The effect of filter-press cake on the physical and chemical properties of soils

Abstract

Data are presented here on soil conditions at the Arecibo and Corozal filter-press-cake experimental fields 18 months after establishing the treatment differentials. The experiments were located on a Bayamón silty clay and a Lares clay, respectively, both representative of the group of soils generally used for growing pineapples in the northern and interior districts of the Island. A previous report indicated that maximum yields of pineapple in the Arecibo region could be obtained with applications of 1,500 pounds to the acre of a 12-6-10 fertilizer, if applications of filter-press cake were made at the rate of 32 tons to the acre. At Corozal, however, both heavy applications of filter-press cake (32 tons) and of fertilizer (3,000 pounds) were necessary for obtaining maximum yields. Soil samples were taken from the top 6 inches at both locations and analyzed for pH, nitrogen, organic matter, total exchange capacity, exchangeable calcium, magnesium, and manganese, and available phosphorus and iron. In addition, undisturbed soil cores were taken at Corozal and data were gathered on the permeability, rapidity of drainage, maximum saturation, water retained at various tensions, porosity, and bulk density. Although no significant differences were obtained in most cases, some trends were observed, such as the retention of larger quantities of available moisture at low tensions in a state of ready availability for plants by soils to which filter-press cake was added than by those to which only fertilizer was applied. The C/N ratios were narrow in all cases, indicative of quick decomposition of the organic residues after application.