Reduction of chemical fertilizer usage in mandarin orchard and effects on yield and quality of mandarin fruits: On farm trial at Fang district, Chiang Mai province

• Main Authors: Viroonrat V., Sangsawang K., Bhromsiri A., Onpraphai T.
• Format: Article
• Published: Chiang Mai University 2015
• Subjects: Multidisciplinary
• Online Access: http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84872225677&origin=inward; http://cmuir.cmu.ac.th/handle/6653943832/38033
• Institution: Chiang Mai University

A field experiment was conducted in mandarin orchard of a farmer in Fang district, Chiang Mai province in order to evaluate the effects of reduction of the chemical fertilizer usage on yield and quality of mandarin fruits. The soil in the orchard had pH of 5.0 and contained high level of soil organic matter (2.5-3.0%), very high level of available P (>100 mg P/kg) and high level of exchangeable K (100-300 mgK/kg). The experimental design was randomized complete block with 5 replications and 4 treatments. In the first treatment, soil application of N, P and K fertilizers including foliar spraying of fertilizer according to farmer practice (NPK+FL) was used. In the second, third and fourth treatments, soil application of P and K fertilizers were omitted. In the second treatment, the same rates of N and foliar fertilizer spraying were the same as those in Tr.1 (-PK+N+FL). In the third treatment, the same rate of N fertilizer as used in Tr.2 was applied but foliar fertilizer was used according to the data of leaf analysis (-PK+N+fl). In the fourth treatment, the same rate of foliar fertilizer spraying as used in Tr.3 was applied while N fertilizer was applied according to N removal by fruit yield plus additional N to compensate N lost by leaching about 40% of N removal by fruit yield (-PK+n+fl). The collected data were, in season fruit yields harvested in December 2008 and January 2009, fruit sizes and the content of soluble solid of the fruits. It was found that in Tr.1, the total fruit yield was 80 kg/tree of which 56% were no.5 size and those with no.6 and no.4 sizes were 19 and 16% respectively. The content of soluble solid was 10.8 °brix for the fruits in the first harvest while those in the second harvest were 11.5 °brix. There were no significant differences of fruit yields and fruit qualities among the four tested fertilizer application rates. In Tr.2, the cost of input on fertilizer application could be reduced 57% compared to that of Tr.1 while in Tr.3 and Tr.4 the costs of inputs were reduced 88 and 97%.