N2O emissions from agricultural lands: a synthesis of simulation approaches

Nitrous oxide (N2O) is primarily produced by the microbially-mediated nitrification and denitrification processes in soils. It is influenced by a suite of climate (i.e. temperature and rainfall) and soil (physical and chemical) variables, interacting soil and plant nitrogen (N) transformations (either competing or supplying substrates) as well as land management practices. It is not surprising that N2O emissions are highly variable both spatially and temporally. Computer simulation models, which can integrate all of these variables, are required for the complex task of providing quantitative determinations of N2O emissions. Numerous simulation models have been developed to predict N2O production. Each model has its own philosophy in constructing simulation components as well as performance strengths. The models range from those that attempt to comprehensively simulate all soil processes to more empirical approaches requiring minimal input data. These N2O simulation models can be classified into three categories: laboratory, field and regional/global levels. Process-based field-scale N2O simulation models, which simulate whole agroecosystems and can be used to develop N2O mitigation measures, are the most widely used. The current challenge is how to scale up the relatively more robust field-scale model to catchment, regional and national scales. This paper reviews the development history, main construction components, strengths, limitations and applications of N2O emissions models, which have been published in the literature. The three scale levels are considered and the current knowledge gaps and challenges in modelling N2O emissions from soils are discussed.

典型草原土壤性状变化对灌丛化的响应

以草原和稀树草原中木本植物多度的增加为特征的草地灌丛化，是全球范围普遍发生的现象，但灌丛化的生态学效应目前仍存在争议。对灌丛化草地生态系统特征与过程的研究，将有助于我们进一步了解草地生态系统的退化和恢复机理，为退化草原恢复与管理实践提供理论依据。 本研究以位于内蒙古锡林河流域, 一个经23年围封恢复、具有明显灌丛化特征的草原生态系统为研究对象，通过分析小叶锦鸡儿灌丛及其相邻草本群落下的土壤容重、机械组成、土壤有机碳(SOC)、全氮(TN)和无机氮(IN)的差异，确定小叶锦鸡儿灌丛对草原土壤物理化学性状的影响。主要结果如下： （1）小叶锦鸡儿灌丛化增加了表层土壤（0-5 cm）粗粒级颗粒的比例，降低了浅层土壤（0-20 cm）的容重，较大灌丛下10-20 cm土层仍存在这种现象。这至少部分归因于灌丛对凋落物的截获积聚，以及小叶锦鸡儿的根系分泌物在质和量上较之草本植物的不同，促进了土壤团聚体的发育。 （2）小叶锦鸡儿灌丛斑块引起了典型草原生态系统土壤有机碳、全氮和无机氮的空间分布的变化。在浅层土壤中（0-20cm），由灌丛斑块内部向外部SOC、TN和IN均趋于降低。随小叶锦鸡儿灌丛大小（存在时间）的增加，0-20 cm和60-100cm土层SOC和TN均有增加趋势。 （3）除表层（0-5cm）外，小叶锦鸡儿大灌丛与邻近草地土壤C/N比值无显著差异。 总之，小叶锦鸡儿灌丛不仅改变了草原土壤的物理性状，而且提高了灌丛下土壤有机碳和氮的含量，改变了草原生态系统C、N的空间分布格局，表明草原灌丛化明显改变了草原生态系统的碳氮循环。基于草原约占陆地面积的40%以及全球草地灌丛化普遍存在的事实，这种伴随草原灌丛化发生的土壤有机碳和氮的变化可能会对全球碳氮循环和气候有显著影响。

三峡水库蓄水对消落带土壤理化性状的影响

三峡水利枢纽工程的调度运行导致水库水位的涨落，从而在三峡水库周边水陆交错带形成周期性淹没与出露于水面的一段特殊区域，被称为三峡水库消落带。三峡水库消落带生态系统的健康是库岸稳定和水库安全运行的重要保障。土壤养分是三峡库区消落带土壤生态系统的重要组成部分。三峡水库蓄水以来，土壤理化性状发生改变，水土流失日益加剧。土壤是植物的基础，因此，对三峡水库消落带土壤性状的研究对消落带植被恢复有一定的指导意义，也为研究水库消落带水土流失提供依据，为研究水库消落带土壤污染与水体污染提供基础。 本文首先通过对重庆忠县石宝寨水库消落带不同水位、不同时期的表层土壤分析，研究了消落带不同水位土壤容重、酸碱度、有机质、全氮、全磷、全钾、硝态氮、氨态氮、速效磷、速效钾的含量变化。实验结果表明：（1）消落带土壤淹水前各测定指标在不同海拔高程之间的差异均不显著（P>0.05）；（2）三峡水库淹水后消落带土壤由微碱性变为碱性，养分平均含量普遍下降，土壤养分缺乏，淹水易造成养分流失；（3）不同淹水强度下，土壤pH 值、有机质、全氮、全磷、氨态氮、速效钾平均含量差异显著（P＜0.001），经过淹水土壤有机质、全氮、速效钾含量进一步降低；（4）不同淹水时期，土壤全钾、硝态氮、氨态氮平均含量差异显著（P＜0.001），速效氮含量随季节变化较大，与土壤水分有密切关系；（5）干湿交替更容易造成氮、磷解吸释放入水体，从而增加富营养化的风险。 其次，通过对石宝寨消落带5 个时间段6个水位的表层土壤分析，研究了消落带不同时期、不同淹水强度土壤酸碱度及Cu、Zn、Pb、Cr 的含量变化。结果表明（1）淹水土壤pH 显著高于未淹水土壤，长期淹水土壤重金属含量显著高于短期淹水土壤与未淹水土壤，146m 土壤重金属含量最高；（2）经过淹水土壤，pH 先升高后下降，铜含量、锌含量都下降，铬含量先上升后下降，铅含量随着土壤暴露先稍微上升，后又下降，但在08 年9 月达到最大值；（3）各土壤重金属之间均存在显著相关关系，表明三峡消落带土壤存在重金属复合污染隐患；（ 4 ） 以三峡水库土壤背景值为评价标准， 消落带土壤污染程度具有Cu>Pb>Zn>Cr 的特征，其中，铜污染相对最为严重，消落带土壤随着淹水强度的加大与淹水时间的延长，污染程度加重，消落带综合污染指数达到1.24，属于轻度污染级。

间伐对仁用杏园土壤理化性质及生长结果的影响

为了探讨密闭仁用杏园衰败的原因,采用常规的方法研究了间伐对仁用杏园土壤养分、水分及树体生长等方面的影响。结果表明:间伐减小了土壤容重,略微增加了土壤孔隙度;间伐显著提高了0-40 cm土层土壤有机质、0-20 cm土层土壤全氮,略微提高了0-20 cm土层土壤全磷;间伐显著提高了0-80 cm土层土壤速效氮、0-40 cm土层土壤速效磷和0-60 cm土层土壤速效钾,且间伐强度越大土壤养分越高;间伐显著提高了0-500cm土层土壤水分,在干旱的春季、夏季优为显著,且间伐强度越大,土壤水分越高;间伐显著促进了仁用杏生长,提高了坐果率和杏仁产量。白于山山区仁用杏间伐后密度应为167~222株/hm2。

黄土丘陵区不同植被恢复模式对土壤酶活性的影响

为了解侵蚀环境下植被恢复对土壤酶活性的影响,以典型侵蚀环境黄土丘陵区纸坊沟流域生态恢复30a植被长期定位试验点为研究对象,选取坡耕地为参照,分析了植被恢复过程中土壤脲酶、磷酸酶、蔗糖酶、淀粉酶、纤维素酶、过氧化氢酶、多酚氧化酶及理化性质的演变特征。结果表明,黄土丘陵区的坡耕地由于不合理的人为干扰,土壤理化性质和酶活性较弱,通过植被恢复可以有效的改善土壤肥力,不同恢复模式对土壤酶活性和肥力的改善作用不同,恢复30a,脲酶活性增加33%～213%,磷酸酶活性增加275%～394%,蔗糖酶活性增加70%～210%,纤维素酶活性增加24%～48%,过氧化氢酶增加32%～96%,多酚氧化酶降低23%～29%,淀粉酶变化规律不同。不同植被恢复模式其生物特性不同,对土壤酶活性影响也不同。相关性分析说明磷酸酶、蔗糖酶、纤维素酶和多酚氧化酶与其它因子相关性相对较强,可以作为评价土壤质量的生物学指标。

干旱胁迫与施N条件下白刺花（Sophora davidii）幼苗生长及其适应机制

干旱环境常常由于多变的降水事件和贫瘠土壤的综合作用，表现出较低的生产力和较低的植被覆盖度。全球性的气候变暖和人类干扰必将使得干旱地区缺水现状越来越严竣。贫瘠土壤环境中已经很低的有效养分含量也将会随着干旱的扩大而越来越低。干旱与半干旱系统中不断加剧的水分与养分的缺失将严重限制植物的生长和植被的更新，必然会使得已经恶化的环境恶化速率的加快、恶化范围的加大。如何抑制这种趋势，逐步改善已经恶化的环境是现在和将来干旱系统管理者面临的主要关键问题。了解干旱系统本土植物对未来气候变化的适应机制，不仅是植物生态学研究的重要内容，也对人为调节干旱环境，改善干旱系统植被条件，提高植被覆盖度具有重要的实践意义。 本研究以干旱河谷优势灌木白刺花（Sophora davidii）为研究对象，通过两年大棚水分和施N控制实验和一个生长季野外施N半控制实验，从植物生长－生理－资源利用以及植物生长土壤环境特征入手，系统的研究了白刺花幼苗生长特性对干旱胁迫和施N的响应与适应机制，并试图探讨施N是否可调节干旱系统土壤环境，人工促进干旱条件下幼苗定居，最终贡献于促进植被更新实践。初步研究结论如下： 1）白刺花幼苗生长、生物量积累与分配以及水分利用效率对干旱胁迫和施N处理的适应白刺花幼苗株高、基径、叶片数目、叶面积、根长、生物量生产、相对含水量和水分利用效率随着干旱胁迫程度的增加而明显降低，但地下部分生物量比例和R/S随着干旱胁迫程度的增加而增加。轻度施N处理下幼苗株高、基径、叶片数目、叶片面积和生物量生产有所增加。但重度施N处理下这些生长指标表现出微弱甚至降低的趋势。严重干旱胁迫条件下，幼苗叶面积率、R/S、相对含水量和水分利用效率也以轻度施N处理为最高。 2）白刺花幼苗叶片光合生理特征对干旱胁迫和施N处理的适应叶片光合色素含量和叶片光合效率随着干旱胁迫程度的增加而显著降低，并且PS2系统在干旱胁迫条件下表现出一定程度的光损害。但是比叶面积随着干旱胁迫程度的增加而增加。在相对较好水分条件下幼苗净光合速率的降低可能是因为气孔限制作用，而严重干旱胁迫条件下非气孔限制可能是导致幼苗叶片光合速率下降的主要原因。叶片叶绿素含量、潜在光合能力、羧化效率、光合效率以及RUBP再生能力等在施N处理下得到提高，并因而改善干旱胁迫条件下光合能力和效率。虽然各荧光参数对施N处理并无显著的反应，但是干旱胁迫条件下qN和Fv/Fm在轻度施N处理下维持相对较高的水平，而两年连续处理后在严重干旱胁迫条件下幼苗叶片光合效率受到重度施N处理的抑制，并且Fv/Fm和qN也在重度施N处理下降低。 3）白刺花幼苗C、N和P积累以及N、P利用效率对干旱胁迫和施N处理的适应白刺花幼苗C、N和P的积累，P利用效率以及N和P吸收效率随干旱胁迫程度的增加而显著降低，C、N和P的分配格局也随之改变。在相同水分处理下，C、N和P的积累量、P利用效率以及N和P吸收效率在轻度施N处理下表现为较高的水平。然而，C、N和P的积累量和P利用效率在重度施N处理下不仅没有表现出显著的正效应，而且有降低的趋势。另外，在相同水分条件下白刺花幼苗N利用效率随着施N强度的增加而降低。 4）白刺花幼苗生长土壤化学与微生物特性对干旱胁迫和施N的适应白刺花幼苗生长土壤有机C、有效N和P含量也随干旱胁迫程度的增加而明显降低。干旱胁迫条件下土壤C/N、C/P、转化酶、脲酶和碱性磷酸酶活性的降低可能表明较低的N和P矿化速率。尽管微生物生物量C、N和P对一个生长季干旱胁迫处理无显著反应，但微生物生物量C和N在两年连续干旱胁迫后显著降低。土壤有机C和有效P含量在轻度施N处理下大于重度施N处理，但是有效N含量随着施N强度的增加而增加。微生物生物量C和N、碱性磷酸酶和转化酶活性也在轻度施N处理下有所增加。但是碱性磷酸酶活性在重度施N处理下降低。 5）野外条件下白刺花幼苗生长特征及生长土壤生化特性对施N的适应植物生长、生物生产量、C的固定、N、P等资源的吸收和积累、其它受限资源的利用效率（如P）在轻度施N处理下均有所增加，但N利用效率有所降低。幼苗生物生产量及C、N和P等资源的分配格局在轻度施N处理下也没有明显的改变。白刺花幼苗叶片数目、生物生产量和C、N、P的积累量在重度施N处理下虽然也相对于对照有所增加，但幼苗根系长度显著降低。生物量及资源（生物量、C、N、P）在重度施N处理下较多地分配给地上部分（主要是叶片）。另外，土壤有机C、全N和有效N含量随外源施N的增加而显著增加，土壤pH随之降低，但土壤全P含量并无显著反应。其中有机C含量和有效P含量以轻度施N处理最高。微生物生物量C、N和P在轻度施N处理下也显著增加，而微生物生物量C在重度施N处理下显著降低。同时，转化酶、脲酶、碱性磷酸酶和中性磷酸酶活性在施N处理下也明显的提高，但酸性磷酸酶和过氧化氢酶活性显著降低，其中碱性磷酸酶和中性磷酸酶活性以轻度施N处理最高。 综合分析表明，干旱河谷水分和N严重限制了白刺花幼苗的生长。施N不能完全改变干旱胁迫对白刺花幼苗的抑制的作用，但是由于施N增加土壤N有效性，改善土壤一系列生物与化学过程，幼苗的生长特性也对施N表现出强烈的反应，表现为植物结构与资源分配格局的改善，植物叶片光合能力与效率的提高，植物生长以及利用其他受限资源（如水分和P）的效率的增加，致使植物自身生长及其生长环境在干旱环境下得到改善。但是过度施N不仅不能起到改善干旱胁迫下植物生长环境、促进植物生长的作用，反而在土壤过程以及植物生长过程中加重干旱胁迫对植物的伤害。因此，建议在采用白刺花作为先锋种改善干旱河谷系统环境的实践中，可适当施加N以改善土壤环境，调节植物利用与分配资源的效率，促进植物定居，得到人工促进种群更新的目的。但在实践过程中也要避免过度施N。 Arid regions of the world are generally noted for their low primary productivity which is due to a combination of low, unpredictable water supply and low soil nutrient concentrations. The most serious effects of global climate change and human disturbances may well be those which related to increasing drought since drought stress has already been the principal constraint in plant growth. The decline in total rainfall and/or soil water availability expected for the next decades may turn out to be even more drastic under future warmer conditions. Nevertheless, water deficit is not the only limiting factor in arid and semiarid environments. Soils often suffer from nutrient (especially N and P) deficiencies in these ecosystems, which can also be worsened by climate change. How to improve the poor soil quality and enhance the vegetation coverage is always the problem facing ecosystem managers. The adaptive mechanisms of native plant to future climate change is always the focus in plant ecology, it also plays important roles in improving vegetation coverage by manual controlled programmes. Sophora davidii is a native perennial shrub of arid valleys, which is often predominant on eroded slopes and plays a vital role in retaining ecological stability in this region. It has been found that S. davidii was better adapted to dry environment than other shrubs, prompting its use for re-vegetation of arid lands. A two-years greenhouse experiment and a field experiment were conducted in order to understand the adaptation responses of Sophora davidii seedlings to different water and N conditions, and further explore if additional N supply as a modified role could enhance the adaptation ability of S. davidii seedlings to dry and infertile environment. Two-month old seedlings were subjected to a completely randome design with three water (80%, 40% and 20% water field capacity (FC)) and three N supply (N0: 0, Nl: 92 and Nh: 184 mg N kg-1 soil) regimes. Field experiment was arranged only by three N supplies in the dry valley. 1) The growth, biomass partitioning and water-use efficiency of Sophora davidii seedlings in respond to drought stress and N supply Seedlings height, basal diameter, leaf number, leaf area, root length, biomass production, relative water content (RWC) and WUE were decreased with increase of drought stress. An increase in below-ground biomass was observed indicating a higher root/shoot ratio (R/S) under drought stress conditions. Low N supply increased seedlings height, basal diameter, leaf number, leaf area, and biomass production, but decreased root length. In contrast, these growth characteristics showed little or negative effect to high N supply treatment. Leaf percentages increased with increase of N supply, but fine root percentages decreased. In addition, Low N supply rather than the other two N treatments increased leaf area ratio (LAR), leaf/fine root mass ratio (L/FR), R/S and RWC under severe drought stress (20%FC), even though these parameters could increase with the high N supply treatment under well-watered condition (80%FC). Moreover, Low N supply also increased WUE under three water conditions, but high N supply had little effect on WUE under drought stress conditions (40%FC and 20%FC). 2) Leaf gas exchange and fluorescence parameters of Sophora davidii seedlings in respond to drought stress and N supply Leaf area (LA), photosynthetic pigment contents, and photosynthetic efficiency were decreased with increase of drought stress, but specific leaf area (SLA) increased. Photodamage in photosystem 2 (PS2) was also observed under drought stress condition. The decreased net photosynthetic rate (PN) under relative well-watered water conditions might result from stomatal limitations, but the decreased PN under other hand, photosynthetic capacity by increasing LA, photosynthetic chlorophyll contents, Pnmax, CE, Jmax were increased with increase N supply, and photosynthetic efficiency was improved with N supply treatment under water deficit. Although N supply did a little in alleviating photodamages to PS2 caused by drought stress, low N supply enhanced qN and kept relative high Fv/Fm under drought stress condition. However, high N supply inhibited leaf photosynthetic efficiency, and declined Fv/Fm and qN under severe drought stress condition after two year continues drought stress and N supply. 3) Carbon accumulation, nitrogen and phosphorus use efficiency of Sophora davidii seedlings in respond to drought stress and N supply C, N and P accumulation, NUE , N and P uptake efficiency (NUtE and NUtE ) P N P were decreased with increase of drought stress regardless of N supply. On the other hand, the S. davidii seedlings exhibited strong responses to N supply, but the responses were inconsistent with the various N supply levels. Low N supply rather than the other two N treatments increased C, N and P accumulation, improved NUEP, NUtE and NUtE under corresponding water condition. In contrast, high N supply N P did few even depressed effects on C, N and P accumulation, and NUEP, although NUtEN and NUtEP could increase with high N supply under corresponding water conditions. Even so, a decrease of NUEN was observed with increase of N supply under corresponding water conditions. 4) Soil microbial and chemical characters in respond to drought stress and N supply The content of soil organic C, available N and P were decreased with increase of drought stress. Decreases in C/N and C/P, and invertase, urea and alkaline phosphatase activity were also observed under drought stress conditions, indicating a lower N and P mineralization rate. Although microbial biomass C, N and P showed slight responses to drought stress after one growth period treatment, microbial biomass C and N were also decreased with increase of drought stress after two year continuous treatment. The content of soil organic C and available P showed the stronger positive responses to low N supply than which to high N supply, although than the other two N treatments increased microbial biomass N and invertase activity under severe drought stress condition, even though invertase activity could increase with high N supply treatment under relative well-water conditions. Moreover, low N supply treatment also increased C/P and alkaline phosphatase activity which might result from higher P mineralization, but high N supply did negative effects on alkaline phosphatase activity. 5) The growth characteristics of Sophora davidii seedlings and soil microbial and chemical characters in respond to N supply under field condition Low N supply facilitated seedlings growth by increasing leaf number, basal diameter, root length, biomass production, C, N and P accumulation and absorption, and enhancing the use efficiency of other limited resources as P. Compared to control, however, low N supply did little effect on altering biomass, C, N and P portioning in seedlings components. On the contrary, high N supply treatment also increased leaf number, biomass and C, N and P accumulation relative to control, but significantly decreased root length, and altered more biomass and resources to above-ground, which strongly reduced the ability of absorbing water under drought condition, and thus which might deep the drought stress. In addition, N supply increased soil C, N and available N content, but declined pH and showed little effects on P content. Low N supply showed higher values of soil C and available P content. Low N supply also increased microbial biomass C, N and P, although high N supply decreased microbial biomass C. N supply significantly enhanced soil invertase, urea, alkaline and neutral phosphratase activity, while declined acid phosphratase and catalase activity. Low N supply exhibited higher alkaline and neutral phosphratase activity compared to the others. The results from this study indicated that both drought and N limited the growth of S. davidii seedlings and their biomass production. Regardless of N supply levels, drought stress dramatically reduced the seedlings growth and biomass production. Although plant growth parameters, including basal diameter, height, leaf number, and biomass and their components were observed to be positive responses to low N supply, N supply alone can not alter the diminishing tendency which is caused by drought. available N content increased with increase N supply. In addition, low N supply rather These findings imply that drought played a primary limitation role and N was only the secondary. Even so, appropriate N supply was seemed to enhance the ability that S. davidii seedlings adapted to the xeric and infertile environment by improving soil processes, stimulating plant growth, increasing recourses accumulation, enhancing use efficiency of other limited resources, and balancing biomass and resources partitioning. Appropriate N supply, therefore, would be recommended to improve S. davidii seedling establishment in this region, but excess N supply should be avoided.

黄延高速公路边坡植被与土壤特性调查研究

采用现场调查、观测、试验等多种试验方法,对黄延高速公路绿化植物、边坡土壤理化性质以及植物群落组成进行了研究。通过分析,总结了中央分隔带、平台和边坡绿化植物种类以及边坡有效配置模式,分析了土壤养分贫瘠的原因和提高措施。在此基础上提出土壤肥力与植物恢复是相辅相成的,土壤肥力随人工植被建立时间的延长而逐渐恢复;随着时间序列的延长,其物种数目和比例也发生较大变化,有利于护坡植物群落最终实现结构稳定。

Space-time monitoring of prescribed burnt soils performance – an effective tool for forest management

Among the most important measures to prevent wild forest fires is the use of prescribed and controlled burning actions in order to reduce the availability of fuel mass. However, the impact of these activities on soil physical and chemical properties varies according to the type of both soil and vegetation and is not fully understood. Therefore, soil monitoring campaigns are often used to measure these impacts. In this paper we have successfully used three statistical data treatments - the Kolmogorov-Smirnov test followed by the ANOVA and the Kruskall-Wallis tests – to investigate the variability among the soil pH, soil moisture, soil organic matter and soil iron variables for different monitoring times and sampling procedures.

Magnetic susceptibility to identify landscape segments on a detailed scale in the region of Jaboticabal, São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Florestas de restinga e de terras baixas na planície costeira do sudeste do Brasil: vegetação e heterogeneidade ambiental

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relações solo-paisagem em topossequência de origem basáltica

Variações nos atributos do solo dependem da posição do solo na paisagem e processos de drenagem, erosão e deposição. Este estudo objetivou avaliar os atributos físicos e químicos do solo, em uma topossequência de origem basáltica, na região de Batatais (SP). A área possui relevo aplanado e altitude oscilando entre 740 m e 610 m, em região dominada por basaltos. Foi estabelecido caminhamento de 3.000 m, a partir do espigão da vertente, no seu declive mais suave. As superfícies geomórficas foram identificadas e delimitadas conforme critérios topográficos e estratigráficos, com base em intensas investigações detalhadas de campo. Foram coletadas amostras laterais aos perfis modais representativos das diversas superfícies geomórficas (S.G.) da topossequência (S.G. I = topo; S.G. II = meia encosta e sopé de transporte; S.G. III = ombro e sopé de deposição), totalizando 142 amostras. Além disto, foram abertas trincheiras, nos segmentos de vertente inseridos nas superfícies geomórficas mapeadas. As amostras coletadas foram analisadas quanto à densidade do solo, textura, bases trocáveis (Ca2+, K+ e Mg2+), soma de bases, capacidade de troca catiônica, saturação por bases, pH (água e KCl), SiO2, Al2O3, Fe2O3 (ataque por H2SO4), óxidos de Fe livres extraídos com ditionito-citrato-bicarbonato e Fe mal cristalizado extraído com oxalato de amônio. Os resultados revelaram que os solos oriundos de basalto apresentaram atributos físicos e químicos com comportamento dependente das formas do relevo. Com o uso de técnicas estatísticas multivariadas, foi possível distinguir três diferentes ambientes, que equivalem às três superfícies geomórficas.

Simulação geoestatística na caracterização espacial de óxidos de ferro em diferentes pedoformas

Os minerais da fração argila, goethita e hematita, são óxidos de ferro (Fe) indicadores pedoambientais com grande influência nos atributos físicos e químicos do solo. O conhecimento dos padrões espaciais desses óxidos auxilia a compreensão das interrelações de causa e efeito com os atributos do solo. Nesse sentido, a qualidade das estimativas espaciais produzidas pode alterar os resultados obtidos e, por consequência, as interpretações dos padrões espaciais obtidos. O presente estudo teve o objetivo de avaliar o desempenho dos métodos geoestatísticos de estimativas (KO) e simulações sequenciais gaussianas (SSG) na caracterização espacial de teores de óxidos de Fe, goethita (Gt) e hematita (Hm), em uma pedoforma côncava e outra convexa. Foram coletadas 121 amostras de solos em cada pedoforma de um Argissolo em pontos com espaçamentos regulares de 10 m. Os teores de óxidos de Fe foram obtidos por meio de difração de raios-X. Os dados foram submetidos a análises geoestatísticas por meio da modelagem do variograma e posterior interpolação por KO e SSG. A KO não refletiu a verdadeira variabilidade dos óxidos de Fe, hematita e goethita, demonstrando ser inapropriada para a caracterização espacial dos teores dos óxidos de Fe. Assim, o uso da SSG é preferível à krigagem quando a manutenção dos altos e baixos valores nas estimativas espaciais é necessária. O desempenho dos métodos geoestatísticos foi influenciado pelas pedoformas. Os mapas E-type devem ser recomendados em vez de mapas de KO para os óxidos de Fe, por serem ricos em detalhes e práticos na definição de zonas homogêneas para o manejo localizado em frente de KO, sobretudo em pedoforma côncava.

Correlação linear e espacial entre a produtividade e o teor de proteína bruta do guandu anão e os atributos de um Latossolo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência de diferentes sistemas de cultivo nos atributos físicos e no carbono orgânico do solo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Métodos geoestatísticos na caracterização espacial de óxidos de ferro em diferentes pedoformas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)