ISSN:
1573-0867
Keywords:
citrus
;
controlled-release
;
fertilization
;
soil nitrogen
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The leaching of N fertilizers in citrus causes important N losses, thus exerting a direct influence on the economy of citrus production, and may have negative consequences on the environment. The use of controlled-release N fertilizers may reduce leaching and be a solution to this problem. The amounts of available N, expressed as g of N in a soil cylinder corresponding to the drip area of the tree and of 0–60 cm depth, were compared at different vegetative periods, in an orange orchard, for four treatments; two doses of a standard fertilizer (ammonium nitrate sulphate, ANS), applied in the quantities of 11.55 kg N/ha (ANS-350) and 49.50 kg N/ha (ANS-2×750) and two doses of a slow-release fertilizer (sulphur-coated urea, SCU), applied in the quantities of 11.55 kg N/ha (SCU-350) and 24.25 kg N/ha (SCU-750), in nine consecutive years. A treatment without N (no N) was included. Available total N throughout the whole of the vegetative cycle, and in partial critical periods, has been determined as another comparison term. In the same way, non-available N has been measured at the beginning and at the end of the experiment. SCU treatment applied in low doses and only in spring maintained high levels of available N in soil during the vegetative cycle, reducing N losses, compared with ANS treatments. In the whole annual cycle, the amounts of N with SCU-750 were 32% greater than those of ANS-(2×750) though the quantity of N applied with this treatment was double. SCU-350 provided 5% less N than ANS-(2×750), though the dose of N applied with this treatment was 4.3 times greater. In all critical periods, SCU-750 maintained quantities of N higher than those with ANS-(2×750). For SCU-350, the amounts of N were similar to those of ANS-(2×750), except in summer as a consequence of the second fertilization with ANS-(2×750). Non-available N increased during the experiment in all treatments providing N except in ANS-350. A good crop and quality of fruits were obtained with SCU treatments, which in conjuntion with the reduction in dosage and rates justified its application.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009866327935
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