Authors: Kudumo LP, Itanna F, Thierfelder C.
This article focuses on the results of the trials developed to monitor the short-term effects of conventionally tilled practices (CP) versus Conservation Agriculture (CA) on soil quality and crop productivity under conditions of the major cropping systems in central, north-central and north-eastern regions of Namibia. The objective of the trials was to test the hypotheses that (a) CA treated plots have a significant higher water infiltration and soil moisture content (b) the CA principles (minimum tillage, soil cover and crop rotation or intercropping) have a significant influence on soil moisture content eventually leading to greater crop productivity. Results from Liselo in the Zambezi region of Namibia on the effects of tillage methods on soil moisture content are as follows. Conventional mouldboard ploughing (CPa), Sub-soiling with a Magoye ripper (SS-M) and Manual tillage using Dibble stick with mulch (MDS-M) were some of the treatments tested among others. Tillage systems appeared to have significantly affected (P<0.05) soil moisture in the 0-30 and 0-60 cm soil depths over the study period. Plots subsoiled with Magoye Ripper (SSM) (14.9mm) had 3.47% higher average soil moisture content in the 0-30cm soil depth and 3.05% higher moisture in the 0-60 cm soil depth than conventional ploughing. Manual tilling with a dibble stick (MDS-M) and conventional tilling with a plough (CTa) were found to be insignificantly different from each other with soil moisture averages of 14.1 mm and 14.4 mm in the 0-30 cm soil depth, respectively, and 39.3 mm for both in the 0-60cm soil depth, respectively.
Results suggest that some tillage methods and CA practices have the potential to increase water conservation and contribute to reduction of risk of crop failure, as was observed where subsoiled plots had more soil moisture content than conventionally tilled plots.
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