Effect of Organic Fertilizers and Soil Conditioners on the Quality of Maiden Apple Trees

Production of maiden (one-year-old) trees under organic management is considered difficult due to the high nutrient requirements for production of trees of good horticultural quality. Maiden trees of the apple cultivars 'Topaz' and 'Ariwa' grafted on M26 rootstocks were produced in an organic nursery with the use of several fertilizers and soil conditioners of different origins: a seaweed extract (BioFeed Quality), a plant extract reinforced with amino acids (BioFeed Amin), a consortium of mycorrhizal fungi and plant growth-promoting rhizobacteria (Micosat), vermicompost extracts (Humus UP, Humus Active + Aktywit PM), an exhausted yeast production culture broth derived from sugar beet molasses (Vinassa), and titanium (Tytanit). These treatments were compared with standard fertilizers used in organic (granulated bovine manure) and conventional (chemical fertilization (NPK)) production and an unfertilized control. Even though the experimental fertilizers and soil conditioners provided 50 to 70% fewer nutrients than the standard manure or NPK treatments, they generally produced maiden trees with trunk thickness and tree height similar to or greater than the chemically fertilized controls. Several products (Micosat, BioFeed Quality, BioFeed Amin and Vinassa) also increased the branching of the maiden trees and length of lateral shoots. The results confirm that these new organic fertilizers can provide plants with an adequate nutrient supply and could be used successfully in organic apple nurseries.