Maria de Fátima Guimarães

Método do Perfil Cultural para avaliação do estado físico de solos em condições tropicais

A new approach is discussed for adoption of criteria in the application of the cultural profile methodology for tropical soil conditions. The evolution of this methodology has been analyzed since its beginning in France in the 1960s, until its proposal for tropical soil management studies. The cultural profile approach can be used to make qualitative diagnosis of the physical state of soil in the field, as well as to help with soil sampling, to study the effect of agricultural machinery, to visualize the physical, chemical and biological soil interactions, and to help with the studies of contraction, expansion, and shearing in the field and in the structural organization of soils and root system analyses.

Resistência à penetração de um Latossolo Vermelho Amarelo do Cerrado sob diferentes sistemas de manejo

The intensification of agricultural production systems has caused soil compaction even when soil conservation technologies are adopted. Soil compaction is one of the main problems for farmers, both in no-tillage and in conventional-tillage systems, as well as in pasture. This study was conducted in Rio Verde, (State of Goias), on Red-Yellow Latosol under the following systems: no-tillage for 14 years (SD14); no-tillage for 8 years (SD8); no-tillage for 2 years (SD2); conventional tillage (CT); pasture (P) and forest (F). The soil resistance to penetration was measured by the impact penetrometer Model IAA/Planalsucar - Stolf, from soil surface to the soil depth of 0.40 m. Soil bulk density and granulometry were also determined. Conventional tillage had lower resistance to penetration at the 0-0.10 m depth, whereas SD2 had more resistance up to 0.40 m in depth. There were no significant differences below 0.15 m in depth among treatments CT, SD8, and SD14. The first two years under the no-tillage system are critical, with regard to the resistance to penetration in to the soil surface layers.

No-tillage greatly increases earthworm populations in Paraná state, Brazil

Summary No-tillage (NT) agroecosystems now occupy >18 million ha in Brazil, of which 5 million are in the state of Parana, where NT began in the early 1970’s. The first NT farmers created an association to promote their practices, the ‘Clube da Minhoca’ (Earthworm Club), thus named because of the observed increase in earthworm numbers in their fields after adopting NT. However, little data were available on the topic until 1996, when more intensive studies began near Londrina, in N Parana. Earthworms were sampled by hand-sorting soil monoliths (25 × 25 cm square, 30‐40 cm depth) at 8 sites, comprising various natural and agricultural land-use and management systems. Data from the literature were collected from a further 6 sites for comparative purposes. The results for N Parana confirm the presence of higher earthworm populations under NT (46‐116 indiv., 0.49-1.06 g f.wt. m-2; mean values in dry-wet seasons, respectively), minimum tillage (42‐179 indiv., 0.68‐1.05 g f.wt. m -2 ), pastures (48‐182 indiv. m -2 ) and native forests (16‐42 indiv., 1.56‐0.83 g f.wt. m -2 ) than under conventional tillage (13‐22 indiv. and 0.13‐0.02 g f.wt. m-2). Soil disturbance thus had a negative impact on earthworm populations, and significant positive relationships were observed between earthworm abundance and age of NT systems, as well as with soil % C. In the Londrina area, some species present in the primary forests were absent in NT, where most earthworms were small-sized endogeic or epi-endogeic species. These results contrasted greatly with those from the cooler region in E Parana, where the exotic epi-endogeic Amynthas spp. dominated, reaching high densities (up to >100 indiv. m-2) and biomass (up to >30 g f.wt. m-2), especially under NT. Given the high abundance of worms under NT, further work should focus on estimating their potential contributions to soil processes, fertility and plant production in these systems.

Soil aggregation under different management systems

Considering that the soil aggregation reflects the interaction of chemical, physical and biological soil factors, the aim of this study was evaluate alterations in aggregation, in an Oxisol under no-tillage (NT) and conventional tillage (CT), since over 20 years, using as reference a native forest soil in natural state. After analysis of the soil profile (cultural profile) in areas under forest management, samples were collected from the layers 0-5, 5-10, 10-20 and 20-40 cm, with six repetitions. These samples were analyzed for the aggregate stability index (ASI), mean weighted diameter (MWD), mean geometric diameter (MGD) in the classes > 8, 8-4, 4-2, 2-1, 1-0.5, 0.5-0.25, and < 0.25 mm, and for physical properties (soil texture, water dispersible clay (WDC), flocculation index (FI) and bulk density (Bd)) and chemical properties (total organic carbon - COT, total nitrogen - N, exchangeable calcium - Ca2+, and pH). The results indicated that more intense soil preparation (M < NT < PC) resulted in a decrease in soil stability, confirmed by all stability indicators analyzed: MWD, MGD, ASI, aggregate class distribution, WDC and FI, indicating the validity of these indicators in aggregation analyses of the studied soil.

Análise conjunta de atributos físicos e biológicos do solo sob sistema de integração lavoura-pecuária

The objective of this work was to evaluate the effects of the integrated crop-livestock system on the morphological, physical and biological properties of soil. The experiment was carried out in Dourados, Mato Grosso do Sul State, Brazil, in a typic Hapludox soil. The following systems were sampled: grain crop under conventional soil tillage system, integrated crop-livestock system under no-tillage, continuous Urochloa decumbens (Syn. Brachiaria decumbens) pasture and natural system. In each system, a trench was opened in order to detect morphological changes caused by different management, using the cultural profile method. Assessments of soil macroinvertebrates were done according to the method Tropical Soil Biology and Fertility. Undisturbed soil samples were also used to assess the physical attributes of soil (soil density, total porosity, macro and microporosity). Among the cultivated systems, better soil structure was observed in the integrated crop-livestock system, in the layers 0-0.1 and 0.1-0.2 m. The systems under crop-livestock and pasture continuously cultivated favored a more biologically active soil environment, among the other agricultural systems. The visualization of soil attributes showed that crop-livestock integration is a promising strategy to develop sustainable production systems and that the period of two years of management is considered suitable for crop-pasture rotation.

Soil physical properties and sugarcane root growth in a red oxiso

Sugarcane, which involves the use of agricultural machinery in all crop stages, from soil preparation to harvest, is currently one of the most relevant crops for agribusiness in Brazil. The purpose of this study was to investigate soil physical properties and root growth in a eutroferric red Oxisol (Latossolo Vermelho eutroferrico) after different periods under sugarcane. The study was carried out in a cane plantation in Rolândia, Parana State, where treatments consisted of a number of cuts (1, 3, 8, 10 and 16), harvested as green and burned sugarcane, at which soil bulk density, macro and microporosity, penetration resistance, as well as root length, density and area were determined. Results showed that sugarcane management practices lead to alterations in soil penetration resistance, bulk density and porosity, compared to native forest soil. These alterations in soil physical characteristics impede the full growth of the sugarcane root system beneath 10 cm, in all growing seasons analyzed.

Fertility and acidity status of latossolos (oxisols) under pasture in the Brazilian Cerrado

The Cerrado region, with over 50 million hectares of cultivated pasture, provides 55% of Brazilian beef production. Previous investigations have shown that about 70-80% of this pasture is affected by some kind of degradation, leading to low productivity. However, until now, few surveys have been carried out on a regional scale. The aim of the present work is both to assess the fertility and acidity levels of Cerrado soils under pasture and compare the variability of the soils characteristics on a regional scale. Two soil depths were sampled in different places within the studied area: (1) a surface horizon (0.0-0.2 m) in order to evaluate its fertility and acidity status for pasture, and (2) a subsurface horizon (0.6-0.8 m), used for classification. Most of soils had levels of nutrients below the reference values for adequate pasture development. Whatever the texture, about 90% of soils had low or very low availability of phosphorus. Only 7 to 14% of soils had low pH, high exchangeable aluminum, and aluminum saturation above the critical acidity level. Except for nitrogen, no significant difference was found between Latossolos Vermelhos and Latossolos Vermelho-Amarelos.

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.

Macrofauna invertebrada do solo em sistema integrado de produção agropecuária no Cerrado

The objective of this work was to evaluate the density and diversity of soil invertebrate macrofauna in a crop-livestock rotation production system under no-tillage. The field experiment was performed in Dourados, Mato Grosso do Sul State, Brazil, on a Typic Hapludox soil, in parcels under a conventional monoculture system, a crop-livestock rotation system under no-tillage and continuous pasture, and a native vegetation fragment. The evaluations were conducted in January 2002, June 2002, January 2003 and July 2003, according to the method recommended by the Tropical Soil Biology and Fertility (TSBF) program. Systems with less anthropic interference showed greater abundance and richness of soil invertebrate macrofauna.

Populações de oligoquetos (Annelida: Oligochaeta) em um Latossolo Vermelho submetido a sistemas de uso do solo

This paper objective was to evaluate earthworm population dynamics in agricultural and livestock systems using as reference an area under native vegetation. The work was carried out in Dourados, MS, in a Typic Hapludox soil under conventional soil tillage (CT), no-tillage (NT), cropping/livestock integration (CLI), a continuous pasture (CP), and a natural system (NS). Samples were taken during summer and winter cropping seasons between 2000 and 2003. SPD, SILP, and PC systems benefited the development and establishment of earthworm population. NS system showed the largest earthworm population, being the majority of organisms from Enchytraeidae family. Among the systems, SPD also benefited the occurrence of organisms from Enchytraeidae family.