Symbiotic N<Subscript>2</Subscript> fixation and nitrate utilisation in irrigated lucerne (<Emphasis Type="Italic">Medicago sativa</Emphasis>) systems     

Huimin Yang  Murray Unkovich  Ann McNeill  Xianzhi Wang 《Biology and Fertility of Soils》2011,47(4):377-385

Symbiotic N₂ fixation by lucerne (Medicago sativa) has capacity to provide significant inputs of N to agro-ecosystems, and the species has also been shown to scavenge soil mineral N and thus act as a sink for excess reactive N. The balance between these two N cycle processes was investigated in an extensive irrigated lucerne growing region where nitrate contamination of groundwater has been reported. We sampled 18 permanent pure lucerne stands under irrigation for standing dry matter, total shoot N, and N₂ fixation using ¹⁵N natural abundance along with activity of the inducible enzyme nitrate reductase as indicators of use of soil NO₃⁻ by lucerne. On average 65% of lucerne N was obtained from symbiotic N₂ fixation. Converting standing dry matter estimates to annual N₂ fixation amounts we calculated average N₂ fixation of 311 kg N/ha, including N in roots and nodules. Uptake of N from soil by lucerne was calculated to be 181 kg N/ha/year. We were not able to identify the source of this soil mineral N, although nitrate reductase activity of lucerne was higher than that of non-N₂ fixing species examined.  相似文献   

生物质液化油分级产物的分离和综合利用研究     

冯君锋  蒋剑春  徐俊明  贺小亮  杨中志  许乐 《林产化学与工业》2014,(6)

以浓硫酸为催化剂,采用甲醇-甘油复合溶剂,在高温高压的条件下对竹屑、杨木、桉木和松木进行液化,并且对液化产物进行了中和、过滤和旋转蒸发等一系列分级处理,并对液化固体残渣和气体产物进行分析。主要研究了以竹屑为原料的液化油的分级产物的组成及成分,研究结果表明:竹屑经甲醇-甘油液化,产物经过分级处理得到的主要产物为杂多酚、多糖苷和乙酰丙酸甲酯。多糖苷相主要含有多糖苷和未反应的甘油及其甘油聚合物,其中多糖苷主要为六元环吡喃糖苷,约占41.81%,甘油及其聚合物占47.27%;杂多酚相主要含有乙酰丙酸酯、杂多酚和甘油等化合物,其中甘油及其聚合物占38.04%,杂多酚相物质为难溶于水的焦油相的相对分子质量大的物质,约占杂多酚相的38.41%,并且杂多酚相的相对分子质量主要集中在990左右。  相似文献   

E. Melanie DuPuis: Nature’s perfect food: how milk became America’s drink     

Evan Perrault 《Agriculture and Human Values》2011,28(4):583-584

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Books received     

Carol J. Pierce Colfer 《Agriculture and Human Values》2011,28(4):589-590

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Performance evaluation of forest co-management: a case study of Chunati Wildlife Sanctuary,Bangladesh     

Umma Tamima 《林业研究》2016,27(4):853-861

The objective was to evaluate the performance of the co-management of Nishorgo Support Project at Chunati Wildlife Sanctuary in Bangladesh. I adopted the Focus Groups Discussion method for opinion survey and applied the SWOTAHP technique for data analysis. Local people did not participate in the decision-making process of forest management and they perceived co-management as a threat to their livelihoods. Moreover, mistrust and misunderstanding among different stakeholders, political and ethical conflicts, lack of property rights of tribal communities, and lack of accountability and transparency were identified as the drawbacks of co-management.  相似文献   

Jody Emel and Harvey Neo: Political ecologies of meat     

Heide K. Bruckner 《Agriculture and Human Values》2016,33(3):739-740

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Brian K. Obach: Organic struggle: the movement for sustainable agriculture in the United States     

Kelly Yearick 《Agriculture and Human Values》2017,34(2):505-506

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A.D. McIntyre (ed): Life in the world’s oceans—diversity,distribution and abundance     

Malcolm Jobling 《Aquaculture International》2011,19(3):597-598

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Immune Responses to Vibrio anguillarum in Yellowtail Kingfish,Seriola lalandi,Fed Selenium Supplementation     

Ky T. Le  Ravi Fotedar 《Journal of the World Aquaculture Society》2014,45(2):138-148

Effects of dietary selenium (Se) on immune competence of yellowtail kingfish, Seriola lalandi, were investigated. The fish were fed one of the three experimental diets including a control diet without Se supplementation and two diets supplemented with Se from Se‐yeast (Selplex) at 2 and 4 mg/kg. After feeding for 6 wk, the fish were challenged by injecting Vibrio anguillarum and observed for 2 wk. Dietary Se had no effect on feed intake, feed conversion ratio, and survival over the course of 6‐wk feeding; however, it significantly increased weight gain and Se content in muscle. Following the bacterial infection, the immune‐stimulating effects of Se were observed in antibody, lysozyme, and bactericidal responses, and there was a corresponding increase in survival and hematocrit by Se. Under infectious condition, antioxidant capacity of fish as measured in terms of resistance of red blood cells to peroxidation and glutathione peroxidase activity also increased by supplementation of Se. Liver necrosis and kidney melano‐macrophages were only seen in surviving fish fed the control diet after the challenge. Furthermore, there was evidence of myopathy in fish fed the diet without Se supplementation. This study suggests that Se, supplemented at 2 or 4 mg/kg, can improve growth and health of yellowtail kingfish.  相似文献   

Comments on soil memory and paleo-environmental reconstruction of soil evolution     

Dan Yaalon 《Eurasian Soil Science》2011,44(4):462-463

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