内蒙古苏尼特右旗草原草群矿质营养元素含量分析     

那日苏  塔娜  王海  范丽  拾涛 《中国草地学报》2013,35(4)

对内蒙古苏尼特右旗6个草场类8个草场型草群的氮、磷、钾、钙、镁、硫、铁、锰、铜、锌、钼、硒的含量及盈缺状态进行分析,结果表明:苏尼特右旗草群8月平均氮含量为16.86g/kg;草群富含钙但缺磷,钙磷比严重不平衡,放牧家畜应注意磷的补充;草群钾、锰、硫含量中等,放牧季可满足家畜的需要;草群富含铁,锰含量也较高,放牧季可满足家畜的需要;草群铜、锌、硒含量很低,家畜日粮中应适当补充.研究区不同植被类型草群微量元素富集顺序为:河泛地、湖盆低地盐生草甸草场类＞＞残丘坡地草原化荒漠草场类＞低山丘陵干草原草场类＞丘陵地荒漠化草原草场类＞高平原荒漠草原草场类＞沙丘植被草场类.  相似文献   

不同贮藏条件对苦荬菜种子活力的影响     

韩玉竹  曾兵  伍莲  马慧敏  肖兰 《河南农业科学》2011,40(7)

以牧草苦荬菜种子为材料,选取4个种子含水量(6.94%、3.27%、1.24%、0.98%)及6个贮藏温度(常温、25℃、15℃、10℃、3℃、-15℃),连续贮藏5个时期(3个月、6个月、9个月、12个月、16个月),研究不同贮藏条件对苦荬菜种子活力的影响。结果表明:贮藏温度和种子含水量均对苦荬菜种子活力有显著影响;贮藏温度在-15~15℃条件下,苦荬菜种子活力相对较高(贮藏16个月发芽率33%~42%),常温和25℃条件下种子活力下降明显,到16个月时种子活力几乎完全丧失(发芽率1.9%~2.4%);种子贮藏的最适含水量受贮藏温度的影响,贮藏温度越高,最适含水量相对要求越低。贮藏温度25℃,种子含水量为0.98%、1.24%、3.27%时种子发芽率相对较高,分别为30%、30%、34.7%,与种子含水量6.94%的种子发芽率(14%)有显著性差异(P<0.05)。  相似文献   

Urea fertilisation affected soil organic matter dynamics and microbial community structure in pasture soils of Southern Ecuador   总被引：1，自引：0，他引：1  

Ute Hamer  Karin Potthast  Franz Makeschin 《Applied soil ecology》2009,43(2-3):226-233

In the mountain rainforest region of the South Ecuadorian Andes natural forests have often been converted to pastures by slash-and-burn practice. With advanced pasture age the pasture grasses are increasingly replaced by the tropical bracken leading to the abandonment of the sites. To improve pasture productivity a fertilisation experiment with urea was established. The effects of urea on soil organic matter (SOM) mineralisation and microbial community structure in top soil (0–5 cm depth) of an active and abandoned pasture site have been investigated in laboratory incubation experiments. Either ¹⁴C- or ¹⁵N-labelled urea (74 mg urea-N kg⁻¹ dw soil) was added to track the fate of ¹⁴C into CO₂ or microbial biomass and that of ¹⁵N into the KCl-extractable NH₄-N or NO₃-N or microbial biomass pool. The soil microbial community structure was assessed using phospholipid fatty acid analysis (PLFA). In a second experiment two levels of ¹⁴C-labelled urea (74 and 110 mg urea-N kg⁻¹ dw soil) were added to soil from 5 to 10 cm depth of the respective sites. Urea fertilisation accelerated the mineralisation of SOC directly after addition up to 17% compared to the non-fertilised control after 14 days of incubation. The larger the amount of N potentially available per unit of microbial biomass N the larger was the positive priming effect. Since in average 80% of the urea-C had been mineralised already 1 day after amendment, the priming effect was strong enough to cause a net loss of soil C. Although the structure of the microbial community was significantly different between sites, urea fertilisation induced the same alteration in microbial community composition: towards a relative lower abundance of PLFA marker characteristic of Gram-positive bacteria and a higher one of those typical of Gram-negative bacteria and fungi. This change was positively correlated with the increase in NH₄, NO₃ and DON availability. In addition to the activation of different microbial groups the abolishment of energy limitation of the microbes seemed to be an important mechanism for the enhanced mineralisation of SOM.  相似文献   

Protein breakdown represents a major bottleneck in nitrogen cycling in grassland soils     

M.T. Jan  P. Roberts  S.K. Tonheim  D.L. Jones   《Soil biology & biochemistry》2009,41(11):2272-2282

Proteins represent the dominant input of organic N into most ecosystems and they also constitute the largest store of N in soil organic matter. The extracellular protease mediated breakdown of proteins to amino acids therefore represents a key step regulating N cycling in soil. In this study we investigated the influence of a range of environmental factors on the rate of protein mineralization in a grazed grassland and fallow agricultural soil. The protein turnover rates were directly compared to the rates of amino acid mineralization under the same conditions. Uniformly ¹⁴C-labelled soluble protein and amino acids were added to soil and the rate of ¹⁴CO₂ evolution determined over 30 d. Our results indicate that the primary phase of protein mineralization was approximately 20 ± 3 fold slower that the rate of amino acid mineralization. The addition of large amounts of inorganic NO₃⁻ and NH₄⁺ to the soil did not repress the rate of protein mineralization suggesting that available N does not directly affect protease activity in the short term. Whilst protein mineralization was strongly temperature sensitive, the presence of plants and the addition of humic and tannic acids had relatively little influence on the rate of soluble protein degradation in this fertile grassland soil. Our results suggests that the extracellular protease mediated cleavage of proteins to amino acids rather than breakdown of amino acids to NH₄⁺ represents the limiting step in soil N cycling.  相似文献   

Effect of urease and nitrification inhibitors on N transformation, gaseous emissions of ammonia and nitrous oxide, pasture yield and N uptake in grazed pasture system   总被引：1，自引：0，他引：1  

M. Zaman  S. Saggar  J. Singh 《Soil biology & biochemistry》2009,41(6):1270-1280

Nitrogen (N) losses via nitrate (NO₃⁻) leaching, ammonia (NH₃) volatilization and nitrous oxide (N₂O) emissions from grazed pastures in New Zealand are one of the major contributors to environmental degradation. The use of N inhibitors (urease and nitrification inhibitors) may have a role in mitigating these N losses. A one-year field experiment was conducted on a permanent dairy-grazed pasture site at Massey University, Palmerston North, New Zealand to quantify these N losses and to assess the effect of N inhibitors in reducing such losses during May 2005-2006. Cow urine at 600 kg N ha⁻¹ rate with or without urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) or (trade name “Agrotain”) (3 L ha⁻¹), nitrification inhibitor dicyandiamide (DCD) (7 kg ha⁻¹) and the use of double inhibitor (DI) containing a combination of both Agrotain and DCD (3:7) were applied to field plots in autumn, spring and summer. Pasture production, NH₃ and N₂O fluxes, soil mineral N concentrations, microbial biomass C and N, and soil pH were measured following the application of treatments during each season. All measured parameters, except soil microbial biomass C and N, were influenced by the added inhibitors during the three seasons. Agrotain reduced NH₃ emissions over urine alone by 29%, 93% and 31% in autumn, spring and summer respectively but had little effect on N₂O emission. DCD reduced N₂O emission over urine alone by 52%, 39% and 16% in autumn, spring and summer respectively but increased NH₃ emission by 56%, 9% and 17% over urine alone during those three seasons. The double inhibitor reduced NH₃ by 14%, 78% and 9% and N₂O emissions by 37%, 67% and 28% over urine alone in autumn, spring and summer respectively. The double inhibitor also increased pasture dry matter by 10%, 11% and 8% and N uptake by the 17%, 28% and 10% over urine alone during autumn, spring and summer respectively. Changes in soil mineral N and pH suggested a delay in urine-N hydrolysis with Agrotain, and reduced nitrification with DCD. The combination of Agrotain and DCD was more effective in reducing both NH₃ and N₂O emissions, improving pasture production, controlling urea hydrolysis and retaining N in NH₄⁺ form. These results suggest that the combination of both urease and nitrification inhibitors may have the most potential to reduce N losses if losses are associated with urine and improve pasture production in intensively grazed systems.  相似文献   

正己烷处理对菜蛾盘绒茧蜂滞育预蛹过氧化氢及抗氧化酶的影响     

侯佳秀  徐登兰  贺宜鹏  陈超  施祖华 《中国生物防治》2014,(1):26-31

在27～29℃温度下,用1.5 mL/L的正己烷蒸气处理菜蛾盘绒茧蜂滞育蛹10～15 min后可以解除其滞育。为探讨解除滞育的机制,测定了正己烷处理后菜蛾盘绒茧蜂滞育预蛹体内的过氧化氢含量（H2O2）和3种抗氧化酶（SOD、POD和CAT）活性。结果表明正己烷处理后,滞育预蛹体内H2O2含量、SOD和POD活性均迅速上升,CAT活性则下降。就5个取样点的平均值而言,H2O2含量和SOD活性显著高于非滞育预蛹和未经处理的滞育预蛹,POD活性低于非滞育预蛹而高于未经处理的滞育预蛹,CAT活性则低于未经处理的滞育预蛹而高于非滞育预蛹。3种抗氧化酶活性的变化与体内H2O2含量的平衡有关,而H2O2含量的变化可能与体内激素水平的调节有关。  相似文献   

Silvopastoralism in New Zealand: review of effects of evergreen and deciduous trees on pasture dynamics   总被引：1，自引：1，他引：0  

Raquel Benavides  Grant B. Douglas  Koldo Osoro 《Agroforestry Systems》2009,76(2):327-350

Complex interactions between livestock, trees and pasture occur in silvopastoral systems. Between trees and pasture, competition for soil resources (nutrients and water) occurs, becoming especially relevant when one of them is in scarce supply. Trees reduce light and water reaching the understorey layers according to tree density and canopy size. However, they may ameliorate extreme climatological features (reducing wind speed and evapotranspiration, and alleviating extreme temperatures), and improve soil properties, for example, deciduous tree litter may contribute to increased pH and soil nutrient concentrations. During tree establishment, there are generally negligible effects on pasture, irrespective of tree type. However, there is a decline in pasture production and nutritive value under shade with increasing tree age and higher stand density. Under the same conditions, deciduous trees affect pasture later (extinction point of pasture occurs at 85% of canopy closure) than evergreen trees (about 67% for Pinus radiata D. Don). This is mainly because deciduous trees have a leafless period that enables pasture recovery, and their litter smothers pasture less intensely because of its relatively fast decomposition. Silvopastoral studies conducted in New Zealand are reviewed to discuss these effects, and differences in the effects of evergreen and deciduous trees are shown using the examples of P. radiata, and Populus and Salix spp. respectively, which exist in many temperate countries. Future research needs are outlined.  相似文献   

不同牧草混播对退化高寒草甸土壤养分及生物量的影响     

张骞  张中华  马丽  杨晓渊  郭婧  徐文华  周秉荣  邵新庆  王芳  贾永忠  贺有龙  金欣  周华坤 《草地学报》2019,27(6):1659-1666

适宜的牧草混播对于改善退化高寒草甸及高寒地区畜牧业现状具有重要的现实意义,但不同牧草混播条件下退化高寒草甸土壤养分及生物量变化特征尚不明确。为此,本研究以垂穗披碱草（Elymus nutans）、早熟禾（Poa pratensis）、呼伦贝尔苜蓿（Medicago falcata）为试验草种,在三江源区重度退化高寒草甸开展为期3年的混播试验,探讨不同牧草混播对退化高寒草甸土壤养分及生物量的影响。结果表明：不同牧草混播条件下,草甸土壤有机碳含量与全氮及不同形态氮素含量呈显著正相关（P<0.05）;草甸土壤养分含量发生显著变化（P<0.05）,EM（垂穗披碱草+呼伦贝尔苜蓿）混播的土壤养分状况最佳;草甸地上、地下生物量显著增加（P<0.05）,EM混播的效果最为显著（P<0.05）。综上,在重度退化高寒草甸恢复过程中,如采取人工草地建植手段,建议选择EM混播。  相似文献   

Effect of grazing intensity and soil characteristics on soil organic carbon and nitrogen stocks in a temperate long-term grassland     

Anja Nüsse  Deborah Linsler  Michael Kaiser  Dorothee Ebeling  Bettina Tonn  Johannes Isselstein 《Archives of Agronomy and Soil Science》2017,63(12):1776-1783

The effects of different grazing pressures (GPs) on soil properties are not sufficiently understood. The objectives were to analyse the effects of three different extensive GPs on stocks of soil organic C and total N, soil microbial biomass C, basal respiration and mineral N in three different soil depths of a long-term pasture in Central Germany (FORBIOBEN field trial). No significant (p ≤ 0.05) effects of GP on weighted stocks of soil organic C, total N, soil microbial biomass C, mineral N and basal respiration rate were observed, suggesting that the C and N cycles are coupled in the three grazing treatments. Oxalate soluble Fe contents explained a marked part of the variation of soil organic C (multiple linear regression: R² = 0.64) and total N contents (R² = 0.64) in the soils, whereas almost all of the variability of soil microbial biomass C contents and basal respiration was explained by soil organic C contents. Overall, variabilities of soil organic C and N contents were largely explained by oxalate soluble Fe contents, whereas grazing intensity did not affect the C and N dynamics.  相似文献   

西北部分地区草样中微生物多样性及乳酸菌种群的研究     

谈重芳  王晶晶  李宗伟  常胜合  秦广雍  王雁萍  蔡义民 《安徽农业科学》2010,38(17):9051-9053,9091

[目的]为牧草青贮饲料科学合理地利用和制作提供一定的参考依据。[方法]分析西北地区牧草样品中的微生物种类和数量,从中分离鉴定了11株乳酸菌,并研究了这些乳酸菌的结构和特性。[结果]分离株都是革兰氏阳性、过氧化氢酶阴性和兼性厌氧菌。所分离得到的菌株中同型发酵占78%。根据所分离的乳酸菌的形态学和生理生化特性,这些乳酸菌可被分为3组（A,B和C）。经表型分类鉴定,A组为乳杆菌（Lactobacillus）,B组为球菌（Leuconostocaceae）,C组为球菌（Lactococcus）。[结论]分离鉴定了西北地区牧草附着微生物的种类和特性,为牧草青贮饲料的制作提供了科学依据。  相似文献