FERTILIZATION SCHEDULING IN PEACH ORCHARDS UNDER TRICKLE IRRIGATION

Effects of different amounts of timings of fertilizer were compared in peach orchards. Increasing amounts of nitrogen improved peach-tree growth and yield. Nitrogen injection through trickle irrigation seemed to promote the 'June fruit drop' and to decrease the level of total soluble solids in the fruit. Nevertheless, nitrogen fertigation enhanced increase of trunk diameter, the weight of prunings and average fruit weights as compared with a single soil application of the same quantity of fertilizer. To explain such results, two hypotheses were formulated: a direct effect of the nitrogen fertilizer timing, or a reduction of the nitrate leaching that may be significant in permeable soil. Nitrogen fertilizing irrigation was particularly suitable when applied in the first year after planting and for fractionated supplies from the beginning of May to the end of September. Furthermore, potassium fertilizing irrigation did not increase fruit production, but the potassium level of the soil was already high at the beginning of the experiment.