Evaluation of the Effect of Surface Soil Removal on the Growth of Wheat

Abstract

The study was conducted at the National Plant breeding Research Station in Njoro. The main objectives of the study were to evaluate the effect of surface soil removal on the growth of wheat, and to determine whether chemical fertilizers can restore the growth of wheat on the desurfaced soil. Three different soil types were used. These were Luvisol, Nitosol and Andosol collected respectively from Katumani Research Station, Kabete Campus and Plant Breeding Station, Njoro. The soils were taken from different depths in the soil profile placed in pots in a raised cage and tested by growing wheat both with and without fertilizer. The performance of the wheat was monitored by taking the measurements of maximum height, number of tillers, weight of straw, length of ears, weight of ears, weight of grains, weight of dry roots. The data collected was then analysed statistically. The results showed that surface soil removal decreased yield in all the parameters that were measured. The greater the depth of surface soil removal the higher the reduction in yie:d. However the impact of removing the first 10cm of topsoil had a more serious effect on yield than the removal of 40cm of topsoil in terms of decrease per cm of topsoil removed. When fertilizer was added at recommended and double the recommended rates there was a general increase in all the parameters. The increase depended on the level of fertilizer, the depth of topsoil removal and the soil type. The increase in yield was different in different parameters, with wheat straw being the least affected while grain weight was most affected. Addition of fertilizer at double the XV recommended rate, after 10cm of topsoil removal raised yields in almost all aspects to that of the control except grain weight and weight of ears. However at 40 cm of topsoil removal parameters such as grain weight, number of grains and weight of ear attained only 84.0, 97.1 and 85.1% respectively as compared with the control. Thus addition of chemical fertilizer may not compensate for loss in productivity in desired parameters such as grain weight which are important in food production.