The presence of rock fragments (RF) is a common feature in agricultural areas with sloping terrain and poorly developed soils, potentially modifying soil physical attributes and water dynamics. We investigated the relationships among RF content, water infiltration, bulk density, and porosity in volcanic agricultural soils of southern Brazil, using 123 sampling points distributed across different soil classes, RF contents, and slope gradients. Infiltration data showed high variability: cumulative infiltration (I) ranged from 3 to 2275 mm, while the steady-state infiltration rate (i) ranged from 2 to 957 mm h- 1, both with large standard deviations. No significant differences in i or I were observed among slope classes. We found greater cumulative infiltration, lower bulk density, and higher fine-earth porosity in poorly developed soils (Leptosols and Regosols) with higher RF content. However, RF content did not significantly influence water infiltration in the evaluated soils. Bulk density and total porosity remained relatively stable despite variations in RF content. Infiltration in these stony agricultural soils exhibited high variability and low correlations with morphological and physical properties, indicating a complex multivariate behavior not easily captured by routine analyses.

Cohesive soil horizon is a pedogenetic, compacted horizon characterized by high penetration resistance, weak aggregate development, and strong moisture-dependent mechanical behavior. Although cohesive horizons are commonly identified in the field through morphological description and manual assessment, this procedure remains partially subjective and strongly influenced by soil moisture conditions. This study evaluated whether rheometry can identify the moisture ranges that best distinguish soils with cohesive horizons and investigated the relationships between rheological behavior, penetration resistance, and other soil physical properties. Samples from soils with and without cohesive horizons located in northeastern Brazil were analyzed using amplitude sweep tests under controlled matric potentials. The evaluated rheological parameters included strain at the end of the linear viscoelastic range (gamma LVR), shear stress at the end of the linear viscoelastic range (zLVR), strain at the yield point (gamma YP), storage and loss modulus at the yield point (G'G"YP), maximum shear stress (zmax), and integral z (Iz). The preliminary moisture screening indicated that the major transition in mechanical behavior occurred between -3 and -6 kPa, where the flow curves shifted from restructuring behavior to predominantly brittle rupture. Across the evaluated soils, stress-based rheological parameters, particularly zmax and zLVR, most consistently differentiated soils with cohesive horizons from non-cohesive soils. At -2 kPa, these parameters showed the strongest and most consistent differentiation between horizons, whereas zmax presented the greatest discriminatory potential at -10 kPa. Penetration resistance showed strong agreement with stress-based rheological parameters, especially under partially unsaturated conditions. The results indicate that the mechanical expression of cohesive behavior is strongly moisture-dependent and associated with microstructural organization and stress transmission within the soil matrix. Rheometry therefore represents a valuable complementary approach for evaluating cohesive horizons, particularly when stress-based parameters are interpreted under carefully controlled moisture conditions.

O presente estudo é parte do trabalho de conclusão de curso em Geografia (Licenciatura) do primeiro autor, que teve como objetivos caracterizar o Projeto Quintais Orgânicos de Frutas junto a agricultores familiares de Morro Redondo-RS e analisar os impactos do projeto na vida destes agricultores. Contou-se com uma pesquisa qualitativa, coletando informações de seis propriedades a partir de questões norteadoras. De acordo com os dados obtidos através da pesquisa de campo identificou-se a motivação dos envolvidos em cultivar seus quintais, associado com outras atividades de fonte de renda externa. Também constatou-se a potencialidade dos quintais orgânicos para produção de alimentos para o autoconsumo, bem como de pessoas ligadas aos beneficiários e comercialização do excedente, assim como os benefícios resultantes da atividade de cultivo nos mesmos, como o bem-estar, a intensificação da relação familiar.

There is an urgent demand to change our intensive crop production systems, replacing them with soil use and management systems that recover, preserve, or improve soil health and are environmentally sustainable, producing healthy and good-quality food. In this work, we compile and present strategies and public policies aimed toward soil and water conservation and food production in Brazil. The results presented may help Brazilian farmers adopt practices to recover, maintain, or improve soil health and politicians to create or modify public policies for healthy soil and food, without the necessity of increasing agricultural areas. Food insecurity was also addressed, with family farming playing an important role in food production and decreasing food insecurity. But these challenges need the combined efforts and engagement of the whole society.

The soil is the base of a sustainable agricultural system; it is the key for food and energy production, a reservoir of water and nutrients [...]

The capacity of soil to retain water and make it available to plants is an essential soil functions for the sustainability of terrestrial ecosystems. A lot of progress has been made in estimating water retention and availability as a function of soil texture. On the other hand, a lower effort has been dedicated to seeking correlations between plant-available water (AW) and soil compaction. In this study, we compiled a dataset with 2479 records from experiments conducted in Brazilian soils to evaluate the relationship between AW and bulk density (BD). The dataset was split into sub-datasets defined by soil textural classes to reduce the effect of texture on AW–BD relationships. In each sub-dataset, AW–BD relationships were described by linear regression. In general, there was a weak association between AW and BD. The strongest correlations were found in the Silty Loam (R2 = 0.26) and Loam (R2 = 0.13) classes. However, the partitioning of the overall dataset by textural classes was not effective to eliminate the effect of texture on AW–BD relationships. Still, the data showed that soil compaction may increase or reduce AW. Nevertheless, more experimental research is needed to bring a better understanding of how AW is affected by changes in BD.

Em uma obra de engenharia, muitas vezes é necessário conhecer, além das características físicas e químicas do solo, a posição e a dinâmica do lençol freático diante das precipitações pluviométricas. Neste sentido, o objetivo do presente estudo foi avaliar o nível freático, estabelecendo relações com as precipitações pluviométricas e com o tipo de solo em uma área sob construção civil no município de Pelotas, Rio Grande de Sul. Para tanto, foram feitos três furos de sondagem em pontos distintos do canteiro de obras, instalando tubo de policloreto de vinila (PVC) para medição do nível freático. As precipitações pluviométricas foram obtidas a partir dos dados do Boletim Climatológico Mensal da Embrapa Clima Temperado. A análise do solo foi feita pela descrição morfológica e a caracterização física e hídrica foi realizada sob as amostras coletadas em trincheiras. A partir dos resultados observados, constatou-se que o nível freático sofreu variação em decorrência das precipitações nos três furos de sondagem. Identificou-se que o lençol freático é superficial e o solo é hidromórfico. As informações apresentadas neste trabalho podem fornecer subsídios ao gerenciamento das águas subterrâneas no município e ao adequado ordenamento da expansão imobiliária, como forma a não comprometer as águas subterrâneas, contribuir para a recarga destas águas e evitar os alagamentos na região.

Penetrometers and penetrographers are widely used to measure soil resistance to penetration, but the results are associated with other soil properties (such as bulk density, water content, and particle size distribution). Thus, for an adequate interpretation of results, site-specific studies are necessary to identify which properties are more related to soil resistance. We aimed to measure the resistance to penetration of a Typic Paleudalf under distinct soil uses and to identify soil properties that influence soil resistance. The soil uses in this study included anthropized forest (composed of tree and shrub species), pasture (5-year-old pasture), Eucalyptus 20 (a 20-year-old Eucalyptus saligna stand), and Eucalyptus 4.5 (a 4.5-year-old Eucalyptus saligna under the second rotation). Soil resistance to penetration was measured with an impact penetrometer, and the data were correlated with other physical and mechanical properties of soil, such as the particle size, soil moisture, air permeability, saturated hydraulic conductivity, porosity, bulk density, precompression stress, and compressibility index. We observed that a resistance of 1.3 MPa matches with other soil property values corresponding to soil compaction, and values greater than 1.3 MPa were verified at depths of 0–8 cm for pasture and 8–30 cm for Eucalyptus 4.5. Analyzing all soil uses together, the correlation was significant (p < 0.05) with gravel (r = 0.34), silt (r = −0.32), clay (r = 0.26), gravimetric moisture (r = −0.27), macroporosity (r = 0.24), and soil bulk density at the end of the compressibility test (r = 0.27). The penetrometer is useful for evaluating the physical conditions of soil, but we highlight that soil resistance is influenced by factors such as particle size and soil moisture, as examples. We recommend using a set of soil properties for a better interpretation of penetration resistance data and to support decision-making regarding soil management.

Este trabalho corresponde a uma avaliação do Canal do Pepino, importante elemento da macrodrenagem urbana no Município de Pelotas/RS, com os objetivos de descrever sua condição estrutural, bem como o acúmulo de resíduos sólidos na sua extensão, além de propor estratégias para o adequado descarte desses resíduos na região de estudo. Percorreu-se toda a extensão do Canal do Pepino a fim de coletar informações sobre o estado de conservação do revestimento e das margens do canal, e identificar e analisar os principais pontos de descarte irregular de resíduos sólidos. A partir da análise de toda a extensão do Canal do Pepino, observou-se que alguns pontos ao longo do Canal necessitam de revegetação com gramíneas nas margens e intervenção no solo, para controlar processos erosivos pontuais, bem como de manutenção das paredes de concreto, para evitar seu colapso estrutural. Há também a necessidade de poda da vegetação arbórea e arbustiva para reduzir o aporte de resíduos orgânicos destas vegetações dentro do Canal. Quanto ao descarte irregular de resíduos, observou-se intensificação de montante para jusante e, tanto nas margens quanto no interior do canal, é muito grande a quantidade e diversidade de resíduos.

Soil erosion is one of the major problems in the agricultural areas in the world, and straw mulching is a conservation practice that may reduce soil runoff. How much straw mulching is necessary to reduce soil runoff? The objectives of this study were to quantify and characterize the runoff under different levels of oat straw mulching, as well as to analyze the cost of soil erosion. An experiment was performed in a site with the soil recently tilled for peach orchard implementation. In the ridges in the row of the peach orchard, plots were placed in order to quantify soil and nutrient losses by surface runoff due to interril erosion on the dates 23 August 2015 and 13 March 2016, considering the treatments were composed of different amounts of oat straw mulching (0, 1, 2, 4 and 8 Mg ha−1). The results showed that the use of oat straw mulching decreased soil runoff, especially the doses ≥2 Mg ha−1, and the cost to replace the available nutrients P, K, Ca and Mg via mineral fertilizer varies from US$ 75.4 (no mulching) to US$ 2.70 per hectare (8 Mg ha−1 oat straw mulching).

Soil compaction is one of the main causes of soil degradation, and some parameters have been used to characterize it, like those related to compressibility and the degree of compactness. To evaluate the rotational grazing time during winter and the presence and absence of grazing, on the compressibility and degree of compactness of a Cambisol, an experiment was installed and consisted of corn planting for silage, a fallow and pasture planting period, with two treatments evaluating the amount of rotational grazing (two and three times in a period of, respectively, 2 and 3 months), subdivided into the presence and absence of dairy cattle grazing. The mean bulk density value of 1.47 Mg/m3 separates the occurrence (plastic deformation) or not (elastic deformation) of additional soil compaction, while the traffic of machinery and animal trampling should occur with soil moisture lower than 0.23 kg/kg, when the soil has a larger load-bearing capacity. For the conservation of soil structure, our study recommends the permanence of cattle in the plots for 30 to 40 min/day and an exit when the pasture height is 0.07 to 0.10 m, with two or three grazing in a period of, respectively, 2 and 3 months.

A no-tillage system (NT) is an alternative to replace soil management with intense soil tillage and degradation. Our objective was to evaluate the physical–hydric properties of soil under NT for four years after undergoing 13 years of minimum (4NTM) and conventional tillage (4NTC) with reference to continuous NT for 17 years (17NT). The soil bulk density, porosity, storage capacities of water and air, visual evaluation of soil structure (VESS), and saturated hydraulic conductivity were determined. The root dry biomass of soybean, maize, and palisade grass was also measured. NT during four years established after receiving 13 years of tillage did not significantly affect soil properties compared to 17NT, which means that four years of NT reached structural stability similar to continuous 17NT. The VESS scores were less sensitive to identifying soil compaction. Crops have no significative influence on soil properties, but the roots of maize seem to be less sensitive to soil compaction, which is important considering it is in a crop rotation system. The treatments (soil tillage and crop rotation) presented soil compaction below a 10 cm depth, and to our loamy textural class soil, a Bd > 1.60 Mg m−3 restricted soil aeration due to macroporosity < 0.10 m3 m−3.

Análises de solo que busquem otimizar e racionalizar o uso de fertilizantes sintéticos em áreas de fruticultura irrigada se fazem necessárias diante dos impactos que estas adubações podem causar ao ambiente se mal manejadas. Com isso, objetivou-se avaliar a fertilidade do solo em diferentes pontos de amostragem em um pomar de pessegueiro com e sem irrigação. O experimento foi instalado em um Argissolo sob pomar de pessegueiro com quatro anos de idade. As coletas de solo foram realizadas no pomar com e sem irrigação, nas camadas de solo 0 a 5 cm e 10 a 15 cm e, nos diferentes pontos de amostragem (passagem do rodado das máquinas, linha e entrelinha de plantio e copa do pessegueiro), em dezembro de 2009. Verificou-se que o pomar de pessegueiro apresenta variabilidade nos teores de nutrientes, seja pela adubação ou pelo manejo diferenciado nas diferentes posições do pomar. De modo geral não se verifica estratificação da fertilidade entre as camadas de solo. Os maiores teores de nutrientes geralmente se encontram na região da linha de plantio e copa, devido a adubação ser realizada nessas regiões, enquanto a acidez do solo é maior. A irrigação apresentou pouca influência na fertilidade do solo.

Quartzipsamments are environmentally fragile soils, being highly susceptible to water and wind erosion. Despite this, it seems that political and economic issues favor the advancement of agriculture in these soils. Therefore, studies are necessary for a better understanding of these soils and to minimize the impacts of land use. This work aims to characterize the morphological, physical–hydric, and chemical properties of Quartzipsamments under sandyzation in southwest Rio Grande do Sul State, Brazil. Soil morphology was evaluated in six profiles in areas under native field with the presence of gullies, and soil samples with preserved and non-preserved structures were collected to evaluate the physical–hydric and chemical properties. We verified that these soils have high macroporosity (0.253 to 0.373 m3 m−3) and saturated hydraulic conductivity (127.85 to 672.26 mm h−1), and predominantly low organic matter (0.05 to 2.36%) and clay (23.03 to 126.29 g kg−1) content, but correlation analysis showed that increasing pH and organic matter can improve the fertility of these soils. Quartzipsamments have a low volume of available water to plants (0.006 to 0.038 m3 m−3) and have a potential risk of leaching and aquifer contamination. The use of these soils demands the adoption of conservation practices.

Peach production is of great economic importance to Brazil. In 2020, over 201 ton of the fruit was harvested in the country, generating a production value of approximately R$456 million. In order to enhance peach productivity, it is necessary to improve soil physical quality in the orchards. Therefore, the aim of this study was to evaluate the degree of compactness, water infiltration rate, as well as perform the visual evaluation of soil structure (VESS) in different sampling positions of three peach producing commercial orchards of different ages in southern Brazil. The results showed that the rows of the orchards had lower values of degree of compactness, soil structural quality score (Sq) and higher infiltration rate, and differed from the interrow and wheeled interrow sampling positions. Regarding orchard age, there was no difference between then. The use of cover crops, maintenance of spontaneous plants in the interrows and the branches from the yearly pruning placed on the interrows, harvesting manually, and opting for using a compact tractor, may be contributing to avoid soil compaction and probably soil erosion, and maintaining soil physical quality in the wheeled interrow and interrow, even in the older orchards. The degree of compactness, soil structural quality score and water infiltration are aligned with each other and with bulk density, macroporosity and total porosity, and were good indicators to identify differences in soil structure in the orchards.

Understanding the soil-plant relationship is important to determine critical limits of soil properties that influence crop growth and yield. The objectives were to quantify the influence of soil compaction levels on physical properties and crop growth and yield in a clayey Oxisol. An experiment was performed having in the main plots, levels of soil compaction (NT: no-tillage during six years, NTC: NT + four passes of a 10 Mg machine in the agricultural year 2003/2004, and Chisel: NT + chiseling and harrowing in the agricultural year 2003/2004), and in the sub-plots, the summer crops soybean and corn, and wheat in the winter season. We measured soil physical and mechanical properties, along with yield of corn, soybean and wheat, and root growth of that last two crops. After four passes of a 10 Mg machine, the soil resistance to penetration increased to a 0.12 m depth, while Chisel disrupted the 0–0.20 m soil layer, with the effects persisting for at least nine months. Soil compaction in no-tillage concentrated in the 0.05–0.15 m layer. Corn yield was similar among the treatments, soybean yield was highest in NT, and the highest yield of wheat was in the sequence with soybean under NT.

Machinery traffic and animal trampling can deform the soil and, consequently, impair soil pore functioning. This study aimed to evaluate how soil structure affects the compressibility, physical properties and air permeability of a Typic Paleudalf under forest, pasture and eucalyptus. Soil samples with preserved structure were used to determine soil physical (bulk density, porosity, degree of water saturation at 33 kPa-tension, air permeability) and mechanical properties (soil deformation, precompression stress, compressibility index). After these evaluations, each soil sample was fragmented, sieved, and the metal rings filled with structureless soil, and underwent the same determinations as the samples with preserved structure. For loads greater than the precompression stress (load greater than 200 kPa), soil with non-preserved structure had the largest deformation. An increase in bulk density decreased macropores linearly (R-2 = 0.77 and 0.87, respectively, to preserved and non-preserved soil structure) and air flow exponentially. The soil with preserved structure was less susceptible to further compaction. Air flow was greatest in soils with lower bulk density, microporosity and water saturation degree, and a high volume of macropores. Soil structure (preserved and non-preserved) had more significative differences in microporosity, compressibility index, soil deformation, and bulk density at the end of the compression test.

Soil compaction is a worldwide problem in agricultural areas, and it is important to define soil properties and reference values that allow knowledge of the compaction level for decision making. The objective of this study was to define the critical values of physical properties associated with the compaction of soils. Three Ultisols and two Oxisols, under different management systems, were collected at different depths for an evaluation of particle size, volumetric moisture, bulk density, and porosity. In the field, soil resistance to penetration and the root length of the soybean and edible black bean crop were measured. The soil profiles presented horizontal layers with similar resistance, but in some cases, there is discontinuity of these layers, which allows the roots to use the zones of lower resistance to deepen in the profile. The values of bulk density and resistance to penetration critical to soybean and edible black bean (only in sandy loam soil) root growth, according to soil textural class, are: sandy loam = 1.66 Mg m−3 and 1.5 to 2 MPa; loam and clay loam = 1.52 Mg m−3 and 1 to 1.5 MPa; silty clay loam and silty clay = 1.32 Mg m−3 and 1.5 to 2 MPa; and clay = 1.33 to 1.36 Mg m−3 and 2 to 3.5 MPa.

Soil compaction is harmful to agricultural and forestry areas, and strategies to avoid soil deformation are of great interest. The objective of this study was to evaluate the compressibility of a soil submitted to different land uses in an area located in southern Brazil. The land uses assessed were a) Anthropized Forest: constituted by tree and shrub species; b) Pasture: five years old; c) Eucalyptus 20: twenty years old; and d) Eucalyptus 4.5: conducted in 2nd rotation, and 4.5 years old, with Eucalyptus harvesting in the first cut made manually with a chainsaw and wood extraction with a Forwarder. Undisturbed soil samples were taken in 2006, and they were submitted to the uniaxial compression test. Bulk density and volumetric moisture were calculated before the test, as well as soil deformation, compression index and precompression stress at the end of the test. Anthropized Forest and Pasture soils presented the highest volumetric soil moisture, a mean of, respectively, 0.301 and 0.304 m3 m- 3. Euca-lyptus 20 had the lowest bulk density (mean of 1.15 Mg m-3), and Eucalyptus 4.5 the highest bulk density (mean of 1.47 Mg m-3). Precompression stress is low for all soil land uses, ranging from 31.24 to 50.92 kPa, and care should be taken to avoid further compaction. Load-bearing capacity of the soil presented positive and negative relationship with, respectively, bulk density and volumetric moisture, but the low coefficient of correlation (r) and determination (r2) shows the need of further studies for a better adjustment of the data. From the knowledge of volumetric soil moisture, it is possible to monitor and define the most suitable soil condition for traffic of machinery and animals trampling into the areas to avoid additional compaction, while the load-bearing capacity of the soil can be estimated by bulk density, being useful to monitor the occurrence or not of additional compaction.

O uso intenso do solo e a não adoção de práticas conservacionistas resulta em sua degradação e impactos ao ambiente. Nesse sentido, o presente estudo teve como objetivo avaliar a capacidade de uso e a aptidão agrícola das terras de algumas propriedades rurais da Bacia Hidrográfica do Arroio Pelotas, localizadas no município de Pelotas/RS, utilizando as metodologias propostas, respectivamente, por Lepsch et al. (1991) e Schneider, Giasson e Klamt (2007). Para isso, foram avaliadas três propriedades rurais com pastagem, uma com lavoura e cinco com pomares de pêssego de diferentes idades (0, 2, 6, 8 e 12 anos). A partir dos resultados levantados, verifica-se que as áreas apresentam limitações quanto a capacidade de uso e aptidão agrícola, especialmente relacionadas à pouca profundidade efetiva do solo e, aos riscos de erosão associados à declividade e à textura média na camada superficial do solo. Apesar das limitações quanto ao uso destas áreas, a pastagem e a fruticultura são usos menos intensos de exploração do solo do que as culturas anuais, contudo, ainda se tornam necessárias a implementação de novas práticas conservacionistas do solo e da água ou manutenção daquelas já utilizadas. Palavras-chave: Degradação do solo. Práticas conservacionistas do solo. Limitações de uso das terras. Capacity of use and agricultural aptitude of land of rural properties located in the Pelotas River hydrographic basin Abstract The intense use of the soil and the failure to adopt conservationist practices, leads to its degradation and impacts on the environment. In this sense, the present study aimed to evaluate the capacity of use and the agricultural aptitude of the lands of some rural properties of the Hydrographic Basin of Arroio Pelotas, located in the municipality of Pelotas/RS, using the methodologies proposed, respectively, by Lepsch et al. (1991) and Schneider, Giasson e Klamt (2007). For this, were evaluated three rural properties with pasture, one with annual crops and five with peach orchards of different ages (0, 2, 6, 8 and 12 years). From the results obtained, the areas have limitations in terms of their use capacity and agricultural aptitude, especially related to the little effective depth of the soil and the risks of erosion associated with the slope and the medium texture in the superficial layer of the soil. Despite the limitations on the use of these areas, pasture and orchards are less intense uses of soil than annual crops, however, it is still necessary to implement new soil and water conservation practices or maintain those already used. Keywords: Soil degradation. Soil conservation practices. Landuse limitations.