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 (EI 30 ), 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.

SUMMARYWater 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.

The objective of this work was to evaluate corn agronomic traits in a cultivation subjected to different N rates, during the fall-winter (off-season) and spring-summer crop seasons, and N recovery from fertilizer. The experiment was set up in a randomized complete block design with four replicates, in a 5x2 factorial arrangement, with the following treatments: five N topdressing rates -0, 30, 60, 90, and 120 kg ha -1 -, using urea as source; and two crop seasons, fall-winter and spring-summer. The following variables were determined: plant height, height of the first ear insertion, number of grains per ear, diameter and length of ear, 1,000-grain weight, N concentration in the leaves and grains, grain-protein concentration, grain yield, N recovery from fertilizer, and soil-N supply. Nitrogen rates in the fertilizer in the fall-winter season had no effect on grain yield, although corn agronomic traits showed a greater reliance on fertilizer-N rates in that season than in the spring-summer, which is a season associated to a greater capacity of soil-N supply to plants. The quantification of soil-N supply enabled knowing the nutrient dynamics during the fall-winter and the spring-summer seasons, which may be useful to guide N fertilization of corn. Características agronômicas do milho e recuperação de nitrogênio do fertilizante durante a safra e a safrinhaResumo -O objetivo deste trabalho foi avaliar características agronômicas do milho em um cultivo submetido a diferentes doses de N, nas safras de outono-inverno (safrinha) e primavera-verão, e a recuperação do N do fertilizante. O experimento foi disposto em blocos ao acaso, com quatro repetições, em arranjo fatorial 5x2, com os seguintes tratamentos: cinco doses de N em cobertura -0, 30, 60, 90 e 120 kg ha -1 -, com uso de ureia como fonte; e duas estações de cultivo, outono-inverno e primavera-verão. As seguintes variáveis foram determinadas: altura de planta, altura da inserção da primeira espiga, número de grãos por espiga, diâmetro e comprimento da espiga, massa de 1.000 grãos, concentração de N nas folhas e nos grãos, concentração de proteína nos grãos, produtividade de grãos, recuperação de N do fertilizante e suprimento de N pelo solo. As taxas de N do fertilizante na estação outono-inverno não influenciaram a produtividade de grãos, embora as características agronômicas do milho tenham apresentado maior dependência do N do fertilizante naquela estação do que na primavera-verão, que é uma estação associada a uma maior capacidade do solo de fornecer N para as plantas. A quantificação do suprimento de N pelo solo permitiu saber a dinâmica do nutriente durante a safrinha e a safra de primavera-verão, o que pode ser útil para guiar a fertilização nitrogenada do milho.Termos para indexação: Zea mays, manejo da adubação nitrogenada, nutrição de plantas, fertilidade do solo, suprimento de N pelo solo.

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.

O dejeto de suíno (DLS) é usado como fertilizante cujos nutrientes são perdidos por erosão e contaminam o ambiente se o dejeto é usado inadequadamente. Objetivou-se avaliar o efeito de DLS no solo e na erosão, num Nitossolo Bruno. Os tratamentos, 0; 50; 100; e 200 m³ ha-1 de DLS foram aplicados superficialmente após a semeadura uma vez em cada um dos cinco cultivos, e na palhada do último cultivo, totalizando 0, 250, 500 e 1000 m³ ha-1, na aveia (Avena strigosa), milho (Zea mays), nabo (Raphanus sativus L.) e soja (Glycine max), e nos resíduos de aveia. A chuva simulada (65 mm h-1 e 75 minutos) foi aplicada três vezes no milho e quatro vezes no nabo, na soja, e nos resíduos, com um simulador de braços rotativos. Antes e depois da pesquisa, determinou-se o teor de K, Ca e Mg no solo. As chuvas aplicadas em cada momento compuseram um teste (T). O T1 ocorreu após a aplicação do DLS e os demais testes em intervalos que variaram entre 14 e 70 dias, em função do clima. Durante o escoamento, em intervalos de cinco minutos coletaram-se amostras de enxurrada para determinar as perdas de água e o teor de K, Ca e Mg na água. O DLS não influenciou o teor dos nutrientes no solo. O teor e as perdas totais dos nutrientes foram maiores com 1000 m3 ha-1 de DLS do que na ausência do dejeto. Com o aumento de escoamento, diminuiu o teor na enxurrada e aumentou a perda total, a qual aumentou também com o aumento de teor dos nutrientes na enxurrada. Recomenda-se aplicar menos do que 500 m3 ha-1 de DLS total no solo, mesmo em aplicações intervalares, devido à elevada perda de K, Ca e Mg pela erosão hídrica.

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 m 3 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 NO 3-, NH 4 + , 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 NO 3-, NH 4 + , P, and K + decreased as the period between PS application and simulated rainfall increased. Regardless of the soil and the treatment, NO 3 was transported in the greatest quantities, followed by K + , NH 4 + , and P.

O objetivo do estudo foi avaliar a qualidade de solos destinados a disposição de resíduos sólidos por meio da Cromatografia de Pfeiffer, a fim de diagnosticar a viabilidade dessa ferramenta de baixo custo para o monitoramento ambiental. Amostras de solo foram coletadas em dois aterros sanitários (AS1 e AS2) e dois lixões (ativo - LA e desativado - LD), em três profundidades (0-20, 20-40 e 40-60 cm), nas distâncias de 1, 5 e 10 m a partir dos taludes das células dos aterros e do ponto central de disposição nos lixões. As amostras foram submetidas a análise cromatográfica. Para a avaliação qualitativa utilizou-se os parâmetros cor, integração entre zonas, radiações, atividade biológica e terminações, aos quais foram atribuídos escores. A quantificação da área das zonas (central, interna, intermediária, externa e periférica) dos cromatogramas foi efetuada com o software ImageJ. A melhor qualidade do solo foi observada em AS2 com escores médios dos parâmetros acima de 8,0, enquanto LA apresentou a pior qualidade do solo, com escores médios igual a 1,7. AS2 e AS1 apresentaram as maiores áreas dos cromatogramas totalizando aproximadamente 13.000 mm2, considerando-se as zonas central, interna, intermediária e externa. Concluiu-se que há padronização das cromas relacionadas aos locais de amostragem, ocorrendo menor qualidade nos solos em áreas de lixões, sendo detectável via cromatografia de Pfeiffer a perda da qualidade edáfica em virtude da forma de disposição de resíduos. A aplicação desta técnica mostrou-se viável para o monitoramento da qualidade ambiental dos solos, uma vez que gera informações que permitem investigar ou confirmar a ocorrência de passivos.