Agriculture at Balad Seet

Objectives: Description of the land use techniques in agriculture, analysis of oasis agroecosystems comprising inter- and intra-species diversity of crops, calculation of nutrient balances (vertical and horizontal matter fluxes), determination of soil conditions and water-use efficiency.

Contact Person: Prof. Dr. Andreas Bürkert and Prof. Dr. Eva Schlecht, Institute of Crop Science, University of Kassel Germany.

Email:tropcrops[at]uni-kassel[dot]de OR tropanimals[at]uni-kassel[dot]de

Scientific staff: Dr. Eike Luedeling, Dr. Stefan Siebert, Dr. Maher Nagieb, Dr. Sulaiman Al-Khanjari, Dr. Jens Gebauer, Dr. Florian Wichern

Study area: Balad Seet, Wadi Tiwi, Maqta

Duration: 2000-2005

At present the agricultural area of Balad Seet, the head oasis of Wadi Bani Awf in the northern Hajar mountain range, consists of 8.8 ha planted with 2,800 date palms and 4.6 ha which are divided into 385 small fields where wheat, barley, sorghum, oats, alfalfa, garlic, onion, lime and banana are cultivated in rotation or in mixed stands. The terrace soils at Balad Seet are all man-made, built of fine silty wadi sediments and coarse rocks. Over the centuries as much as 100 000 t of this material has been transported with simple tools to built the terraces of Balad Seet.
The analysis of the land use pattern across the year (winter compared to summer months) shows a characteristic fluctuation of used and unused plots (Figure 1). In the cooler winter months, the fallow rate is only 15-20% and a larger diversity of crops is maintained compared with the summer months, when the total proportion of fallow plots is 50-70% and more drought-tolerant crops such as sorghum are preferred.
A major proportion of the farm income is derived from the up to 200 small ruminants (sheep and goats) fed mainly alfalfa, fodder barley and crop residues at home in addition to a minor amount of forage browsed during two 3-hour herded grazing periods per day in the oasis neighbourhood. On separate grazing grounds in the surrounding mountains and at altitudes above 1,300 m, small ruminants are also herded by semi- nomadic families commonly referred to as Shawawi.

The basis for the calculation of nutrient budgets is a thorough determination of all agricultural inputs and outputs, as well as the determination of the quantities of nitrogen, phosphorus and potassium contained in these per type of crop, land unit and season.Annual inputs, outputs and balances of nitrogen (N), phosphorus (P) and potassium (K) in cropland and palms groves at Balad Seet (Oman) are shown in Table 2. All data are given as amounts per unit area and as totals for each landuse system and represent averages of a 24-months measurement period from October 2000 to October 2002. The partial balance data indicate large surpluses for all nutrients indicating substantial potential for losses (such as by N-leaching and -volatilisation) to the environment.

While horizontal nutrient fluxes leading to partial balances at the field and oasis level could be established with reasonable accuracy (Buerkert et al., 2005), data were lacking on the magnitude of vertical fluxes (leaching and volatilization losses) as affected by cropping system and irrigation. To fill this gap of knowledge, anion- and cation exchange resins and a multi-gas monitor is used to measure leaching losses and volatilization of NH₃, CH₄, N₂O and CO₂ as affected by manure application, temperature and moisture. In combination with the horizontal flow measurements these data will allow to determine the carbon and nutrient turnover and together with water and soil data will allow to assess the sustainability of oasis agriculture. In cooperation with the other disciplines of the project scenarios of future development options for Oman’s oasis agriculture have been developed.