The response of Citrus sinensis ‘Midknight’ (Nelspruit, Mpumalanga, South Africa) and Citrus paradisi ‘Orri’ (De Wet, Western Cape, South Africa) to excessive fertilisation (double the normal rate) with nitrogen (N), phosphorus (P), potassium (K) and magnesium (Mg) was investigated. The goal was to determine whether early-season leaf mineral compositions respond to fertilisation rates so that in-season adjustments of the fertilisation programme can be made.
A specific focus was the changes in the nutritional status of the trees as expressed by leaf analysis. Except for N, a lack of responsiveness of the trees to excessive rates of mineral nutrition was observed. Consequently, it was concluded that using foliar analysis to make in-season changes to fertilisation rates of orchards that are amply fertilised cannot be justified.
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Source:
P.J. Raath, C.R. Broeksma, M. Stofberg and V.G. White
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