EFFECT OF SOIL MANAGEMENT ON TREE NUTRITION AND YIELD IN APPLE ORGANIC ORCHARDS

Influence of soil management systems on apple tree mineral nutrition and yield was investigated in organic orchards in Lithuania. The experiment was conducted in 2009-2012 with ‘Lodel’ apple trees on rootstock P 60 planted at 4 x 1.25 m. Soil between rows was managed as sward or fallow in all interrows; sward and fallow in alternate interrows or green manure and fallow in alternate interrows. Soil in the rows of fallow treatment was cultivated mechanically. The experiment revealed differences in fruit tree nutrition. The highest leaf nitrogen content was where soil was cultivated in the interrows; the lowest in frequently mown sward treatment. Combinations of white mustard for green manure with fallow or frequently mown sward with fallow resulted in intermediate leaf nitrogen values. Leaf phosphorus, boron, calcium, manganese and zinc content in sward interrow treatment were higher in some years of the experiment. The highest yield and better fruit colouring was in sward treatment. Higher supply with nitrogen had a negative effect on tree winter hardiness.