A note on the effect of incorporated groundnut stover on the soil physical properties, biological activity, sorghum growth and yield

Ahmed, A.E., Mukhtar, N.O., Ibrahim, A.M.

           Abstract

           The central clay plain of the Sudan is characterized by low nitrogen, low carbon and poor soil physical properties. Under such conditions, sustainable agricultural production implies measures to improve the soil properties. In this context, an experiment was conducted for two consecutive seasons in the Gezira Research Farm to study the effect of incorporating groundnut (G/N) residue on the subsequent soil properties and on the succeeding sorghum crop within the normal 5 course rotation of the Gezira Scheme. Following the harvest of the G/N, the residues in one half of the area (2100 m 2) were incorporated into the soil (I), while in the other half of the area, the residue was removed (N). The quantities of the incorporated G/N residue were 2930 kg /ha in 2003 and 3859 kg/ha in 2004. The subsequent sorghum crops were sown on July 2004 and 2005 for the first and second year respectively. In comparison with the (N) treatment, Incorporation of G/N stover increased the soil biological activity as monitored by the microbial count (fungi total count and azotobacter) and resulted in higher microbial activity as measured by high CO2 release. Moreover, the (I) treatment increased water infiltration rate, reduced bulk density and increased the water availability. Regarding the soil chemical aspects, the (I) treatment increased soil N, P and soil organic carbon. Therefore, the G/N residue incorporation eventually increased sorghum shoot and root dry weight by 45% and 27% respectively and resulted in a higher sorghum grain yield (2.9 t/ha in 2004) and 4.7 t/ha in 2005).