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.     

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.     

生态农业的给排水循环系统的探讨

生态农业的发展，是经济、社会和环境保护协调发展的产物。作者提出生态农业的给排水循环系统作为现有模式的延伸和补充，让生态农业在经济、社会、环境的协调发展中发挥更大的作用，最大限度地消除农业污染，为农业可持续发展提供技术支持和可靠保证。     

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.     

黑龙江省勃利县生态环境问题及其保护对策

经过对勃利县的自然生态和地理环境的调查,收集了大量的资料,并根据生态环境的问题,提出了相应的保护对策措施,例如实施天然林保护工程、建立自然保护区、发展生态农业和绿色食品。     

资源循环型农业理论的探索与实践

资源循环型农业是在循环经济理论和可持续发展思想指导下形成的一种新型农业发展模式.以青岛为例,用理论和实践相结合的方式,论证了资源循环型农业对推进我国农业现代化进程,实现农业可持续发展具有非常重要的意义,是一种值得推广的农业模式.     

HYDROLOGICAL MODELING OF THE IROQUOIS RIVER WATERSHED USING HSPF AND SWAT1

ABSTRACT: The performance of two popular watershed scale simulation models — HSPF and SWAT — were evaluated for simulating the hydrology of the 5,568 km² Iroquois River watershed in Illinois and Indiana. This large, tile drained agricultural watershed provides distinctly different conditions for model comparison in contrast to previous studies. Both models were calibrated for a nine‐year period (1987 through 1995) and verified using an independent 15‐year period (1972 through 1986) by comparing simulated and observed daily, monthly, and annual streamflow. The characteristics of simulated flows from both models are mostly similar to each other and to observed flows, particularly for the calibration results. SWAT predicts flows slightly better than HSPF for the verification period, with the primary advantage being better simulation of low flows. A noticeable difference in the models' hydrologic simulation relates to the estimation of potential evapotranspiration (PET). Comparatively low PET values provided as input to HSPF from the BASINS 3.0 database may be a factor in HSPF's overestimation of low flows. Another factor affecting baseflow simulation is the presence of tile drains in the watershed. HSPF parameters can be adjusted to indirectly account for the faster subsurface flow associated with tile drains, but there is no specific tile drainage component in HSPF as there is in SWAT. Continued comparative studies such as this, under a variety of hydrologic conditions and watershed scales, provide needed guidance to potential users in model selection and application.     

论四川发展生态农业和保护农业生态环境的对策

四川是中国生态环境保护和建设的重点地区。在20世纪80年代初期，科学家提出四川要发展生态农业，生态农业才是农业发展的方向。原始森林减少，生态功能削弱，土地荒漠化和水土流失面积大，不合理的资源开发和建设加速水土流失，城市生活坟圾和工业废弃物、酸雨、农药、化肥过量使用、农用薄膜的残留、畜禽粪尿污染是四川农业生态环境存在的主要问题。改善四川农业生态环境的对策是大力保护天然林，退耕还林还草；加强农业生态环境保护和治理，强化生态农业工程建设；启动农业清洁生产工程；重视生态农业技术创新。大力发展生态农业科技产业，以构筑生态安全体系为根基，以公司加农户的产业运管模式，以信息技术的有机整合，有力推进生态农业的科技产业模式。