Cultivation Influences on Soil Organic Carbon Associated with Texture in Seasonally Frozen Zones

[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events.[Method] Three chronosequences were selected for paired comparisons.Soil samples were collected at six depths with a 10 cm increment.Analysis of variance with general linear model and regression was performed for statistical analysis.[Result] In seasonally frozen soils where fragmentation of macroaggregates was stimulated,soil organic carbon level was positively associated with clay ＋ silt proportion due to a wider textural range,better than sole clay content.Exponential function better fitted the experimental data to present progressively increased effectiveness of clay ＋ silt content in maintaining carbon.Clay content explained 12％-41％ and 14％-43％ of variation via linear and exponential functions,respectively.Accordingly,clay ＋ silt content explained 47％-65％ and 46％-70％.[Conclusion] Texture reflected soil organic carbon occurrence as consequences of reclamation.For seasonally frozen soils with wider textural ranges,it is robust to adapt clay ＋ silt content as dependent variable and exponential function.The generated algorithms provided an available pathway to estimate soil organic carbon losses following cultivation and to evaluate soil fertility.     

环保畜牧业与健康养殖发展探讨

当今,养殖业面对的环保要求越来越高,且人类社会对畜禽产品的质量也是高度关注。本文从畜牧业污染产生的危害、治理思路、控污的具体措施以及健康的养殖模式展开分析,并做出一些对未来养殖业发展的预测,旨在为环保养殖提供参考与借鉴。     

抚育间伐对燕山北部山区山杨林物种多样性的影响

为了了解抚育间伐对燕山北部山区山杨林物种多样性的影响,对山杨林抚育间伐前后的物种多样性进行了调查和分析,结果表明:抚育后林地草本植物的物种多样性高于未抚育林地,抚育间伐林地草本植物的Patrick指数、Margarlef指数、Simpson指数和Shannon-Wiener指数分别为35.0、6.13、0.89和2.76,未抚育样地分别为29.0、4.90、0.32和1.91;抚育林地灌木的Patrick指数、Margarlef指数、Simpson指数和Shannon-Wiener指数分别为9.0、1.41、0.43和0.98,未抚育林地则分别为8.0、1.48、0.68和1.51,除Patrick指数外,抚育林地的其他多样性指数都低于未抚育林地;抚育间伐使乔木层优势种的优势更为明显。由此得出结论,抚育间伐对山杨林的物种多样性有明显影响,但草本、灌木与乔木对抚育间伐的响应有所不同。     

Increased N fertilizer input enhances CH4 and N2O emissions from soil amended with low amount of milk vetch residues

Paddy and Water Environment - The combined use of chemical N fertilizer and crop residue could influence greenhouse gas emissions in agriculture. A pot experiment was performed to examine the...     

2010年中国小麦市场回顾与2011年行情展望

全球谷物市场在2011年春节期间的整体走势可谓异常火爆．从节后郑州强麦期货市场首日涨停的“飞天舞”．到国际市场上饲用和优质小麦、期货和现货小麦价格的“比翼双飞”组合．使得国内农户更倾向于挺价待涨。其主要利多题材来自于2010年全球范围内多发的灾害性天气．