Development of a Labor-saving Fertilization Method Using Controlled-release Fertilizer in Central Leader Trained ‘Ishiji’ Satsuma Mandarin

Abstract

We developed a labor-saving fertilizer application method in ‘Ishiji’ satsuma mandarin whereby the nitrogen quantity of summer and autumn fertilizer can be reduced by 30%, using controlled-release fertilizer to reduce the working time for spreading fertilizer under permeable and reflective sheet mulching on steep sloping orchards. The developed fertilizer application method reduced the working time by 20% per year compared with the control of three times a year, because autumn fertilizer application and mulch opening and closing could be omitted. The 30% reduction in the quantity of summer and autumn fertilizer nitrogen had no influence on the yield or fruit quality for 3 years. From the above, it was suggested that the working time can be reduced and the yield and fruit quality are unaffected when using the developed fertilization method.