No abstract

The faxinal management system is an endangered agro-silvopastoral system which forms part of the local traditional management in the Paraná federal state (Brazil). Significant changes in land management since the 1970s caused farmers to look for alternatives to increase the productivity of their farms. The introduction of new pasture species is causing land degradation problems, of which soil erosion is the most important challenge. Therefore, in this study, we assessed the environmental consequences of introducing exotic pasture species, such as Brachiaria decumbens. To achieve this goal, ten erosion plots were installed with exotic and native pastures (Paspalum notatum Flüggé) to quantify soil and water losses in paired plots. Total rainfall per event, soil properties (soil cover, texture, organic matter, bulk density, porosity, and soil penetration resistance), and pasture production were also estimated. Our results showed a decrease in organic matter and porosity and an increase of the bulk density in the exotic pasture plots. Soil erosion monitoring showed higher soil losses for the exotic cultivated plots (359.8 g m −2 or 3.6 mg ha −1) than for the native plots (90.7 g m −2 or 0.91 mg ha −1). The highest percentage of bare soil surfaces and compaction coincided with the highest soil erosion rates measured in the exotic pastures. However, the mean fodder production in the exotic plots was almost five times higher (987 kg DM ha −1) than in the native ones (204 kg DM ha −1). These findings confirm that farmers have an internal conflict. They want to optimize the production of fodder, but this leads to high soil erosion rates and reduces soil fertility in the medium-and long-term. The traditional, less productive pastoral system is more sustainable from an environmental and cultural point of view. However, this system may not be sustainable from an economic point of view.

Brazil is one of the main producers of pork meat in the world. It is well-known that the agricultural sector is a key component of the economic development of this country, where super-intensive fields are only competitive in the globalized market. For the farmers, the application of swine manure to fertilize the soil can increase the yearly income, but it also may cause serious environmental problems related to soil health and soil quality. In this research, we assessed the effects of applying liquid swine manure in a tropical soybean (Glycine max) plantation to better understand when this technique stops being effective and starts causing a threat to soil health and quality. Therefore, we compared values of several soil properties and the soybean yield on treated fields at 10 random points belonging to 7 different plots that were treated with the liquid swine manure over a period ranging from 0 to 15 years. The results showed a positive linear trend in soybean production from 2.45 to 3.08 Mg ha−1 yr−1. This positive trend was also recorded for some key soil parameters such as porosity and exchangeable cations content (Ca, Mg, K, and Al). Additionally, positive effects were also found for organic matter content after 10 years of application. Our findings suggest that the use of liquid swine manure has a positive effect on soybean yield and improves soil quality, particularly on mixed farms where pigs are intensively raised nearby cultivated fields.

O entendimento da produção e transferência de sedimento das vertentes para o fundo de vale e canal fluvial é essencial aos propósitos da Geomorfologia. Os objetivos desse trabalho foram: verificar a produção de sedimento em barranco de estrada e canal fluvial; reinterpretar estudos anteriores no sentido de avaliar a proveniência de sedimento em diferentes usos da terra e estimar balanço de proveniência de sedimento em cabeceira de drenagem enfocando a participação das estradas rurais não pavimentadas. A metodologia constou de mapeamento para identificação das áreas fontes de sedimento; observações em campo e monitoramento sistemáticos por meio de técnica volumétrica (pino de erosão). Concluiu-se que as estradas rurais não pavimentadas foram as principais fontes de sedimentos na área de estudo (46,5%), apesar de representar 1,6% da área ocupada. As estradas rurais aumentaram a densidade de drenagem da cabeceira em 48,7%. As estradas configuram-se como conectoras entre as vertentes e o canal fluvial, facilitando a entrada de sedimento nos riachos.Palavras-chave: cabeceira de drenagem, áreas fontes de sedimento, proveniência, uso da terra, estradas rurais não pavimentadas.

No-tillage and inter-crops have been progressively introduced into traditional Brazilian tobacco plantations. However, there is a lack of information about their impact on soil erosion rates and soil properties. We studied 10 experimental plots in Paraná (Brazil) that rotated from no-tillage tobacco to two different inter-crop types (black beans and oats) and conventionally tilled tobacco to quantify erosion rates from September 2014 to February 2016. The results show that soil loss (18 Mg ha −1 ) and runoff coefficient (8.3%) were higher under conventional tillage tobacco than under no-tillage tobacco (3.4 Mg ha −1 and 0.6%). Bulk density was higher at the end of the cropping cycle than at the beginning. We concluded that conventional crops increased soil erosion, and the use of inter-crops and no-tillage is highly recommended for soil and water conservation. The findings should be valid for other regions that have similar cropping systems and environmental conditions.