聚丙烯酰胺增加土壤降雨入渗减少侵蚀的模拟试验研究 Ⅰ.入渗

土壤 (特别是黄绵土 )在雨水作用下 ,表面会形成结皮 ,显著地降低降雨入渗率 ,聚丙烯酰胺 (PAM)能有效地抑制降雨过程中土壤结皮的形成 ,提高降雨入渗率。为了获得PAM使用量和覆盖率与入渗率之间的关系 ,进行了一系列的人工降雨模拟试验。试验采用了三个雨强 :5 0、1 0 0和 1 5 0mmh- 1,四个坡度 :8.74%、1 7.63 %、3 6.4%和 46.63 % ,及五种地表处理 :对照、秸秆覆盖和三个PAM覆盖率 (A、B和C) ,试验设三次重复。试验分Ⅰ、Ⅱ两个降雨阶段进行 ,第Ⅱ阶段在第Ⅰ阶段降雨结束土壤放置 2 4h后进行。分析建立了降雨入渗率与PAM的覆盖率间的相关关系 ,确定了PAM的覆盖率对降雨入渗的影响。     

黄土表面结皮对夏闲坡耕地土壤水分的影响研究

土壤结皮是土壤在降雨作用下团聚体发生物理变化而形成的。黄土高原的坡耕地普遍存在着表土结皮现象。试验表明 ,表土结皮对黄土地区坡耕地 5 0cm土层内的土壤含水量有明显影响 ,打破结皮可使土壤入渗率提高 ,并有效地抑制和减少水分蒸发 ,提高土壤保水能力。耕层土壤含水量随地面坡度的增加而减少 ,土壤结皮可使地面坡度对土壤含水量的影响程度加大     

聚丙烯酰胺增加土壤降雨入渗减少侵蚀的模拟试验研究Ⅱ.侵蚀

土壤侵蚀和雨水的流失是干旱、半干旱地区制约农业发展乃至生态环境良性循环的两个主要因素。聚丙烯酰胺 (PAM ,Polyacrylamide)对土壤的性质有着明显的改进作用 ,PAM具有良好的黏结力 ,能有效改良土壤的表层结构 ,提高土壤的稳定性 ,增加土壤的入渗率 ,减少土壤侵蚀。本文试图通过人工降雨模拟实验 ,获得不同的PAM的使用量及覆盖率与土壤侵蚀量在不同的雨强、不同的坡度条件下的关系。实验表明 ,经PAM处理后土壤的入渗性能和抗侵蚀的性能都有所提高 ,PAM能明显地黏结着土壤表面的颗粒 ,形成大的团聚体 ,阻碍土壤结皮的形成 ,减少土壤侵蚀。     

土壤结皮对黑土区坡面产流产沙的影响

土壤结皮对坡面产流形成和侵蚀过程有重要的影响。基于室内人工模拟降雨试验,研究了土壤结皮对黑土区坡面产流产沙的影响。结果表明:土壤结皮促使坡面产流提前发生,但对坡面产流量的影响不甚明显;对坡面侵蚀产沙量却有明显的作用。试验条件下,5°坡面有土壤结皮处理的坡面侵蚀产沙量较无土壤结皮处理减少了54%。有土壤结皮处理的10°坡面,在降雨过程中结皮尚未破坏前,其坡面侵蚀产沙量较无土壤结皮处理的对照减少了40%;一旦土壤结皮被破坏,之后的坡面侵蚀产沙量较无土壤结皮处理的对照增加了46%;在整个降雨过程中,10°有土壤结皮处理的坡面侵蚀产沙量较无土壤结皮处理增加了16%。表明土壤结皮对坡面侵蚀的影响与地面坡度有密切关系。     

聚丙烯酰胺(PAM)对黄土溅蚀的影响

采用人工模拟降雨方法,用摩根溅蚀盘测定土壤的溅蚀量,研究聚丙烯酰胺(PAM)对溅蚀的影响.结果表明,使用聚丙烯酰胺(PAM)会改变土壤的溅蚀速率,不同浓度PAM溶液对溅蚀速率的影响程度不同,而且随降雨历时的延长结皮埘溅蚀速率的影响作用会占主导地位.一般来说,在降雨初期,由于PAM的聚合作用,使得土壤团聚体的稳定性增加,土壤溅蚀速率较小,随着时间的延长,溅蚀速率开始上升,但是当土壤表面开始发育结皮时,结皮的形成使土壤表面抗溅蚀的强度增强,土壤溅蚀速率减小.     

PAM与不同土壤调理剂混合施用对降雨入渗和土壤侵蚀的影响

土壤中施用聚丙烯酰胺(PAM)可以提高降雨入渗率,减少土壤侵蚀量。PAM大多施用于土壤表面。为了研究PAM与不同土壤调理剂混合施用对入渗率和侵蚀量的影响,对PAM(22.5kg/hm2)与保水剂(45kg/hm2)、粉煤灰(1 500kg/hm2)、腐殖酸(900kg/hm2)混合的6种施用方法进行了试验。结果表明,施加了PAM的土壤调理剂均能显著提高降雨入渗率和减少土壤侵蚀量。与对照相比,施加了PAM处理的降雨入渗率较对照试验提高了1.8～2.7倍,土壤侵蚀量减少约50%～70%,PAM与粉煤灰和腐殖酸混合施用提高降雨入渗率效果最为显著,PAM和保水剂混合施用减少土壤侵蚀量最多,PAM与粉煤灰和腐殖酸混合施用相比单独施用PAM均没有显著性差异。综合比较结果发现,PAM与粉煤灰混合施用增加降雨入渗率和减少径流的效果最好,PAM与保水剂混合施用抗土壤侵蚀效果最好。     

人工降雨条件下土壤结皮的形成以及与土壤溅蚀的关系

通过人工模拟降雨溅蚀实验,测定土壤溅蚀速率,同时采样制作土壤切片,观察分析结皮的发育特征以及与土壤溅蚀的关系。结果表明,降雨过程中有两种类型结皮形成,即沉积结皮和结构结皮。土壤结皮随着土壤表面大团聚体或者大颗粒的分散而形成,并且伴随着下层大孔隙的出现。土表结皮的完善过程,也是土壤抗溅蚀能力增强的过程     

坡耕地土壤结皮形成的影响因素分析

以天然降雨侵蚀特征为依据 ,在室内研究了坡耕地土壤结皮的形成特征。通过对结皮坚实度、容重和厚度的测定发现 ,在结皮的形成过程中 ,降雨以打击夯实作用为主 ,径流以淤积压实作用占主导地位 ,且随雨强、径流深度的增加 ,这种作用也愈加显著 ;但随坡度增大 ,两者的作用受到了抑制 ,使结皮形成的完善程度降低。总体来看 ,降雨的作用要大于径流作用     

土壤表面特性与坡度对产流产沙的影响

通过不同坡度下，前期有、无发育土壤结皮及前期打破土壤结皮的对比试验．分析了土壤表面特性与坡度对产流产沙的影响。结果发现，土壤结皮与坡度对产流均有影响，土壤结皮与坡度均通过降低入渗而增加产流；随着坡度的增加土壤结皮的贡献率降低，坡度的贡献率增加；不同坡度下，随着降雨历时的增加，土壤结皮的影响在降低。产生土壤结皮后，侵蚀力的增大远远大于抗蚀力的增大，导致产沙量增大。打破土壤结皮下产流量与产沙量仍旧很高，说明仅在表层扰动并不能彻底消除土壤结皮的影响。     

PAM喷施量与施用方式对风沙土风蚀的影响

固定流沙和减少风蚀是一个世界性的难题。PAM(聚丙烯酰胺,polyacrylamide)作为一种线性高分子聚合物,喷洒在土壤表层能形成结皮,能有效抵御风蚀,但喷施PAM溶液的结皮状况及抗风蚀能力与PAM的喷施量及土壤特性等密切相关,且PAM溶液的浓度越大则黏性越强,越不易喷洒。为了探寻PAM防风固沙的适宜喷施量及简便施用方法,该研究以乌兰布和沙漠流动沙丘的风沙土为试验材料,以风沙土的风干土及饱和湿土为对照,首先探讨PAM不同喷施量对风干土(风沙土)表层结皮状况、土壤含水率及土壤风蚀量的影响,以寻求PAM的适宜喷施量,然后再将适量的PAM干撒、干撒后喷水和喷施于风干土表层,探寻PAM的简便施用方法。结果表明:1)PAM不同喷施量的结皮覆盖度、结皮厚度、结皮抗剪强度均随PAM喷施量的增加而增加,均显著高于风干土和饱和湿土;PAM不同喷施量的土壤含水率均高于风干土,且随时间的延续均显著高于饱和湿土;喷施1、2、3和4g/m2的PAM风蚀量分别为风干土的26.83%、14.10%、13.01%和13.00%,为饱和湿土的28.78%、15.12%、14.02%和13.94%,当PAM喷施量达到2 g/m2时,PAM能有效降低风沙土的风蚀量。2)将2g/m2的PAM干撒、干撒后喷水和喷施于风干土表层,干撒PAM后喷水和喷施PAM溶液的土壤结皮覆盖度、结皮厚度、结皮抗剪强度均高于风干土、饱和湿土和干撒PAM,干撒PAM的土壤表层结皮覆盖度低于饱和湿土但高于风干土,结皮厚度和结皮抗剪强度高于风干土及饱和湿土,干撒PAM后喷水及喷施PAM溶液的土壤含水率高于风干土、饱和湿土及干撒PAM,干撒PAM的土壤含水率与风干土基本一致。干撒PAM、干撒PAM后喷水和喷施PAM溶液的风蚀量分别为风干土的53.13%、11.17%和6.35%,为饱和湿土的76.34%、16.05%和9.12%,干撒PAM后喷水的抗风蚀能力接近于风沙土表层喷施PAM溶液。3)由于喷施PAM溶液需消耗大量的水分及人力,建议风沙区可在降雨前将2 g/m2的PAM干撒于土壤表层或干撒后向土壤喷水,可有效减少风蚀量。     

Soil Erodibility and Physicochemical Properties of Collapsing Gully Alluvial Fans in Southern China

In southern China, collapsing gully erosion produces massive deposits of sediment on the plough layer of alluvial fan farmland, leading to reduced nutrients, increased erodibility, and even desertification. The aim of this study was to investigate soil erodibility (the factor K in the universal Soil Loss Equation, USLE) and physicochemical properties of the alluvial fans of the most severe collapsing gully erosion areas (Hubei, Jiangxi, Fujian, and Guangdong provinces) in southern China. The soils of the collapsing gully alluvial fans had a higher bulk density, but a lower total porosity, saturated water content, and silt and clay fractions than the control (CK) soils from the farmland without desertification. Soil quality gradually decreased from fan edge to fanhead. Significant decreases were found in soil pH, organic matter, cation exchange capacity, and total potassium, nitrogen, and phosphorus, as well as available nitrogen, phosphorus, and potassium, resulting in a gradual decrease in soil nutrients from the fanedge to the fanhead. Soil erodibility was greatest in the fanhead, and soil erodibility K values of the alluvial fans were 53.71%, 66.28%, 67.53%, and 71.68 % greater than that in those of the CK soils of Hubei, Jiangxi, Fujian, and Guangdong, respectively, indicating a significant correlation between the soil erodibility K values and physicochemical properties, particularly sand fraction and organic matter content. The results provide new insights into the relationship between soil physicochemical properties and erodibility of alluvial fans, and suggest that improving soil structure might increase soil fertility in the collapsing gully alluvial fan farmland.     

长期化肥有机替代对黑土颜色及腐殖物质的影响

基于30年长期定位试验,通过测定黑土光谱反射率和不同腐殖质组分含量,探究了不同施肥对黑土土壤腐殖质含量、土壤颜色及二者之间的关系。试验设置5个处理:(1)休耕(Fallow);(2)不施肥处理(CK);(3)单施化肥(NPK);(4)有机肥部分替代化肥(NPKM);(5)秸秆部分替代化肥处理(NPKS)。结果表明:与NPK处理相比,Fallow、NPKS、NPKM分别显著提高49.7%,74.3%,27.0%的土壤有机碳含量(p<0.05)。NPKM处理中胡敏酸(HA)含量最高为3.9 g/kg,随后依次为CK、NPKS、NPK、Fallow。NPKM、NPKS和Fallow处理中土壤富里酸(FA)含量为2.2~2.3 g/kg,显著高于NPK和CK。NPKM处理中胡敏素(HM)含量为18.6 g/kg,显著高于其他处理(p<0.05)。不同处理间土壤光谱反射率由高到低依次为NPK>Fallow、CK>NPKS>NPKM,与CK处理相比,NPK土壤光谱反射率在平均提高6.5%,NPKS和NPKM则分别降低11.1%和15.1%。根据线性相关分析结果,黑土土壤光谱反射率与土壤HAHM均呈显著负相关关系(p<0.01),相关系数(r)分别为-0.858,-0.681。综合上述结果,长期有机物料投入可以显著提高黑土腐殖物质含量,降低黑土光谱反射率,使黑土颜色加深,而长期化肥施入则使黑土光谱反射率提高,出现"褪色"现象,有机粪肥在黑土中对土壤有机质和腐殖质含量的提升效果优于秸秆。     

金沙江干热峡谷中退化的土壤生态系统生物学特征初探

Distribution characteristics of soil animals,microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River,China.Results showed that Hymenoptera,Araneae and Collembola were the dominant groups of soil animals in the polts studied.The numbers of groups and individuals and density of soil animals in the dry red soil series were higher than those in the Vertisol series,and the numbers of individuals and density of soil animals decreased with the degree of soil degradation.Bacteria dominated microbiococnosis not only in the dry red soils but also in the Vertisols.Microbial numbers of the dry red soil series were higher than those of Vertisol series,and decreased with the degree of soil degradation.The activities of catalase,invertase,urease and alkaline phosphatase declined with the degradation degree and showed a significant decline with depth in the profiles of both the dry red soils and the Vertisols,but activities of polyphenol oxidase and acid and neutral phosphatase showed the same tendencies only in the Vertisols.It was concluded that the characteristics of soil animals,microorganisms and enzymatic activity could be used as the bio-indicators to show the degradation degree of the dry red soils and Vertisols.Correlation among these soil bio-indicators was highly significant.     

不同炭基改良剂提升紫色土蓄水保熵能力

通过连续2a田间试验,研究了5种改良剂(秸秆、有机肥、生物炭、炭基改良剂I和炭基改良剂Ⅱ)对紫色丘陵区坡耕地土壤水分库容、孔隙度和团聚体组成及稳定性的影响,分析了土壤水分特征参数与孔隙度和团聚体组成的关系,以期为紫色土区水土保持和土壤改良提供科学依据。结果表明,与不施改良剂(对照)相比,5种炭基改良剂都能提高土壤对降水的截存和保贮能力,显著提高了土壤饱和含水量、田间持水量、水分总库容、有效水库容及重力水库容,降低了土壤凋萎点含水量和无效水库容;不同改良剂提升作用大小为改良剂Ⅱ改良剂I生物炭有机肥秸秆对照。施用改良剂I、改良剂Ⅱ、生物炭和有机肥显著提高了土壤孔隙度,降低了土壤容重,秸秆的效果不显著。施用炭基改良剂降低了0.25mm的微团聚体含量,促进了小团聚体向大团聚体的转化,其中对粒径5mm的机械稳定性大团聚体提升幅度最大,比对照提高14.5%~60.7%;5种炭基改良剂都显著提高了团聚体的平均重量直径及稳定性指数,以炭基改良剂I、炭基改良剂Ⅱ和生物炭的作用效果最大。土壤总库容、重力水库容和有效水库容与总孔隙度和毛管孔隙度以及土壤大团聚体含量呈正相关,而与土壤非毛管孔隙度和小团聚体呈负相关,土壤蓄水保水能力与土壤团聚体组成和孔隙度密切相关。因此,施用炭基改良剂通过促进土壤团聚作用,提高大团聚体含量和土壤孔隙度,进而增大土壤持水量和土壤有效水库容,是改善紫色土结构和提高紫色土坡耕地保水蓄水能力的有效措施。     

不同改良剂对宁夏地区盐碱土土壤结构的影响

采用玉米室内盆栽试验的方法,研究了宁夏回族自治区石嘴山市平罗县姚伏镇大兴墩村的盐碱土在施用硫磺、有机肥、石膏、PAM等不同土壤改良剂对土壤结构的影响.研究结果表明,4类改良剂均有效降低了土壤容重,土壤空隙度随之增加,土壤物理结构的改善与水分利用相互配合,共同促进了当地盐碱土的改良;硫磺的最佳用量确定为在30.45 g/盆,并需要注意土壤通气性,防止发生反硫化作用,对玉米根系产生毒害;综合而言,PAM改良效果最佳.其次是石膏和S3处理.     

Short-term spatiotemporal variation of soil CO2 emission,temperature, moisture and aeration in sugarcane field reform areas under the influence of precipitation events

Soil CO₂ emission (FCO₂) in agricultural areas results from the interaction of different factors such as climate and soil conditions. Our objective was to investigate the spatiotemporal variation of FCO₂, temperature (T_soil), moisture (M_soil) and air-filled pore space (AFPS), as well as their interactions, during the sugarcane field reform. The study was conducted on a 90 × 90 m sampling grid with 100 points at 10 m spacings. Ten assessments of FCO₂, T_soil and M_soil were carried out at each point over a 28-day period. The greatest mean values of FCO₂ (0.74 g m⁻² hr⁻¹) and M_soil (31.7%) were obtained on Julian day 276, 2013, being associated with precipitation events at the study site. Also, the smallest values of AFPS (19.17%) and T_soil (20.90°C) were observed on the same day. The spatial variability of FCO₂, T_soil, M_soil and AFPS was best described by an adjusted spherical model, although an exponential model better fitted some results. The spatial pattern of all soil attributes showed little temporal persistency, indicating a high complexity for FCO₂ during precipitation. Correlation maps assisted in identifying regions where M_soil and AFPS better controlled the emission process and where T_soil was important. A major challenge for world agriculture is to increase the efficiency of conventional soil management practices. We highlight the importance of the spatial pattern of soil properties that directly influence the CO₂ emission dynamics. Future mitigation actions should involve less intense tillage and ensure homogeneous applications of soil inputs, thereby reducing production costs and the contribution of these activities to CO₂ emissions during the sugarcane field reform.     

不同改良剂对酸性土壤的修复效应

为明确不同改良剂对酸性植烟土壤的修复效应,采用盆栽试验,分析了施用丰收延酸性土壤改良剂、金叶酸性土壤改良剂及石灰后土壤pH、水解性酸、潜性酸及土壤交换性能的动态变化。结果表明:施用改良剂可提高土壤pH 3.01%~24.11%,降低土壤水解性酸16.08%~50.46%、交换性Al 3+51.80%~64.27%、交换性H+含量84.12%~93.56%,提高土壤交换性盐基总量45.18%~46.16%、阳离子交换量0.33%~20.10%、盐基饱和度21.35%~49.78%。施用土壤改良剂后,土壤pH先升高后下降,至移栽60天后趋于稳定;土壤水解性酸在烤烟移栽后30~90天差异较小,至移栽后120天略有增加。施用石灰的土壤交换性氢、交换性铝一直下降,但施用丰收延、金叶酸性土壤改良剂的土壤交换性铝下降至烟苗移栽后120天略有增加,土壤交换性氢上升至烟苗移栽后120天大幅度下降。施用土壤改良剂后,土壤交换性盐基总量、阳离子交换量、盐基饱和度一直提高,但变化幅度较小。不同土壤改良剂的材料来源及组成成分不同,其对酸性土壤的恢复效果也不同,以施用石灰的效果最好。     

土壤可蚀性研究现状及展望

<正> 土壤可蚀性(soil erodibility)是指土壤是否易受侵蚀破坏的性能,也就是土壤对侵蚀介质剥蚀和搬运的敏感性。与侵蚀营力一样,土壤可蚀性是影响土壤侵蚀量大小的又一个重要因子。在水土保持学科中,我国习惯上把“水”和“土”并列使用,而国际上则用“soil loss”、“soil erosion”、“soil conservation”或“soil and water conservation”等术语。显然,土壤是水土保持学科的重点。另一方面,土壤侵蚀营力等是土壤流失过程中的外部因素,而土壤性质才是内在因素,因此,水土保持学科中核心的也是重要的问题,应该是土壤保护。土壤可蚀性研究在水土保持研究工作中具有重要意义,国际上把土壤可蚀性研究一直作为水土保持学科研究的重要内容之一。     

A review of visual soil evaluation techniques for soil structure

Soil structure forms a key component of soil quality, and its assessment by semi‐quantitative visual soil evaluation (VSE) techniques can help scientists, advisors and farmers make decisions regarding sampling and soil management. VSE techniques require inexpensive equipment and generate immediate results that correlate well with quantitative measurements of physical and biochemical properties, highlighting their potential utility. We reviewed published VSE techniques and found that soils of certain textures present problems and a lack of research into the influence of soil moisture content on VSE criteria. Generally, profile methods evaluate process interactions at specific locations within a field, exploring both intrinsic aspects and anthropogenic impacts. Spade methods focus on anthropogenic characteristics, providing rapid synopses of soil structure over wider areas. Despite a focus on structural form, some methods include criteria related to stability and resiliency. Further work is needed to improve existing methods regarding texture influences, on‐farm sampling procedures and more holistic assessments of soil structure.