Abstract
The reuse of organic byproducts in agroforestry systems is a sustainable proposal, since, in addition to preserving the natural resources, it has allowed the fertilization of the soils, obtaining a reduction of costs with mineral fertilizers. Therefore, the objective of this research was to evaluate the chemical attributes of the soil after two years of successive fertilizations using cattle manure and sewage sludge in agroforestry systems. The study was conducted in Goiânia, state of Goias, Brazil. The experimental design used randomized blocks on a 2 x 4 factorial (cultivation systems and fertilizations), with four repetitions. The cultivation systems were: agroforestry and monoculture systems. The fertilizations used were: cattle manure, sewage sludge, mineral fertilizer and control (no fertilization). Regardless of the cultivation system, the fertilizations with sewage sludge increases the calcium, phosphor and zinc contents of the soil, as well as the pH values, sum of bases and cation exchange capacity, at 0-10cm depth. However, the potassium contents are lower in relation to the use of mineral fertilizers, both at 0 to 10 cm depth and at 0 to 20 cm. Teak plants in agroforestry systems presents similar heights to the monoculture plants, and they are higher on fertilizations with sewage sludge. The soybean grain productivity in the agroforestry system presents similar outputs in relation to the use of sewage sludge and mineral fertilizers. Therefore, it is recommended for farmers to adopt agroforestry systems and the organic fertilization practice with sewage sludge, associating the quality of the chemical attributes of the soil, the growth of forest species and soybean grain yields. Key words: Tectona grandis, sewage sludge, cattle manure, intercropping systems, soybeans.
Highlights
The increase in the productivity of forest cultures by area unit is the current objective in order to meet the worldwide growing demand for wood (Smitha et al, 2016)
The highest phosphorus contents (P) in the soil were observed at the 0 to 10 cm depth on fertilizations with sewage sludge (SS) (p
P showed the same behavior on the principal component analysis (PCA) with a high correlation with the SS treatment
Summary
The increase in the productivity of forest cultures by area unit is the current objective in order to meet the worldwide growing demand for wood (Smitha et al, 2016). One highlight is cattle manure, since it offers benefits to the chemical attributes of the soil, helping to increase mineralization and the availability of nutrients to the plants (Tejada et al, 2008), mainly due to its capacity to interact with metals and metal oxides and hydroxides, creating organometallic compounds, in addition to potentiate the nitrogen and phosphor stocks (Muraishi et al, 2011). Another byproduct, from an urban origin, sewage sludge has been deeply investigated regarding the potential improvements of the chemical attributes of the soil (Ricci et al, 2010; Bittencourt et al, 2012; Costa et al, 2014; Cavalcanti et al, 2015). Considering these questions, the search for solutions for an adequate destination for this byproduct has been considered vital, and agricultural recycling seems like the most promising alternative from the economic and environmental perspective (Barbosa et al, 2007)
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