Tillage and Farmyard Manure Effects on Crusting Compacting Soils at Katumani, Semi-arid Kenya

  • G Sterk
  • L Stroosnijder
  • E.K Biamah
Keywords: Zero tillage, conventional tillage, farmyard manure, crusting and compacting soils, semi-arid Kenya

Abstract

In semi-arid Kenya, the most dominant soil types are of limited agricultural productivity due to crusting and
compaction. The occurrence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical
soil properties and bad tillage practices. Soil crusting and compaction decrease rainwater infiltration and increase
surface runoff. Seasonal rainwater losses through increased runoff volumes reduce soil moisture and hence result in
agricultural drought. The objective of this study was to examine the hydrological effects of two tillage practices with
and without farmyard manure on surface runoff and soil loss of crusting and compacting soils under field conditions
at Katumani in semi-arid Kenya. Field investigations on rainfall characteristics, surface runoff, soil loss, soil bulk
density and soil shear strength covered two rainy seasons (short and long rains) and were done on a Chromic Luvisol.
The field treatments were zero tillage and conventional tillage, and two farmyard manure applications (5 and 10
Mg ha-1). The results obtained showed significant effects of conventional and zero tillage and farmyard manure on
infiltration and soil moisture, surface runoff and soil loss. Soil crusting and compaction significantly influenced
the hydrological response of all treatments. These responses were attributed to seasonal rainfall events of varying
amounts, intensities and duration, and treatment differences in soil surface conditions and aggregation. Farmyard
manure (FYM) application enhanced infiltration and reduced soil crusting, compaction, and surface runoff during
the initial stages of the rainy season. But in the mid-stages of the rainy season, the effects of FYM on soil aggregation
diminished. Conventional tillage without farmyard manure led to high surface runoff and soil loss in this structurally
unstable soil. Zero tillage performed poorly under these soil conditions because of high soil crusting and compaction,
low rainwater infiltration and subsequent increase in surface runoff generation.
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eISSN: 1015-079X