Nutrition management in conversion-to-organic citrus orchard in the Indonesian citrus and subtropical fruits research institute

One of the main challenges in organic citrus cultivation is how to manage land and nutrients so that plant needs can be met all the time while maintaining soil quality. This paper provides information on applied nutrition management, evaluation of changes in soil characters, and production in the conversion-to-organic citrus orchard in the Indonesian Citrus and Subtropical Fruits Research Institute. The citrus used are 5-year-old Siam citrus (Citrus nobilis Lour.) grafted on Japansche Citroen rootstock. The initial stage in the conversion to organic farming is the creation of ecosystems that support organic agriculture and improvement of soil fertility through the cultivation of gliricidia (Gliricidia sepium) and marigold (Tagetes erecta L.) as living hedges around the garden, planting citronella grass (Cymbopogon nardus) and marigold (Tagetes erecta L.) in the embankment, and planting land cover crop. Nutrition management in the orchard includes the application of green manure sourced from biomass of the living hedges, soybeans (Glycine max (L.) Merill) and wild plants obtained from the orchard; application of compost from dolomite enriched goat manure; and application of liquid organic fertilizer from fermented goat manure with local microorganisms. Nutrition management applied in the organic conversion orchard in the first year was followed by improvement in some soil characters, namely pH, organic matter content, cation exchange capacity, total N and exchangeable Ca but vice versa for available P, exchangeable K, and Mg. Citrus production in the first year fell by about 11% from the previous year and was followed by a decrease in the other quality parameters of fruits, except for the levels of vitamin C and total acid.