农户田块尺度冬小麦不同产量水平土壤细菌群落差异

为了明确土壤细菌群落对小麦产量的影响，以河南省济源市冬小麦种植户田块为研究对象，通过采集扬花期麦田土壤样品，利用Illumina高通量测序技术测定细菌16S rRNA V3+V4区序列，分析冬小麦不同产量水平土壤的细菌群落差异。结果表明，高产组土壤铵态氮含量显著高于低产组(P<0.05),土壤有机质含量、速效钾含量、有效磷含量、硝态氮含量、pH值在组间均无显著差异，土壤酸性磷酸酶、碱性磷酸酶、脲酶和过氧化氢酶活性在组间也均无显著差异。酸杆菌门(Acidobacteria)和变形菌门(Proteobacteria)是土壤细菌群落的主导菌门。门水平上，小麦产量与芽单胞菌门(Gemmatimonadetes)、装甲菌门(Armatimonadetes)、纤维杆菌门(Fibrobacteres)、Latescibacteria、Dadabacteria相对丰度显著相关。属水平上，Bryobacter、黄杆菌属(Flavisolibacter)、芽单胞菌属(Gemmatimonas)、丰佑菌属(Opitutus)、黏液杆菌属(Mucilaginibacter)、Dongia、Chryseo...     

Effects of soil water availability on development of suberin lamellae in the endodermis and exodermis and on cortical cell wall thickening in red bayberry (Myrica rubra Sieb. et Zucc.) tree roots

The effects of soil water availability on suberin lamellae formation in the endodermis and exodermis and the occurrence of cell wall thickening in the cortex in red bayberry (Myrica rubra Sieb. et Zucc.) tree roots were examined during tissue aging. For several months, red bayberry trees were grown in small baskets under dry, normal, and waterlogged soil water conditions. Transverse sections of roots from 5 mm from the tip to the basal portion were stained with several staining solutions and the cell structure was observed. Root anatomical development was significantly changed by soil water conditions. The suberin lamellae in the endodermis formed later in plants grown under dry conditions than in those grown under waterlogged conditions. Cell wall thickening in the cortex near the endodermis was promoted by drought, but apparently not by waterlogged conditions.     

Temporal changes of soil physical quality under two residue management systems

Although crop residue management is known to affect near‐surface soil physical quality, little is known about the temporal variability of these indicators over short time intervals. This study evaluates the temporal changes of nine indicators of soil physical quality. These are organic carbon content, structural stability index, bulk density, macroporosity, air capacity, relative field capacity, plant available water capacity, Dexter's S‐index and saturated hydraulic conductivity. A second set of soil physical indicators, based on the distribution of soil pore volume, was also evaluated. The indicators were determined in three different times during the growing cycle of winter durum wheat cultivated within a long‐term field research carrying out in Southern Italy and comparing two types of crop residue management, that is, burning (B) and soil incorporation (I). Only the bulk density changed over time for both treatments, although the air capacity also changed for the incorporation of wheat residues. Residual effects of the autumnal soil tillage and soil compaction were a common source of variability, irrespective of which treatment was used. Based on the existing guidelines for evaluating the physical quality of these agricultural soils, optimal or near‐optimal values were detected in about half of the cases under consideration. This suggests that both B and I create sufficiently good conditions for crop growth during the crop cycle. The comparison between observed and optimal soil pore distribution function was always poor. The pore volume distributions showed lower densities of small pores and relatively higher densities of large pores than the proposed optimal distribution. This study also suggests that the considered optimal or references curves probably cannot be applied successfully to a wide range of agricultural soils.     

根土空间对花生生长发育和产量的影响

为明确花生生长过程中是否存在生长冗余,探讨花生高产的适宜生长度,以高产花生品种青花7号为试材,设长×宽×深分别为40 cm×20 cm×20 cm、40 cm×20 cm×40 cm、40 cm×20 cm×60 cm、40 cm×20 cm×80 cm4种规格不等的根土空间,采用网袋法,研究了根系生长空间对花生生长发育和产量的影响。结果表明,随着根土空间增大,株高逐渐增高,分枝数逐渐增多,根系干质量和茎叶干质量逐渐增大,其生育进程的推进差异越来越大。根土空间过小显著影响各时间段花生开花数、下针和结果;根土空间过大则中前期开花数、下针和结果少,中后期开花数、下针和结果多;适当的根土空间(如限根深度60 cm)则中前期开花数、下针和结果多,中后期开花数、下针少。说明根土空间过小影响产量提高的主要原因是生长量不足,而根土空间过大影响产量提高的主要原因是冗余生长。适当空间则既能保证足够的生长量,产生的冗余生长又少,从而提高荚果产量和籽仁产量,为花生高产新品种的选育和栽培提供理论依据。     

两种林龄中山杉(Taxodium hybrid 'Zhongshanshan')林地土壤质量评价

以江苏省靖江市牧城公园和东湖公园两种种植年限分别为5 a和9 a的中山杉(Taxodium hybrid'Zhongshanshan')人工林土壤和无林地为研究对象,对0~15 cm、15~30 cm和30~45 cm深度土层土壤理化性质、养分含量和微生物生物量进行了分析。典型相关分析表明,土壤微生物生物量的变化是一个复杂的过程,是土壤各因子共同作用的结果,3种土壤U、V值均表现出层次性,随着土壤深度的增加逐渐降低;不同取样点相同深度土层U、V值为9 a林5 a林对照;单相关分析表明,土壤微生物生物量与速效磷、速效钾、有机质和全氮呈极显著正相关(P0.01),因此土壤微生物可以作为评价中山杉人工林在促进林地土壤质量改善过程中的重要生物指标;主成分分析表明,综合得分最高的9 a林为2.993,其次是5 a林为0.748,作为对照的无林地则为-3.742,说明9 a林地土壤质量最高。可见,中山杉对林下土壤质量有显著提高作用。     

Soil conservation on road embankments using palm‐mat geotextiles: field studies in Lithuania

The application of geotextile mats constructed from the palm leaves of Borassus aethiopum (Borassus) and Mauritia flexuosa (Buriti) was investigated in field experiments. The use of geotextiles caused improved soil moisture storage during dry summer periods on a steep (21–25°) roadside slope in Lithuania. The enhanced soil moisture under the Borassus and Buriti mats encouraged better root development of perennial grasses, increased the number and weight of earthworms and increased the dry biomass of perennial grasses by 50.5 and 18.2%, respectively, compared with a grassland control. The mean rate of water erosion from bare soil during the study period from 17/04/2007 to 11/12/2008 was 33.21 Mg/ha. The cover of palm‐mat geotextiles decreased soil losses from bare fallow soil by 94.8–91.1%. An erosion rate of 0.85 Mg/ha over this 21‐month period was measured on the slope under perennial grasses without geotextile cover. Application of geotextile cover on perennial grasses completely prevented soil erosion by water. Therefore, use of geotextiles has clear soil and water conservation benefits on industrial slopes susceptible to erosion. The use of geotextiles has multiple benefits including soil conservation, the improvement of plant growth conditions and the encouragement of earthworm populations.     

高产型徐香猕猴桃树体结构及土壤养分状况分析

为明确猕猴桃果园的生产潜力，在普查的基础上对两个管理水平较高的徐香猕猴桃果园的树体结构及土壤养分状况进行分析。结果表明，高产型徐香猕猴桃树体的合理结构为成龄树冬季修剪后单株保留17个左右结果母枝，每枝保留15~21个有效芽，折合每667 m留长枝量为1 496个，留芽量为22 440~23 760个，7月份叶果比为3.33∶1。土壤速效氮为16.5 mg/kg，速效磷64.8 mg/kg，速效钾209.6 mg/kg，速效镁和速效铁分别156.6 mg/kg和3.58 mg/kg，有机质含量1.13%。可见，充足的肥料投入、枝芽数量及合理的叶果比是高产稳产的基本保证。     

《中国水土保持科学》性质及学科分类

根据期刊性质和学科分类方法,以文献数量为依据对《中国水土保持科学》进行分类。结果发现,《中国水土保持科学》2010年刊登的文献以学术性为主,农业基础科学类、农艺学类文献分别占当年发表文献总量的63.38%、49.30%,其余学科文献均较少,不能划入相应学科,因此应将该刊同时归类为农业基础科学类和农艺学类专业学术期刊。     

Use of regression analysis for converting quicktest‐measured lime and fertilizer recommendations into actual values based on longer equilibration times

Abstract

Soil tests should produce data useful for making accurate lime and fertilizer recommendations aimed at optimizing chemical conditions for plant growth or providing available nutrient levels sufficient for maximum yields. In order to attain these objectives, we believe, quicktest‐computed rates have to be made equivalent to actual values through a regression adjustment. Although it may not be most desirable to use this adjustment for each new population of soils, it may be worse to try to use a function derived from one group of soils on a second group not well represented by the first.     

Predicting total soil lead from an acetic acid‐sodium acetate buffered solution

Abstract

Total soil lead was predicted satisfactorily from the Lead extracted by the Standard Morgan soil testing solution (sodium acetate with acetic acid, pH 4.8). Using 161 soils, 85% of the variance in total lead content was accounted for by:

Total Lead = ‐115 + 106.4 √Sodium Acetate Extracted Lead A modified Morgan solution, utilizing EDTA as a chelating agent, extracted greater than 3 times as much lead as the regular Morgan's solution, but was no better in predicting total lead.