Comparison of the Phosphorus Sorption Characteristics of a Conservation Reserve Buffer and an Adjacent Crop Field

The U.S. Department of Agriculture's Conservation Reserve Program (CRP) was established by the Food Security Act of 1985. Since its inception, thousands of acres of cropland in stream riparian zones have been converted to conservation buffers through the planting of trees and native grasses. The objectives of this study were to determine the phosphorus (P)–sorption characteristics of the surface soil in a 13‐year‐old CRP buffer and an adjacent continuously cropped production area from which the buffer was created and to assess differences in P‐sorption maxima and P‐buffering capacity between the sites. Phosphorus sorption was modeled with both the simple Langmuir and the two‐surface Langmuir equations. There were significant differences in all P‐sorption parameters between the cropped area and the buffer over most of the depth increments studied. The cropped area soil had higher sorption max (Smax), binding energy (k), and P equilibrium buffering capacity (PEBC) than the buffer soil. However, the buffer had higher equilibrium P concentration (EPC). These findings imply that it may not be appropriate to assume that a buffer will act as a P sink simply because it is not receiving P fertilization. Any assessment of buffer or filter strip effectiveness for P retention should include an examination of the P‐sorption properties of the soils present.     

加热法装配与过盈配合技术

机械设备在维修、装配过程中经常遇到孔、轴类零件过盈配合问题,但由于施工现场一般不具备实施现代化装配工艺技术的条件,而利用热膨胀法进行孔、轴类零件的过盈装配是实际施工中最常用的技术手段。对孔、轴类零件过盈装配过程中如何根据过盈量计算加热温度,控制零件的加热过程,防止被加热零件过热,本文给出了方法。     

氮肥对谷子的增产效应研究

以赤谷9号为试验材料，研究不同的施氮量（0、150、300、450、600kg／hm2）对谷子产量的影响。结果表明：氮肥施用量为450kg／hm2时，谷子产量达到最高为5210．95kg，hm2，比不施氮肥增产713．15ke：／hm2，增加经济效益729．19元／hm2。     

银川市不同立地二氧化碳固定效益研究

以银川市宁夏大学北校区、西夏公园、大团结广场、枕水花园的总面积，不可绿化面积，绿化面积和建筑物投影面积为调查对象，对4个不同立地条件下二氧化碳固定量和绿化合格率进行计量分析。结果表明：4个不同立地条件下二氧化碳总固定量的大小顺序为大团结广场（128642887．00kg）〉宁夏大学北校区（71860396．12kg）〉西夏公园（57034734．88kg）〉枕水花园（18729879．20kg），绿化合格率都达标。     

Soil Sample Depth in Pasture Soils for Environmental Soil Phosphorus Testing

Phosphorus (P) in runoff from agricultural land is a major contributor to eutrophication of surface waters. This study investigated the relationship between dissolved P in surface runoff and soil-test P measured at different sample depths (0–2 and 0–10 cm). Soil at these depths was collected from 136 sites in southeast New South Wales, Australia, under pastoral agriculture, covering a wide range of soil types and land-use intensity, from native pasture to intensive dairying. Bicarbonate-extractable soil P concentrations at these two depths were curvilinearly related over a very wide range of P (r² = 0.91). Small-plot rainfall simulations were conducted at 14 of these locations, for which the relationship between the sampling depths was even closer (r² = 0.95). After dividing the soils into two groups based on parent material (basalt and nonbasalt), linear relationships were found between extractable soil P and runoff dissolved reactive P, with more of the variance being accounted for with the sedimentary soils (r² = 0.89, 0–10 cm; 0.91, 0–2 cm) compared with basalt soils (r² = 0.63; 0–10 cm; 0.57, 0–2 cm). The results suggest that agronomic soil P testing in pastoral soils (typically 0–10 cm depth) is sufficient for estimating the potential for losses of P in runoff and that there is no need to collect shallow soil samples especially for this purpose.     

森林火灾后蒙古栎林碳素分布及储量的分析

以黑龙江塔河林业局施业区内的杜香—蒙古栎林和草类—蒙古栎林为对象,对火灾前后碳素的分布和储量进行了研究。结果表明:森林火灾发生后,蒙古栎林地上、地下部分的碳储量均表现为减少。杜香—蒙古栎林碳储量变化量为-33.812 9 t.hm-2,其中:地上部分为-0.499 4 t.hm-2,地下部分为-33.313 5 t.hm-2,贡献率分别为1.5%和98.5%;杜香—蒙古栎林碳储量变化量为-104.944 6 t.hm-2,其中:地上部分为-76.452 7 t.hm-2,地下部分为-28.491 9 t.hm-2,贡献率分别为72.9%和27.1%。蒙古栎林地上、地下火灾前后碳储量的分布与变化同林分类型密切相关。     

Loss of soil resources from water‐eroded versus uneroded cropland sites under simulated rainfall

Soil erosion is widespread in agricultural lands of the US Corn Belt. The objective of this study was to examine the impact of antecedent erosion on loss of soil under laboratory simulated rainfall. The soil was obtained from the surface layer of eroded (ER) and uneroded (UN) sites within a conservation agro‐ecosystem in central Ohio, USA. Air‐dried soil was subjected to a rainfall simulation for 60 min (dry run), and to another simulation (wet run) 24 h after the dry run. In the dry run, the cumulative water runoff, sediment yield, and soil organic carbon loss were higher in ER (12.3 L/m², 169.3 g/m², and 5.6 g/m², respectively) than in the UN (7.3 L/m², 22.6 g/m², and 0.9 g/m² respectively). An opposite trend was observed for the cumulative water infiltration (0.9 and 3.9 L/m², respectively). In the wet run, despite a similar cumulative water runoff from the two erosional phases (20.1 and 19.6 L/m² in ER and UN respectively), sediment yield and soil organic carbon loss were higher in ER (484.4 g/m², and 16.3 g/m² respectively) than in the UN (146.6 g/m², and 5.3 g/m² respectively). Also for the wet run, an opposite trend was observed for the cumulative infiltration (0.8 and 5.8 L/m² respectively). This study suggests that past erosional processes increase the susceptibility of remaining soil to accelerated erosion.     

日本壶链蚧危害规律研究

[目的]了解不同寄主植物、栽植方式、树体方位等对日本壶链蚧[Asterococcus muratae(Kuwana)]发生危害的影响。[方法]对苏州地区不同寄主植物、栽植方式、树体方位日本壶链蚧的虫口数量、雌介壳大小、卵量进行了调查。[结果]日本壶链蚧对寄主植物具有选择性,在木兰科植物上虫口数量、雌蚧大小、产卵繁殖力均高于在其他科植物上;寄主植物各方位受害程度不同,多以北面受害较重;广玉兰群植比单株栽植受害重。雌蚧壳大小、质量与卵量呈显著线性关系,质量与卵量关系密切;通过测雌蚧质量,利用方程y=2E-05x+0.003 7能准确预测产卵量。[结论]为制定有效的日本壶链蚧防治方案提供了参考。     

论铁路交通事故赔偿协议——以“7·23”事故赔偿协议为例

铁路交通事故的发生,必然会引发赔偿问题,赔偿协议无疑是解决这一问题的有效途径。赔偿协议主要涉及三个方面的问题,协议的性质、协议的当事人、协议的内容。赔偿协议在性质上属于单务合同;死者的近亲属与被抚养人是权利主体,运输企业与铁路通信信号集团是义务主体,事故调查组不是赔偿协议的当事人;赔偿的数额应当由当事人依据《侵权责任法》及相关法律法规协商确定。     

粳稻新品种“津星一号”高产栽培技术

近几年，津星一号品种在天津市及周边地区种植面积逐渐扩大，单产显著增加，但还没有达到该品种的最高产量。通过近几年高产地块调查，摸索出津星一号能达到１１２５０ｋｇ／ｈｍ２的综合栽培技术措施。从品种的３个方面阐述了获得高产的条件，首先是充分了解品种的各项生物学特性；其次是建立合理的群体结构；三是高产措施——平衡施肥，育壮秧，合理灌溉，及早预防病虫草害