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Tropentag, October 5 - 7, 2004 in Berlin
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Nutrient Cycling and Field-based Nutrient Balances in Mountain Oases of Northern Oman
Andreas Buerkert1, Maher Nagieb1, Stefan Siebert1, A. Al-Maskri2
1University of Kassel, Institute of Crop Science, Germany
2Sultan Qaboos University, Department of Agriculture, Al Khod, Oman
Abstract
Little is known about cropping systems and nutrient fluxes in traditional agriculture of Arabia. To overcome this gap of knowledge, GIS-based field research on terraced cropland and date (Phoenix dactylifera L.) palmyards was conducted between 2000 and 2002 in two mountain oases of northern Oman. About 55% of the 385 tiny fields at Balad Seet received total annual N inputs of 100-500 kg ha-1, 26% of 500-1400 kg ha-1 and 19% who lay fallow did not receive any N. Annual P applications of 1-90 kg were applied on 46% of the fields, whereas 27% received 90-210 kg ha-1. No K was applied on 27% of the fields, whereas 32% received 1-300 kg K ha-1 and the remaining fields up to 1400 kg ha-1. Large positive balances of N, P and K were noted on most fields, whereas 16% of them had net losses of 1-100 kg ha-1, 19% of 1-30 kg ha-1 and 27% of 1-200 kg ha-1.
At Maqta palm groves clearly dominated the cultivated land. Inputs of N varied from 61-277 kg ha-1 in palm groves and from 112-225 kg ha-1 on wheat (Triticum sp.) fields, P inputs were 9-40 kg ha-1 in palm groves and 14?29 kg ha-1 on wheat fields and K inputs were 98-421 kg ha-1 in palm groves and 113-227 kg ha-1 on wheat fields. Nutrient balances were strongly positive regardless of terrace use in all systems except for K in wheat fields of two terraces. Excess N was 47-222 kg ha-1 in palm groves and 63-157 kg ha-1 in wheat fields, P surplus 7-34 kg ha-1 in palm groves and 7-19 kg ha-1 in wheat fields and K surplus 79-266 kg ha-1 in palm groves and -13-85 kg ha-1 in wheat fields.
The data showed that high rates of N2-fixation by alfalfa (Medicago sativa L.), the use of large amounts of animal manure and mineral fertilisers and the recycling of human faeces from an artificially high population living partly of imported food characterised both oases as large nutrient sinks.
Keywords: Animal manure, irrigation agriculture, N2-fixation, sustainability
Contact Address: Andreas Buerkert, University of Kassel, Institute of Crop Science, Steinstraße 19, 37213 Witzenhausen, Germany, e-mail: buerkert
uni-kassel.de
