Sonia Carmela Falci Dechen

The costs of soil erosion

The aim of this study was a survey of the estimated costs of soil erosion, an issue of fundamental importance in view of the current worldwide discussions on sustainability. A list was drawn up of research papers on erosion (on-site and offsite effects) and their respective costs. The estimates indicate the amount of resources spent in the process of soil degradation, raising a general awareness of the need for soil conservation. On-site costs affect the production units directly, while off-site costs create a burden borne by the environment, economy and society. In addition, estimating the costs of soil erosion should be effective to alert the agricultural producers, society and government for the need for measures that can be implemented to bring erosion under control. Among the various estimates of soil erosion costs between 1933 a 2010, the highest figure was 45.5 billion dollars a year for the European Union. In the United States, the highest figure was 44 billion dollars a year. In Brazil, estimates for the state of Parana indicate a value of 242 million dollars a year, and for the state of Sao Paulo, 212 million dollars a year. These figures show, above all, that conservation measures must be implemented if crop and livestock farming production are to be sustainable.

Valuation and assessment of soil erosion costs

Soil is an essential natural resource for humans and an important part of the environment. However, soil is often used and managed inappropriately, causing its erosion and degradation, with concomitantly negative social, political and economic impacts. This study aimed to discuss sustainable development; and losses and problems caused by soil erosion, and to suggest a model for assessing erosion costs. The relevance of economic models for costing soil erosion is stressed. Based on an economic theory, it presents a procedure for assessing economic costs of soil erosion, centered on the on-site and off-site costs that are generated. The physical processes of soil erosion are described and their economic effects reviewed, drawing on theoretical and empirical sources. Limited data and information is available on the economic losses resulting from erosion, which hampers assessment and valuation.

Variabilidade espacial da agregação do solo avaliada pela geometria fractal e geoestatística

This work explored the applicability of the fractal theory for studies into space variability of soil aggregation. Fractal geometry has become a model for soil size particle distribution. The distribution of soil aggregates in terms of its mass was obtained, and model parameters such as the fractal dimension D, which is a representative measure of the soil fragmentation (the larger its value, the larger the fragmentation), and the largest aggregate size RL were defined as descriptive tools for soil aggregation. The aggregates were collected at a depth of 0-10 cm of a Clayey Ferrasol in Angatuba, Sao Paulo. A regular grid of 100 x 100 m was used and samples collected from 76 points, where the aggregate distribution was determined by humid way (water, alcohol and benzene). Spatial dependence was verified by semivariogram exams. Simple kriging was used as interpolator, and contour maps were elaborated, proving to be useful tools to describe the spatial variability of soil aggregation.Este trabalho teve por objetivo explorar a aplicabilidade da teoria de fractais no estudo da variabilidade espacial em agregacao de solo. A geometria de fractais tem sido proposta como um modelo para a distribuicao de tamanho de particulas. A distribuicao do tamanho de agregados do solo, expressos em termos de massa, e apresentada. Os parâmetros do modelo, tais como: a dimensao fractal D, medida representativa da fragmentacao do solo (quanto maior seu valor, maior a fragmentacao), e o tamanho do maior agregado RL foram definidos como ferramentas descritivas para a agregacao do solo. Os agregados foram coletados em uma profundidade de 0-10 cm de um Latossolo Vermelho distrofico tipico alico textura argilosa, em Angatuba, Sao Paulo. Uma grade regular de 100 x 100 m foi usada e a amostragem realizada em 76 pontos nos quais se determinou a distribuicao de agregados por via umida, usando agua, alcool e benzeno como pre-tratamentos. Pelo exame de semivariogramas, constatou-se a ocorrencia de dependencia espacial. A krigagem ordinaria foi usada como interpolador e mapas de contorno mostraram-se de grande utilidade na descricao da variabilidade espacial de agregacao do solo.

Variabilidade espacial de atributos físicos e químicos relacionados com o estado de agregação de dois latossolos cultivados no sistema de semeadura direta

A variabilidade espacial dos atributos fisicos e quimicos do solo possui relacao direta com a formacao e manutencao dos seus agregados. No entanto, os sistemas de manejo do solo tambem interagem com esses atributos modificando sua variabilidade natural, e consequentemente, a variabilidade do estado de agregacao do solo. Assim, este trabalho teve como objetivo estudar a variabilidade espacial de atributos fisicos e quimicos de dois Latossolos do Estado de Sao Paulo, sob o sistema de semeadura direta e sua relacao com a estabilidade de agregados. As amostras de solo foram coletadas na camada de 0,0 - 0,1 m, utilizando grade de amostragem de 100 m entre pontos. Uma das areas esta localizada no municipio de Angatuba (SP) e outra no municipio de Campos Novos Paulista (SP). Os atributos fisicos analisados foram: argila, areia grossa, areia fina, areia total e a estabilidade de agregados avaliada por meio do diâmetro medio ponderado dos agregados (DMP). Os atributos quimicos estudados foram: materia orgânica, calcio e magnesio. Os dados foram analisados por meio da estatistica descritiva e de ferramentas geoestatisticas. Uma vez detectada a variabilidade espacial por meio do semivariograma, foram construidos mapas de isolinhas utilizando-se a tecnica de interpolacao por krigagem. A variabilidade espacial para os atributos fisicos e quimicos e sua relacao com a estabilidade de agregados foi influenciada pelo historico de manejo das areas de estudo. Observaram-se valores mais baixos de efeito pepita (C0), quando comparados aos demais atributos estudados, Latossolo em Campos Novos Paulista. O espacamento utilizado no Latossolo em Campos Novos Paulista nao foi suficiente para detectar a dependencia espacial do DMP.

Sewage sludge application on cultivated soils: effects on runoff and trace metal load

The use of sewage sludge in agricultural soils as a macro and micronutrient source and as a soil conditioner has been one of the alternatives for its disposal. However, sewage sludge contains trace metals, which are potential sources of pollution. The goal of this study was to evaluate the effect of sewage sludge application on surface water contamination through runoff when it was applied in a soil cultivated with corn. The effect of sludge application on the concentration and load of copper, nickel and zinc and the volume of runoff water and sediment were evaluated. The experiment was set up in plots used to study erosion losses in Campinas, Sao Paulo State, Brazil. The soil is a clayey Rhodic Hapludox. Three treatments were studied: no sewage sludge, sewage sludge to supply the N required by the crop and twice that amount, with four replications. The water and sediment lost by runoff were measured after each rainfall, and sampled for chemical analysis. The volumes of water and sediment lost by runoff decreased after sewage sludge application. The waste application increased trace metal concentration in the runoff water and sediment, especially zinc, which was present in high concentration in the sewage sludge used. Nevertheless, the load of trace metals transported from the plot was mostly dependent on the total runoff volume. Most of the Cu, Zn and Ni losses were via sediment, and occurred in a few highly erosive rainfall events in the period studied.

Perdas e custos associados à erosão hídrica em função de taxas de cobertura do solo

O objetivo deste estudo e estimar custos da erosao hidrica associados as perdas de nutrientes em quatro taxas de cobertura artificial do solo. O experimento foi conduzido de 1987 a 1996, em talhoes coletores de perdas por erosao, em Campinas (SP), em Latossolo Vermelho distroferrico, sob chuva natural. O delineamento experimental foi inteiramente ao acaso, com quatro tratamentos (taxas de cobertura do solo: 0%, 24%, 40% e 90%) e tres repeticoes. Para estimar os custos, os teores de P, K+, Ca2+ e Mg2+ na agua da enxurrada e na terra carreada pela erosao foram somados, convertidos em superfosfato triplo, cloreto de potassio e calcario dolomitico, e multiplicados pelos seus precos de mercado. Os resultados indicam, para as condicoes experimentais, que quanto maior o percentual de cobertura do solo, menores as perdas de agua, terra, materia orgânica e nutrientes. O solo com 90% de cobertura, em comparacao aquele com 0%, reduziu as perdas medias de agua em 51,97%, de terra em 54,44% e de materia orgânica em 54,91%. Em solo sem cobertura, foram estimadas perdas de 16% de P2O5 e 8% de KCl em relacao a quantidade de fertilizantes recomendada. Os custos variaram de US

Intervalo hídrico ótimo em um Latossolo vermelho cultivado em sistema semeadura direta por 25 anos

107,76 ha–1 ano–1 no solo com 0% de cobertura a US

Spatial variability studies in São Paulo, Brazil along the last twenty five years

18,15 ha–1 ano–1 no solo com 90%. A partir desses valores, estimaram-se para o Brasil perdas de 616,5 milhoes de toneladas de terra ao ano, decorrentes do processo de erosao do solo em lavouras anuais, e custos da ordem de US

Teores de zinco, cobre, manganês e ferro em dois latossolos sob plantios direto e convencional

1,3 bilhao ao ano.

Caracterização física de substratos para plantas

Least Limiting Water Range (LLWR) integrates soil physical properties related to crop growth and corresponds to the interval between the upper and lower limits of water content in the soil within which limitations to root growth are minimal. In agricultural areas, soil management can lead to changes in its structure, mainly due to compaction and, subsequently, bulk density can reach values outside the limits in which conditions are ideal for plant growth. Therefore, the aim of this study was to use the LLWR to evaluate soil physical quality and to identify areas that restrict plant growth, with a view toward localized management. This study was carried out using the LLWR to evaluate soil physical quality so as to identify areas in which bulk density is higher than critical bulk density in an Oxisol under no-tillage system since 1985, in Campinas, Sao Paulo, Brazil. Undisturbed samples were collected at the depths of 0.00-0.10, 0.10-0.20 and 0.20-0.30 m to obtain the following attributes: bulk density, penetration resistance curve, water retention curve and soil porosity. Data on spatial variability of bulk density and critical bulk density were analyzed by semivariograms to map these attributes. The LLWR decreased in depth and was limited at the top by the moisture at field capacity and at the bottom by resistance to penetration at the three depths studied. Critical soil density was 1.42 Mg m-3 for the 0.00-0.10 m layer and 1.39 and 1.41 Mg m-3, respectively, for the 0.10-0.20 and 0.20-0.30 m layers. It was observed that soil bulk density was higher than critical soil density in the 0.00-0.10 and 0.10-0.20 m layers in the lower portions of the field, indicating a critical condition for plant growth. The use of LLWR, associated to maps of spatial variability of soil bulk density to determine points at which it is higher than critical soil bulk density aids decision making for intervention or modification of soil tillage, while the selection criterion of the critical value of penetration resistance can contribute to the interpretation of field results.