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71.
利用方式和土壤肥力对土壤团聚体和养分的影响   总被引:6,自引:0,他引:6  
The size distribution of water-stable aggregates and the variability of organic C, N and P contents over aggregate size fractions were studied for orchard, upland, paddy, and grassland soils with high, medium, and low fertility levels. The results showed that > 5 mm aggregates in the cultivated upland and paddy soils were 44.0% and 32.0%, respectively, less than those in the un-tilled orchard soil. Organic C and soil N in different size aggregate fractions in orchard soil with high fertility were significantly higher than those of other land uses. However, the contents of soil P in different size aggregates were significantly greater in the paddy soil as compared to the other land uses. Soil organic C, N and P contents were higher in larger aggregates than those in smaller ones. The amount of water-stable aggregates was positively correlated to their contribution to soil organic C, N and P. For orchard and grassland soils, the > 5 mm aggregates made the greatest contribution to soil nutrients, while for upland soil, the 0.25-0.053 mm aggregates contributed the most to soil nutrients. Therefore, the land use with minimum disturbance was beneficial for the formation of a better soil structure. The dominant soil aggregates in different land use types determined the distribution of soil nutrients. Utilization efficiency of soil P could be improved by converting other land uses to the paddy soil.  相似文献   
72.
In the Three Gorges Area of China, soil erosion and the resultant non-point source pollution and ecological degradation have endangered agricultural ecosystems and fresh water reservoirs. Although efforts have been undertaken to reduce soil and water losses from slope land used for citrus production, information on the effects of management practices on soil fertility indices is either limited or nonexistent. This study was conducted to compare the effects of 10 years of various management practices, citrus intercropped with white clover (WC), citrus mulched with straw (SM), citrus intercropped with contour hedgerows (CH), citrus orchard land with impermeable membrane (IM), and citrus intercropped with wheat (Triticum aestivum) and peanut (Arachris hypogaea) (WP), as treatments on soil fertility indices with that of the conventional citrus management (CM). Results showed that the soil organic carbon, total and available nitrogen, available potassium, and water-stable aggregate (> 0.25 mm) contents at the 0–5 cm depth were higher for the WC and SM treatments than the CM treatment. There was also spatial variation in soil fertility along slopes of the WC and SM treatments. The soil total and available nitrogen, phosphorus, and potassium, and water-stable aggregate (> 0.25 mm) contents at both the 0–5 and 5–20 cm depths were higher for the CH and IM treatments than the CM treatment. The average soil available nitrogen and available potassium contents were higher for the WP treatment than the CM treatment, but the WP treatment had little effect on the soil organic carbon, total nitrogen, and water-stable aggregate (> 0.25 mm) contents. These suggested that white clover intercropping and straw mulching were the most effective approaches to improve soil fertility in citrus orchard land of the Three Gorges area.  相似文献   
73.
不同巨桉人工林土壤分形特征及抗蚀性分析   总被引:3,自引:1,他引:2  
谢贤健  韩光中 《土壤》2014,46(4):725-731
为探讨耕地退耕成人工巨桉林后对土壤团粒结构及土壤抗蚀性能产生的影响,在野外调查与室内分析的基础上,选择4.5年生巨桉纯林、巨桉+果树、巨桉+粮食作物土壤作为研究对象,农耕地作为对照,研究了不同巨桉人工林下水稳性团聚体分形维数的变化特征,分析了分形维数与土壤养分状况、土壤结构稳定性以及土壤抗蚀性能的关系。结果表明,4种模式土壤分形维数介于2.142~2.296;在0~15 cm土层分形维数表现为耕地林果林粮纯林,纯林和农耕地之间差异显著,其他3种模式之间差异不显著;在15~30 cm土层分形维数表现为耕地纯林林粮林果,4种模式之间差异不显著。分形维数与土壤有机质含量、大团聚体含量呈显著和极显著负相关;与土壤平均重量直径、水稳性指数有负相关趋势;与土壤体积质量、微团聚体含量呈极显著正相关。说明土壤分形维数越小,土壤有机质、大团聚体含量越高,土壤平均重量直径、水稳性指数越大,土壤体积质量、微团聚体含量越低,土壤结构越稳定,抗蚀力越强。因此,团聚体的分形维数值能反映土壤性质的变化,通过对土壤分形维数特征的研究可以定量揭示不同巨桉模式下土壤抗侵蚀的能力。  相似文献   
74.
为探索施用有机肥对咸水灌溉农田耕层土壤水稳性团聚体的调控效应,在麦玉两熟制农田咸水灌溉(1,2,4,6 g/L)配施有机肥(OF)和未施有机肥(NOF)长期定位试验的基础上,研究了2018-2019年不同处理对农田耕层0-20 cm土壤盐度(EC1:5)、土壤有机质(SOM)含量和水稳性团聚体稳定性的影响。结果表明:咸水灌溉有增加耕层土壤盐度,降低SOM含量和水稳性团聚体稳定性的趋势,随灌溉水矿化度的升高,SOM含量、>0.25 mm水稳性大团聚体质量分数(WR0.25)、团聚体平均重量直径(MWD)和几何平均直径(GMD)逐渐减小,土壤EC1:5和分形维数(Dm)逐渐增大,其中4,6 g/L与1 g/L灌水处理间的差异达显著水平。增施有机肥可降低咸水灌溉农田0-20 cm土壤EC1:5,当灌溉水矿化度 ≥ 2 g/L时,OF处理的耕层土壤EC1:5较NOF处理降低4.64%~48.29%;施用有机肥显著提高农田SOM含量、WR0.25、MWD和GMD,各灌水处理的提高幅度分别为80.75%~127.32%,10.36%~90.44%,12.90%~129.11%和11.88%~81.57%。在该研究条件下, ≥ 4 g/L咸水灌溉会显著增加土壤盐度,降低有机质含量,破坏土壤团粒结构,应谨慎使用;施用有机肥能促进耕层土壤盐分淋洗,降低盐分对土壤环境的负面影响,有助于实现咸水资源安全高效利用。  相似文献   
75.
研究植被恢复条件下土壤水稳性团聚体颗粒有机碳的分布特征及影响因素,为退化红壤区生态系统重建与土壤质量改善提供理论依据。在江西省泰和县植被恢复与重建基地,选取立地条件基本一致的马尾松纯林、湿地松纯林、木荷纯林、马尾松补植木荷、湿地松补植木荷、湿地松—木荷原始混交林6种恢复模式,于2019年通过调查取样和试验分析,探索不同植被恢复模式土壤各粒级水稳性团聚体颗粒有机碳(POC agg)、土壤物理化学性质变化特征及相互关系。结果表明:(1)退化红壤以水稳性大团聚体(>0.25 mm)为主(百分比含量为87%),木荷纯林、马尾松补植木荷林土壤大团聚体含量最低。表层(0—10 cm)土壤POC agg受恢复模式影响最显著(P<0.05),以湿地松纯林POC agg含量为最高(14.44 g/kg);(2)土壤物理化学性质因恢复模式的不同而呈显著性差异,其中湿地松补植木荷林下土壤有机质(SOM)、木荷纯林下土壤全氮(TN)、湿地松纯林下土壤全磷(TP)含量分别为最高;(3)人工针叶纯林中团聚体组成对POC agg影响最大,团聚体组成、SOM和TN是影响POC agg的重要因素(P<0.01),且土层越深关联度显著增加(P<0.01);其中微团聚体(<0.25 mm)POC agg受其直接或间接效应均较高,TN在<0.053 mm粒级团聚体POC agg的影响最大。木荷纯林能明显改善土壤结构和肥力,且湿地松对林下土壤养分尤其是POC agg固持能力较高。结合退化红壤区生态修复实践,以湿地松纯林作为先锋树种进行植被恢复,抚育过程中补植木荷可能会更好地改善土壤性质。  相似文献   
76.
India is the largest cotton‐growing country (8.9 million hectares) in the world and most of the area is rain‐dependent. Large amount of pesticides are used for the control of sucking pests and lepidopterans. Increasing demand for clean organic fibre has led to an interest in organic cotton. However, information on the effects of organic cultivation on fibre quality is limited. Seed cotton yield and fibre quality (length, strength, micronaire and uniformity) were determined for an organic and modern method of cultivation during 3 years (2002–2003 to 2004–2005) of a 11‐year (1994–1995 to 2004–2005) study. Vertical and horizontal distribution of bolls on a cotton plant was also determined in 2003–2004 and 2004–2005. At the end of year 11, soil samples were collected and analysed for soil organic carbon content, water‐stable aggregates (%), and mean weight diameter. Averaged over 3 years, an additional 94 kg seed cotton ha?1 was produced in the organic over the modern method of cultivation and the difference was significant. The year × treatment interaction was significant. Seed cotton yield in the organic plots was significantly greater than the modern method of cultivation plots in 2003–2004 because of a well‐distributed normal rainfall and low pest incidence. The main stem nodes 13–22 accounted for the largest numbers of bolls present on the plant. Plants of the organic plots had significantly (37–71 %) more bolls on nodes 13–27 than those for the plants of the modern method of cultivation. Lateral distribution of bolls on a sympodial (fruiting) branch, was noticed up to fruiting point 11. However, treatment differences were not significant. With regard to fibre quality (length, strength, fineness and uniformity), differences between years were significant. Inferior quality fibre was produced in 2004–2005 because of delayed planting and early cessation of rain. On average, cotton grown under organic conditions compared with the modern method of cultivation had significantly better fibre length (25.1 vs. 24.0 mm) and strength (18.8 vs. 17.9 g tex?1). Soil samples of the organic plots had significantly greater C content, water‐stable aggregates and mean weight diameter than the modern method of cultivation plots. Differences were restricted to the top layers (0–0.1 and 0.1–0.2 m). Yield benefits of growing cotton in an organic system over the modern method of cultivation are expected to be greater in years receiving normal rainfall and having low pest incidence.  相似文献   
77.
黑土开垦后水稳性团聚体与土壤养分的关系   总被引:3,自引:0,他引:3  
Water-stable aggregates, which are an index for the evaluation of the structural properties of the soil, are affected by many factors. Zhaoguang Farm, Longzhen Farm, and Jiusan Farm were chosen as the representative study sites in the region of black soils, a typical soil resource in Northeast China. The variation in the content of 〉 0.25 mm water-stable aggregates and its relationship with the nutrients in black soil were investigated after different years of reclamation. The results showed that the 〉 0.25 mm water-stable aggregates were more in the surface than in the subsurface soil and they changed in the following order: Longzhen Farm 〉 Zhaoguang Farm 〉 Jiusan Farm. The water-stable aggregates decreased sharply at the initial stage of reclamation and then became stable gradually with time. They were significantly correlated with the contents of organic C, total N, total P, and CEC in black soil, with the correlation coefficients r being 0.76, 0.68, 0.61, and 0.81 (P 〈 0.01), respectively; however, their relationships with available P, available K, and total K were unclear. These showed that organic matter was the cementation of soil water-stable aggregates. Increasing decompositions and decreasing inputs of organic matter after reclamation were responsible for the amount of reduction of the water-stable aggregates. Thus, to maintain good soil aggregate structure, attention should be paid to improvement of soil nutrient status, especially the supply of organic C and N.  相似文献   
78.
采用PAM、β-环糊精、沃特保水剂、腐殖酸等4种土壤结构改良剂,通过室内土柱培养,以研究其对风沙土有效的改良效果,并探讨其作用机理和合理的施用浓度。结果表明,4种改良剂均可促进〉0.25mm水稳性团聚体的形成,在低浓度(0.05%~0.1%)下其趋势为:沃特保水剂〉β-环糊精〉PAM〉腐殖酸,在高浓度(0.2%~0.4%)下趋势为:PAM〉β-环糊精〉沃特保水剂〉腐殖酸。4种改良剂在浓度为0.05%~0.4%时,均可有效地降低风沙土团聚体的分形维数,改善风沙土结构,尤其沃特保水剂改良效果最明显。在低浓度下,4种改良剂均可有效地降低土壤容重。回归分析和方差分析表明,沃特保水剂主要作用于5~1mm粒径的团聚体,其适宜浓度为0.05%左右。  相似文献   
79.
Soil water-stable aggregation is an important process for carbon sequestration and is a key factor controlling soil sustainability and resilience; therefore, the objectives of the present study were to (1) evaluate the differences in soil organic matter state, its specific and labile fractions and their importance in the formation of water-stable aggregates in vineyard soils differing in their genesis and texture under different soil management (vineyard rows – tilled and grassed in-between strips), and (2) estimate the ability of the vineyard soils to sequester soil organic carbon (SOC) into water-stable macro-aggregates (WSAma). The results showed that the WSAma content of the soils ranged from 47% to 97%. Soils with grasses had a higher SOC and labile carbon (CL) contents than the bulk soil and, as a result, the higher total WSAma content. Soils ranged in a decreasing order in their ability to sequester SOC and CL from bulk soil to WSAma: Haplic and Stagni-Haplic Luvisols > Calcaric Fluvisol = Rendzic Leptosol > Haplic and Luvi-Haplic Chernozem > Dystric and Eutric Cambisols. Our results showed that the maximum ratio of SOC content in WSAma to that in bulk soil was 1.0 at the maximum WSAma content regardless of the soil type. An increase in the ratio above this threshold value (1.0) resulted in a decrease in WSAma content.  相似文献   
80.
几种侵蚀红壤中有机质和团聚体的关系   总被引:6,自引:2,他引:6  
以3种侵蚀红壤(轻度、中度、严重)为供试材料,利用干湿筛法获得其不同粒径的水稳性团聚体(〉4 mm,2~4 mm,1~2 mm,0.5~1 mm,0.25~0.5 mm),分析团聚体中有机质的分布。结果显示,随着侵蚀程度的增强,〉0.25mm水稳性团聚体的含量逐渐下降,而团聚体的分散度却依次升高;无论何种侵蚀程度,湿筛后团聚体的组成均以小粒径团聚体(〈0.25 mm)占优势。轻度和中度侵蚀的红壤,其有机质含量随着团聚体粒径的增大而增大,严重侵蚀的则相反;侵蚀红壤有机质含量和〉0.25 mm水稳定性团聚体呈显著正相关,3种侵蚀红壤团聚体对土壤有机质的贡献为轻度侵蚀〉中度侵蚀〉严重侵蚀。  相似文献   
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