Evaluation of composts for growth of grass sod

Abstract

Composts prepared from sewage biosolids-wood chips, mixed municipal solid wastes, autumn leaves, mixed yard wastes, or agricultural wastes were assessed for their effects on growth and composition of perennial ryegrass (Lolium perenne L. ‘Pennfine’). Two biosolids based composts, one mature and one immature, were evaluated. All of the other composts were mature. No supplemental fertilization was provided. Composts were evaluated without amendment or by mixing with soil and sand to create media (proportions by volume) of 100% compost, 90% compost:10% soil-sand, and 75% compost:25% soil-sand. Grass sods were grown in plastic flats in a greenhouse. Quality of sods was assessed by emergence of grass and weeds and by clipping mass in two successive harvests. Macronutrients, micronutrients, and nonessential elements were determined in the grass clippings of each harvest. Grass emergence was lowest in the mixed municipal solid waste compost, which had the highest soluble salt contents of the media. Slight inhibition in grass emergence was noted with the immature biosolids-wood chips compost and the agricultural compost, both of which were nitrogen (N)-rich media. Mean emergence of grass seedlings was increased in all composts, except the yard waste, by additions of sand and soil to dilute the compost. However, emergence of soil-borne weeds lowered the quality of sods as the proportions of soil-sand increased in the media. The principal effects on mass of grass clippings were due to type of compost, harvest, and the interaction of these factors. High N or ammonium restricted the growth in the immature biosolids-woodchips compost, whereas N deficiencies limited growth in the leaf and yard waste composts. Mass of clippings was higher in the second harvest than in the first harvest. Potassium (K) accumulation was low in grass grown in the immature compost, but nutrition with calcium (Ca), magnesium (Mg), and micronutrients was not limiting in any medium. Bioaccumulation of nonessential elements [aluminum (Al), leaf (Pb), cadmium (Cd)] was not apparent. In general, N-rich, well-matured composts were good media for sod growth.