Manuring and rotation effects on soil organic carbon concentration for different aggregate size fractions on two soils in northeastern Ohio, USA

Soil carbon (C) sequestration is important to the mitigation of increasing atmospheric concentration of CO₂. This study was conducted to assess soil aggregation and C concentration under different management practices. The effects of crop rotation, manure application and tillage were investigated for 0–5 and 5–10 cm depths on two silt loam soils (fine-loamy, mixed, active, mesic Aquic Fragiudalfs and fine-loamy, mixed, active, mesic Aeric Fragiadalf) in Geauga and Stark Counties, respectively, in northeastern Ohio, USA. Wet sieve analysis and gravity fractionation techniques were used to separate samples in aggregate and particle size groups, respectively. In the Stark County farms water stable aggregate (WSA) is higher in wooded (W) controls (WSA = 94.8%) than in cultivated soils with poultry manure (PM, 78.7%) and with chemical fertilizers (CF, 79.0%). Manure applications did not increase aggregation compared to unmanured soils. The C concentrations (%) within aggregates (C_agg) are higher in W than in cultivated soils (W = 5.82, PM = 2.11, CF = 1.96). Soil C (%) is enriched in the clay (W = 9.87, PM = 4.17, CF = 4.21) compared to silt (4.26, 1.04 and 0.98, respectively) and sand (0.93, 0.14 and 0.32, respectively) fractions. In the Geauga County farm, continuous corn (CC) with conventional tillage has lower WSA (83.1%) than soils with rotations (R) (93.9%), dairy manure (DM) application (93.2%) and no-till (NT) (91.1%). The C concentrations within macroaggregates (C_agg) were higher in W soils (4.84%) than in cultivated soils (ranging from 2.65 to 1.75%). The C (%) is enriched in clay (W = 8.56, CC = 4.18, R = 5.17, DM = 5.73, NT = 4.67) compared to silt (W = 2.35, CC = 0.90, R = 0.96, DM = 1.57, NT = 1.06) and sand (W = 0.44, CC = 0.33, R = 0.13, DM = 0.41, NT = 0.18). Cultivation decreased C concentration whereas reduced tillage, rotation and manure enhanced C concentration in soil.     

省级耕地田坎系数汇总方法研究——以四川省为例

以四川省为例,采用标准差统计方法对省级耕地田坎系数进行了汇总。结果表明,利用该方法汇总得到的数据比较合理。     

Effect of plant species, nitrogen fertilizer and grass age on the dynamics of intra-aggregate SOM

Plant wax compounds (n-alkanes and alcohols) were used to trace C from the dominant pasture species to different water-stable aggregate (WSA) size classes to investigate if changes in the plant community composition caused by grass ley age and N amendment were reflected in the dynamics of intra-aggregate SOM. Age of the ley influenced the formation of aggregates, and fertilizer N application decreased %C and %N of the macroaggregates. Although changes in the plant community composition due to N amendment and ley age were reflected in the concentrations of plant wax compounds in the different WSA classes, the results of this study are more indicative of the direct effect of N fertilizer, than of the effect of dominant plant species, on intra-aggregate OM dynamics. The results of this study were found to support the suggestion that N amendments increase intra-aggregate OM dynamics especially in the smaller WSA size classes.     

豆田蒙古灰象甲田间分布型的初步研究

聚集度指标测定、Iwao’s M·、x线性回归和Taylor’s幂的法则分析结果表明:豆田蒙古灰象甲的田间分布型呈聚集型,其基本成分是个体群,且聚集度随种群密度增减而升降。理论抽样数的计算结果表明:在每样方(1m~2)虫口密度(x)为2左右,允许误差(D)在0.3时,理论抽样数为13.6m~2。     

优良基因聚合利用及高油大豆‘合丰53’的创新

为了探索优良大豆种质资源的利用及筛选优异育种中间材料,选育和推广北方春中早熟区组高油大豆新品种,采用梯级杂交育种方法,将多亲本优良基因进行聚合累加,经过多年连续定向选择和利用先进的品质分析与病害鉴定技术,创新出既高油又高产、抗病的大豆新品种‘合丰53’,该品种油分含量21.94％,国家北方春大豆中早熟组区域试验平均公顷产量为3036.0 kg,比对照品种‘绥农14’平均增产8.6％;生产试验平均公顷产量2613.0 kg,比对照品种‘绥农14’增产9.9％.该品种的育成与推广创造了巨大的经济效益与社会效益.     

Comparison of Soil Physical Properties between a Permanent Fallow and a Long-Term Rice–Wheat Cropping with Inorganic and Organic Inputs in the Humid Subtropics of Eastern India

A comparison was made between a long-term rice–wheat cultivation with fertilizer nitrogen–phosphorus–potassium (NPK) or added organics [farmyard manure (FYM), paddy straw (PS), green manure (GM)] and a permanent fallow on bulk density (BD), saturated hydraulic conductivity (K_sat), available water capacity (AWC), maximum water-holding capacity (MWHC), aggregation, and soil organic carbon (SOC) dynamics on an Inceptisol of humid subtropics of eastern India. Continuous cropping caused a net decrease in SOC content. Undisturbed fallow was comparable to soils with FYM, PS, and GM amendments in structural and hydrophysical properties. Maximum WHC and AWC values were in the order of FYM followed by PS, GM, fallow, NPK, and control. The relative efficacy of the organics for physical buildup was FYM > PS > GM, which increased structural indices. This study represents further steps toward understanding the ecological importance of fallow management and integrated use of balanced fertilizer and organics.     

亚洲玉米螟越冬幼虫空间分布型调查

2012和2013年调查了亚洲玉米螟越冬幼虫在玉米田的分布形式,通过聚集度指标分析了玉米螟越冬幼虫的空间分布型。结果显示,该虫在玉米田中主要呈均匀分布,其次是聚集分布,表现了分布形式的多样性。     

Aggregate formation of zein and its structural inversion in aqueous ethanol

Zein is a prolamine of maize. Conventionally, 70–90% aqueous ethanol is used to dissolve zein. When the hydrodynamic radii of zein molecules in aqueous ethanol were monitored with a dynamic light scattering instrument, it was found that zein aggregates in the solvent and the degree of aggregation depends on the composition of the solvent mixture. As the ethanol content of solvent increased from 70% to 90%, the aggregation number of zein molecules decreased from 10,000 until it reached a minimum. The aggregation number then increased abruptly to greater than 10,000 as the ethanol content of the solvent mixture increased to 92%. Since zein has amphiphilic characteristics, this behavior was interpreted as the formation of a micelle-like structure in its solution whereby ca. 90% ethanol that showed minimum aggregation number is regarded as a structural inversion point. This point of view was supported by a simple experiment that showed selective interaction of zein molecules with hydrophilic or hydrophobic particles.     

我国茶销售市场的空间布局与影响因素研究

对我国茶销售市场进行空间分布特征的研究,有助于茶产业的供需平衡.本文利用地理集中指数和GIS技术,从空间分布类型、均衡性和分布密度3个方面来分析我国茶销售市场空间分布特征.结果表明,我国茶类经营点整体呈集中化分布,但集聚性稍弱,全国范围内高密度核心地区包括广州、南京和郑州等为核心的周边部分城市,而西部等地区大多未形成相...     

宁夏荒漠草原白星花金龟成虫空间分布型的初步研究

通过对白星花金龟(Potosia brevitaris Lewis)成虫空间分布格局的测定,应用聚集度指标法、Taylor幂法则和Iwao回归法对白星花金龟成虫的空间分布型进行分析和检验,以期对该害虫实施预测预报及防治提供科学依据。结果表明:白星花金龟成虫在盐池荒漠草原呈聚集分布,分布的基本单位是个体群,引起聚集的原因主要是白星花金龟成虫自身习性,与环境因素也有一定关系。种群数量动态研究显示白星花金龟种群数量在6个不同样带表现基本一致,除了撂荒2年后形成的以蒙古冰草(Agropyron mongolicum)为优势植物的样带外其他样地也都出现3次高峰。