Compost Quality Assessment for Use in Horticulture: Impact of the Composting Process

Abstract

Although there are many potential opportunities for the use of agricultural composts in horticultural production systems, lack of communication between compost producers and end-users has impeded the effective recycling of manure-based composts to benefit soil health. Our survey of compost users found that compost performance in terms of plant production was a primary concern in choosing which products to use, but that there was little agreement on which parameters of compost quality would predict satisfactory performance. Twenty-five agricultural manure-based composts from NY State were analyzed in terms of 1) method of production, 2) parameters of finished material, and 3) performance as measured by seed germination and plant growth. Results showed that these composts were appropriate for a variety of horticultural uses. Manure type (poultry vs. dairy) as well as separation (separated and unseparated dairy manure) had a major impact on compost parameters. Certain aspects of the composting process affected characteristics of the finished material, with pad type (soil, gravel or concrete) impacting nitrogen, phosphorus and organic matter content and the use of CuSO4 foot baths for hoof health impacting both copper levels and soluble salts. A detailed information sheet for agricultural composts that provides sufficient information for horticultural end users to make informed purchasing choices is proposed.