Advances in improving agricultural profitability and overcoming land degradation in savanna and hillside agroecosystems of tropical America - Ayarza, Miguel Angel; Amézquita Collazos, Edgar; Rao, Idupulapati M.; Barrios, Edmundo; Rondón, Marco Antonio; Rubiano Sanabria, Yolanda; Quintero, Marcela (Springer, 2007)