimated to increase total output by US$2,028,576, household income by US$1,379,676, and employment by 56 persons, indicating that it has positive net economic impacts on the regional economy.