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从生态学的观点出发,农业是转化农业环境自然资源的生产行业。为了提高农业生态系统的生产力,生态农业一方面要求具有最多的绿色植被,使尽可能多的太阳光能转化为生物能,另一方面还要求光合产物能够得到最有效的利用。 要充分利用光能,获得最大的初级生产力,首先就要充分利用土地资源,让尽可能多的有阳光照射、能够生长植物的地方都种上各种植物。牧草具有很强的适应性,在一般农作物难以生存的恶劣条件下,许多牧草都能茂盛生长。我国北方干旱半干旱地区土壤瘠薄,农作物生长受到很大限制,那里光照时间虽长,光能却很难有效利用,但那些耐旱耐寒的牧草却能适应这样的环境。其实,我国广大农区都有一些不适应种植农作物而适于各种牧草生长的荒坡、荒地、荒水、荒滩和农田隙地,如沿海大面积的海涂滩地。这些沿海滩涂含盐量高,未改造前种植农作物很困难,耐盐碱能力强的大米草、沙打旺、田菁、紫花苜蓿、三叶草、牛尾草等牧草却适于生长。因此,种植各种牧草、大力发展草食牲畜,就可以把这些土地资源有效地利用起来。其次要进行合理的间作套种,通过农作物、经济林木和牧草的合理配置,建立多层多种的立体群落结构,从时间和空间上提高光能利用率。目前各地都有大面积的疏林地,光能利用率很低。如果有意识地培育 相似文献
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采用IPCC推荐的温室气体清单计算方法,从温室气体排放总量、排放强度等方面分析了华中地区畜牧业温室气体排放现状;根据不同牲畜饲养数量,采用Logisticgrowth model、Gompertzcurve model等非线性时间序列模型模拟2030年华中地区牲畜数量,并计算畜牧业温室气体排放量.结果显示,2015年华中地区温室气体排放为6289.09万t CO2-eq,单位GDP温室气体排放量为1.13万t CO2-eq/亿元,单位肉类产量排放强度为3.73t CO2-eq/t;2030年华中地区畜牧业温室气体排放总量约为4990.06(温室气体排放预测1)~5932.74万tCO2-eq(温室气体排放预测2).应当进一步优化畜牧业饲养技术及条件来提高产业温室气体排放效率,科学合理的规划不同牲畜的饲养规模,优化牲畜饲养结构来降低畜牧业温室气体排放量. 相似文献
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东北海伦地区农村地下饮用水硝态氮污染特征及其影响因素分析 总被引:9,自引:4,他引:5
地下水硝态氮污染已成为一个全球性的问题,直接影响到人们的生活用水和身体健康.通过对海伦地区157口农村饮用水井取样分析,探讨了该地区地下水硝态氮污染的时空特征及其影响因素.结果表明,地下水中硝态氮平均含量14.01 mg·L-1,超标率(≥10.00 mg·L-1)达到26.11%.地下饮用水硝态氮的污染表现出明显的空间分异特征,在空间上地下水硝态氮污染程度从高到低依次为中部漫川漫岗农业区、东北丘陵漫岗农业区,西南平川漫岗农业区.在此基础上,从水井本身性质和污染物来源两方面分析了地下水硝态氮污染影响因素.在水井本身性质方面,水井管道材料不同导致地下水硝态氮受污染程度不同,其中单节管道水井的污染程度显著低于多节管道,平均浓度分别为5.08、 32.57 mg·L-1,超标率分布为12.26%、 82.35%;整个地区水井硝态氮污染程度与水井绝对深度无显著关系,但在28个同一取样单元,深水井污染程度显著低于浅水井,其中单节管深井、单节管浅井、多节管深井、多节管浅井的平均浓度分别为1.84、 12.02、 25.14、 45.61 mg·L-1.分析污染物来源可以发现,污染程度较高的地区多处于氮肥施用量较高、户均家禽牲畜量较多的地区,表明地下水硝态氮污染与化肥施用量以及家禽牲畜排泄量呈一定的正相关关系. 相似文献
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Microbial community structure in an integrated A/O reactor treating diluted
livestock wastewater during start-up period 总被引:1,自引:0,他引:1
In order to investigate the correlation between reactor performance and the microorganisms, an integrated A/O reactor was operated
for 72 days to treat diluted livestock wastewater. Chemical oxygen demand (COD) removal e ciency increased from 79% to 94%,
with total nitrogen (TN) removal e ciency from 37% to 50% (HRT 7.4 hr) when the influent COD and TN were ca. 1500 mg/L and 95
mg/L, respectively, and the outlet COD concentration was less than 100 mg/L at the end. Microbial community was monitored during
start-up period by denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA gene. DGGE profiles showed that microbial
community had changed significantly during the start-up and these shifts were in accordance with the reactor performance. UPGMA
clustering analysis showed that 14 anaerobic samples fell into five main groups and so did the aerobic ones, but the grouping patterns
were di erent. Phylogenetic analysis indicated that microbial populations in the anaerobic compartment belonged to Firmicutes,
Proteobacteria, Chloroflexi and Bacteroidetes, while Proteobacteria, Bacteroidetes, Firmicutes, Verrucomicrobiae and Nitrospira were
present in the aerobic compartment. In the anaerobic compartment, more fermentative and acetogenic bacteria were detected during the
start-up while denitrifying bacteria faded away. Two functional populations such as Nitrospira defluvii and Dechloromonas denitrificans
were observed when nitrogen removal was high, indicating that simultaneous nitrification and denitrification occurred in the aerobic
compartment. 相似文献
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Preliminary study on treatment of waste organic matter from livestock
by bacteria-mineral technology
The present study dealt with relationships between the degradation and humification process that the organic matter underwent during bacteria-mineral technology.An inverse correlation was found between the protein,lipid,and some of the humification indices considered,suggesting that the humification theory is actually humic substances produced from simple-structured natural organic substrates.Weight-average molecular weight (Mw),number-average molecular weight(Mn),and the ratio Mw/Mn of dissolved organic matters at difierent stages of the process were measured by gel permeation chromatography.The results showed that Mn and Mw increased with reaction time from 352 to 17,191,and from 78,707 to 104,564,respectively.The ratio of Mn/Mw decreased from 223.3 to 6.1.This reflected the growth of the polymerization degree of dissolvable organic matters in the process;furthermore,it indicated the formation of complex molecules (humic substances) from more simple molecules.Bacteria-mineral water(BMW) (the effluent of the process) treatments can exert hormone-like activity for enhanced seed germination of wheat and rice and greatly improved chlorophyll synthesis in wheat and rice leaves.Major polyamines (plant regulators) putrescine,spermidine,and spermine,were found in BMW by a high performance liquid chromatography (HPLC) method,which may explain the hormone-like activity of BMW. 相似文献