Soil and nutrient loss in sugarcane (saccharum officinarum L.) Under centre-pivot system in swaziland




Дата канвертавання26.04.2016
Памер5.14 Kb.
SOIL AND NUTRIENT LOSS IN SUGARCANE (SACCHARUM OFFICINARUM L.) UNDER CENTRE-PIVOT SYSTEM IN SWAZILAND
G. S. Dlamini1, E. M. Ossom*2, D. N. Mbewe2 and O. T. Edje2
1Ubombo Sugar Limited, P.O. Box 23, Big Bend, Big Bend L311, Swaziland

2Crop Production Department, Faculty of Agriculture, University of Swaziland,

Private Bag Luyengo, Luyengo M205, Swaziland



*Corresponding author - Email: emossom@agric.uniswa.sz
[TARGET THEME: WATER AND LAND; FOR ORAL PRESENTATION]
ABSTRACT

The most important cash crop in Swaziland is sugarcane (Saccharum officinarum L.). Among the factors that influence sugarcane growth and yield is the amount of moisture available to the crop. Most of the sugarcane in Swaziland is grown under irrigation. Commercial sugarcane growers are increasingly adopting centre-pivot irrigation system; while nutrient and soil loss in this system has been evaluated in other countries, it has received little or no assessment in Swaziland. The objective of this investigation was to assess the amount of soil and nutrient loss attained through soil erosion under the centre-pivot irrigation system. Four irrigation rates (10-mm, 15-mm, 20-mm and 25-mm water/hour) were investigated using a completely randomized design in the Lowveld ecological zone of Swaziland. Results showed significantly (P < 0.05) higher soil loss (10.0 tonnes/ha) under 25-mm/hr irrigation than under 10-mm/hour (6 t/ha). Soil loss under 15- and 20-mm/hour rates were 8 and 9 t/ha, respectively. Sediment analysis showed significant (P < 0.05) differences in phosphorus, potassium, calcium, and magnesium concentrations among the irrigation regimes, the highest water application rate resulting in the greatest macronutrient losses. Cane yields significantly (P < 0.05) varied among the irrigation rates: 10-mm/hr, 123.3 t/ha; 15-mm/hr, 137.4 t/ha; 20 mm/hr, 130.6 t/ha; and 25-mm/hr, 131.7 t/ha. Yield differences could be attributed to nutrient and soil losses associated with the variations in irrigation rates. It is recommended that in Swaziland, 15-mm/hr of irrigation water be used in centre-pivot irrigation systems, as this rate results in reduced soil and nutrient loss and has the advantage of higher sugarcane yield and quality compared to the 25-mm/hr application rate.


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Keywords: Sugarcane, water loss, soil erosion, irrigation, centre-pivot


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