Precision nitrogen fertigation for improved apple quality and reduced leaching
Swarts, ND and Hardie, M and Green, S and Close, DC, Precision nitrogen fertigation for improved apple quality and reduced leaching, 29th International Horticultural Congress 2014, 17-22 August 2014, Brisbane, Australia (2014) [Conference Extract]
Nitrogen (N) management is a balance to meet tree demands for current seasons’ crop as well as for internal storage for the subsequent season whilst reducing N loss. Whilst fertigation is commonly practised by apple growers in Australia, research into tree nutrient requirements and therefore approaches to supply is limited. In the Huon valley of southern Tasmania, we applied N (Ca(NO3)2) treatments pre- and post-harvest combined with three seasonal irrigation treatments over two seasons to 10 year-old ‘Galaxy’ trees grafted on M26 rootstocks. Above-ground, we measured yield, fruit quality attributes, leaf and fruit N content. Below ground, we measured soil N content and leaching below the root zone using drainage lysimeters. Pre-harvest N application and high irrigation treatment significantly increased fruit size, however, firmness was reduced both at harvest and after four weeks cold storage (under normal atmosphere). Fruit background colour significantly decreased under greater N inputs. No influence of N application was observed in leaf, fruit and soil N content in the first season, however, the accumulation of N in tree leaf, fruit, soil and drainage lysimeters was observed in the second season. Irrigation treatments significantly influenced the amount of water collected in the drainage lysimeters, however, the greatest N leaching was observed during the winter months when the soil moisture content reached field capacity. This study demonstrates the importance of N and irrigation management on the above and below ground components of orchard production. Precision fertigation can significantly improve the efficiency of N use through benefiting fruit quality whilst minimising the loss of N below the root zone.