Abstract
Sustainable fertiliser management involves maximising production, preventing
on-site soil degradation and minimising off-site movement of nutrients. In the
past, fertiliser management has been driven by the need to maximise
production. Fertiliser costs are generally less than 10% of the
variable production costs in horticultural enterprises and this has often led
to excessive application of nutrients.
Fertiliser experiments have not generally provided calibrated soil or leaf
test data because of their short-term nature, the biennial or variable
production of many tree crops, their narrow focus and the difficulty in
demonstrating yield responses because tree crops have relatively low rates of
nutrient removal over long periods of time. Nutrient balance is a basically
sound approach to developing fertiliser recommendations and can be easily
estimated from crop nutrient removal data. This approach has been used
successfully for crops such as low-chill stonefruit (Huett and Stewart 1999)
and a simplified approach is presented for passionfruit, mango and avocado
based on nutrient uptake by well-managed, mature, productive orchards.
Macronutrient removal by a 20 t/ha passionfruit crop was (kg/ha) 55
nitrogen (N), 78 potassium (K), 6 phosphorus (P), 6 sulfur (S), 5 calcium (Ca)
and 4 magnesium (Mg). For a 10 t/ha mango crop it was (kg/ha) 11 N, 15
K, 2 P, 1 S, 2 Ca and 2 Mg. For a 10 t/ha avocado crop it was (kg/ha)
41 N, 61 K, 8 P, 4 S, 7 Ca and 8 Mg. Passionfruit, in contrast to tree crops,
is generally a 3-year crop and nutrient uptake by developing leaf, vines and
roots will inflate nutrient uptake by a factor of 2–3. Nutrient losses
due to leaching, runoff and fixation will further inflate fertiliser
requirements. However, the inclusion of these additional factors still means
that nutrient application rates will be substantially less than current
fertiliser recommendations.
Subject
General Agricultural and Biological Sciences
Cited by
19 articles.
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