| heal.abstract |
The effects of soil properties that affect water availabilty to plants such as soil depth, rock fragments, parent material and degree of erosion on biomass production of rainfed wheat were studied on hilly soils under different weather conditions. Total above ground biomass production (TAGBP) of wheat was measured along catenas of marl and shale-sandstone formations in two successive growing periods. During the first growing period which was extremely dry (total amount of rainfall R = 95 mm versus 370 mm in an average year), the soils on marl, free of rock fragments, produced an average TAGBP of 1100 kg ha-1 despite their great soil depth, whereas on shoulders and footslopes of the stony soils on shale-sandstone formations TAGBP values of 4620 and 11,100 kg ha-1 were measured, respectively. The opposite occurred the following growing period which was exceptionally wet (R = 663 mm). Soils on marls were more productive due to the higher fertility status than the soils on shale-sandstone formations. Rock fragments, more responsible for the lower exploitable soil volume and the generally lower biomass production under wet climatic conditions, play an important role on soil water conservation under dry climatic conditions. © 1994. |
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