广西水耕人为土黏粒矿物组成及其空间分布特征

黏粒矿物影响着土壤理化性质，可指示成土因素特征和土壤发生发育过程/强度，也是中国土壤系统分类的基层单元土族矿物学类型划分的重要依据。本研究选择了广西不同纬度和成土母质的18个代表性水耕人为土的剖面，应用X射线衍射（XRD）方法分析了其典型水耕氧化还原层（Br层）的黏粒矿物组成及其空间分布特征，并确定了其中“黏质”剖面的土族控制层段矿物学类型。结果表明：（1）供试土壤的黏粒矿物主要包括高岭石、伊利石、三水铝石、1.42 nm过渡矿物、蒙脱石和蛭石等，依次分别出现在100%、88.9%、72.2%、61.1%、44.4%和38.9%的剖面中。（2）黏粒矿物组成在纬度空间分布上具有明显规律性特征。随着纬度降低，土壤黏粒中的高岭石增加，伊利石、蒙脱石、1.42nm过渡矿物逐渐减少；纬度＞23°N区域内，成土母质对黏粒矿物组成影响明显。（3）纬度23°N是黏粒矿物组成和土族矿物学类型分界线，＜23°N区域，黏粒矿物均以高岭石为主，是“黏质”剖面的土族控制层段的主要矿物学类型；＞23°N区域，黏粒矿物组成以高岭石、蒙脱石、伊利石或1.42 nm过渡矿物为主，因成土母质不同而异，“黏质”剖面的土族控制层段矿物学类型包括高岭石混合型、混合型和伊利石型。     

南方丘陵区三种母质水耕人为土有机碳的累积特征与影响因素分析

本研究分析了南方丘陵区3种母质水耕人为土有机碳的累积特征与影响因素。结果表明：紫色砂页岩和第四纪红黏土母质的水耕人为土在发育过程中有机碳较易累积,在种稻初期土壤有机碳的增加主要集中在耕作层,到一定阶段后下层(耕作层以下)也明显增加;相比之下,红砂岩母质的水耕人为土在发育过程中有机碳较难累积。利用逐步回归方法得到的丘陵区水耕人为土耕作层有机碳动态变化模型表明丘陵区水耕人为土有机碳的动态变化主要受细颗粒(黏粒+细粉粒)的影响。     

Particle Size Distribution (Texture) of Eroded Soil Material

The total quantity of erosional drift on a Stagnic Luvisol on which six tillage methods were used was measured over 5 years of investigation. The texture of the tilled soil and the erosional drift for each trial method was recorded in the same plots. The results obtained suggested that erosional drift was generally richer in silt and clay particles. The standard deviations of coarse sand indicated that approximately the same quantity of coarse sand was found in plot soil and in erosional drift for all tillage methods. Sometimes more and sometimes fewer fine sand particles were found in erosional drift than in plot soil. In most cases, more silt particles were found in erosional drift than in plot soil. The standard deviation and coefficient of variation for clay and silt were higher in erosional drift than in plot soil for all methods. The highest content of clay particles was recorded in erosional drift from the no‐tillage treatment in all investigation years. The results suggest that the correct choice of tillage method (no‐tillage and ploughing across the slope) on a Stagnic Luvisol can protect the soil on a slope.     

Runoff and soil loss under different tillage methods on Stagnic Luvisols in central Croatia

Owing to humid climate and unfavourable relief, the problem of extensive soil erosion in central Croatia is of prime importance. The main objective of this research was to determine how soil erosion is influenced by deep (30 cm) soil tillage practised for deep-rooted row crops in comparison with other tillage methods, on Stagnic Luvisols. Soil loss quantity was recorded during the 4-year investigation cycle (1994–1998), under common field crops grown under six tillage methods. Appreciably higher rates of soil erosion were recorded in low-density row spring crops than in high-density winter crops under the same tillage methods. The time immediately following the sowing of spring crops was the most critical period, i.e. the period when highest soil loss occurs. The results showed that erosion processes cannot be completely stopped; however, they can be reduced to an acceptable level by an appropriate tillage method. Efficient soil conservation on Stagnic Luvisols was achieved by no-tillage and all across the slope tillage methods.     

Plaggen Soils: landscape history,properties, and classification

Plaggen soils were produced by farmers in the sandy lowlands of Denmark, NW Germany, Belgium, and the Netherlands by long‐term application of plaggen manure. The present paper summarizes the genesis, the properties, and the landscape impact of plaggen soils. The objectives and methods of plaggen management are outlined. Evidence for the plaggen management can be traced back to the late Bronze Age. It has continued until the last century. Numerous references indicate the geographical expansion of plaggen management over Europe. The various conditions of plaggen soil formation are reflected by their basic physical and chemical properties. Recent investigations of soil organic matter composition in sandy plaggen horizons revealed large proportions of lipids and fatty acids and some similarity with organic matter in Podzol B horizons. Finally, the classification of plaggen soils is discussed. In the World Reference Base of Soil Resources (ISSS/ISRIC/FAO, 1998), most of them are classified as a separate subunit: within the reference soil group of Anthrosols, they differ from other artificially transformed soils, and are classified as Plaggic Anthrosols.     

成陆时间和沉积环境对宁绍平原水耕人为土形成的影响

为了解低平原地区水耕人为土分布的空间规律,以宁绍平原为例,探讨了成陆时间和沉积环境对水耕人为土性状与剖面发育的影响。田间调查表明,宁绍平原因成陆时间和成因的差异可被划分为近代浅海沉积区、低洼湖沼沉积区、古水陆相沉积区和古滨岸河湖沉积区等4种沉积环境,相应地分布的水耕人为土类型及性状有较大的差别。近代浅海沉积区主要分布普通简育水耕人为土,其性状变化与海涂围垦时间有关。低洼湖沼沉积区主要分布普通潜育水耕人为土或底潜简育水耕人为土,其性状的差异主要与距古湖沼中心距离有关。古水陆相沉积区主要分布普通铁聚水耕人为土,局部区域因上层滞水可形成铁聚潜育水耕人为土。古滨岸河湖沉积区的土壤类型主要为普通铁聚水耕人为土或普通简育水耕人为土。研究认为,通过沉积环境的识别有助于低平原地区水耕人为土类型的鉴定。     

Fractal Characteristics of Stagnic Anthrosols and the Relationship with Soil Micro-Structure

The Stagnic Anthrosols developed from quaternary yellow sedimentary parent material occupied an important position in Southwest China. Fractal dimensions of particle size and micro-aggregate size distributions of Stagnie Anthrosols and their relationship to soil micro-structure had been probed. Results showed that the soil particle size distributions were dominated by clay, the fractal dimensions of particle size distributions （Ds） were high and between 2.676-2.925, as the fractal dimensions of micro-aggregate size distributions （Da） were between 2.354-2.853. The fractal dimensions of particlesize distributions were preferably related with the ratio of coarse particles and fine particles （c/f20 ,m） and the micromorphological feature of skeleton grains. The evolution degree of micro-structure among horizons were reflected by the coefficient of variation of Ds within the profile. The fractal dimensions of micro-aggregate size distributions were related with the quantities, distributions of micro-aggregates and micro-pores. Results revealed that the soil micro-structures could be quantified by fractal dimensions preliminarily.     

南方丘陵区不同母质水耕人为土发育速率的比较

如何度量水耕人为土的发育程度和发育速率是土壤发生学的一个难题。选择南方丘陵区3种常见母质(紫色砂页岩类坡积物PS、第四纪红黏土RC和红砂岩类坡积物RS)发育的水耕人为土时间序列作为研究对象,尝试利用属性距离和土壤发育指数来表征水耕人为土的发育程度,揭示母质对水耕人为土发育速率的影响。结果表明,水耕人为土剖面形态特征经定量后和属性距离一样能够表征水耕人为土发育的时间趋势,在指示水耕人为土的发育程度和估算发育速率上有重要意义。有机碳(SOC)、pH、黏粒含量和磁化率(MS)在计算发生层距离(HD)中贡献很大,而土壤颜色和湿结持性在计算发生层指数(HI)中起着重要作用。RC母质的土壤,土层较厚,颜色红,黏粒含量较高,保肥和保水状况好,土粒的黏结性和可塑性较好,SOC容易累积,发育速率最快。PS母质的土壤,土层较厚,细颗粒(黏粒+细粉粒,0.01mm)含量高,保肥和保水状况好,土粒有一定的黏结性和可塑性,SOC容易累积,发育速率次之。RS母质的土壤,黏粒和细颗粒含量均很低,土层薄,保肥和保水状况以及黏结性和可塑性差,SOC很难累积,发育速率最慢。母质对水耕人为土发育过程的影响可以通过影响其发育速率表现出来。研究同时显示,水耕人为土平均发育速率远较自然土壤快,并在人为培育下快速定向发育。但随着种稻年限的增加,水耕人为土的发育速率普遍下降,水耕人为土发育速率和成土年龄的关系大致符合对数关系。这种定量方法可以提高对水耕人为土形成过程的理解并能实现不同地区水耕人为发育速率的定量比较,有较好的使用前景。但此方法仍处于试验探讨阶段,有待更多的研究来验证和改进。