Assessment of Effects of Zero and Conventional Tillage Practices on Soil Moisture and Wheat Grain Yield in Arid and Semi-Arid Land of Laikipia, Kenya

Soil water conservation through tillage is one appropriate way of addressing soil moisture deficit in rain-fed agriculture. The influence of zero and conventional tillage on soil moisture and yield of wheat was investigated in arid and semi-arid lands (ASAL) of Laikipia County, during short rain season of 2015/2016 (September to February). Field trials were carried out with two tillage treatments, zero tillage (ZT) and conventional tillage (CT), with four varying sowing onset dates namely early (SD1), normal (SD2), late (SD3), and a control treatment with supplemental irrigation under normal sowing dates (WTSD2). The zero tillage fields used had been under the tillage practice for over 10 years while adjacent conventional tillage field was disturbed by plowing and harrowing. This was laid out in a randomized complete block design in split plot arrangement with three replicates. Undisturbed soil samples for gravimetric soil moisture determination were taken every 10 days from four depths (10 cm, 25 cm, 45 cm, and 60 cm) in the root zone during the entire growing season from each sub-plot. Irrespective of the sowing date, soil water content at the root zone between the two tillage practices and crop yields was significantly different at p < 0.05. The mean yield was 5.70 ± 1.08 ton/ha (CT) and 8.69 ± 0.54 ton/ha (ZT) in rain-fed trials. Supplemental irrigation trials for the two tillage practices had comparatively equal mean grain yield (12.91 ± 1.37 ton/ha (ZT) and 13.61 ± 0.46 ton/ha (CT)). It was concluded that zero tillage conserved moisture better leading to higher grain yield gap of up to 3 ton/ha.