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Tropentag, September 17 - 19, 2018 in Ghent

"Global food security and food safety: The role of universities"

Combined Tied Ridge, Fertiliser Microdosing and Biochar Effects on Maize Production under Contrasting Water Supply

Hannah A. Graef1, Denis K. Kiobia2, Paul Saidia3, Frederick C. Kahimba2, Frieder Graef4, Bettina Eichler-Loebermann1

1University of Rostock, Fac. of Agricultural and Environmental Sciences, Germany
2Sokoine University of Agriculture, Dept. of Agric. Engin. & Land Planning, Tanzania
3Sokoine University of Agriculture, Dept. of Crop Science and Horticulture, Tanzania
4Leibniz Centre for Agric. Landscape Res. (ZALF), Inst. for Land Use Systems, Germany


In many developing countries staple food production is limited due to soils with low agricultural potential, constraints in terms of fertiliser accessibility and low and/or erratic rainfall. There are well-known agricultural practices to meet those challenges: In-situ rain-water harvesting with tied ridges, fertiliser microdosing and biochar application to soil. However, their combinations have rarely been studied under varying irrigation frequencies.
We conducted a field trial in split-plot design on soil with low natural fertility in Tanzania over two seasons with contrasting water supply in 2016 and 2017. Tied ridges, chemical fertiliser microdosing (25 %) and maize cob biochar were applied and their effects on maize grain yield, biomass, plant height, leaf area index, and soil moisture content were investigated.
The slightly alkaline biochar provided P and K to the soil. Under low irrigation frequency, tied ridges conserved soil moisture and tended to increase yield. Fertiliser microdosing increased yield under both irrigation frequencies compared to the control. Biochar alone increased grain yield only at high rates of 10 t/ha and only under low-frequency irrigation. However, in combination with fertilizer microdosing, biochar application had greater impact on yield: Even at lower application rates of 5 t/ha, biochar combined with fertiliser microdosing increased yields under flat tillage and under both irrigation frequencies compared to the control.
Thus, for higher yields, fertiliser microdosing combined with biochar can be recommended under either precipitation frequency. Furthermore, the crop position on the tied ridge needs to be considered carefully depending on the water supply situation to optimise water management.

Keywords: Biochar, fertiliser microdosing, maize, rainwater harvesting, tied ridge

Contact Address: Hannah A. Graef, University of Rostock, Fac. of Agricultural and Environmental Sciences, Justus-Von-Liebig-Weg 6, 18059 Rostock, Germany, e-mail: hagraef@gmx.de

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