RESUMO No Brasil para conservar o solo e a água faz-se necessário a adoção do pacote tecnológico da agricultura conservacionista, em conjunto com o plantio em nível e o uso dos terraços agrícolas. Porém pouco se sabe sobre a percepção e o nível de adoção dessas práticas pelos agricultores. Neste contexto, o objetivo do estudo foi verificar a percepção e o nível de adoção de práticas de conservação do solo e da água por agricultores, em áreas agrícolas com culturas anuais, o objetivo do estudo foi verificar a percepção e o nível de adoção de práticas de conservação do solo e da água por agricultores, em áreas agrícolas com culturas anuais, em uma bacia hidrográfica; além de analisar a relação entre a adoção destas práticas e as características socioeconômicas destes agricultores. Para tanto, foi realizada uma pesquisa do tipo survey junto a agricultores da bacia hidrográfica do Rio Vermelho, no sul do Brasil. Com base nos resultados, verificou-se que a grande maioria dos agricultores tem percepção adequada acerca do uso das práticas de conservação do solo e da água. A manutenção da produtividade foi apontada como principal motivo para se conservar o solo e a água, enquanto que a redução de custo de produção e o controle da erosão aparecem como motivos secundários. O uso dos terraços agrícolas e o plantio direto foram as práticas mais adotadas pelos agricultores, e a rotação de culturas foi a menos adotada. Cerca de 78,3% dos proprietários de terra e 50% dos arrendatários adotaram o plantio direto. Porém, apenas 26,8% dos agricultores adotaram a agricultura conservacionista. No geral, verificou-se que a maioria dos agricultores adota medidas conservacionistas, mas de forma parcial, que podem não ser suficientes para garantir a conservação do solo e a da água. A conscientização sobre a conservação do solo e da água precisa ser melhorada.

ABSTRACT In Brazil, to conserve soil and water, the adoption of a complete array of conservation agriculture technologies in conjunction with contour farming and agricultural terraces is necessary. However, there is little knowledge about the awareness and adoption level of conservationist practices by farmers. In this context, the objective of the study, which took place in a watershed containing agricultural areas dominated by annual crops, was to verify farmers’ perception and adoption level of soil and water conservation practices and the relationship between their adoption level of conservation practices and their socioeconomic characteristics. For this purpose, a survey was carried out with farmers in the Rio Vermelho watershed in southern Brazil. It was found that the majority of farmers have adequate awareness about the use of soil and water conservation practices. Maintaining productivity was identified as the main reason to conserve soil and water, while reducing production costs and controlling erosion stood out as secondary reasons. Agricultural terraces and no-tillage were the most adopted practices by farmers. No-tillage was implemented by approximately 78.3% of landowners and 50% of tenants. However, only 26.8% of farmers adopted conservation agriculture. Overall, most farmers adopt conservationist practices, but in a partial manner, which may not be sufficient to ensure soil and water conservation. Awareness of soil and water conservation needs to be further improved.

RESUMO A agricultura conservacionista é fundamental para melhorar a sustentabilidade agrícola. No entanto, a qualidade do manejo do solo em sistemas de agricultura conservacionista é altamente variável. O objetivo deste estudo foi verificar se o índice de qualidade participativa do plantio direto (IQP) está associado aos atributos físicos, químicos e microbiológicos do solo. Dessa forma, buscou-se validar sua utilização como indicador da qualidade do manejo do solo. Foi realizado um levantamento para avaliar as práticas agrícolas utilizadas por agricultores da mesorregião oeste do estado do Paraná, Brasil, para a obtenção do IQP. A qualidade do manejo do solo para as lavouras anuais está relacionada ao IQP, conforme evidenciado por sua associação com atributos físicos, químicos e microbiológicos do solo. Os resultados confirmaram a utilidade da metodologia do IQP como ferramenta de avaliação da qualidade do manejo do solo, demonstrando sua sensibilidade às mudanças de curto prazo nas práticas de manejo. Consequentemente, isso pode permitir o monitoramento da qualidade do manejo e inferências sobre os efeitos benéficos das práticas implementadas. agrícola entanto variável (IQP físicos forma buscouse buscou Paraná Brasil Consequentemente implementadas

ABSTRACT Conservation agriculture is fundamental for improving agricultural sustainability. However, the quality of soil management in conservation agriculture systems is highly variable. The goal of this study was to verify whether a no-tillage participatory quality index (PQI) is associated with the physical, chemical, and microbiological attributes of soil. Thus, we sought to validate its use as an indicator of soil management quality. A survey was conducted to assess the agricultural practices of farmers from the western mesoregion of the state of Paraná, Brazil to evaluate the PQI. The quality of soil management for annual crops was related to the PQI, as evidenced by its association with soil physical, chemical, and microbiological attributes. These results confirmed the usefulness of the PQI methodology as a tool for assessing the quality of soil management, demonstrating its sensitivity to short-term changes in management practices. Consequently, this may allow for the monitoring of management quality and inferences about the beneficial effects of the implemented practices. sustainability However variable notillage no tillage (PQI physical chemical Thus Paraná shortterm short term Consequently

ABSTRACT Heavy clayey Ferralsols are known for their high capacity to form water-stable macroaggregates. However, little is known about how different size classes of macroaggregates exchange mass with increasing organic matter content. This study aimed to characterize and detail aggregation dynamics with increasing organic matter content in these soils. Profiles of three heavy clayey Ferralsols were sampled to isolate the role of organic matter on the stability of aggregates. In this sampling scenario, a conceptual model was established to calculate the aggregation rate of different size classes of water-stable aggregates. This approach allowed the establishment of a critical value for classifying microaggregates in the studied soils (≤0.50 mm) based on their behavior as “building blocks” for macroaggregates when organic matter content is increased. In surface soil layers, where organic matter is higher, most dynamics are expected to happen between macroaggregates classes because free microaggregates are scarce. Consequently, it is important to subdivide macroaggregates into different size classes when evaluating their stability. Quantifying macroaggregates as a single class (e.g., >0.25 or >0.50 mm) was insufficient in representing the macroaggregation dynamics in heavy clayey Ferralsols.

ABSTRACT Soil aggregates and their stability affect a wide range of soil properties. This study aimed to (a) verify whether biogenic aggregation provides higher macro- and microaggregate stabilization, and (b) evaluate whether biogenic aggregates are associated with higher labile organic carbon and glomalin contents. Three management systems were evaluated (permanent pasture, PP; no-tillage system, NT; and no-tillage + Brachiaria system, NT+B) as well as a reference area (Atlantic Forest biome vegetation, NF). According to their origin or formation pathway, the aggregates were separated, identified, and classified as biogenic (formed by biological processes) and physicogenic (resulting from chemical and physical actions). The PP system provided the greatest stabilization of the macroaggregates, regardless of the formation pathway, as reflected by a greater mean weight diameter (MWD). The PP system also influenced the degree of microaggregate stability by increasing the bond strength and reducing the dispersion of the clay fraction. Finally, the PP system elevated the contents of labile organic carbon (POXC), easily extractable glomalin (GRSP-EE), and total glomalin (GRSP-T) under both formation pathways. The NT+B system favored the stabilization of macroaggregates, especially in the subsurface soil layer, compared with the NT area. In the aggregates of the NT and NT+B areas, the highest values observed were for water-dispersible clay (WDC) and the lowest values observed were for non-dispersible clay (NDC), a pattern opposite to that observed in the aggregates of the PP and NF areas. In the biogenic aggregates of all areas, a high POXC content was quantified, and biogenic aggregation proportionally increased the values of MWD, GRSP-EE, and GRSP-T relative to physicogenic aggregation. The results showed that grain production systems, pasture systems, and non-anthropized environments differentially influenced aggregation and the concentrations of organic fractions associated with aggregate stability. This study highlights the need for future studies using these indicators to monitor the quality of soils, especially those with sandy texture, which are considered more fragile.

ABSTRACT Sugarcane culture in Brazil has expanded the planting area to degraded pastures and sandy soils. Sugarcane field reform is carried out after five or more harvest cycles, with conventional tillage, followed by planting sugarcane, or growing soybeans or a cover crop. This study aimed to analyze the effects of these different managements in the conventional sugarcane reform on the physical properties and organic carbon in an Argissolo Vermelho distrófico arênico (sandy Ultisol), located at latitude 21° 13’ 40” south, longitude 50° 52’ 06” west, and altitude of 449 m. In each management study, areas of 10 ha were delimited in which 36 months after the renovation period, during the 3rd crop cycle, soil samples were collected in eight trenches measuring 1.0 × 1.0 × 0.5 m, 30 m apart between the crop rows and 0.25 m from the planting furrow, to analyze: the stability index of aggregates in the layers of 0.00-0.10 and 0.10-0.20 m and density and porosity (total, macro, and microporosity) of the soil in addition to organic carbon, in the layers of 0.00-0.10, 0.10-0.20, 0.20-0.30 and 0.30-0.40 m. The results allowed us to conclude that the tillage+sugarcane and tillage+soy managements negatively affected the physical properties compared to the tillage+cover crop management, whose use of Crotalaria spectabilis provided higher Pt, higher Ma, and Mi, higher AS. Furthermore, the increase in carbon contents was low, with small variations between treatments.

Abstract The presence of unsaturated flow in tropical lateritic soils of unknown hydromechanical behavior may lead to severe geotechnical problems. It is known that soil-water characteristic curves (SWCC) are a valuable tool to define this behavior and facilitate the suction estimation, acting on tests performed with no control of such parameter. This article aimed to determine and model the SWCC for 3 unprecedented tropical soils, in the undisturbed and the compacted conditions, from the Paraná state, located in the south of Brazil. The soils studied are one clay and two sands, all lateritic. The pressure plate and the filter paper methods were used to determine the SWCC. The samples were carved and submitted to the drying paths. Furthermore, Mercury Intrusion Porosimetry (MIP) tests were performed in samples of the studied soils in order to obtain the pore size distribution (PSD), contributing to the bimodal definition of curves and the prediction of SWCC main parameters. Both techniques (pressure plate and filter paper) were combined and the SWCC was adjusted by Gitirana & Fredlund model, which efficiently represents the shape of the traditional curves for tropical soils. Furthermore, the SWCCs were predicted by PSD and obtained satisfactory numerical fits. All SWCC presented air entry values in the macropores that are characteristic of soils as the lateritic, given that its structure was considered a key factor in the shape of the curves.

ABSTRACT In some rural properties of Brazil, soil and water conservation practices are partially or inappropriately implemented, intensifying soil erosion, even in no-tillage (NT) areas. This study aimed to check the farmer’s understanding of conservation agriculture (CA) and assess whether they are using practices appropriate to soil conservation. A basin in the state of Paraná, in Southern Brazil, was selected. Surveys were conducted based on a structured questionnaire and in-person interviews of 234 farmers. Among these farmers, 67 % do not understand CA pillars adequately, and 68 % stated they have been using NT for over 12 years. However, 58 % stated that they carried out some kind of soil preparation. Furthermore, some of the farmers only partially implemented CA, adopting a low level of crop diversification. The main problems pointed out by the farmers to justify simplifying the CA approach were soil compaction, low production of plant biomass and resistance of weeds to herbicides. Most farmers in the study do not have enough knowledge of the pillars of CA. As a result, there is little diversification in crop rotation, and the soil is continually disturbed with chiseling. Furthermore, although most farmers use terracing, they drive sprayers crossing terraces and following the slope, a practice that can impair the capacity of terraces to control surface water runoff. These practices do not contribute to soil and water conservation and endanger the sustainability of agricultural production systems.

ABSTRACT: Land use and tillage practices may change soil structure and undermine sustainable agriculture; however, such changes are hardly identified in the short term. In this sense, agroforestry systems have been used to reduce soil degradation and promote sustainable production in coffee plantations. These areas are expected to have well-structured soils and hence improved root distribution. This study aimed to evaluate soil quality by the morphostructural and root distribution analyses comparing open-grown coffee and coffee in agroforestry systems with rubber trees for 19 years, in an Oxisol in northern Paraná State (Brazil). Treatments consisted of open-grown coffee (OG), coffee partially shaded by rubber trees (PSH), and coffee fully shaded by rubber trees (FSH). The mapping of morphostructural features and soil resistance to penetration in “cultural profile” walls identified changes in soil structure resulting from different tillage systems. Root distribution was better in coffee plants grown in PSH and FSH systems. At greater depths, cultural profiles of FSH and PSH showed a larger numbers of roots compared to OG. Among the three systems, PSH provided a better environment for root growth and distribution. This result could be attributed to the high biological activity and interaction between roots and aggregates in that profile. The FSH agroforestry system provided less compact morphological structures and more roots throughout the soil profile. The agroforestry systems presented fewer soil structural changes by tillage operations and lower values of soil penetration resistance. Coffee root distribution was an effective indicator of soil quality and consistent with the morphostructural characterization of cultural profile.

ABSTRACT: The soil particles can be gathered through physical and/or chemical processes in association with the biological activity, leading to the formation of aggregates. Soil aggregates has several functions in the soil, increasing macroporosity and water circulation - consequently reducing soil erosion and mechanical resistance to root growth, contributing to greater fixation of plants to the soil and absorption of water and nutrients, and protection of intra-aggregate organic matter. The aggregates were initially classified morphologically and in terms of their stability. In recent years, another way of evaluating aggregates, regarding their formation or origin pathway, has gained prominence in the studies conducted in Brazil. As for their origin, the aggregates can be classified morphologically as physicogenic, biogenic, or intermediate. This manuscript presents the techniques used to sample aggregates, the morphological patterns for their distinction observed in different soil classes and management types, and the chemical and physical properties. Additionally, we present analyses that are not commonly used to evaluate aggregates but which have the potential to be used as tools for a better understanding of their origin and to evaluate their modifications when subject to different types of management. In practical terms, identifying the aggregate origin and determining the related attributes allows recognizing the effect of vegetation/soil/management on soil aggregate forming agents, mainly roots and soil fauna, which reflects soil quality. For future studies, and especially to determine the importance of biogenic aggregation in improving edaphic properties, we suggest the use of micromorphology, near-infrared spectroscopy, X-ray computed tomography, clay dispersion analyses in addition with chemical, physical, and biological analysis. This approach can contribute to the identification of other patterns related to pedogenesis and the pathways of aggregate formation.

ABSTRACT: Few approaches have been developed to measure the isolated effect of exchangeable cations on clay dispersion in soils. In this study, the charge sparsity (CS) index was proposed using the ratio between the cations hydrated ionic radius and valence. The index capacity to measure cation effects on clay dispersion in soils was also evaluated. Three Ferralsols, sampled at different sites in Paraná State, Brazil, were homoionized with Ca2+, Mg2+, K+, or Na+ prior to evaluation of the clay dispersion degree. Published independent data for two soils and clays were also used. We tested the capacity of CS and II, the latter proposed by Marchuck and Rengasamy (2011), to predict clay dispersion in soils. The CS predicted the dispersion degree more accuratelly than the ionicity index did, in soils where Ca2+ and Mg2+ behaved similarly. The response of Paraná soils to CS varied with soil characteristics. Soils with a lower pH at the isoelectric point were more dispersible by cations with high CS (K+ and Na+). The CS was efficient to quantify the isolated effect of cations on the clay dispersion process in soils. Therefore, qualitative and quantitative studies can benefit from the CS as an index to understand the effect of cations on clay dispersion in soils.

Resumo Este estudo teve como objetivo determinar a proporção de NO3-/NH4+, fornecidos por fertirrigação que permita o melhor crescimento de plantas de rosa do deserto cultivadas em vaso. As plantas foram cultivadas em casa de vegetação, em vasos de polipropileno, tendo como substrato uma mistura de areia e pó de pinus compostado (1:1, v v-1). Utilizou-se o delineamento experimental inteiramente casualizado, com seis tratamentos (controle, 0/100 25/75, 50/50, 75/25 e 100/0, de NO3– e NH4+ respectivamente), e dez repetições. As fertirrigações foram realizadas semanalmente na quantidade de 100 mL por vaso durante um período de 180 dias. As variáveis avaliadas foram: altura da parte aérea, diâmetro basal do cáudice, número dos ramos, massa seca de raízes, folhas e cáudice e determinação dos teores e acúmulo de macronutrientes de folha, cáudice e raiz. As proporções de NO3– e NH4+ promoveram maior alteração no teor de nutrientes nas folhas comparado ao cáudice e raízes. Recomenda-se para o cultivo de rosa do deserto a proporção 25/75 de NO3-/NH4+, por proporcionar melhor acúmulo de massa seca pelas plantas, bem como aumento na altura e diâmetro do cáudice das plantas.

Abstract This study aimed to determine NO3-/NH4+ proportion delivered by fertigation that allows greater desert rose plants growth in pots. Plants were cultivated in greenhouse in polypropylene pots, using a mixture of sand and composted Pinus powder (1:1, v v-1) as substrate. Experimental design was completely randomized, with six treatments (control, 0/100 25/75, 50/50, 75/25 and 100/0 of NO3– and NH4+ respectively), and ten replications. Fertigation was performed weekly in the amount of 100 mL per pot for 180 days. Variables evaluated were: shoot height, basal diameter of the caudice, number of branches, roots, leaves and caudice dry mass and macronutrient contents determination and accumulation in leaves, caudice and root. NO3– and NH4+ proportion promoted a greater change in nutrient content in leaves compared to caudice and roots. The proportion 25/75 NO3–/NH4+ is recommended for desert rose cultivation, as it provides the best results for most of the characteristics studied.

O solo integra os ecossistemas terrestres e o papel dele na produção de alimentos é essencial, embora nos últimos anos tenha se constatado sua degradação física em razão das diferentes práticas culturais utilizadas que modificam sua estrutura e, consequentemente, seu funcionamento. O objetivo deste trabalho foi avaliar possíveis mudanças estruturais, bem como a degradação de Latossolo Vermelho submetido a diferentes manejos por 20 anos. As avaliações foram realizadas em diferentes manejos: semeadura direta com e sem rotação de culturas; cultura perene; e preparo convencional, além de uma área de mata (referência). Inicialmente, fez-se a descrição do perfil cultural e, na sequência, coletaram-se 10 amostras de solo em cada manejo considerado e sob mata nativa para quantificar o teor de matéria orgânica, o grau de floculação, a densidade e a macroporosidade do solo. Os resultados indicaram mudanças estruturais até 50 cm de profundidade com predomínio de unidades estruturais ∆μ (nível intermediário de compactação) nos manejos cultura perene e semeadura direta com rotação de culturas e unidades estruturais ∆ (compactado), nos manejos preparo convencional e semeadura direta. A degradação do solo, da menor para a maior, ocorreu na seguinte ordem: Mata => semeadura direta com rotação de culturas => cultura perene => semeadura direta sem rotação de culturas => preparo convencional. Em todos os manejos, os valores de matéria orgânica e macroporosidade sempre foram abaixo; a densidade do solo, sempre acima dos valores de referência (mata); e o grau de floculação, nos manejos semeadura direta com rotação de culturas e cultura perene, foi proporcionalmente igual ao valor de referência (mata).

Soils are the foundation of terrestrial ecosystems and their role in food production is fundamental, although physical degradation has been observed in recent years, caused by different cultural practices that modify structures and consequently the functioning of soils. The objective of this study was to evaluate possible structural changes and degradation in an Oxisol under different managements for 20 years: no-tillage cultivation with and without crop rotation, perennial crop and conventional tillage, plus a forested area (reference). Initially, the crop profile was described and subsequently, 10 samples per management system and forest soil were collected to quantify soil organic matter, flocculation degree, bulk density, and macroporosity. The results indicated structural changes down to a soil depth of 50 cm, with predominance of structural units ∆μ (intermediate compaction level) under perennial crop and no-tillage crop rotation, and of structural units ∆ (compacted) under conventional tillage and no-tillage. The soil was increasingly degraded in the increasing order: forest => no-tillage crop rotation => perennial crop => no-tillage without crop rotation => conventional tillage. In all managements, the values of organic matter and macroporosity were always below and bulk density always above those of the reference area (forest) and, under no-tillage crop rotation and perennial crop, the flocculation degree was proportionally equal to that of the reference area.