Soil fertility and productivity of apple orchard under a long-term use of different fertilizer systems
Uman National University of Horticulture, 1 Instytutska str., UK20305 Uman city, Ukraine *Correspondence: firstname.lastname@example.org
An apple should be planted on suitable soils which can be used for growing two or more generations of gardens for decades. This can be reached by creating and supporting an optimum level of mineral nutrients for fruit trees. The aim of this study was to compare the long-term effect of mineral or organic fertilization on apple tree growth and yield and soil fertility. The research has been conducted since 1931, when an apple orchard of Winter-Calville on seedlings was established on dark-grey heavy loam soil of Uman National University of Horticulture. The non-irrigated trees were subjected to the following treatments: 1. Unfertilized (control); 2. Application of cattle manure 40 t ha-1 (organic); 3. N120 P120 K120 (mineral); 4. 20 t ha-1 of humus N60 P60 K60 (organic-mineral). In 1982 the first orchard was removed and 2 year later another one was re-planted on the same soil. The second orchard, that included, beside the same variety also Idared grafted on seedling and on M4, was subjected to the same treatments.
Soil fertility and apple tree productivity increased under the use of organic fertilizer system. Organic-mineral fertilizer system provided almost the same response, while mineral fertilizer system provided the lowest one.
During the study a decreased uptake of nutrients applied with fertilizers was often related to insufficient soil moisture supply. Soluble nitrogen was washed out of root layer into ground water, while phosphorus and potassium were transformed into compounds and forms inaccessible for plant nutrition. Thus it is necessary to apply those rates of fertilizers that are insufficient in the soil to reach the optimal levels of content of corresponding nutrients which should be determined by agrochemical analysis.
It is possible to maintain an optimal fertility of soil in orchards by applying only organic fertilizers. Alkalization of inter-row spacing with regular grass mowing (turf and humus soil management system) provided the same humus content in soil as application of 40 t of humus per ha in a year after the use of fallow system.