In search of the optimal N fertigation dose for ‘Conference’ pear trees

Fertigation is the dispersion of fertilizers trough an irrigation system and allows a precise distribution of the nutrients in the root zone. Fertigation is often used in combination with drip irrigation in ‘Conference’ pear tree in Belgium and the Netherlands to maximize fruit yield. To optimize the efficiency of the N fertigation, the fertigation can be applied at the end of the vegetative growing period at the beginning of fruit maturing. This way vegetative growth of the pear tree is minimized while fruit yield is maximized. In search for the optimal N fertigation strategy this study discusses the effect of three different fertigation doses (0, 25 kg N, 50 kg N), applied six weeks before harvest, in a humid and a dry irrigation treatment. The experiment was conducted in three different fruit orchards with varying soil profiles and plating systems in two successive years (2008-2009). Fertigation with 25 to 50 kg N resulted in a 20 % higher fruit yield in two of the three orchards independently from the irrigation regime. Water stress induced yield decline and increased the risk of an excessive N residue in autumn. The study proves the necessity of N during fruit maturing but also discusses the risks accompanied with excessive N fertilization.