Influence of Rice Husk - Mulch on Soil Water Balance Components under Sorghum and Millet Crops in Maiduguri, Semi Arid Northeast Nigeria

A 2 x 3 factorial experiment was conducted at two sites in Maiduguri, Borno State during the 2009 cropping season. The objective was to evaluate the influence of rice husk-mulch on soil water balance components under sorghum and millet crops. The treatments comprised of two test crops (sorghum and millet) and three rates of application (0, 10 and 15 t ha-1) of rice husk mulch, fitted in a split-plot design. The test crops were assigned to the main plot, while the mulch application rates were assigned to the sub-plot. The treatments were replicated three times. The components of soil water balance determined were annual rainfall, moisture storage within sorghum and millet root zone, drainage below crop root zone and seasonal crop evapotranspiration. Profile moisture content was measured weekly with the aid of a neutron probe installed at a depth of 2.0 m using access tubes. Also, soil (0 – 30 cm depth) moisture content was determined gravimetrically on weekly basis. Rainfall was measured using a manual rain gauge installed at each of the two sites. Findings in this study indicated that, under the prevailing circumstances, annual rainfall was lower than the amount observed over a ten-year period in Maiduguri. Consequently, soil moisture storage, drainage and seasonal crop evapotranspiration generally declined. An average of over 90 % of this low annual rainfall was lost as seasonal crop evapotranspiration. Sorghum plots stored higher moisture within the root zone, had higher drainage and lower seasonal evapotranspiration than millet plots. Moisture storage and drainage increased with increasing mulch application rate, while, seasonal crop evapotranspiration decreased with it.