酸性土壤中决明属牧草高效根瘤菌的分离及筛选

为提高豆科决明属（Chamaecrista spp.）牧草的结瘤能力和固氮效率，促进决明属牧草在酸性土壤中的应用及推广，本研究以圆叶决明（Chamaecrista rotundifolia）和羽叶决明（Chamaecrasta nictitans）为试验材料，通过分离、纯化、nodA基因鉴定等方法，从酸性土壤里决明属牧草的根瘤中分离到10株候选根瘤菌株系。16S rDNA测序及系统发育树分析表明，这10株根瘤菌均属于慢生型根瘤菌。回接试验表明，上述10株根瘤菌均能与圆叶决明共生，形成根瘤。与不接种的对照相比，其固氮酶活性为0.08~4.65 μmol·g^-1·h^-1，植株干重、SPAD值和氮含量分别提高了99.17%~372.14%，399.27%~789.05%，235.00%~1043.33%。其中，4株根瘤菌TXR2，TXN1，WYSR1，JYN6对圆叶决明氮营养贡献最大，并且TXN1与宿主共生形成的根瘤数目最多，而JYN6的固氮酶活性最高。说明本研究分离鉴定到4株决明高效根瘤菌，具有较好的应用前景。     

猪的福利与放牧养猪

通过对动物福利的概况阐述,分析了我国猪饲养环境中存在的动物福利问题以及放牧养猪对猪只福利的影响,提出了发展放牧养猪的思路。     

种植方式对青海湖流域人工草地植被和土壤养分特征的影响

为探究多年生人工草地在青海湖流域的适应性和稳定性,本研究以青海草地早熟禾(Poa pratensis. Qinghai)和青海中华羊茅(Festuca sinensis. Qinghai)单播及混播人工草地为研究对象,分析不同种植方式下人工草地植被和土壤养分特征的变化。结果表明：青海草地早熟禾+青海中华羊茅混播草地和青海草地早熟禾单播草地的生物量和盖度高于青海中华羊茅单播草地,且在生长旺期(8月),青海草地早熟禾+青海中华羊茅混播草地生物量最高,为586.2 g·m^-2;青海草地早熟禾单播、青海中华羊茅单播和青海草地早熟禾+青海中华羊茅混播草地间土壤有机质、全氮、全磷、硝态氮、铵态氮和土壤含水量在相同土壤深度下差异不显著,但土壤氮、磷及有机质间存在显著的相关性。综上所述,在青海湖流域建植青海草地早熟禾+青海中华羊茅混播型人工草地可以获得较高的产量,但需在种植和管理过程中协调好土壤氮、磷间的关系。     

Effects of silvopastoral areas on milk production at dual-purpose cattle farms at the semi-humid old agricultural frontier in central Nicaragua

In extensive cattle production systems, the composition of grazing areas may significantly influence productivity. In dual-purpose cattle production systems in the lowland tropics, pasture lands with trees, so-called silvopastoral areas, are considered as being important, particularly to facilitate the management of crossbred European native cattle. The aim of the study was to quantify the effects of silvopastoral areas on production at dual-purpose cattle farms in the semi-humid lowlands of central Nicaragua. The relationships between seasonal milk production and herd data, and the proportions of land use types were examined for 74 farms by stepwise regression analysis.     

基于Landsat TM影像的半干旱牧区天然打草场面积的遥感监测

天然打草场是中国草地畜牧业的物质基础,也是中国内陆的生态屏障。目前中国打草场分布状况、分布面积、产量高低等信息十分缺乏,严重制约饲草储备和救灾应急功能发挥。为解决这些问题,该文基于2009－2011年的Landsat TM5影像数据,并借助野外调查点和目视解译方法对中国半干旱牧区天然打草场状况进行监测分析。结果表明,中国半干旱牧区天然打草场面积达800.35万hm2,目视解译结果的平均解译精度达到76.78%。其中,内蒙古天然打草场面积居首位,面积为688.04万hm2,其次是松嫩平原草原区,打草场面积为91.80万hm2,河北半干旱农牧交错区的打草场面积最小,为20.51万hm2。在内蒙古,呼伦贝尔草甸草原天然打草场约为180.89万hm2,科尔沁沙化草原天然打草场约为96.44万hm2,锡林郭勒典型草原天然打草场面积约为395.40万hm2。研究区天然打草场的植被类型以温性草原类、温性草甸类、低地草甸类为主,少量分布在山地草甸类和温性荒漠草原类。该研究结果可为进一步分析全国半干旱区域打草场变化提供数据支撑。     

Responses of subshrub sagebrush rangeland in North-Western China to changes in livestock numbers and rainfall over 10 years (2004–2013)

Seriphidium transiliense, or subshrub sagebrush, is one of the most important forage resources for livestock in many arid lands, but such resources have been threatened by overgrazing for a long time. A 2013 vegetation survey of an original sagebrush rangeland (2400?ha) in the Tianshan Mountains revealed that nearly half of the area once under sagebrush has been replaced by annual species. This is due to the continual and rapid increase in livestock numbers over the past 30?years. Three smaller sites with different grazing scenarios: no grazing (Site N), a decline (Site 1), and an increase (Site 2) in livestock numbers, were selected to monitor recent changes (from 2004 to 2013) in vegetation biomass and the degree of dominance by sagebrush. Supplanting happened at Site 2 but little occurred at Site 1. There were significant differences between Site 2 and Site 1 in standing biomass in Spring and Summer, but no significant differences in Summer between Site 1 and Site N. The supplanting of sagebrush marks the completion of a dynamic process – in which rainfall plays a crucial role – of damage to sagebrush from heavy grazing in drought years and its rehabilitation by light grazing in some good years. Plant biomass loss was greatest when the land was first subjected to heavy grazing. Sagebrush tends to exist as a sole-dominant species rather than a companion species in sagebrush communities. This suggests that sagebrush continued to survive in pockets where grazing pressure had declined.     

我国北方半干旱草原沙漠化防治中压力转移模式的检讨——以内蒙古巴林右旗为例

以内蒙巴林右旗为例,详细分析了目前我国北方半干旱草原沙漠化防治中所主要采用的几种方法——围封禁牧、生态移民、舍饲和小草库伦。提出这些方法都属“压力转移模式”,并指出了其失效的各种表现。进而通过分析我国北方半干旱草原沙漠化的主要原因和根本矛盾,指出其失效的根本原因。据此,提出要将“压力转移模式”转向“攻坚模式”才是解决问题的根本出路的见解。     

Crop responses to applied soil compaction and to compaction repair treatments

Crop responses to annual compaction treatments (applied to whole plots) and management treatments to ameliorate compacted soil were determined in a field experiment on a Vertisol. Initially, all treatments except a control were compacted with a 10 Mg axle load on wet soil (26% gravimetric water content compared with a plastic limit of 22%). Annually applied axle loads of 10 and 6 Mg on wet soil (25–32% soil water) tended to reduce seedling emergence, grain yield (wheat, sorghum and maize), soil water storage and crop water use efficiency (WUE). Annual applications of an axle load of 6 Mg on dry soil (<22% soil water) had little effect on crop performance. Mean reductions in the yield of five crops (three wheat, one sorghum and one maize) in comparison with the uncompacted control were 23% or 0.79 Mg ha⁻¹ (10 Mg on wet soil), 13% or 0.44 Mg ha⁻¹ (6 Mg on wet soil) and 1% or 0.03 Mg ha⁻¹ (6 Mg on dry soil). Maize grown in the fifth year of treatment application was most affected by compaction of wet soil, its WUE being reduced from 14.3 to 9.7 kg ha⁻¹ mm⁻¹ in response to an axle load of 10 Mg. Reduced WUE was associated with delayed soil water extraction at depth. A 3-year pasture ley was the most successful amelioration treatment. A wheat and a maize crop grown after the ley outyielded the control by 0.33 and 0.90 Mg ha⁻¹, respectively. So the pasture not only ameliorated the initial compaction damage, with respect to crop performance, but resulted in improvements in two subsequent crops.