The exhausting effect of dura for a single year in a rotation was shown. Rotations including dura consistently yielded less than those including lubia or fallow. With 2 successive years of dura the reduction in yields of cotton was extremely large.

Substantial increases in yields of cotton were obtained when the first fallow of the CFF rotation was replaced by lubia. The superiority of the rotation CLF appeared to be firmly established in the Gezira, where the soil was known to be deficient in nitrogen. By growing lubia, instead of leaving a fallow 2 years preceding cotton, an average annual increase of 0·65 k.p.f. of cotton was obtained. Itwas interesting to note that fertility of rotation CLF over CFF was still increasing.