Formation and Evolution of Vertisols in Huaibei Plain

The objectives of the present paper are to restore soil-forming environment of the Vertisols,to reveal their regularities of formation and evolution and to found soil chronology.In regard to formation and evolution of the Vertisols in the Huaibei Plain,they have undergone 3 cycles of deposition-formation during different geologic time (Q3^3;Q4^2 and Q4^3).Therefore,they are considered as the soils developed on heterogeneous parent material.The Vertisols as a paleosol can be divided into relict Vertisols and buried Vertisols.The former is shajiang black soils called by local people,the latter is shajiang black soils underlying Warp soil or warp soil horizon.

Stable Carbon and Oxygen Isotopes of Pedogenic Carbonates in Ustic Vertisols: Implications for Paleoenvironmental Change

Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic compositions of pedogenic carbonates have been used to rebuild paleoecology (biomass and vegetation) and to estimate paleotemperature and paleoprecipitation during past geological time. By utilizing the stable carbon and oxygen isotopic compositions (δ13C and (δ18O) of secondary nodules in Ustic Vertisols, this study looked into the climatic and environmental changes in the dry valleys of the Yuanmou Basin, Yunnan Province, in southwestern China. The results showed that during the early Holocene, a warm-humid or hot-humid climate existed in the Yuanmou Basin, but since then fluctuations in climate have occurred, with a dry climate prevailing. A highly significant correlation (r = 0.92, n = 9) between δ13C and δ18O values of carbonates illustrated that there had been a continual shifting between cold-humid and warm-dry climates in southwestern China including the Yuanmou Basin since the early Holocene.

Effects of Long-Term Fertilization on Organic Carbon and Nitrogen Dynamics in a Vertisol in Eastern China

Mineral fertilizers and organic amendment can affect the various soil organic matter (SOM) pools and the distribution of organic carbon (OC) and nitrogen (N) in these pools. It is unknown how OC and N are distributed in different SOM pools under different long-term fertilization regimes. Therefore, this study aimed to examine the effects on OC and N concentrations in various SOM pools after 33 years of application of chemical fertilizer and organic amendment in Anhui Province in the Huang-Huai-Hai Plain, eastern China. This long-term experiment consisted of five fertilization treatments measuring changes in the OC and N concentrations in the soils and different SOM fractions of each experiment plot. Organic amendment increased the OC and N concentrations in the mineral-associated fraction, the coarse mineral-associated fraction and the aggregates compared with the values obtained without fertilizer application. Mineral fertilizer application alone increased the abovementioned indexes, but this increase was small. There was a small but significant increase in the OC and N concentrations in the free particulate fraction, and the change in magnitude had no obvious effect on the total OC (TOC) and total N (TN) concentrations in soils. More than 80% of the water-stable aggregate-associated C was stored in macroaggregates >2 mm in size. More than 60% of the TOC and TN accumulated within mineral associations in the soil, and organic amendment increased this proportion to 80%. These results suggest that the OC in Vertisols is dominated by mineral-associated OC and that the effect of organic amendment on mineral-associated OC is obvious.

Properties, Formation and Fertility of Vertisols in Fujian Province

The zonal soils in the south subtropical zone of Fujian are lateritic red soils. A type of dark clayeysoils, which was historically defined as lateritic red soils, derived from weathering products of the basalts wasindicated by the investigation results to be markedly different from lateritic red soils and could be classifiedas Typical Hapluderts. They are distributed as complex zones with the lateritic red soils. The vertisolsin this region were considered as a type of lithogenic soils and the vertic chararteristics delay and inhibitthe soils from allitic processes and then formed an independent soil type. The vertisols have higher fertilityand better agricultural production characters than the lateritic red soils. The different ways in utilizing andmanaging these soils arcording to their properties and fertility are also suggested.

Radiocarbon Dating of Vertisols in China

Vertisols,which are mainly developed on fiuvial and lacustrine deposits and basalt,are extensively distributed in China. 66 samples of them for radiocarbon dating were collected across 5 provinces and 1 autonomous region, ranging from warm-temperate to subtropical and tropical zones in China.The soil organic matter was dated via surfaCe horizon, black soil horizon and dark-colour horizon of the vertisols,whereas carbonate through calcareous concretions and dispersed carbonate in soil profile using radiocarbon method. The present article elucidates the dates of genetic horizons,and of surfaCe and buried vertisols as well. 14C dating indicates that the surface vertisols were formed during the end of the late Pleistocene,ca.15600 years ago.Correlation between depth of sampling and measured 14C age shows that age characteristics of the vertisols of China are close to those of West Germany,Italy,Turnisia,Australia and Argeentia. However, two buried vertisols developed on fluvial and lacustrine deposits were formed during different geological periods.The buried soils in warm-temperate zone were formed in the mid Holocene, while those in subtropics were buried at 12930 years B.P.,and formed in the end of the late Pleistocene.

Agronomic and Economic Efficiency of Manure and Urea Fertilizers Use on Vertisols in Ethiopian Highlands

Soil fertility depletion is among the major impediments to sustained agricultural productivity especially in the less developed countries because of limited application of fertilizers. Soil fertility maintenance requires a balanced application of inorganic and organic nutrient sources. This study was conducted on a Vertisol in Ethiopia to determine the optimum farm yard manure （M） and nitrogen （N） application rates for maximum return under cereal-pulse-cereal rotation system. The main and interaction effects of M and N significantly affected biomass, grain and straw yields of wheat （Triticum durum） and tef （Eragrostis tear）, but the residual effect on chickpea （Cicer arietinum） was not significant. Application of 6 t M ha^-1 and 30 kg N ha^-1, gave the largest grain yield of both crops but a comparable result was obtained due to 3 t M ha^-1 and 30 kg N ha^-1. The economic analysis revealed that 6.85 t M ha^-1 and 44 kg N ha^-1 for wheat, and 4.53 t M ha^-1 and 37 kg N ha^-1 for tef were the economic optimum rates. The additional benefit obtained due to these rates was about 450 USD ha^-1. Therefore, application of the economic optimum combination of both organic and inorganic sources of nitrogen is recommended for use on cereals in the cereal-legume-cereal rotation system.

Morphogenesis of Vertisols：A Model Study

Studies on Vertisols of Southwest China show that the distribution of organic matter, mechanicalcomposition, carbonates and spore-pollen in their profiles exhibits a definite differentiation and the radiocarbon age has a functional variation with soil depth, which suggests that pedoturbation model is a kind of incomplete model for genetic study and that the disturbance and inversion of solums of Vertisol are not as rapid and absolute as expected. In further consideration of the characters of swelling pressure and shear strength of Vertisol, vertic soil and other zonal soils, it is speculated that soil mechanics model is more adaptable for interpreting the morphogenesis of Vertisols without any contradiction with soil properties.

Evaluation of the Compaction of a No-Till Vertisol Field Using Methods of Cone Index and Pedotransfer Function in Semi-arid Context of Morocco

This study evaluated compaction level of a 15-year old no-till vertisol field crop(40.91%clay,44.16%loam and 14.93%sand)having organic matter contents of 2.23%and 2.91%in 0-10 cm and 10-20 cm profiles,respectively.The bulk density ranged from 1.30 g/cm^3 to 1.80 g/cm^3 in the field boundaries,and from 1.01 g/cm^3 to 1.40 g/cm^3 in its center.The field showed a gradient of limestone from 3%to 13%.Measurements were done to evaluate soil strength(cone index)and soil plasticity(Atterberg limits).The soil strength showed different levels of compaction from 4.5 MPa to 16 MPa to distinct five spatial clusters in the field.The soil compactness was related to limestone gradient according the correlation found between the soil strength and limestone levels.The soil plasticity test showed occurrence of plastic limits when the moisture content decreased from 26%to 15%within 5 d interval.The Atterberg limits showed the importance of respecting intervention delays to avoid soil compaction due to its plasticity.A pedotransfer function was developed using soil parameters of texture,organic matter,bulk density,cohesion,internal friction angle and moisture content to compute its precompression stress.Results showed importance of compaction in the field extremities due to importance of machines/tools traffic without avoiding cropping interventions during soil plasticity state.The soil strength(as measured value)was correlated to precompression stress(as estimated values)to show the importance of using pedotransfer function as significant method to evaluate indirectly compactness or susceptibility to compaction of the studied vertisol.

Technology for the Production of Sorghum for Grain in the Vertisols of Campeche, Mexico

This research was conducted in the state of Campeche, Mexico, between 2017 and 2018. On the one hand, the sorghum yield was explored in plots with Vertisol-type soils, which were supplied with rainwater. This had the purpose of knowing the results obtained by the producers in the area. On the other hand, an experiment was established with three factors: the genetic material of sorghum, planting density and fertilization. Finally, different varieties of soybeans and sorghum hybrids were also tested in large plots, to identify those that are best adapted to crop rotation. In the farmers’ plots, the grain yield was between 4377 and 5543 kg∙ha−1. The planting density was from 142,667 to 197,334 plants per hectare, which indicated that, for each unit that increased the planting density, the yield increased by 37.5 grams. The experiment with three factors indicated that the best planting density was 300 thousand plants per hectare, with a grain yield of 5176 kg∙ha−1;and the best hybrids were DKS-32 and SYN5515, with grain yields of 5794 and 3791 kg∙ha−1, respectively;likewise, the best dose of fertilizer was between 150 and 200 kg∙ha−1 of diammonium phosphate, with a grain yield of 4527 - 4562 kg∙ha−1. In relation to crop rotation, the varieties that stood out for their yield were Huasteca 300 and Vernal, in the case of soybeans;and the hybrids DKS-32 and SYN5515, in sorghum. Soybeans suffered greatly in their early stages of development from the excessive moisture retained by the soil, while sorghum seemed to be little affected by the lack of rain;for this reason, advancing the sowing date in soybeans and consequently in sorghum, is a strategy that could benefit grain yield in both species.

Morphological and Physico-Chemical Characteristics and Classification of Vertisol Developed on Deltaic Plain

The name of Vertisol is derived from Latin “vertere” meaning to invert. This case restricts development of soil horizons in profile. These soils have the capacity to swell and shrink, inducing cracks in the upper parts of the soil and distinctive soil structure throughout the soil. The formation of these specific features are caused by a heavy texture, a dominance of swelling clay in the fine fraction and marked changes in moisture content. The swell-shrink behavior is attributed to the wetting and drying of the soil mass. In this study, morphology, physico-chemical characteristics and classification of vertisols that were formed on alluvial delta plains, were investigated. Those soils formed on the Bafra Plain found in the K?z?l?rmak Delta and located in the central Black Sea region of Turkey. All studied Vertisols are characterised by a dark colour in surface soil, a heavy clayey texture, hardpan formation under top soil (high bulk density a high compaction) and very high COLE values. In addition, they have deep wide-opened desiccation cracks at the surface, slickensides at the middle part of the profiles and a poor differentiation of their horizons. Physico-chemically, the studied soils are slightly basic to very basic, non-saline and poor in organic matter, which is slightly higher in the surface horizon. In addition, cation exchange capacity, sum of exchangeable bases and base saturation of soils are very high. On the basis of morphological and physicochemical analysis, soil profiles were classified as Sodic Haplustert, Typic Calciaquert, Sodic Calciustert according to Soil Taxonomy (Soil Survey Staff, 1975 and 1999) and as Sodic Vertisol and Calcic Vertisol according to FAO/ISRIC (2006) classification systems.

Land use impact on clay dispersion/flocculation in irrigated and flooded vertisols from Northern Cameroon

Clay dispersion by water is important for soil and water conservation as well as for irrigation scheduling. In the present study, clay dispersion/flocculation of irrigated and flooded vertisols in North Cameroon was investigated using clay dispersion/stability indices. Nine vertisols topsoils (0–20 cm) samples were collected on different land use and their clay dispersion indices were assessed. Vertisols were acidic to slightly basic, with smectites as dominant clay mineral. The water dispersible clay (160–340 g kg-1), the dispersion ratio (0.55–0.79) and the clay dispersion ratio (0.48–0.83) were high in the studied vertisols while the clay flocculation index (0.17–0.54) and the clay aggregation (70–230 g kg-1) were low to moderate, indicating their high dispersion. Cropped vertisols displayed the higher amount of water dispersible clay while not cropped recorded the smaller amount. Concerning the cropped soils, irrigated vertisols displayed the highest clay dispersion indices suggesting that agricultural practices (irrigation) enhance clay dispersion. Globally, the clay dispersibility trend was: irrigated paddy ? rainy sorghum ? rainfed paddy ? dry-season sorghum ? not cropped. Statistical analyses revealed that amorphous Al, Na+ and electrical conductivity enhance clay dispersion while organic matter, nitrogen and Ca++ promote clay flocculation/aggregation. The overall findings emphasized that practices such as heavy tillage and irrigation induce clay dispersion. Minimum tillage, electrolytes concentration monitoring in irrigation water, irrigation scheduling based on soil moisture control, organic matter inputs and implementation of adapted dams are measures susceptible to limit their degradation through clay dispersion.

秸杆还田改良砂姜黑土的效果及其机理研究

通过田间定位试验、室内培育试验以及一系列物理、化学性质的测定 ,探讨了秸杆直接还田、堆沤还田和过腹还田等有机物质对改良淮北低产土壤—砂姜黑土的效果及机理。结果表明 ,增施有机物料能增加土壤孔隙度 ,降低容重 ,改善土壤通透性和保水、保肥性能 ,提高土壤的缓冲性 ,提供多种有效养分 ,培肥土壤 ,并最后表现为增加作物产量。其机理不仅在于所提供的腐殖质能降低砂姜黑土中含量过高的蒙脱石矿物的剪切应力 ,抑制其胀缩性 ,而且还在于它们能提供形成有机无机复合团聚体所必需的活性有机胶体 ,以及其有机酸能溶解土中原有的 Ca CO3成为活性的 Ca2 + 离子 ,后者是形成复合团聚体的桥梁 ,从而改善了土壤的结构性能等等。

有机物料对砂姜黑土的改良效应及其机制

通过田间定位试验、温室培育试验和一系列物理、化学性质的测定 ,探讨了三种有机物料对淮北低产土壤—砂姜黑土的改良效果及机理。结果表明 ,有机物料回归土壤能增加土壤孔隙度 ,降低容重 ,改善土壤通透性和保水保肥性能 ,提高土壤的缓冲性。同时提供多种有效养分 ,培肥土壤 ,并表现为增加作物产量。其机理不仅在于所提供的腐殖质能降低砂姜黑土中含量过高的蒙脱石矿物的剪切应力 ,抑制其胀缩性 ,而且还在于它们能提供形成有机无机复合团聚体所必须的活性有机胶体 ,以及其有机酸能溶解土中原有的CaCO3成为活性的Ca2 + 离子 ,后者是形成复合团聚体的桥梁 ,从而改善了土壤的结构性能等。

水分胁迫对燥红土和变性土上生长的玉米叶片几种酶活性的影响

采用盆栽控制试验 ,研究了不同处理条件下 ,水分胁迫对金沙江干热河谷典型土壤 (燥红土和变性土 )生长的玉米 (ZeamaysL .)叶片中几种酶活性的影响 .结果表明 :(1)在一定的水分胁迫范围内 ,玉米叶片的过氧化物酶 (POD)、过氧化氢酶 (CAT)、抗坏血酸过氧化物酶 (ASP)和多酚氧化酶 (PPO)活性均随着土壤含水量的降低而升高 ,但过度胁迫时 ,酶活性降低 ;(2 )随着土壤含水量降低 ,玉米叶片中保护酶活性的变化规律略有差异 ,这与二者的土壤物理性质有关 ;(3)施肥处理和栽培方式对玉米叶片的酶活性有影响 ,增施有机肥和Zn肥可提高适度水分亏缺条件下玉米叶片中POD、CAT、ASP和PPO活性 .图 4参

金沙江干热河谷区云南土壤退化过程研究

通过对云南省金沙江干热河谷典型区不同生态景观下土壤典型剖面系列的比较研究,初步确定了燥红土系列和变性土系列土壤退化过程的阶段及其土壤性状特征。研究结果表明,土壤腐殖质层(A) 厚度及其有机质含量、土壤结构性和容重、土壤全氮量、土壤开裂状况、粘粒活度等指标,可用于表征土壤退化过程的阶段特征;并提出了土壤退化过程有渐变、突变、跃变和复合型等演化型式。

砂姜黑土区不同花生品种对氮磷钾养分吸收、分配和利用的差异

采用大田裂区随机区组设计试验,研究了花生不同基因型品种对氮磷钾养分吸收、分配和利用的差异,为豫南花生主产区砂姜黑土上花生高效施肥提供技术支撑。结果表明,施肥能显著增加花生对氮、磷、钾的吸收量,豫花22对氮、磷、钾的吸收量最高,为283.6、32.8、105.9kg/hm^2,远杂6吸收量最小,为274.9、28.4、87.3kg/hm^2;花生吸收的氮主要分配在果仁和叶中,分别占吸收总量的66.7%~71.3%、11.1%~13.3%;磷主要分配在果仁和茎中,分别占总吸磷量的67.4%~75.6%、12.2%~18.3%;钾主要分配在茎和果仁中,分别占吸收总量的41.2%~49.4%、18.3%~26.5%。不同基因型品种对氮、磷、钾在花生叶、茎、根、仁和果壳中分配的比例有明显的差异。远杂9102的氮磷钾的养分利用率最高,为27.7%;其次是豫花22,为25.6%;远杂6最低,为21.6%。在N150kg/hm^2、P_2O_590kg/hm^2、K_2O 150kg/hm^2的施用量下,远杂9102是氮钾利用高效的花生品种,远杂6是磷、钾利用低效型的花生品种,豫花22是磷利用高效、氮利用低效型的花生品种。

秸秆还田对砂姜黑土理化性质与锰、锌、铜有效性的影响

采用田间试验与实验室培育试验研究作物秸秆还田对砂姜黑土理化性质及Cu、Zn、Mn有效性的影响,结果表明,秸秆还田可降低土壤容重,增大土壤总孔隙度,特别是毛管孔隙度显著增加。土壤中胡敏酸和富里酸含量显著增加,胡敏酸含量的增加对提高土壤有机质活性和改善土壤肥力具有良好效应。与单施化肥比较,秸秆配施化肥土壤中交换态锰、锌、铜含量分别增加11%、21%和41%,有机结合态锰、铜分别增加19%和103%。培育试验表明,加入粉碎的作物秸秆培育90d后,土壤中有效锰、有效铜含量分别增加21%和27%。

砂姜黑土农田土壤障碍因子消减技术浅析

砂姜黑土是黄淮海平原三大中低产土壤之一,研究砂姜黑土区农田土壤障碍因子消减技术,对于砂姜黑土改良和提升该区耕地粮食生产力具有重要意义。在分析砂姜黑土农业利用障碍因子的基础上,详细阐述了消减这些障碍因子的技术措施:适当控水;起垄种植;改进耕作,调控土壤水分状况,防止土壤发生旱涝危害;添加外来物质改性;科学合理施肥,推广测土配方技术;建立农田防护体系等。

铁锰结核的元素组成及微形态特征

本文研究了钙质变性土中铁锰结核的矿质全量组成、微量元素丰度、微形态特征以及土壤和铁锰结核中各形态铁锰氧化物的组成特点。结果表明，铁锰结核中仍以ＳｉＯ２含量最高，但Ｆｅ２Ｏ３含量增加超过了Ａｌ２Ｏ３，ＭｎＯ含量大大增加超过了Ｋ２Ｏ、Ｎａ２Ｏ、ＴｉＯ２和ＭｇＯ的含量。所测定的９种微量元素中以Ｂａ含量最高，其次是Ｖ、Ｎｉ、Ｃｏ３种铁族元素，Ｃｕ和Ｐｂ含量也较高，但Ｚｎ和Ｃｒ含量较低。一般黑土层中的结核较小，颜色较深，薄片观察可见粗骨颗粒表面有亮线状光性定向粘粒，凝团、结核外部均有光性定向粘粒与铁共聚现象，含方解石较少。砂姜层中的铁锰结核大多是铁质方解石混合凝团或复合凝团，含较多碳酸盐及方解石，凝团表面仍可见光性定向粘粒与铁共聚呈同心圆垒结。铁锰结核中的氧化铁主要是游离铁，铁游离度达７８％，晶化度达８２．２％，远高于土壤中的铁氧化物。氧化锰的游离度在９０％以上，高于铁游离度。锰的活化度多在３０％以上，明显高于铁的活化度，并且不同层次中的铁锰结核，其锰的游离度和活化度没有明显差异，说明锰在土壤中比铁更加活跃。

基于长期定位试验的变性土养分持续供给能力和作物响应研究

8年定位施肥试验结果表明，不施N肥，淮北变性土N素自然供给能力，第1年降为原来的64％，第2年则降为22％，此后，在20％左右振荡；不施P肥，土壤P素自然供给能力第1年后为95％，8年后逐渐下降为45％左右；不施K肥，土壤K素自然供给能力，第1年后为90％，8年后逐渐下降为60％～70％；而且，土壤P、K素自然供给能力对小麦、玉米有所差异。作物产量响应特点是，CK、N、NP、NK和PK处理区小麦、玉米产量分别为NPK全营养区的26．9％、54．3％、85．2％、53．2％、31．8％和21．4％、68．9％、73．5％、81．6％、28．0％。作物养分浓度响应特点是，施N或P肥提高了籽粒和秸秆的N或P养分浓度，施K肥对籽粒K浓度影响较小，但显著提高了秸秆K浓度。与试验前相比，8年后，土壤全氮含量，不施N处理区降低5％～10％，施N处理区增加12％～16．5％；土壤全磷含量，不施P处理区降低20％左右，施P处理区略有不同程度提高；土壤有效磷含量，不施P处理区降低75％～85％，施P处理提高56．9％～119．3％；土壤全钾含量变化不大；土壤速效钾含量，不施K肥处理区降低35％，NPK处理区降低5．9％，NK和PK处理区增加10％左右；土壤有机质含量，CK和PK处理区降低10％，其他处理基本持平。小麦和玉米对N、P、K肥的表观利用率分别为59．8％、47．3％、50．2％和51．1％、33．2％、49．5％。通过模拟，土壤有效磷消长与P素平衡盈亏的模型为，，（土壤有效磷消长）=0．1138x（P素平衡的盈亏）-0．406l（n=6，r=0．9594），土壤速效钾消长与K素盈亏的模型为y（土壤速效钾消长）=0．1075x（K素平衡的盈亏）-8．787l（n=6，r=0．9021）。