ABSTRACT Conventional tillage and intensive machinery traffic are the major causes of physical soil degradation in sugarcane fields. This study evaluates the impact of adopting conservation management practices during sugarcane planting on soil physical properties and stalk yield of sugarcane in the municipality of Ibitinga, state of São Paulo, Brazil. The experimental design (split-block) included four cover crops and three soil tillage systems, with three repetitions. For comparison purposes, a control treatment was also included (without cover crop and under conventional tillage). Sampling for soil physical analysis was performed in three layers that coincide with soil horizons A (0.00-0.20 m), AB (0.20-0.30 m), and Bt (0.30-0.70 m), during cane-plant and first sugarcane ratoon cycles. The results showed that cultivation of sunn hemp associated with deep subsoiling induced high stalk yield of sugarcane in both production cycles, cane plant (116 Mg ha -1 ) and first ratoon (114 Mg ha -1 ), with a net gain of 11 and 9 Mg ha -1 compared with the control treatment, respectively. However, these results were not sufficient to induce significant differences in sugarcane yield. Nonetheless, the use of sunn hemp and millet, associated with subsoiling (at 0.40 or 0.70 m depth) during sugarcane planting, are promising management strategies to sustain better soil’s physical quality when compared to traditional management, conventional soil tillage without cover crops and/or cash crop, as peanuts, that increase the risks of soil compaction and physical degradation.

ABSTRACT: The Random Forest algorithm is a data mining technique used for classifying attributes in order of importance to explain the variation in an attribute-target, as soil CO2 flux. This study aimed to identify prediction of soil CO2 flux variables in management systems of sugarcane through the machine-learning algorithm called Random Forest. Two different management areas of sugarcane in the state of São Paulo, Brazil, were selected: burned and green. In each area, we assembled a sampling grid with 81 georeferenced points to assess soil CO2 flux through automated portable soil gas chamber with measuring spectroscopy in the infrared during the dry season of 2011 and the rainy season of 2012. In addition, we sampled the soil to evaluate physical, chemical, and microbiological attributes. For data interpretation, we used the Random Forest algorithm, based on the combination of predicted decision trees (machine learning algorithms) in which every tree depends on the values of a random vector sampled independently with the same distribution to all the trees of the forest. The results indicated that clay content in the soil was the most important attribute to explain the CO2 flux in the areas studied during the evaluated period. The use of the Random Forest algorithm originated a model with a good fit (R2 = 0.80) for predicted and observed values.

ABSTRACT: The use of data mining is a promising alternative to predict soil respiration from correlated variables. Our objective was to build a model using variable selection and decision tree induction to predict different levels of soil respiration, taking into account physical, chemical and microbiological variables of soil as well as precipitation in renewal of sugarcane areas. The original dataset was composed of 19 variables (18 independent variables and one dependent (or response) variable). The variable-target refers to soil respiration as the target classification. Due to a large number of variables, a procedure for variable selection was conducted to remove those with low correlation with the variable-target. For that purpose, four approaches of variable selection were evaluated: no variable selection, correlation-based feature selection (CFS), chisquare method (χ2) and Wrapper. To classify soil respiration, we used the decision tree induction technique available in the Weka software package. Our results showed that data mining techniques allow the development of a model for soil respiration classification with accuracy of 81 %, resulting in a knowledge base composed of 27 rules for prediction of soil respiration. In particular, the wrapper method for variable selection identified a subset of only five variables out of 18 available in the original dataset, and they had the following order of influence in determining soil respiration: soil temperature > precipitation > macroporosity > soil moisture > potential acidity.

RESUMO As práticas de manejo utilizadas na cultura da cana-de-açúcar (cana crua - CC e cana queimada - CQ) interferem na dinâmica dos atributos e expressão magnética do solo. Foi estudado o potencial da suscetibilidade magnética como indicador de qualidade do solo em áreas sob cultivo de cana-de-açúcar. O experimento localiza-se em uma área limítrofe de material de origem, entre o Basalto do Grupo São Bento, Formação Serra Geral, e o Arenito do Grupo Bauru, Formação Adamantina. Foram coletadas 20 amostras de solo em dois sistemas de manejo (com e sem queima da cana-de-açúcar para colheita) na profundidade de 0,0-0,2 m. O solo foi classificado como Latossolo Vermelho Eutroférrico, textura muito argilosa. Foram avaliados os atributos químicos, físicos, emissão de CO2 e a suscetibilidade magnética (SM) do solo na terra fina seca ao ar (SMTFSA), fração total sand (SMAT) e fração argila (SMARG). A assinatura magnética expressa pela suscetibilidade magnética foi eficaz na identificação de mudanças nas características físicas, químicas e mineralógicas de Latossolos sob sistemas de colheita da cana-de-açúcar com e sem queima. As informações geradas neste trabalho podem balizar futuros estudos sobre a gênese de minerais com expressão magnética em ambientes e expostos a presença de fogo.

ABSTRACT Sugarcane management practices (unburned cane - UC and burned cane - BC) interfere with dynamics of soil magnetic properties. This study focused on determining the potential of magnetic susceptibility as soil quality indicator in areas under sugarcane cultivation. The experiment area is on the limit between basalt from São Bento Group, Serra Geral Formation, and sandstone from Bauru Group - Adamantina Formation. Twenty soil samples were collected from two management areas (burned and unburned sugarcane prior to harvest) at a depth range of 0.0-0.2 m. Local soil was classified as eutroferric Red Latosol (Oxisol), with highly clayey texture. Chemical and physical properties, CO2 emissions and magnetic susceptibility (MS) in air-dried fine earth (MSADFE), total sand fraction (MSTS) and clay fraction (MSCF). The magnetic signature from MS was effective in identifying changes of physical, chemical and mineralogical traits in Latosols under burned and unburned sugarcane crop. The information provided here can guide further studies on the genesis of minerals with magnetic expression in environments and exposed to fire burning.

RESUMO: Este trabalho teve por objetivo avaliar a sensibilidade de isolados dos fungos Metarhizium anisopliae (Metsch.) Sorok. e Beauveria bassiana (Bals). Vuill. ao efeito das radiações solar e ultravioleta e da temperatura. Conídios dos isolados foram expostos, por vários períodos, aos raios de um simulador solar em diversas irradiâncias e a uma lâmpada de raios ultravioleta germicida. Os conídios do isolado de M. anisopliae foram também expostos às temperaturas de 19,5; 24,2 e 31,0ºC, e os do isolado de B. bassiana a 19,4; 20,8 e 28,3ºC, e 18,7; 23,8 e 30,9ºC. Avaliou-se a germinação de conídios pelo teste de viabilidade. Os isolados dos fungos se mostraram bastantes sensíveis aos raios do simulador solar e aos raios ultravioleta. A germinação de ambos sofreu significativa redução a partir de 30 minutos de exposição à radiação do simulador solar. O efeito mais severo foi evidenciado pelo isolado de B. bassiana, com grande redução da germinação dos conídios em todas as irradiâncias testadas. A sensibilidade à radiação ultravioleta também foi grande, pois ocorreu acentuada redução da germinação dos conídios do isolado de M. anisopliae (38,2%) e de B. bassiana (65%) já aos 30 segundos de exposição. A temperatura afetou a viabilidade de ambos os fungos. Temperaturas entre 23,8 e 31ºC favoreceram a germinação dos conídios, enquanto temperaturas próximas de 20ºC dificultaram a germinação.

ABSTRACT: This study aimed to access the sensibility of isolates of the fungus Metarhizium anisopliae (Metsch.) Sorok. and Beauveria bassiana (Bals.) Vuill. to the effect of solar and ultraviolet radiation and temperature. Conidia were exposed for various periods to the rays from a solar simulator at various irradiances, and to light germicidal ultraviolet rays. Conidia of the isolate of M. anisopliae were also exposed to temperatures of 19.5, 24.2 and 31.0ºC and the isolate of B. bassiana to 19.4, 20.8 and 28.3ºC, and also to 18.7, 23.8 and 30.9ºC. The germination of conidia was evaluated by the viability test. The fungal isolates showed to be very sensitive to the solar simulator and ultraviolet rays. Germination of both was significantly decreased starting from 30 minutes of exposure to the rays of the solar simulator. The most severe effect was evidenced by the isolate of B. bassiana with great reduction in conidia germination in all the tested irradiances. Sensitivity to ultraviolet radiation was also great, showing a marked reduction in the germination of M. anisopliae (38.2%) and B. bassiana (65%) conidia after 30 seconds of exposure. The temperature affected the viability of both fungi. Temperatures ranging of 23.8 to 31ºC favor the germination of conidia while temperatures around 20ºC constrained germination.

ABSTRACTSoil CO2 emissions (fCO2) in agricultural areas have been widely studied in global climate change research, but its characterization and quantification are restricted to small areas. Because spatial and time variability affect emissions, tools need to be developed to predict fCO2 for large areas. This study aimed to investigate soil magnetic susceptibility (MS) and its correlation with fCO2 in an agricultural environment. The experiment was carried out on a Typic Eutrudox located in Guariba-SP, Brazil. Results showed that there was negative spatial correlation between fCO2 and the magnetic susceptibility of Air Dried Soil (MSADS) up to 34.3 m distant. However, the fCO2 had no significant correlation with MSADS, magnetic susceptibility of sand (MSSAND) nor clay (MSCLAY). However, MSADS could be a supplemental mean of identifying regions of high fCO2 potential over large areas.

O preparo mecânico do solo é uma das práticas agrícolas que contribuem para o aumento da perda de carbono via emissão de CO2 do solo (FCO2). Com este trabalho objetivou-se investigar o efeito de três sistemas de preparo do solo na FCO2, temperatura e umidade do solo em área de reforma da cultura de cana-de-açúcar. A área experimental foi constituída de três parcelas, cada uma recebendo um dos preparos do solo: preparo convencional (PC), subsolagem convencional (SC) e subsolagem localizada (SL). A FCO2, temperatura e a umidade do solo foram avaliadas durante o período total de 17 dias. A FCO2 foi maior no preparo PC (0,75 g CO2 m-2 h-1). A temperatura do solo não diferiu (p > 0,05) entre as subsolagens: SL (26,2 ºC) e SC (25,9 ºC). A umidade do solo foi maior na SL (24%), seguida pela SC (21,8%) e preparo PC (18,3%). Apenas no preparo PC foi observada correlação significativa (r = –0,71; p < 0,05) entre FCO2 e a temperatura do solo. O preparo PC apresentou emissão total (2.864,3 kg CO2 ha-1), superior às emissões nas subsolagens: SC (1.970,9 kg CO2 ha-1) e SL (1.707,7 kg CO2 ha-1). A conversão do sistema de preparo PC para a SL diminuiu as emissões de CO2 do solo, reduzindo a contribuição da agricultura para o aumento dos gases de efeito estufa na atmosfera.

Soil tillage is one of the agricultural practices that may contribute to increase the loss of carbon through emission of CO2 (FCO2). The aim of this study was to investigate the effect of three soil tillage systems on FCO2, soil temperature and soil moisture in a sugarcane area under reform. The experimental area consisted of three tillage plots: conventional tillage (CT), conventional subsoiling (CS), and localized subsoiling (LS). FCO2, soil temperature and soil moisture were measured over a period of 17 days. FCO2 showed the highest value in CT (0.75 g CO2 m-2 h-1). Soil temperature presented no significant difference (p > 0.05) between LS (26.2 °C) and CS (25.9 °C). Soil moisture was higher in LS (24%), followed by CS (21.8%) and CT (18.3%). A significant correlation (r= ‒0.71; p < 0.05) between FCO2 and soil temperature was observed only in CT. The conventional tillage presented a total emission (2,864.3 kg CO2 ha-1) higher than the emissions observed in CS (1,970.9 kg CO2 ha-1) and LS (1,707.7 kg CO2 ha-1). The conversion from CT to LS decreased soil CO2 emissions, reducing the contribution of agriculture in increasing the concentration of greenhouse gases in the atmosphere.

Soil CO2 emission (FCO2) is one of the main sources of carbon release into the atmosphere. Moreover, FCO2 is related to soil attributes governing the transfer of gases from soil to the atmosphere. This study aimed firstly to describe the spatial variability of hematite (Hm), goethite (Gt), iron extracted with sodium dithionite-citrate-bicarbonate (Fed) contents, soil CO2 emission (FCO2) and free-water porosity (FWP) and secondly, to develop statistical models to predict the above mentioned factors in an Oxisol cultivated under manual harvesting of sugarcane (Saccharumspp.) in southeastern Brazil. The study was conducted on an irregular 50 m × 50 m grid containing 89 points, each 0.5-10 m apart. The 0-0.1 m soil layer at each sampling point was used to assess soil FCO2, moisture and total pore volume. The results were subjected to descriptive statistical and geostatistical analyses using auto- and cross-semivariograms. All soil attributes exhibited a spatial dependence structure and the experimental semivariograms fitted spherical and exponential models. The Gt content was the individual attribute that exhibited the highest linear and spatial correlation, especially with FCO2. We were able to use diffuse reflectance spectroscopy to map large areas, which allows for easy identification and estimation of soil attributes such as FCO2 and FWP. Geostatistical techniques faciltate the interpretation of spatial relationships between soil respiration and the examined properties.

A emissão de CO2 do solo (FCO2) em áreas agrícolas é resultante da interação de diversos fatores, sendo alterada pela prática de manejos do solo e da cultura, além das condições edafoclimáticas locais. Neste estudo, objetivou-se quantificar a FCO2 em função da calagem e posição da aplicação (antiga linha e entrelinha) da cultura da laranja em área de conversão para a cultura da cana-de-açúcar, no município de Frutal-MG. Os tratamentos avaliados foram: Linha/CC (linha com aplicação de calcário); Entrelinha/CC (entrelinha com aplicação de calcário); Linha/SC (linha sem aplicação de calcário), e Entrelinha/SC (entrelinha sem aplicação de calcário). FCO2, temperatura do solo (Ts) e umidade do solo (Us) foram avaliadas durante 12 dias. O maior valor médio da FCO2 ao longo do período de estudo foi observado no tratamento Linha/CC (9,63 µmol m-2 s-1); e o menor, no tratamento Entrelinha/CC (5,92 µmol m-2 s-1), segundo teste de Tukey. A FCO2 foi negativamente correlacionada à Us na Linha/CC (r = - 0,56; p < 0,05) e na Linha/SC (r = - 0,66; p < 0,05). Entre a FCO2 e a Ts, verificou-se correlação positiva e significativa na Linha/CC (r = 0,76; p < 0,001), na Linha/SC (r = 0,89; p < 0,001) e na Entrelinha/SC (r = 0,66; p < 0,05). Observou-se que a calagem e a posição de aplicação (linha e entrelinha) influenciaram nas emissões de CO2 do solo.

The soil CO2 emission (FCO2) in agricultural areas is resulting from the interaction of several factors, as amended by the practice of soil management practices and crop, in addition to the local edaphoclimatic conditions. In this study, we aimed to quantify FCO2 influenced by liming and application position (row and interrow old) of the orange crop in conversion area for cultivation of sugar cane in the municipality of Frutal-MG. The treatments evaluated were: Row/CC (row with lime application), Interrow/CC (interrow with application of lime), Row/SC (row without liming) and Interrow/SC (interrow without liming). FCO2, temperature (Ts) and soil moisture (Us) were evaluated over 12 days. The highest average value of FCO2 over the study period was observed in the treatment Row/CC (9.63 µmol m-2 s-1) and the lowest in Interrow/CC (5.92 µmol m-2 s-1) according to the Tukey test. The FCO2 was negatively correlated with Us in Row/CC (r = - 0.56, p < 0.05) and in Row/SC (r = - 0.66, p < 0.05). It was also observed a significant and positive correlation between FCO2 and Ts in Row/CC (r = 0.76, p < 0.001), Row/SC (r = 0.89, p < 0.001) and in Interrow/SC (r = 0.66, p < 0.05). It was observed that liming and position of application (row and interrow) influenced the soil CO2 emissions.

Melhores condições de trabalho, produção sustentável e competitividade levaram a mudanças substanciais no sistema de colheita de cana-de-açúcar. Tais mudanças alteraram uma série de atributos do solo, incluindo os óxidos de ferro e a matéria orgânica, assim como alguns atributos químicos como a capacidade máxima de adsorção de P no solo. O objetivo deste trabalho foi caracterizar a relação entre óxidos de ferro e a qualidade da matéria orgânica nos sistemas de colheita de cana-de-açúcar. Para este fim, duas parcelas de 1 ha em áreas colhidas mecanicamente e manualmente foram utilizadas para obter amostras de solo da camada de 0,00-0,25 m em 126 pontos diferentes. Os resultados das análises mineralógicas, químicas e físicas foram submetidos às análises da estatística descritiva, com teste de comparação de médias, estatísticas multivariadas e análises de componentes principais. A aplicação da estatística multivariada possibilitou a divisão de todos os atributos estudados de acordo com o sistema de colheita: colheita manual com a queima dos resíduos da cana e colheita mecanizada sem queima. O sistema de colheita mecânica promoveu condições pedoambientais, que conduzem a mudanças na cristalinidade dos óxidos de ferro, no aumento no grau de humificação da matéria orgânica e na diminuição relativa de adsorção de P nessa área, em relação ao sistema de cana queimada.

Improvements in working conditions, sustainable production, and competitiveness have led to substantial changes in sugarcane harvesting systems. Such changes have altered a number of soil properties, including iron oxides and organic matter, as well as some chemical properties, such as the maximum P adsorption capacity of the soil. The aim of this study was to characterize the relationship between iron oxides and the quality of organic matter in sugarcane harvesting systems. For that purpose, two 1 ha plots in mechanically and manually harvested fields were used to obtain soil samples from the 0.00-0.25 m soil layer at 126 different points. The mineralogical, chemical, and physical results were subjected to descriptive statistical analyses, such as the mean comparison test, as well as to multivariate statistical and principal component analyses. Multivariate tests allowed soil properties to be classified in two different groups according to the harvesting method: manual harvest with the burning of residual cane, and mechanical harvest without burning. The mechanical harvesting system was found to enhance pedoenvironmental conditions, leading to changes in the crystallinity of iron oxides, an increase in the humification of organic matter, and a relative decrease in phosphorus adsorption in this area compared to the manual harvesting system.

Na agricultura, a obtenção de maiores produtividades das culturas com base no manejo sustentável do solo tem levado a uma busca gradativa do conhecimento das variáveis envolvidas nos sistemas de produção. Determinar as causas da variabilidade dos atributos passa a ser uma etapa do planejamento estratégico no setor sucroenergético. Este trabalho teve por objetivo estudar a variabilidade espacial dos óxidos de ferro da fração argila e sua relação com atributos físicos e químicos do solo, em diferentes sistemas de colheita de cana-de-açúcar na Região de Ribeirão Preto, SP. Duas parcelas de 1 ha foram delimitadas em áreas com sistema de colheitas mecanizada e manual. Foram retiradas, em cada área, amostras de solos em 126 pontos, na profundidade de 0,00-0,25 m. Os resultados das análises mineralógicas e químicas foram submetidos às análises geoestatísticas, obtendo-se a dependência espacial, os semivariogramas e os mapas de krigagem dos atributos estudados. Para analisar a correlação espacial entre os atributos estudados, foram construídos semivariogramas cruzados. A variabilidade espacial dos atributos químicos é maior em áreas com colheita de cana crua, quando comparada com áreas de colheita de cana queimada, ao contrário dos atributos mineralógicos, que apresentaram os maiores alcances na área de cana crua. Os atributos matéria orgânica, diâmetro médio do cristal da goethita apresentaram correlação espacial negativa, enquanto a argila apresentou correlação positiva com a adsorção de fósforo nos dois sistemas de colheita de cana-de-açúcar avaliados.

In agriculture, the search for higher crop yields based on sustainable soil management has led to a gradual pursuit of knowledge of the variables related to production systems. The identification of the causes of variability of these properties has become a part of strategic planning in the sugar and ethanol industry. This study investigated the spatial variability of iron oxides in the clay fraction and its relationship to soil physical and chemical properties in different sugarcane cultivation systems in the region of Ribeirão Preto, São Paulo State. Two 1-ha plots were outlined in areas with mechanical and manual harvesting systems. Soil samples were taken at 126 points from the 0.00-0.25 m layer in both areas. The mineralogical and chemical data were subjected to geostatistical analyses, to determine the spatial dependence, semivariograms and kriging maps of the properties. To analyze the correlation between the parameters cross-semivariograms were constructed. The spatial variability of chemical properties was greater in areas with mechanical harvesting than burnt harvesting (manual harvesting), whereas the range of the mineralogical properties was largest in the area of green-harvested sugarcane. The properties organic matter, mean crystal diameter goethite had a negatively spatial correlation, while clay was positive correlated with P sorption in the two sugarcane harvest systems.

A gestão adequada dos resíduos de culturas agrícolas pode produzir benefícios em um mundo mais quente e mais propenso à seca. Experimentos de campo foram conduzidos em áreas de produção de cana-de-açúcar no Sudeste do Brasil a fim de avaliar a influência dos resíduos de cultura na superfície do solo, em emissões de CO2 de curto prazo. O estudo foi conduzido por um período de 50 dias após a instalação das 6 parcelas com e sem resíduos de cultura aplicados sobre a superfície do solo. Os efeitos dos resíduos da cana-de-açúcar sobre as emissões de CO2 foram imediatos; as emissões das parcelas cobertas com restos vegetais de cultura e densidades equivalentes a 3 (D50) e 6 (D100) t ha-1 (massa seca) foram inferiores quando comparadas às parcelas sem cobertura vegetal (D0). Além disso, as parcelas cobertas com restos vegetais tiveram a temperatura do solo mais baixa e a umidade do solo mais elevada para a maioria dos dias de estudo, especialmente durante o período sem chuvas. As emissões totais foram tão elevadas quanto 553,62 ± 47,20 g CO2 m-2, e tão baixas quanto 384,69 ± 31,69 g CO2 m-2 nas parcelas sem cobertura vegetal e com uma densidade equivalente a 3 t ha-1, respectivamente. Os resultados indicam redução significativa das emissões de CO2 do solo, indicando a conservação de carbono no solo durante o período de curto prazo após a aplicação de resíduos de cana-de-açúcar na superfície do solo.

The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 ± 47.20 g CO2 m-2, and as low as 384.69 ± 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

Soil CO2 emission (FCO2) is governed by the inherent properties of the soil, such as bulk density (BD). Mapping of FCO2 allows the evaluation and identification of areas with different accumulation potential of carbon. However, FCO2 mapping over larger areas is not feasible due to the period required for evaluation. This study aimed to assess the quality of FCO2 spatial estimates using values of BD as secondary information. FCO2 and BD were evaluated on a regular sampling grid of 60 m × 60 m comprising 141 points, which was established on a sugarcane area. Four scenarios were defined according to the proportion of the number of sampling points of FCO2 to those of BD. For these scenarios, 67 (F67), 87 (F87), 107 (F107) and 127 (F127) FCO2 sampling points were used in addition to 127 BD sampling points used as supplementary information. The use of additional information from the BD provided an increase in the accuracy of the estimates only in the F107, F67 and F87 scenarios, respectively. The F87 scenario, with the approximate ratio between the FCO2 and BD of 1.00:1.50, presented the best relative improvement in the quality of estimates, thereby indicating that the BD should be sampled at a density 1.5 time greater than that applied for the FCO2. This procedure avoided problems related to the high temporal variability associated with FCO2, which enabled the mapping of this variable to be elaborated in large areas.

Monitoring of soil carbon storage may indicate possible effects of climate change on the terrestrial environment and it is therefore necessary to understand the influence of redox potential and chemical characteristics of humic substances (HS) of Antarctic soil. Five soils from King George Island were used. HS were extracted, quantified and characterized by potentiometry and the content of total carbon and nitrogen determined. HS of these soils had greater aliphatic character, low content of phenolic groups, lower acidity and lower formal standard electrode potential, compared to HS of soils from other regions, suggesting they are more likely to be oxidized.

A avaliação e adequação do potencial agrícola são realizadas com base na visão unidimensional do perfil do solo, porém a produção sustentável tem estimulado estudos sobre técnicas e métodos de avaliação do potencial agrícola em escalas detalhadas, que sejam mais rápidos e precisos. Assim, o objetivo deste trabalho foi investigar o potencial da suscetibilidade magnética do solo na identificação de compartimentos da paisagem em escala detalhada na região de Jaboticabal (SP). A área estudada possui duas curvaturas de relevo: côncava e linear, sendo subdividida em três compartimentos da paisagem: encosta superior (ES), meia encosta (ME) e encosta inferior (EI). Foram amostrados 20 pontos em cada compartimento, de forma aleatória, a partir de um banco de dados composto por 207 amostras oriundas de um gradeado amostral regular instalado em cada compartimento da paisagem. Foram avaliados os atributos físicos e químicos, a emissão de CO2 (FCO2) e a suscetibilidade magnética (SM), representada por: suscetibilidade magnética da terra fina seca ao ar (SM TFSA), da fração areia total (SM AT) e da fração argila (SM ARG), na profundidade de 0,00 - 0,15 m. Os resultados, obtidos por meio da análise de componentes principais, demonstraram que a SM é um importante atributo, capaz de ser empregado na identificação dos compartimentos da paisagem, pois a correlação desse atributo dentro do primeiro componente principal foi alta. A análise de cluster, método hierárquico, permitiu identificar dois grupos, segundo as variáveis selecionadas por meio da análise de componentes principais, entre os quais três das seis variáveis selecionadas correspondem à suscetibilidade magnética. A distinção dos compartimentos da paisagem na análise de componentes principais foi similar à do agrupamento formado na análise de cluster utilizando-se somente os atributos de maior poder discriminatório. A submissão da SM TFSA, SM AT e SM Arg à análise de cluster possibilitou a formação de três grupos que concordam com a divisão de compartimentos estabelecida em campo. O agrupamento observado na análise de cluster evidencia a possibilidade de a SM ser utilizada como ferramenta que facilite a identificação de compartimentos da paisagem e viabilize o mapeamento de áreas mais homogêneas em locais semelhantes.

The agricultural potential is generally assessed and managed based on a one-dimensional vision of the soil profile, however, the increased appreciation of sustainable production has stimulated studies on faster and more accurate evaluation techniques and methods of the agricultural potential on detailed scales. The objective of this study was to investigate the possibility of using soil magnetic susceptibility for the identification of landscape segments on a detailed scale in the region of Jaboticabal, São Paulo State. The studied area has two slope curvatures: linear and concave, subdivided into three landscape segments: upper slope (US, concave), middle slope (MS, linear) and lower slope (LS, linear). In each of these segments, 20 points were randomly sampled from a database with 207 samples forming a regular grid installed in each landscape segment. The soil physical and chemical properties, CO2 emissions (FCO2) and magnetic susceptibility (MS) of the samples were evaluated represented by: magnetic susceptibility of air-dried fine earth (MS ADFE), magnetic susceptibility of the total sand fraction (MS TS) and magnetic susceptibility of the clay fraction (MS Cl) in the 0.00 - 0.15 m layer. The principal component analysis showed that MS is an important property that can be used to identify landscape segments, because the correlation of this property within the first principal component was high. The hierarchical cluster analysis method identified two groups based on the variables selected by principal component analysis; of the six selected variables, three were related to magnetic susceptibility. The landscape segments were differentiated similarly by the principal component analysis and by the cluster analysis using only the properties with higher discriminatory power. The cluster analysis of MS ADFE, MS TS and MS Cl allowed the formation of three groups that agree with the segment division established in the field. The grouping by cluster analysis indicated MS as a tool that could facilitate the identification of landscape segments and enable the mapping of more homogeneous areas at similar locations.