Assessment of the potential of a novel newspaper/horse manure-based compost

The use of a newspaper/horse manure compost as an alternative to peat-based compost or coir fibre was assessed by comparing various physical, chemical and biological properties. The concentration of nitrogen in the newspaper/horse manure compost (1.7%) was significantly greater than the nitrogen concentrations in the peat-based compost (1.3%) and coir fibre (0.9%). The concentrations of potassium, magnesium, calcium and phosphorus were similar in all substrates, as were pH values, while the water holding capacity was twice as high in coir fibre as in peat-based or newspaper/horse manure composts. Toxicity tests, carried out using a cress bioassay, gave a germination index for newspaper/horse manure compost of 6896, higher than for peat-based compost or coir fibre (6776 and 6632, respectively) indicating that no inhibitory compounds were present. Tomato plants were grown in each substrate for nine weeks to assess the usefulness of the different substrates. The plants grew well in all substrates and no significant differences in biomass (shoots, roots or leaves), or in the nutrient concentrations of leaf material, could be detected. The chemical and biological properties of the newspaper/horse manure compost suggest that this compost could be used as an alternative to peat-based compost and could provide a technology to utilise large quantities of waste paper. (C) 2000 Elsevier Science Ltd. All rights reserved.