Cobbina , J. , Kang , B.T. and Atta - Krah , A.N. ( 1989 ) Effect of soil fertility on early growth of Leucaena and Gliricidia in alley farms . Agroforestry Systems , 8 , 157-164 . Kang , B.T. and Mulongoy , K. ( 1987 ) Gliricidia ...