SILVA, L. V. B. D.; http://lattes.cnpq.br/9189485400834209; SILVA, Leda Veronica Benevides Dantas.
Resumo:
The use of byproducts in agriculture has become quite a promising alternative by providing
a destination for the highly-organic waste materiais produced by a variety of human
activities, it serves to bolster both environmental and economic factor, providing elevated
leveis of nutrients to the plants which, in turn, brings about a reduction in the costs of
chemical fertilization. The objective of this study was to evaluate the residual effects of
organic fertilization using castor cake as well as the impact of the disposal of treated
sewage effluents on the chemical properties of the soil and the development and
production of cotton cultivated in succession to a crop of sesame plants. Cotton plants were cultivated in pots which had been previously used for the cultivation of sesame that had been submitted to treatments resulted from the factorial design of five leveis of castor cake in the substrate (0, 2, 3, 4 and 5 ton ha"1), two qualities of irrigation water (potable water and treated domestic effluent) in addition to two additional treatments with chemical
fertilization (NPK + potable water and NPK + wastewater). The residual effect of the
castor cake and fertilizer sources applied in the first cycle and the inherent impact of the
application of the two different sources of irrigation water on the cotton crop and the plant-
soil system were evaluated through the determination of growth and cotton production, soil
chemical properties and nutritional state of cotton plants at the end of the cycle. It was
possible to conclude that the irrigation with wastewater contributed to reduce the soil
acidity and elevate phosphorous and potassium contents in the soil and plant. Additionally,
the domestic effluent was capable of partially supplying the nitrogen content and
completely supplying the leveis of boron and iron required by the plants, contributing to
the growth and production of cotton. However, the sodium leveis were elevated plant and
soil as a result of irrigation with potable water. The castor cake applied during the first
cycle resulted in a residual effect, with the increasing leveis of biofertilizer increasing the
organic material content, phosphorous and iron in the soil, in addition to increasing the leaf
area, height, dry matter of the aerial part and cotton production during the second cycle.