Fertigation of agricultural crops that are not directly used in human food, with domestic wastewater is a viable alternative for the sustainable use of water resources. The development of agricultural practices that provide high productivity with the sustainability of agroecosystems has been a great challenge. Thus, our aims were to use of domestic wastewater in the planting of Brachiaria brizantha cv Marandu, as an alternative for animal feed production in Cerrado soils, and to study the physical-chemical and microbiological impacts of the fertigation. These impacts were evaluated, respectively, by physical-chemical indicators content and diversity of nitrogen fixing bacteria (NFB) and arbuscular mycorrhizal fungi (AMF) in the DGGE profile. The NPK contents of the wastewater were used to determine the five fertigation managements (M1 to M5). M1 and M2 managements had no wastewater and M3 to M5 contained 20, 40 and 60% of NPK from the wastewater. The managements in a completely randomized design with 20 plots and 4 replicates were distributed. Soil samplings prior to fertigation and at the end of the experiment were performed. Leaf biomass productivity was determined in three different grass cuts. After fertigation, changes in physical-chemical indicators and in the viable microbial cells counts were observed. The NPK of wastewater increased the abundance of NFBs and AMFs. Leaf biomass productivity per hectare was directly proportional to NPK concentration. In addition, wastewater did not alter the nutritional composition of Marandu grass. Therefore, the fertigation with domestic wastewater showed to be a viable and promising alternative for reuse of this water in Cerrado soil for animal feed production.

Population growth and improved gross domestic product may increase food consumption. Soybean is the main source of protein, lipids and mineral salts for human and domestic animals’ foods. Brazil is responsible of most of the soybeans produced in the world. However, soybean production in Tocantins/Brazil state caused a decrease in the Cerrado’s biome. Therefore, the aim of this study was to evaluate the anthropic impact of planting of soybean on microbial and physical-chemical properties of Cerrado’s soil. Soil samples were collected in three soybean farms (SF) of the Tocantins/Brazil state. They were collected in the soybean field, in native vegetation field, and in anthropogenic fragmentation area in the dry and wet seasons. The diversity of arbuscular mycorrhizal fungi (AMF) and nitrogen-fixing bacteria (NFB) were analyzed by denaturing gradient gel electrophoresis (DGGE). Regardless of the SF, physico-chemical indicators did not present significant differences between the seasons. The DGGE profiles of NFB and AMF genes were different between the soybean field and native vegetation field in both seasons. The viable cells counts and NFBs and AMFs diversity were influenced by the substitution of native vegetation for soybean. The increase of the agricultural production in Cerrado soil is worrisome, due to the endemic microorganisms that was observed in this study. In addition, anthropic action on the microbial community was more effective in the soybean field during the dry season, which showed the importance of maintaining an environmental reserve area within agricultural production units.

The wastewater has been an environmental problem, but your used as fertilizers could reduce or eliminate the application of commercial fertilizers in soil. Arbuscular mycorrhizal fungi (AMF) and nitrogen fixing bacteria (NFB) are a good parameter to analyze the impacts of this fertigationon soil. We aimed to evaluate the distribution and diversity of AMF and NFB before and after applications of wastewater or manure from green line of a cattle slaughterhouse in the irrigation of B. brizantha cv Marandu in Cerrado soil and leaf biomass productivity. The experimental design was performed in completely randomized blocks with ten biofertigation managements. The seeds of the forage were distributed in grooves with spacing of 5 cm. This seeds were covered with a soil layer. NFB and AMF diversity was performed by denaturing gradient gel electrophoresis (DGGE). The leaf biomass productivity in the biofertigation managements was higher than in the managements without the use wastewater/manure. After biofertigation managements, changes in the DGGE profile of the NFB and AMF communities were observed. These changes may be due to the difference in the sample collection period and in the soil humidification. Thus, these DGGE profiles was a good parameter to diagnose the efficacy of wastewater/manure as an alternative biotechnological irrigation.

Cattle slaughterhouses are potential causes the environmental impacts, as it require a large volume of water in meat processing, generate large effluents amount, and promote the Cerrado deforestation for animal husbandry. Therefore, we aim was carried out to assess the effects of the soil application of a green line wastewater from a cattle slaughterhouse in the Brachiaria brizantha growth. The M1 and M2 managements did not contain wastewater of slaughterhouse. The wastewater from the 3 rd stabilization pond (M3 to M5), from reception box (M6 to M8), and manure (M9 and M10) were used in the biofertigation managements. The physical-chemical indicators levels did not show significant differences (p < 0.05) before soil preparation and after managements. However, biofertigation in the Cerrado soil can provide a mitigation of the leaching of fine soil particles and cations. In addition, maximum nitrogen dose of wastewater provided a higher leaf biomass productivity than commercial nitrogen. Thus, the fertigation with wastewater can reduce the use of water bodies to crops irrigation and the incorporation of new areas with native vegetation to the agricultural production systems.

RESUMOAvaliaram-se os efeitos das variações espacial e temporal dos parâmetros da equação de Kostiakov-Lewis, na estimativa da infiltração acumulada. Foram realizadas avaliações de campo num sistema de irrigação por sulco, para cada evento de irrigação ao longo da estação de cultivo, durante a qual foram observadas variações espaciais máximas de 94,7, 44,3 e 55,2% e, espacialmente, as variações temporais máximas foram 80,0, 42,5 e 43,8%, respectivamente, nos parâmetros fo, k e a.