Experimental Assessment of Soils to Be Used for Land Application of Vegetable and Fruit By-products

Abstract

Infiltration and chemical transport rates are needed to select sites for land application of food-processing vegetable by-products. Sandy soils and dry, cracked clay soils tested with double-ring infiltrometers have infiltration rates of 0.08 to 0.26 cm/min, whereas silty soils have rates of less than 0.05 cm/min. Infiltration rates measured using a tomato slurry are lower, regardless of the nature of the soil (0.01 cm/min or less) because the suspended solids plug soil porosity. Chemical transport was quantified by repeated sampling of control (not dosed) and experimental (dosed with vegetable by-products) lysimeters filled with silty sand and silty clay. The silty sand lysimeters showed progressive increases in the values of copper, HCO3, chlorine (Cl), total dissolved solids (TDS), fixed dissolved solids (FDS), calcium (Ca), magnesium (Mg), iron (Fe), sodium (Na), and potassium (K) between the control and experimental lysimeters, and decreases in pH and SO4 at a solute front rate of about 0.5 cm/d. The silty clay lysimeters showed progressive increases in the values of Cl, TDS, FDS, Ca, Mg, and Fe between the samplings; mild increases for HCO3, Na, and K; and decreases in pH and SO4. Anions were not retained by adsorption onto the soil, monovalent cations (Na, K) were slightly retarded by adsorption, and divalent cations were significantly retarded (Ca, Mg). The infiltration study indicated a better hydraulic performance from silty sands than from ripped or cracked clay soils, but the chemical transport observations suggest good adsorption of cations onto clay soils. Silty sands with some clay are the best compromise for hydraulic performance and chemical transport.