Use of calcium fertilizers in apple orchards grown on neutral and alkaline soils
1990
Svagzdys, S.
Results of long-term experiments on nutrition of apple trees have shown that systematic and abundant applications of mineral fertilizers do not increase apple yields and do not improve nutritional status of the trees but, on the contrary, they break nutrient equilibrium. The greatest unbalance was noted between potassium and magnesium. Potassium fertilization was not able to regulate balance of those elements. Experiments carried out by Lithuanian Horticultural Research Institute indicate that calcium fertilizers (phosphogypsum) influence fruit yields by changing levels of nutrients in soil and apple tree leaves as well. In the 1st and 2nd year after application of phosphogypsum fruit yield increased by 26,7% while after using mineral fertilizers it increased by 49,7%. During the subsequent 3rd and 4th year of the experiment effect of fertilizers upon apple fruit yield was insignificant. The concentration of nitrates in apples did not exceed the background nitrate quantity. An increase of leaf potassium was accompanied by a decrease of leaf magnesium content. Phosphorus and potassium were distributed rather evenly in the soil profile. The experimental data have shown that phosphogypsum is effective in acid soil as well.
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