Effect of Green-Manuring and Fallowing on Soil Nitrogen and Organic Carbon and on the Succeeding Crop in the Central Clay Plain of the Sudan

Under green-manure and bare fallow the soil organic nitrogen increased. The increase in organic nitrogen under leguminous green-manure crops was more than the increase under sorghum, green-manure or bare fallow. There was no significant effect of green-manuring and bare fallowing on the soil organic carbon content. The C/N ratio of the soil tended to narrow down under the treatments and this was more due to an increase in the organic nitrogen content rather to decrease in the organic carbon content.