THE EFFECTS OF ORGANIC AMENDMENTS ON SOIL PROPERTY AND PRODUCTIVITY OF GREENHOUSE-GROWN BRIDAL PINK ROSES

The effects of organic amendments on the chemical and physical propert ies of soil and the productivity of greenhouse-grown 'Bridal Pink' ros es were studied for four years. This trial consisted of seven syntheti c soil mixes plots and were combined with two fertilizer treatments. T hree plots contained 70, 50, and 30 % (by volume) of an equal amount o f well fermented cow manure and wood chips; the remainder was made up of volcanic black ash soil. Three plots had similar percentage composi tions of amendments except that they consisted of hemlock bark manure. The seventh plot consisted of 50 % Danish sphagnum peat moss and volc anic soil. The fertilizer treatments were : A) a mixture of organic fe rtilizers and liquid fertilizer and B) a mixture of a soluble and slow release chemical fertilizer. Six 'Bridal Pink' plants grafted on seed lings of Rosa multiflora were planted per wooden box (72 x 90 x 30 cm depth) lined with a plastic net to retain the soil. The leachings were collected periodically after watering and analyzed for nutrients. Flo wers were harvested annually for four years and graded for quality. 1. No difference in yield and stem length of cut flowers was observed in the first year; the stem lengths were shorter in the second year, esp ecially in the 70 and 50 % wood : manure mixtures. 2. In the third and fourth years,a severe decrease in soil volume occurred in the 70 and 50 % mixtures. The soil was replenished in these plots at the beginnin g of the third year; none was added to the 30 % mixture of the wood : manure and 30 % bark manure plots,and 50 % peat moss plot. In the thir d and fourth years, a slight reduction in yield occurred in the plots without soil replenishment. 3. No difference in yield was noted in the first year between fertilization plots; yield was higher in the third year in the chemical plot compared to the organic fertilizer plot. 4. While large accumulations of nutrients in the soil occurred in soils containing high amounts of cow manure, analysis of the leaching showed that many nutrients were being lost by the daily watering. Hence, at replanting time, the soils were leached with excessive irrigation. The trial showed that the physical conditions of the soil could be kept f avorable by the addition of peat moss, followed by that of bark manure addition. Though cow manure in large volume can improve the physical property of a synthetic soil, temporarily, for growing roses in the gr eenhouse, it would not suitable for long term growing because of signi ficant decrease in gaseous phase in soil.