Abstract The application of pig slurry (PS) to soil is known to change its chemical and physical properties. However, little is known about the alterations that PS causes in pore morphology and water erosion. This research evaluated the influence of PS on the morphology of the pores in the surface layer of the soil and on water erosion in an Inceptisol subjected to simulated rainfall. The soil was cultivated with black oats and the treatments (doses) 0, 50, 100 and 200 m3 ha-1 of PS were applied to the crop residue. The experimental design was completely randomized. Six simulated rainfall lasting 60 minutes and planned constant intensity of 65 mm h-1 were applied to the treatments. Undisturbed soil samples were collected in the 0-0.05 m layer, 24 h before and 24 h after the first, third and sixth rainfall events. Image analysis was performed, determining the percentage of macropores and mesopores, number, diameter and shape of the pores, using the micro morphometry technique. PS doses of 100 and 200 m3 ha-1, combined with simulated rainfall, favored surface sealing and pore rearrangement. There was an increase in the number of small and rounded pores, without interconnection between them, with a consequent increase in water erosion until the moment of stabilization of the superficial crust.

Resumo O dejeto líquido de suínos (DLS) aplicado no solo reconhecidamente altera as propriedades químicas e físicas. Porém, ainda são pouco conhecidas as alterações que o DLS causa na morfologia dos poros e na erosão hídrica. Com esta pesquisa objetivou-se avaliar a influência do DLS na morfologia dos poros da camada superficial do solo e na erosão hídrica, em um Cambissolo submetido à chuva simulada. O solo foi cultivado com aveia preta e os tratamentos (dose) 0, 50, 100 e 200 m3 ha-1 de DLS foram aplicados sobre o resíduo da cultura. O delineamento experimental foi o inteiramente casualizado. Seis chuvas simuladas com duração de 60 minutos e intensidade constante planejada de 65 mm h-1 foram aplicadas aos tratamentos. Amostras indeformadas de solo foram coletadas na camada de 0-0,05 m, 24 h antes e 24 h após o primeiro, terceiro e sexto eventos de chuva. Foi realizada análise de imagem, determinando-se a porcentagem de macroporos e mesoporos, número, diâmetro e forma dos poros, pela técnica de micromorfometria. As doses 100 e 200 m3 ha-1 de DLS, combinadas com a chuva simulada, favoreceram o selamento superficial e o rearranjo dos poros. Houve aumento do número de poros pequenos e arredondados, sem interligação entre eles, com consequente aumento da erosão hídrica até o momento de estabilização da crosta superficial.

ABSTRACT: Runoff in agricultural areas with intensive application of pig slurry can transport significant amounts of nutrients. This study evaluates the effects of different pig slurry (PS) application rates (0, 50, 100, and 200 m3 ha-1) on nutrient loss through runoff during soybean cultivation under no-tillage. It was conducted at two sites in southern Brazil, one on an Alfisol (27° 43' south and 50° 3' west) and one on an Inceptisol (27° 47' south and 50° 18' west). The PS was applied to the soil once at the beginning of the soybean cycle. Each plot was 11 m long in the direction of the slope and 3.5 m wide. To induce runoff, artificial rainfall was applied in four different tests (T1, T2, T3, T4), with an intensity of 65 mm h-1 for 90 minutes. The first test was performed one day after PS application, while the other tests were performed throughout the soybean cycle. During each test, runoff samples were collected at 10-min intervals after the beginning of runoff. The runoff amount and the NO3-, NH4+, P, and K+ concentrations in the runoff were measured. In T1, nutrient transport from the Alfisol and the Inceptisol increased with increasing PS doses. In some cases, this effect was still noticeable in T2 and T3, but not in the last test (T4). The transported amounts of NO3-, NH4+, P, and K+ decreased as the period between PS application and simulated rainfall increased. Regardless of the soil and the treatment, NO3- was transported in the greatest quantities, followed by K+, NH4+, and P.

Resumo: O objetivo deste trabalho foi determinar parâmetros de ajuste para a equação universal de perda de solo revisada (Rusle) de um solo submetido à aplicação de dejeto líquido de suínos. Os tratamentos consistiram de 0, 50, 100 e 200 m3 ha-1 de dejeto líquido de suínos (DLS), após o cultivo de aveia-preta (Avena strigosa), além da aplicação de 50 m3 ha-1 de DLS por seis vezes à superfície do solo, em uma sequência temporal, e de um controle com solo sem cultivo e sem dejeto. As avaliações foram feitas quanto à massa de matéria seca da parte aérea da aveia-preta, à massa de raízes e aos resíduos da cultura semi-incorporados ao solo, às perdas de solo por meio de chuva simulada e aos parâmetros para modelagem de erosão hídrica. A aplicação de dejeto líquido de suínos à superfície do solo causou a diminuição dos valores de consolidação do solo (Cf), o aumento da massa de raízes vivas e mortas e dos resíduos culturais incorporados à camada superficial (0.0-0.1 m) do solo (Bu), e a redução dos valores de uso anterior da terra (PLU) na Rusle.

Abstract: The objective of this work was to determine adjustment parameters for the revised universal soil loss equation (Rusle) of a soil subjected to pig slurry application. Treatments consisted of 0, 50, 100, and 200 m3 ha-1 pig slurry (PS), after the cultivation of black oat (Avena strigosa), besides the application of 50 m3 ha-1 PS for six times onto the soil surface in a temporal sequence, and a control treatment of soil without cultivation and without pig slurry application. The evaluations were performed for black oat shoot dry mass, root mass and crop residues semi-incorporated into the soil (RMR), soil losses by means of simulated rain, and the parameters for water erosion modeling. The pig slurry application onto soil surface caused a reduction in the values of the soil consolidation parameter (Cf), an increase in the mass of living and dead roots and cultural residues incorporated in the upper layer (0.0-0.1 m) of the soil (Bu), and a reduction in the subfactor prior land use (PLU) of the Rusle.

ABSTRACT Water erosion degrades the soil and contaminates the environment, and one influential factor on erosion is slope length. The aim of this study was to quantify losses of soil (SL) and water (WL) in a Humic Cambisol in a field experiment under natural rainfall conditions from July 4, 2014 to June 18, 2015 in individual events of 41 erosive rains in the Southern Plateau of Santa Catarina and to estimate soil losses through the USLE and RUSLE models. The treatments consisted of slope lengths of 11, 22, 33, and 44 m, with an average degree of slope of 8 %, on bare and uncropped soil that had been cultivated with corn prior to the study. At the end of the corn cycle, the stalk residue was removed from the surface, leaving the roots of the crop in the soil. Soil loss by water erosion is related linearly and positively to the increase in slope length in the span between 11 and 44 m. Soil losses were related to water losses and the Erosivity Index (EI30), while water losses were related to rain depth. Soil losses estimated by the USLE and RUSLE model showed lower values than the values observed experimentally in the field, especially the values estimated by the USLE. The values of factor L calculated for slope length of 11, 22, 33, and 44 m for the two versions (USLE and RUSLE) of the soil loss prediction model showed satisfactory results in relation to the values of soil losses observed.

A infiltração de água no solo é um importante processo hidrológico que ocorre na interface solo-atmosfera; assim, o manejo do solo tem forte influência nesse processo. Este estudo teve por objetivos avaliar a infiltração de água no solo e comparar as equações para estimativa da sua taxa de infiltração de água em Argissolo Vermelho distrófico típico, após a colheita da cultura do feijão (Phaseolus vulgaris L.) sob chuva simulada. Os testes de campo, com uso de simulador de chuvas, foram realizados nos sistemas de manejo do solo: cultivo mínimo (CM), preparo convencional (PC) e plantio direto (PD). No PD, foram feitas avaliações sobre quatro níveis de resíduo vegetal na superfície do solo: 0, 3, 6 e 9 Mg ha-1. Os modelos de Kostiakov-Lewis, Horton e Philip foram utilizados para estimativa da taxa de infiltração. No CM, a taxa de infiltração final foi de 54 mm h-1, enquanto no PC e no PD, com até 3 Mg ha-1 de resíduo vegetal na superfície, a taxa foi próxima de 17 mm h-1. No PD, houve aumento na taxa de infiltração com cobertura de resíduo acima de 6 Mg ha-1, ou seja, houve correlação positiva entre cobertura vegetal e taxa de infiltração de água. O modelo de Horton foi o mais adequado para representar o comportamento da taxa de infiltração de água no solo, podendo ser recomendado para a estimativa dessa variável independente do sistema de manejo de solo utilizado.

Water infiltration in the soil is an important hydrological process that occurs at the interface of the soil-atmosphere system; thus, the soil management practice used has a strong influence on this process. The aim of this study was to evaluate water infiltration in the soil and compare equations for estimating the water infiltration rate in an Ultisol after harvesting common bean (Phaseolus vulgaris L.) under simulated rainfall. Field tests with a rainfall simulator were carried out in three soil management systems: minimum tillage (MT), conventional tillage (CT), and no tillage (NT). In NT, four levels of plant residue on the soil surface were evaluated: 0, 3, 6, and 9 t ha-1. The models of Kostiakov-Lewis, Horton, and Philip were used to estimate the infiltration rate. In the MT system, the final infiltration rate was 54 mm h-1, whereas in the CT and NT systems with up to 3 t ha-1 of plant residue on the soil surface, the rate was near 17 mm h-1. In addition, the results indicated that in the NT system the infiltration rate increased with plant residue coverage greater than 6 t ha-1, i.e., there was a positive correlation between plant cover and the water infiltration rate. The Horton model was the most suitable in representing the water infiltration process in the soil. Therefore, this model can be recommended for estimation of this variable regardless of the soil tillage system used.