Effects of reduced amounts of fertilizer on nutrition, fruit yield and quality of satsuma mandarin receiving frequent spraying with a small volume of liquid fertilizer
2010
Uematsu, T., Ehime-ken. Research Inst. of Agriculture, Forestry and Fisheries, Matsuyama (Japan)
Effects of overhead liquid fertilizer application on tree nutrition, yield and fruit quality of satsuma mandarin (Citrus unshiu Marc.) were investigated. Liquid fertilizer was prepared by dissolving solid fertilizer containing 15% nitrogen in water at 300-fold dilution. Fourteen-year-old 'Nichinan No.1' trees top-grafted on 'Nankan No. 20' (interstock)/trifoliate orange rootstocks were used. The soluble fertilizer was applied eighteen times between March and November. As controls, pellet-shaped solid fertilizer containing 10% nitrogen, 8% phosphorus and 7-9% potassium was applied on soil surfaces at a rate of 70 kg (middle March or early April), 80 kg (early October) and 50 kg (early November or middle November) per ha as nitrogen equivalents. In addition, plots in which the nitrogen content was reduced by 30% in both liquid and solid fertilizer were allocated. Both plots with reduced liquid fertilizer and solid fertilizer plots demonstrated equal yields, nitrogen concentrations in the leaves, brix and citric acid concentrations in the fruit juice. When liquid fertilizer was sprayed on the trees 18 times annually, it was thought that reduction by 30% was better. This indicates cost efficient overhead application of liquid fertilizers in satsuma mandarin orchards.
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