膜下空调控温储粮试验

为了控制高温季节高大平房仓表层粮温急剧上升,在粮堆表面用薄膜进行密闭,将空调产生的冷气导入膜下进行降温处理.结果表明,在高温季节可将表层粮温控制在22℃以下,全仓平均粮温控制在16℃以下,能够长期保持储粮的低温环境,达到延缓粮食陈化的目的.     

Temporal Variability of Soil Property Dynamics in a Grazed Pasture

The seasonal change in soil nutrients influences when producers can accurately sample fields for fertilization and compliance with environmental regulations. The objective of this study was to determine temporal variability of soil tests in a grazed pasture system. Soil samples were collected monthly from two different pastures analyzed for soil pH, plant-available nitrogen (NO₃-N), phosphorus (P), and potassium (K). Temporal variability did not exist for Mehlich 3 P and K during the study, but significant temporal variability was observed for the mobile nutrient NO₃-N during the study. Similarly, significant temporal variability was found for soil pH during the study, but the differences were rather small and probably would not affect management decisions. The results of our study indicate sampling time had no significant effect on plant-available P and K and a small but significant effect on soil pH, but this is very important for NO₃-N assessment when correct sampling protocols are followed.     

基于“3S”技术与地面调查相结合的草原监测——以青海省黄南和海南地区为例

以青海省黄南地区和海南地区为例,详细论述了“3S”技术与地面调查相结合的草原监测技术路线流程;用2007年产草量观测资料,经GPS定位,与MODIS植被指数建立地上生物量反演模型,同时,利用粮食、青稞等农作物产量与林地面积资料,估算了农林副产品载畜量,分析了黄南地区和海南地区总体牲畜承载力及超载情况。结果表明：黄南地区和海南地区的总体载畜量分别为302.82万和386.25万个羊单位,超载率分别为67.48%和125.65%,两地区平均超载率为96.57%,说明这2个地区应适当降低牲畜数量或加大补饲力度,以减轻对当地草原生态的压力。提出最大超载率和平均超载率的概念,把两者结合起来,以便综合地反映研究区放牧超载情况。建议构建和开发基于Web-GIS的草原监测网站,以期为《草原法》的执行提供依据,促进我国草原生态建设和草原恢复的发展。     

干旱对内蒙古草原牧草生物量损失的评估方法研究

为探索草原干旱对牧草生物量造成损失的评估方法,以内蒙古扎鲁持旗北部的巴雅尔图草原为例,利用水分亏缺量作为内蒙古草原干旱评估指标,建立不同生长阶段牧草生物量损失评估模型。结果表明,牧草生物损失量与牧草返青期、旺盛生长期的水分亏缺量有着显著的Logistic曲线关系。依此确定了不同干旱等级相对应的牧草生物损失量,以满足草原干旱监测与灾损评估需要。     

伊犁河谷春秋草地围封恢复过程中种间关联性研究

采用样方调查法,通过对方差分析、x2检验及种间关联度OI值的计算,对伊犁河谷春秋草地围封6年、5年、1年和未围封的草地群落中主要种群间的联结性进行了比较。结果表明,围封6年和5年的总体表现无关联,种间关联松散,围封1年和未围封表现轻微负关联。随着围封植被的恢复正关联显著的种对增加,负关联显著的种对明显减少,正负关联率表现为先减小后增大的趋势。优势种分布相对稳定,与其他种群表现中性联结,其他种群易受物种和环境的影响。种间联结测定值在一定程度上反映了物种间的相互关系以及它们与环境因子的关系,在未围封和围封初期种间关系受环境因素影响较大,随着群落生境的改善,生物因素对种间关联影响逐渐增强。     

热带人工草地建植技术

介绍了适合我国热带地区种植的主要牧草品种,全面总结了热带人工草地的建植技术,包括地面处理、种子处理、播种技术及热带人工草地管理技术等。     

新型矿基土壤调理剂对滨海盐土理化性状和水稻产量的影响

以自主研发的矿基土壤调理剂为试验材料,采用盆栽方法研究了土壤调理剂不同施用量(0、5.0、7.5、10.0、12.5 g·kg^-1)对滨海盐土理化性状[pH值、土壤电导率(EC),及有机质、全氮、碱解氮、速效钾、有效磷含量]、水稻养分吸收和产量的影响。结果表明,施用土壤调理剂后,土壤pH值、EC值和速效钾含量与不施土壤调理剂的对照相比显著(P<0.05)降低,而土壤有机质、全氮、碱解氮、有效磷含量,水稻秸秆、籽粒中的全氮、全磷和全钾含量,以及水稻株高、生物量和产量显著(P<0.05)增加。水稻的有效穗数、每穗粒数、株高、千粒重、生物量和产量与土壤pH值和EC值呈极显著(P<0.01)负相关,与土壤的有机质、全氮、碱解氮和有效磷含量呈显著(P<0.05)正相关,与速效钾含量无显著相关性。各施用量下,以10 g·kg^-1处理的效果最优。研究结果可为合理应用土壤调理剂改良滨海盐土、提高水稻产量提供理论依据。     

高寒牧区牦牛冬季暖棚育肥试验研究

试验结果表明 :在暖棚舍饲条件下 ,第 1组牦牛的绝对增重、相对增重分别比第 2组和对照组高 5 .9kg、4.94%和 3 1.44 %、2 6.5 9% ,第 2组比对照组高 2 5 .5 4kg和 2 1.65 % ,两处理之间同一放牧期牦牛的日增重之间差异极显著 (P <0 .0 1) ,处理内不同放牧期牦牛的日增重之间差异显著 (P <0 .0 5 ) ,而且牦牛的日增重与采食量之间呈极显著的线性回归关系Y =-aX +b ,(a >0 )。     

Impacts of land use and cropland management on soil organic matter and greenhouse gas emissions in the Brazilian Cerrado

The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land-use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non-living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no-tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NT_SSo), soybean/millet (NT_SMi) and maize/sorghum (NT_MSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m⁻² and 0.5 kg N m⁻², 0–0.3-m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NT_MSo and 15% lower in the croplands with soybean compared to NV. δ¹³C values clearly distinguished between the C-origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile-C (625 g C m⁻²), microbial-C (70 g C m⁻²) and microbial-N (5.5 g N m⁻²), whereas other land uses presented values three times lower. GHG emissions (expressed as C-equivalent) were highest in the NV (1.2 kg m⁻² year⁻¹), PA (1.3 kg m⁻² year⁻¹) and NT_MSo (0.9 kg m⁻² year⁻¹) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above- and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions.     

SOIL QUALITY AND SPATIAL VARIABILITY ASSESSMENT OF LAND USE EFFECTS IN A TYPIC HAPLUSTOLL

Soil management practices can have negative or positive effects on soil quality. Our objective was to assess the effect of long‐term agricultural practices by evaluating selected soil physical and chemical properties. Soil samples were collected from two depths (0 to 15 and 15 to 30 cm) within a native pasture and an adjacent agricultural field that was being used for three different crop rotations. Soil quality was quantified using aggregate stability, bulk density, soil texture and available water content as physical properties and pH, electrical conductivity, organic matter and available phosphorus as chemical properties. The farmland soils were functioning at 71 and 70 per cent of their full potential at the 0‐ to 15‐ and 15 to 30‐cm‐depth increments, respectively, whereas those from the pasture were functioning at 73 and 69 per cent, respectively. The assessment showed substantial loss in soil organic carbon following 50 years of farmland cultivation. Tillage and fertilizer applications were presumably the primary reasons for weaker spatial dependence within farmland at the 0‐ to 15‐cm depth. Grazing was postulated as the main reason for weaker spatial dependence within the pasture soils at the 15‐ to 30‐cm depth. Overall, we conclude that 50 years of cultivation has not caused soil quality to decline to a point that threatens sustainability of the agricultural fields. Copyright © 2011 John Wiley & Sons, Ltd.