Practical Use of Quality Compost for Plant Health and Vitality Improvement

Abstract

High quality composts were produced and applied at practical scale. The effects of these compost treatments on the health of potted plants were tested in a series of five laboratory trials. (1) Cress inoculated with Pythium ultimum was grown in pots containing 30% of two compost from two different origins. The disease developed with one compost, and was inhibited by the other. (2) Seedlings of cucumber were grown in substrate containing 0, 33, 67 or 100% of compost, and were inoculated with P. ultimum. With increasing proportions of compost, the disease was reduced. (3) Freshly steamed soil was amended with 10% compost (control: no compost). In the treated soil, far less nitrite was measured than in the control soil, and cucumbers were less attacked by P. ultimum. (4) Soil from a field treated with compost for five years was compared with soil not treated with compost. In the treated soil, cucumber seedlings were less attacked by P. ultimum, and lettuce seedlings were less attacked by Rhizoctonia solani, than in the control soil. (5) Barley was grown in pots containing 0, 10, 30 or 50% of composts from four different origins. With increasing proportions of compost, the incidence of powdery mildew was reduced, and there were significant differences between the compost origins.

The composition and the maturity of the compost influence the potential for suppression of plant disease. The management of the composting processes, and the oxygen supply in particular, seem to affect compost quality strongly. This has consequences on the storage management of the end products, as inappropriate storage measures can lead to reduction of product quality.