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Approximately 5% of the total emissions (0.11 Gt CO2 and GWP-AR5) originate in Rio Grande do Sul state (RS), a representative agricultural region in Southern Brazil. This study assessed SOCS (soil organic C stocks) in Latossolos of the Planalto of RS, with up-to-date data obtained from recent field campaigns and legacy data, and relate these SOC stocks to environmental variables. A literature search identified 195 documents with SOCS in layers 0-30 cm and 0-100 cm. The mean SOCS (0-30 cm) in the Latossolos was significantly higher (73.6 Mg ha-1) than the suggested IPCC default (55 Mg ha-1). The highest stocks (237 ± 39 Mg ha-1) were measured in uncultivated Latossolos Brunos in the 0-100 cm layer, especially at higher altitudes and lower mean annual temperature. The most frequently occurring soil Latossolo Vermelho distroférrico-LVdf (25% of the Planalto), also had high SOCS. Surprisingly Latossolos Vermelho Distrófico (LVd) also had high SOCS, in spite of the coarser texture. The estimated SOCS in Latosoolos of the Planalto is 419.9 Tg C, 36% larger than reported previous studies. We concluded that, despite significant land use changes, soils of this region maintain large SOCS which had been underestimated in previous studies. [ABSTRACT FROM AUTHOR]

RESUMO Com a pesquisa objetivou-se avaliar as modificações nos atributos químicos do solo e o efeito disso no desempenho dos atributos agronômicos do milho, após converter o manejo conduzido como preparo convencional para a forma de semeadura direta, em um Cambissolo Húmico alumínico léptico. A pesquisa foi conduzida em um experimento onde o preparo convencional (PC) e a semeadura direta (SD) vinham sendo estudados há 20. Após a conversão de manejo, a SD foi mantida e denominada semeadura direta consolidada (SDc) e o PC foi convertido à SD a qual foi denominada semeadura direta implantada (SDi). Determinou-se pH em água, alumínio, potássio, cálcio e magnésio trocável, fósforo extraível e carbono orgânico total (COT), antes e ao final de 30 meses da conversão de manejo. Ao final da pesquisa avaliouse também os atributos agronômicos do milho cultivado na SDi e SDc. Ao final da pesquisa, a SDi propiciou aumento do alumínio e potássio trocável e do COT, e diminuição do pH e do Ca, em comparação ao início da pesquisa. Maior massa da parte aérea e raízes e produtividade de grãos de milho foi observada na SDc em comparação a SDi.

Soil tillage restricted to the sowing line in area under no-till farming (NTF) promotes reaggregation and rearrangement of the structure, causing an increase in soil bulk density due to machine traffic. The objective of the research was to evaluate the effect of scarification associated with the use of cover crops on the physical attributes of an Oxisol in no-till area. The study was carried out in July 2017, the year in which the first cycle of cover crops was scarified and sown. The treatments consisted of two soil management systems: with scarification and without scarification; and three combinations of cover crops: fallow (FO), turnip + oats (TO) and mixture of cover crops (MX). In three periods, total porosity (Tp), macroporosity (Ma), microporosity (Mi) and soil density (Sd) were determined in different layers. At thirty-three months, scarification maintained higher Ma in the 0.20-0.30 m layer depth and in the scarified PO in the 0.30-0.40 m layer depth compared to turnip + oats. There is no long-lasting effect of soil scarification after forty months, but the cover crop mixture promotes an increase in Pt and a reduction in Ds specifically in the 0.10-0.20 m layer depth. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate whether soil management and the type of cover crop (MP) mixture, components of multifunctional agroecosystems, alter soil quality in a mango orchard (cv. 'Kent') irrigated in semi-arid environment, as well as identifying chemical and physical properties with potential for use as quality indicators. The data used is part of a long-term study that evaluates two soil management practices (tillage - T and no tillage -NT) associated with two compositions of cover crop mixtures (PM1- 75% legumes+25% of grasses and oilseeds; PM2- 75% of grasses and oilseeds+25% of legumes) and spontaneous vegetation (SV). The experiment was installed in 2007 and, for this study, the 2nd (2008) and 9th cycle (2017) of cultivation were used. The data were subjected to principal component analysis (PCA). The type of PM does not change soil quality, regardless of the management used, but the type of management used is a preponderant factor. The most superficial layer (0 - 0.05 m) in the system without disturbance showed better quality, characterized mainly by the greater accumulation of C in the soil. It was also not possible to discriminate differences in soil quality at other depths, regardless of the management or plant mix used. The variables identified as potential soil quality indicators are the chemical characteristics: H+Al, SB CTC, V, contents of C, P, Ca, Mg, K and on; and the physical characteristics Mi and Pt. [ABSTRACT FROM AUTHOR]

This research aimed to evaluate the changes in the soil chemical attributes and their effects on the agronomic attributes of corn, after conversion from conventional tillage (PC) to no-tillage (SD), in a Inceptisol soil (Cambissolo Húmico alumínico léptico). In an experiment where PC and SD effects had been studied for 20 yr, main plots under PC were converted to SD and referred to as implemented SD (SDi) while plots under SD remained unaltered and were referred to as consolidated NT (SDc). The pH in water, exchangeable aluminum, potassium, calcium, and magnesium, extractable phosphorus, and total organic carbon (COT), were determined at the beginning of the experiment and after a 30-month period. The agronomic attributes of corn grown under SDi and SDc were also evaluated. At the end of the experiment, plots under SDi evidenced an increase in exchangeable aluminum and potassium and COT, and a decrease in pH and exchangeable calcium. Corn biomass accumulation in shoots and roots increased and higher grain yields were observed under SDc compared to SDi. [ABSTRACT FROM AUTHOR]

As atividades antropogênicas em qualquer ecossistema natural causam modificações que afetam o ambiente físico e biológico, gerando degradação. Da mesma forma, essas atividades podem causar modificações significativas nos fatores químicos e físicos do solo, impactando também a comunidade microbiológica. O estudo objetivou avaliar a influência de características bioquímicas e físico-químicas do solo sobre o desenvolvimento de comunidades fúngicas em diferentes solos do bioma Pampa. Os tipos de solo selecionados foram: área de floresta nativa, área de plantação de eucalipto e área de pastagem, em dois períodos distintos: quente e frio. Foram realizadas análises microbiológicas, físico-químicas e bioquímicas dos solos. Identificaram-se os seguintes gêneros e espécie de fungos: Aspergillus sp., Aspergillus niger, Fusarium sp., Geotrichum sp., Isaria sp., Penicillium sp., Scedosporiumsp., Trichoderma sp., Verticillium sp. Os resultados mostraram que a comunidade fúngica está sendo afetada pela composição das características do solo, independentemente das áreas amostradas. Aspergillus sp. está associado a maiores quantidades de manganês, boro e da relação Ca+Mg/K no solo, enquanto A. niger e Trichoderma sp. têm relação negativa com essas variáveis. Aspergillus sp. mostrou elevada capacidade de tolerância ao Mn. A área mais diversa foi a de pastagem no período quente, e a menos diversa foi a área de eucalipto no período frio. Os táxons analisados tiveram redução no período frio em relação ao período quente, com exceção de Aspergillus sp. na área de eucalipto, que apresentou maior quantidade em período frio em relação ao período quente. Pode-se constatar que a utilização do solo no bioma Pampa, para plantação de monoculturas ou para a geração de pastagens, interfere em suas características e afeta distintamente a comunidade fúngica.

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Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Organic waste from agribusiness by-products has an effective capacity to improve the physical, chemical and biological attributes of soils, thus reflecting the stability and productivity of agricultural systems. Therefore, the present work aimed to evaluate the physical and chemical attributes of a Red-Yellow Oxisol with clay texture cultivated with soybean and corn in succession after five years of application of agro-industrial residues. The experiment began in 2012, in which three residues (sugarcane filter cake, peroba and cedar wood sawdust and eucalyptus sawdust) were applied in three doses, 6, 12 and 18tha-1, in two management systems (with and without residue incorporation), with three replications and two controls (without residue application with and without soil tillage). The experimental design was in randomized blocks with subdivided plots, being the management plots and the residues and doses the subplots. Five years after the application of the residues the physical and chemical attributes of the soil in the 0 to 20 cm layer were evaluated. The results demonstrate that the physical (macroporosity, microporosity, soil density, soil moisture equivalent to field capacity, available water capacity, S index) and chemical (total carbon) attributes were altered only by soil management. Soil revolving with the incorporation of high C/N and low degradability residues can increase long-term carbon content and thus improve soil physical attributes. [ABSTRACT FROM AUTHOR]

There has been an investigation using the association between three soil tillage systems (conventional, minimum, and no-tillage) with different previous crops (Pearl millet, Sun hemp, pigeon pea, and cowpea) and combination of nitrogen fertilization with Azospirillum brasilense in order to assess the technical efficiency of growing green corn under different soil tillage systems associated with crops before the planting of green corn under the combined presence of nitrogen fertilization and A. brasilense. The experiment was carried out on the Experimental Farm of the Universidade Federal de Sergipe, municipality of São Cristóvão, state of Sergipe, Northeast region, Brazil, from February to October, 2020. The chosen design was conducted in experimental strips with divided subplots, where the strips were made of by the systems. The subplots where the crops were randomized within each strip in three replications. This experiment evaluated green corn regarding: a) plant height; b) total leaf chlorophyll content; c) dry biomass yield; d) dry matter; e) mineral matter; f) crude protein; g) neutral and acid detergent fiber; h) total digestible nutrients. The CT/Guandu/N treatment promoted a greater increase in corn plant height and chlorophyll content; MT/Pearl millet/I obtained higher dry biomass yield; GO NT/Cowpea/N had the highest dry matter content; MT/Guandu/I promoted higher crude protein. Neutral and acid detergent fiber, total digestible nutrients were better in NT/Guandu/I, NT/Cowpea, and MT/Cowpea, respectively. The objective of the study was to evaluate the technical efficiency of forage production from green corn residues. [ABSTRACT FROM AUTHOR]

Na Amazônia o sistema convencional de cultivo da palma de óleo (Elaeis guineensis) está modificando a paisagem através do aumento do desmatamento, perda da biodiversidade e aumento do desgaste do solo. Um sistema alternativo de cultivo baseado na inserção de palma de óleo em Sistemas Agroflorestais (SAFs) foi proposto no município de Tomé-Açu (Pará, Brasil) a fim de avaliar o impacto desse sistema na qualidade do solo em comparação ao cultivo convencional (monocultivo). O objetivo deste estudo foi avaliar os impactos dois tipos de SAFs diferentes (com alta e baixa diversidade de espécies vegetais) sobre a porcentagem de colonização micorrízica (PCM) na palma de óleo e a densidade de esporos no solo em relação ao cultivo convencional. Foi avaliada a PCM em raízes finas (diâmetro ≤ 2 mm) e coletada amostras de solo (0-10 cm). A colonização micorrízica no cultivo de palma de óleo inserido nos SAFs foi maior em relação ao monocultivo, por outro lado a densidade de esporos foi mais elevada no sistema convencional. O manejo do solo baseado em Sistemas Agroflorestais com alta ou baixa diversidade de espécies vegetais podem contribuir para a colonização micorrízica na palma de óleo na Amazônia.

Copyright of Revista Verde de Agroecologia e Desenvolvimento Sustentável is the property of Revista Verde de Agroecologia e Desenvolvimento Sustentavel and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A baixa fertilidade natural e a compactação dos solos agrícolas do cerrado são as principais limitações para produção agropecuária. Mudanças nos sistemas de manejo são necessárias para otimização do uso de recursos naturais. O objetivo do trabalho foi mapear e avaliar a presença da resistência a penetração e sua relação com os atributos químicos do solo em áreas de pastagens no cerrado piauiense. O experimento foi realizado no município de Corrente-PI. A área foi dividida em duas subáreas de 0,5 ha cada: a primeira é de vegetação remanescente, e a segunda de pastagem. Foram retiradas 50 amostras de solos nas camadas: 0.00-0.20 e 0.20-0.40 m, com malha amostral de 10 x 10 m. Foram analisados, pH em água, matéria orgânica, cálcio, magnésio e resistência do solo a penetração. A introdução de animais na área de pastagem, aumentou a compactação do solo em 2%. Os atributos químicos, pH, matéria orgânica, cálcio e magnésio, variam de conforme a compactação do solo em 2%. A área de mata nativa apresenta resistência do solo à penetração em níveis aceitáveis ​​

Limestone, a common soil amendment in agriculture, is used to correct soil acidity by raising pH, increasing Ca and Mg levels, and neutralizing Al. This study evaluated the effectiveness of surface application of calcitic limestone doses to correct acidity at different soil depths. The research was conducted in a Eutroferric Red Latosol using a randomized block experimental design with eight repetitions in 30 m² plots, covering a total area of 960 m². Four doses of calcitic limestone (0, 3, 6, and 9 t ha-1) were applied without mechanical incorporation into the soil. Evaluations were performed at 12 and 24 months after the doses were applied, at depths of 0-0.05, 0.05-0.10, and 0.10-0.20 m, measuring chemical attributes such as pH, H+Al, Al, Ca, Mg, BS, and m. As the calcitic limestone doses increased, there were improvements in pH, approaching neutrality, an increase in Ca content, and an elevation in BS, reducing Al content and potential acidity. This demonstrated the effectiveness of calcitic limestone in increasing BS and reducing m. After 2 years, liming with calcitic limestone provided improvements to the root environment up to a depth of 0.20 m, with increased pH and base saturation, as well as reduced Al and H+Al levels. Furthermore, calcitic limestone doses did not influence soil Mg levels. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The low natural fertility and compaction of agricultural soils in the Cerrado are the main limitations for agricultural production. Changes in management systems are necessary to optimize the use of natural resources. The objective of this study was to map and evaluate the presence of penetration resistance and its relationship with soil chemical attributes in pasture areas in the Cerrado of Piauí. The experiment was carried out in the municipality of Corrente-PI, Brazil. The area was divided into two sub-areas of 0.5 ha each: the first is remaining vegetation and the second is pasture. Fifty soil samples were collected in the 0.00-0.20 and 0.20-0.40 m layers, with a sampling grid of 10 x 10 m. The pH in water, organic matter, calcium, magnesium, and soil penetration resistance were analyzed. The introduction of animals in the pasture area increased soil compaction by 2%. Chemical attributes, pH, organic matter, calcium and magnesium vary according to soil compaction by 2%. The native forest area has soil penetration resistance at acceptable levels (<2 MPa) and availability of nutrients at adequate levels. The maps of variability of organic matter, calcium, magnesium and penetration resistance showed the heterogeneity of the areas, allowing decisions based on specific management zones, localized application of nutrients and decompaction, and recovery of areas with inefficient management. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil management techniques applied by industrial farming have a profound impact on neighboring bodies of water, posing a threat to their aquatic biota. Therefore, water quality monitoring is essential to pinpoint areas of risk and propose remediation strategies. This preliminary study combined analysis of water quality physicochemical parameters and a trophic state index based on phosphorus concentration to characterize and compare two reservoirs in Pindorama/SP located in areas of distinct agricultural land management. Analyses showed that both reservoirs had total phosphorus concentrations above the federal threshold. It was then hypothesized that the excess of this nutrient was caused by the runoff of agricultural products from the surrounding area as no point sources of pollution were found. The first reservoir had a high density of floating macrophytes, which virtually covered the water surface, and was characterized as in a eutrophic state. The second reservoir, with lower macrophyte density and lower phosphorus levels, was characterized as in a mesotrophic state. These results evidenced that the overpopulation of macrophytes in the first reservoir may be a consequence of the eutrophication process. Furthermore, the presence of a more consolidated riparian forest which decreases the impacts of runoff in the second reservoir may explain its lower phosphorus levels. Finally, despite low turbidity, oxidation-reduction potential values in both reservoirs indicated low oxygen intake. The results demonstrate that these ecosystems are at risk of deterioration, thus strategies to improve the surrounding soil management and increase water circulation must be implemented. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

O objetivo deste trabalho foi avaliar os efeitos da irrigação localizada sobre os atributos físicos e hídricos de um Argissolo cultivado com pessegueiro. O experimento foi instalado em um pomar com quatro anos, em parcelas com e sem irrigação, onde foram coletadas amostras de solo em duas camadas (0,00 a 0,05 m e 0,10 a 0,15 m), nas posições de entrelinhas no rodado e entre o rodado das máquinas, e na linha entre e sob a copa das plantas. Amostras de solo com estrutura preservada foram coletadas para avaliação da densidade, porosidade, diâmetro de agregados, condutividade hidráulica e retenção de água. Observou-se que a irrigação localizada não influenciou os atributos físicos e hídricos do solo. Porém, as posições na linha e copa apresentaram maior macroporosidade e condutividade hidráulica, e menor densidade do solo, possivelmente pela construção do camalhão na linha de plantio e por não haver trânsito de máquinas nessas posições. O trânsito de máquinas fez aumentar a densidade do solo nas entrelinhas, ocorrendo diminuição da macroporosidade, particularmente, na camada superficial na posição do rodado. O volume de água disponível foi pouco sensível em identificar diferenças em relação aos efeitos da irrigação, camada de solo e posição no pomar e das variáveis relacionadas à estrutura do solo.

O objetivo desse trabalho foi avaliar o efeito de culturas de entressafra e fertilização com N mineral na implantação da soja sobre os teores de nitrato e amônio no solo durante a entressafra e a safra da soja. O delineamento experimental foi de blocos completos casualizados, com cinco repetições e em esquema de parcelas subdivididas. Nas parcelas foram alocados seis tratamentos de entressafra: pousio, milho segunda safra com 0 ou 80 kg de N ha-1 em cobertura, trigo, braquiária ruziziensis e crotalária spectabilis, sendo as duas últimas destinadas à cobertura do solo. Nas subparcelas foram alocados dois níveis de N na implantação da soja (0 e 30 kg de N ha-1). De abril de 2016 a fevereiro de 2017 foram realizadas 26 coletas de solo na camada de 0,0-0,1 m, sendo avaliados os teores de nitrato e amônio nas amostras. Durante o período de entressafra da soja, os maiores teores de nitrato no solo foram observados no milho segunda safra adubado com 80 kg de N ha-1, enquanto os teores de amônio variaram menos entre os tratamentos de entressafra. As culturas de entressafra não influenciaram os teores de nitrato e amônio no solo durante o ciclo da soja em sucessão. Na fase vegetativa da soja, os teores de nitrato no solo foram superiores quando a soja foi adubada com 30 kg de N ha-1, em relação à ausência de adubação, mas nas fases de formação de vagens e de grãos essa diferença não ocorreu.

O objetivo deste estudo foi avaliar a incidência e danos de tripes em cebola, em dois sistemas de manejo de solo com plantio direto na palha em sistema orgânico e no convencional com revolvimento, e sua relação com a produtividade. A cultivar de cebola utilizada foi a Epagri 362 Crioula Alto Vale. O estudo foi realizado durante os anos de 2014, 2015, 2016 e 2017. A incidência de tripes na maioria das avaliações foi menor em sistema orgânico com plantio direto na palha e menor densidade de plantas comparado ao convencional. Os danos foliares causados por tripes tenderam a ser similares entre os sistemas. A produtividade não foi correlacionada de maneira negativa com a incidência e danos de tripes. A produtividade foi superior em sistema convencional.

Buscou-se avaliar o desempenho fenológico de plantas de cobertura de solo utilizadas no verão e a produção de fitomassa nas condições edafoclimáticas da região de Vacaria, RS. O experimento foi conduzido no campo experimental da Fepagro Nordeste, em Vacaria, RS, na safra agrícola 2014/2015, com delineamento inteiramente casualizado com 4 repetições e 15 tratamentos: 1) calopogônio; 2) Crotalária breviflora; 3) Crotalária juncea; 4) Crotalária ochroleuca; 5) Crotalária spectabilis; 6) feijão de porco; 7) feijão guandu; 8) feijão guandu (anão); 9) lab lab; 10) milheto; 11) mucuna anã; 12) mucuna cinza; 13) mucuna preta; 14) soja perene e 15) testemunha (solo em pousio). Foram avaliados parâmetros fenológicos: data de emergência e altura das plantas. Avaliação da produtividade: massa verde e massa seca. Análise estatística teste Tukey 5%. As espécies Crotalária juncea, feijão de porco, lab lab, milheto foram as que tiveram rápido crescimento inicial. As espécies feijão guandu e o milheto apresentaram maior altura média. A espécie milheto foi a que produziu mais massa verde. A produção de massa seca foi maior na espécie feijão guandu. Considerando as produções de massa verde e seca destacam-se como as mais produtivas as espécies milheto, seguido pelo feijão guandu e a lab lab.

A argila dispersa está diretamente relacionada com a erosão hídrica, especialmente durante o desprendimento e arraste de partículas. O plantio direto é uma das mais importantes estratégias para conservação do solo e da água nas regiões tropical e sub-tropical, e quando associado com a rotação de culturas, pode reduzir o grau de dispersão de argila. O objetivo desse estudo foi avaliar, após 24 anos, o efeito de diferentes sistemas de manejo e de culturas no grau de dispersão de argila de um Latossolo Vermelho. O delineamento experimental foi inteiramente casualizado em um esquema fatorial 4x2, com quatro manejos do solo (plantio direto contínuo, plantio direto com escarificação a cada três anos, aração de discos seguida de gradagem leve e gradagem pesada seguida de gradagem leve) e dois sistemas de cultivo (sucessão de cultura e rotação). O grau de dispersão da argila foi avaliado e associado aos atributos químicos do solo da camada 0,00-0,10 m. O grau de dispersão da argila é afetado pelos sistemas de manejo do solo sem efeito dos sistemas de cultivo. O sistema de manejo de solo com menor perturbação do solo (plantio direto contínuo) possui o maior grau de dispersão de argila do que os que perturbam o solo, independentemente do implemento agrícola utilizado ou da intensidade do distúrbio do solo. O desequilíbrio eletroquímico do solo, causado principalmente pela acidez potencial do solo, está positivamente correlacionado ao aumento do grau de dispersão de argila da camada superficial do solo sob plantio direto contínuo.

O sistema plantio direto (SPD) reúne o maior complexo de tecnologias conservacionistas para solos tropicais e subtropicais, entretanto muitos produtores estão adotando parcialmente estes preceitos, potencializando a degradação do mesmo. O objetivo deste trabalho foi avaliar a qualidade do SPD em uma localidade, localizada no Planalto Médio do Rio Grande do Sul, observando qual a situação atual do manejo do solo e das glebas agrícolas da região conduzidas sob SPD. Foi realizado o monitoramento do uso do solo da localidade de Linha Cristal, situada no município de Selbach, RS, bem como a avaliação de glebas agrícolas que representassem diferentes manejos ali observados, além de uma mata nativa servindo de referência. Para isso, nestas glebas foram determinados os aportes de fitomassa seca (FMS) e o índice de cobertura (IC) da superfície do solo, a densidade (Ds), densidade crítica (Dsc) e grau de compactação (GC) do solo, além dos teores de matéria orgânica do solo (MOS). A análise estatística consistiu em análises univariadas (média e desvio padrão), já os resultados entre os teores de MOS e a Ds, também foram submetidos à análise de regressão. A área cultivada apresentou baixa diversidade de culturas no período de verão, predominando a soja (88,6%). Maior parte do milho em 2016/2017, destinou-se a produção de silagem (59%). Os cultivos de inverno foram mais diversificados, predominando a cultura do trigo, cevada, aveia branca e aveia preta. As médias anuais de FMS adicionada ao solo (13.147 e 11.508 kg/hectare/ano) estiveram acima do mínimo para manter os níveis de MOS estipulado pela literatura (9.000 kg/hectare/ano). As glebas agrícolas apresentaram a camada de 7-14 centímetros mais densa, onde apenas uma das glebas apresentou valor de Ds inferior a Dsc. Houve correlação linear inversa entre Ds e MOS, onde as áreas que continham maiores teores de MOS, apresentavam menores Ds.

The non-tillage system (NTS), until now considered an effective management tool for the control of erosion, has gradually increased the loss of soil. The objective of this research is to identify and understand the probable causes of the return of erosion in rural properties under the NTS in three municipalities in northern Paraná. For this research, a questionnaire was used to collect information on soil management and the use of agricultural terraces. Data collection was completed with 145 landowners and NTS users, along with rural extension and agricultural cooperatives. The results demonstrated that the return of erosion is likely due to the absence of crop rotation in favor of repetitive year-to-year planting of the same plant species (early soybean/maize [second harvest]/wheat), soil revolving to decompress the surface layer, and the elimination of agricultural terraces and the consequential downslope planting.

Em Sergipe, a alface (Lactuca sativa L.) é uma das hortaliças mais produzidas em sistemas irrigados, portanto é importante estudar meios que propiciem o melhor rendimento para a cultura. O objetivo deste trabalho foi avaliar a influência de diferentes tipos de cobertura do solo e a necessidade de adubação orgânica (esterco bovino) na produção de alface – cultivar Babá de Verão. O estudo foi desenvolvido na Fazenda Experimental – Campus Rural da Universidade Federal de Sergipe, localizada no município de São Cristóvão (SE). O delineamento utilizado foi de blocos casualizados com três repetições, em esquema fatorial de 4 x 2, com quatro tipos de cobertura (plástico preto, plástico preto e branco, plástico preto e prata e ausência de cobertura), e duas condições de adubação orgânica (ausência e presença). As características avaliadas da planta foram: diâmetro, matéria fresca e seca da parte aérea e número total de folhas. Houve efeito significativo para o fator adubação, em que as plantas que receberam adubação orgânica obtiveram resultados superiores em relação às plantas não adubadas. A cobertura que proporcionou melhores resultados foi a com plástico preto e branco, chegando a valores de diâmetro, massa seca e fresca da parte aérea e número de folhas totais iguais a 32,6 cm, 17,11 g, 307,9 g e 54 folhas, respectivamente. A cobertura com o plástico preto e branco melhora o desempenho do cultivo da alface cv. Babá de Verão. O uso de adubo orgânico é fundamental para a melhoria do desenvolvimento da alface.

A sustentabilidade dos sistemas de plantio direto e preparo convencional do solo em regiões semiáridas deve considerar as variações dos atributos do solo ao longo do tempo. Assim, objetivou-se avaliar as alterações nos atributos físicos e biológicos de um Typic Eutrustox (Latossolo) sob diferentes usos (plantio direto, preparo convencional e mata nativa) na região semiárida. O experimento foi realizado em unidades com 18 x 18 m dentro de sistema de plantio direto (SPD), preparo convencional (SPC) e mata nativa (MN). Para cada uso determinou-se a densidade de partículas, densidade do solo, porosidade, resistência à penetração, respiração microbiana e carbono orgânico nas profundidades 0,00-0,05; 0,05-0,10; 0,10-0,20 e 0,20-0,40 m. O SPD e SPC alteram os atributos físicos do solo superficial em relação à MN, com maior compactação na camada arável do SPC. O solo sob MN, além das vantagens físicas, também possui atributos biológicos superiores ao SPD e SPC em todas as profundidades avaliadas. O SPD é o uso mais próximo das condições de MN em relação à qualidade biológica, representada pela respiração microbiana. Após nove anos de implantação do SPD e SPC, destaca-se a necessidade de aporte contínuo de matéria orgânica para manutenção das vantagens do SPD em relação ao SPC nas condições do semiárido.

Soil degradation caused by erosion is one of the biggest environmental problems. The Geographic Information System (GIS) QGIS and ArcGIS were used to prepare thematic maps. The average slope resulted in smooth wavy (42.1%), flat (27.8%), and wavy to strong wavy (19.9%) over the entire length of the sub-basin. Erodibility resulted in very high (41%) mainly in sectors with a predominance of Neossolos Quartzarênicos soils, on average (7.1%) in the South and Southwest and low (51.1%) of the area corresponding to the soil of the type Dystrophic Yellow Latosol. The expansion of the agribusiness associated with inadequate soil management in areas susceptible to erosion at BHRG can compromise long-term environmental, social, and economic sustainability. It is important develop suitable agricultural techniques appropriate to the soil to optimize its use and its sustainable production capacity. [ABSTRACT FROM AUTHOR]

The productivity and quality of watermelon fruits can be influenced by several factors, edaphic or associated with cultural management, such as, the type and form of soil preparation and planting methods, which can be by direct sowing or through transplanted seedlings. The objective of this work was to evaluate productive characteristics and quality of watermelon fruits grown under different forms of soil preparation and planting methods. The experimental design used was randomized blocks, organized in a 2x3 factorial scheme, containing three replications, with 24 plants per plot. The evaluated factors were two forms of soil preparation and three forms of cultivation. The fruits were harvested when their tendrils showed visible signs of dryness, when their productive and qualitative characteristics were analyzed. The variables analyzed were the number of fruits per plant, fruit mass, transverse and longitudinal circumference of the fruits, total soluble solids (° Brix), total titratable acidity, maturation index (ratio) and total productivity. The planting methods do not alter the productive characteristics and the quality of the watermelon fruits, which proved to be adequate to the standard demanded by the national market. Conventional tillage, with plowing followed by harrowing, increases the number of fruits per plant and total productivity, reaching 30.7 Mg ha-1, a value 35.08% higher than the average for the state of Rondônia and 28.33 % above the national average. [ABSTRACT FROM AUTHOR]

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The aim of this study was to determine the effect of four soil management systems on the physical attributes of an Oxisol for Eucalyptus crops in western Mato Grosso, Brazil. The management systems are differentiated by the soil preparation form during the implantation and initial forest establishment phases, namely a conventional system (plowing, harrowing and subsoiling for preparation and harrows for weed control after planting) and a conservationist system (pasture desiccation, subsoiling, herbicide weed control and cover crop), with added differences in the eucalyptus fertilizer supply manner (haul and furrow). Nine soil layers were sampled continuously for each management system in between the sowing lines using 100 cm2 volumetric rings (0.05 m in diameter and height), totaling a studied layer of 0.45 m. The following variables were evaluated: total pore volume, microporosity, macroporosity, density and soil resistance to penetration. The different managements did not lead to significant differences for the studied attributes two years after forest establishment, with only a small depth effect observed. The attribute values are within the appropriate limits for eucalyptus crop development, indicating good soil quality under the eucalyptus forest for the study conditions. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Agricultura Irrigada - RBAI is the property of Revista Brasileira de Agricultura Irrigada - RBAI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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One of the strategies for the recovery of degraded soils is the planting of fast-growing forage species with high biomass production. In this sense, the objective of this research was to evaluate the initial growth of sorghum in degraded soils with organic fertilization and different phosphorus levels. A completely randomized design with a 4 x 3 x 2 factorial arrangement was used, with four soil types, three levels of phosphorus fertilization and two levels of organic fertilization. At 64 days after sowing the characteristics of the initial growth were analyzed: plant height, stem diameter, leaf number and fresh shoot mass. The height was measured by measuring the neck of the plant until the end of the newest fully expanded leaf, measured with the aid of a measuring tape and expressed in centimeters. The diameter of the stem, by means of a digital pachymeter. The application of phosphorus and organic matter in degraded soils is necessary for the initial development of sorghum plants, due to the low availability of this element, caused by the high adsorption of P in the soil colloids. Besides that, the lack of organic matter in the studied soils led to a decrease in the growth of sorghum, therefore, it is concluded that soil management in saline environments is necessary for the application of phosphorus and organic matter for a sustainable and technically viable production. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ciencias Agroveterinarias is the property of Revista de Ciencias Agroveterinarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

No-tillage is conservationist soil management for agricultural production and it is based on soil cover by crop residues and restricted mobilization to the sowing line. However, its structure can be affected by the excessive compaction resulting from the traffic of machines. The objective of this study was to evaluate soil physical properties and crop performance in no-tillage with and without scarification, combined with different successions of plant species, in a Humic Cambisol. For this, the species of black oat, wheat and forage turnip were cultivated in winter, and later, corn and beans in summer. Soil samples were collected at the beginning and at the end of the experimental period, while evaluations of plant yield were carried out in the final stage of development. Soil scarification reduces relative density (RD) and soil resistance to penetration (RP) after preparation of soil, with effect restricted to the surface layer. Such effects persist for one year, however RD and RP increase over time, regardless of soil management. RP is more sensitive for evaluation of soil compaction and correlates positively with RD, with exponential adjustment. The aerial biomass of black oat, wheat and forage turnip was not affected by soil scarification, and crop yield of beans and corn showed to be more related to the previous cultivation than the scarification in no-tillage. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Agricultura Irrigada - RBAI is the property of Revista Brasileira de Agricultura Irrigada - RBAI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The organic carbon present in the landfill leachate (LL) can improve the physical quality of the soil when applied in agricultural areas, minimizing the problem of disposal of this waste. The objective of this work was to evaluate the effect of the application of different doses of LL on the physical quality of the Red Latosol (Oxisol) after five years of applications. The treatment consisted of applications of LL in doses of 32, 65, 98 and 130 m3 ha-1 crop-1 and the treatment that receives mineral fertilizer. The physical quality of the soil was evaluated in soil samples collected in the layers 0.00-0.10 and 0.10-0.20 m, through the analysis of stability and diameter of the aggregates, soil density, total aeration capacity, field capacity and available water content. After five years of application of LL, at doses of 65, 98 and 130 m3 ha-1 crop-1 have promoted a linear increase of the aggregates with diameter greater than 2.00 mm, of the weighted average and geometric diameters and of the soil density, with a consequent reduction of the ratio between macro and micropores and the aeration capacity of the layers 0.00-0.10 and 0.10-0.20 m. After five years of these applications, the soils that received the dose of 32 m3 ha-1 crop-1 presented the best physical quality in relation to the other doses, since this dose did not promote an increase of the aggregates larger than 2 mm in the superficial layer (0.00-0.10 m) and was the dose with lower effect in the reduction of aeration of the soil, in relation to the others (65, 98 and 130 m3 ha-1 season-1) in the layers 0.00-0, 10 and 0.10 - 0.20 m.

The implementation of agricultural systems such as viticulture can quantitatively and qualitatively affect the contents of soil organic matter (SOM). These changes may modify the edaphic features of the soil as well as the soil quality. The objective of this study was to evaluate the chemical and physical fraction of SOMand to analyze changes in the carbon stock and C management index in areas of implanted vineyards in altitude regions of Santa Catarina. Four regions were selected: Region I (Urubici); Region II (San Joaquim); Region III (Campos Novos) and Region IV (Água Doce). In each region, we selected vineyards implanted between 2001 and 2005 as well as surrounding forested areas. Disturbed and undisturbed samples were collected from the 0-5, 5-10, and 10-20 cm layers of the soil. Samples were prepared in the laboratory to obtain air-dried soft soil, which was then used for the analysis of several parameters, namely total organic carbon (TOC), carbon stock,and chemical fractionation of the soil. The chemical fractionation was then used to determine carbon content in the fulvic acid fraction (C-FAF), humic acid fraction (C-HAF), and humin fraction (C-HUM). We also analyzed particle size, quantified the levels of particulate carbon (COp) and carbon associated with clay and silt (COam), and calculated the carbon management index (CMI). We evaluated normality and homogeneity for all data. The results were evaluated with an analysis of variance and subsequent F-test. Mean values were compared using a 5% Student’s t-test and subsequently submitted to a Tukey’s test. The highest TOC levels were observed in Region II in the 0-5 cm layer in both vineyard and forested areas. Vineyard areas exhibited lower values of TOC, Cop, and COam compared to forested areas indicating that the management adopted in these areas contributed to the reduction of these fractions. Forested areas exhibited a higher proportion of Cop compared to vineyard areas. The humin fraction represented the largest portion of the TOC and comprised the highest values in both forested and vineyard areas. The carbon management index indicated a low contribution of vineyard areas or a reduction in carbon storage in their soils.

Com a intensificação das atividades humanas, com aumento das taxas de uso e ocupação dos solos, aumentaram as discussões no âmbito da reforma agrária e da viabilidade dos assentamentos rurais. Assim, este estudo teve como objetivo comparar o uso e a ocupação dos solos em áreas de assentamentos rurais na região norte de Minas Gerais. Três assentamentos rurais foram selecionados para comparação das classes de uso da terra nos anos de 2003 e 2014, com auxílio de técnicas de sensoriamento remoto. A amostragem de solo foi realizada nas classes do uso definidas para determinação dos atributos químicos. Os resultados obtidos foram submetidos à análise de variância e as médias pelo teste de Tukey (p

Copyright of Engenharia na Agricultura is the property of Engenharia na Agricultura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engenharia na Agricultura is the property of Engenharia na Agricultura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Traditional cassava cultivation involves mechanical manipulation of the soil with one plowing and two harrowings, a practice that may generate problems such as soil erosion, compaction and nutrient loss. These issues may be even bigger in sandy soils. The objective of this study was to evaluate the cassava roots components and the soil physical attributes in planting rows and between planting rows in tillage systems substituting the conventional tillage before the Mombasa grass pasture (Panicum maximum), in Northwestern Paraná, Brazil. Soil tillage treatments in 2014 were carried out as follows: conventional (disc harrow, moldboard plow and disking), minimum (disc harrow and chisel plow - clod breaking) and zero tillage. In 2015, soil samples were collected in layers 0.0-0.1, 0.1-0.2 and 0.2-0.4 m deep, between, and within cassava planting rows, for soil bulk density and macroporosity determinations. Number of plants, number of tuberous roots per plant, fresh and dry mass of cassava tuberous roots were evaluated as well. The soil physical attributes within the planting rows negatively affected the production of cassava tuberous roots in zero tillage in succession to the Mombasa grass pasture. The minimum and conventional tillage systems did not present soil physical limitations to the cassava yield components in succession to Mombasa grass pasture. Minimum tillage may be an alternative to conventional tillage without compromising soil physical attributes and cassava root yield in the Mombasa pastureland reform areas, in northwestern Paraná. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the effect of off-season crops and fertilization with N mineral at soybean sowing on the nitrate and ammonium contents in the soil during the off-season and soybean development cycle. The experimental design was of randomized complete blocks, with five replications and in split plod scheme. Six off-season treatments were evaluated in the plots: fallow, maize with 0 or 80 kg of N ha1, wheat, Urochloa ruziziensis and Crotalaria spectabilis. In the subplots two levels of N were evaluated in the soybean sowing (0 and 30 kg N ha-1). From April 2016 to February 2017, 26 soil samples were collected in the 0.0-0.1 m layer, and the nitrate and ammonium contents in the samples were evaluated. During the off-season, the highest contents of nitrate were observed in maize fertilized with 80 kg de N ha-1, while ammonium contents varied less among off-season crops. The off-season crops did not influence the soil nitrate and ammonium content during the soybean cycle. In the vegetative phase of soybean, nitrate contents were higher when the soybean received nitrogen fertilization in relation to the absence of fertilization, but in the pod and grain formation there was no effect of the nitrogen fertilization on the contents of inorganic N. [ABSTRACT FROM AUTHOR]