Nitrogen and carbon management in Australian mango orchards to improve productivity and reduce greenhouse gas emissions

Abstract

Australian mango orchards, particularly of the 'Kensington Pride' cultivar, are often characterized by low yields and irregular bearing. Improved nutrition management techniques which increase total soil carbon sequestration and reduce nitrogen losses (nitrous oxide) may improve productivity and also reduce greenhouse gas emissions. A factorial trial was established in a 'Kensington Pride' mango orchard at Mareeba, Australia to assess the benefits of applying organic hay mulch to tree rows in combination with three nitrogen fertiliser treatments including two controlled-release fertiliser products. Three years after the initiation of treatments it was found that mango tree growth and fruit productivity was significantly improved when mulching was used to increase soil organic matter. Mulched soils had improved soil water holding capacity, less temperature variability, increased root biomass in the top soil, greater canopy leaf area and higher plant tissue potassium levels. Average fruit weights were increased by 10% and mango fruit yields per tree increased by 11%. Fruit quality was not affected when standard fungicide management treatments were used, although disease levels were higher with no post-harvest fungicide treatment. The nitrogen fertiliser products investigated did not have a significant influence on mango growth or final productivity. Trial results suggest that the adoption of mulching practices in mango orchards is a management practice which can increase orchard productivity and the sequestration of soil organic carbon, without detrimental effects on fruit quality.