OIL PALM BIOMASS ASH IMPREGNATED WITH PHOSPHORUS IN Lactuca sativa CULTIVATION
Agro-industrial waste, fertility, soil conditioner.
The need to recycle nutrients, reincorporating them into agricultural systems, and the proper destination of residues produced in agro-industries, demand studies to define the potential of these residues as soil conditioners. Palm oil ash (POA) is an agro-industrial waste resulting from the incineration of plant residues in the oil extraction process, the disposal of which can cause environmental damage. The rational use of these ashes can improve soil conditioning. Therefore, there is a need to characterize and define the quantities that can be used to improve soil fertility and increase agricultural productivity. The characteristics and the effect of doses of two ashes on soil fertility and the residual effect were studied, using lettuce (Lactuca sativa L.) as a test plant. Two types of ash were used: C1 - produced at temperatures of 400 to 500 oC and C2 - produced at temperatures of 800 to 1000 oC. Physicochemical characteristics, soil fertility were determined after application of the CPO and the growth and nutrition of lettuce were evaluated. The two ashes showed similar results in terms of pH and electrical conductivity, while C1 had a higher CTC and C2, a higher particle density. High total levels of P were observed, mainly K, Ca, Mg, Mn, Mo, Cu, Zn and B, with C2 being richer in nutrients. The ash has the power to neutralize the exchangeable Al, raise the pH and reduce the potential acidity. Both CPO increased and increased the inorganic carbon in the soil, with C1 increasing the organic carbon and presenting a higher CTC. The CPO increased the concentrations of P, K, Ca and Mg in the soil. The lettuce culture responded positively to the application of the CPO, with significant increases in height, diameter, number of leaves, leaf area, fresh and dry mass of the aerial part and roots until the application of 3% of CPO. The greatest responses were obtained when C2 was applied and DMEAs ranged from 3,3 to 4% for C1 and 3,6 to 5,1% for C2.