Mulching, irrigation and plantation density were studied in coffee plantations of Zimbabwe by Cassidy and Kumar (1984). Mulching increased the distribution of roots at the soil surface, but had a lower effect at high plant densities (> 4.000 plants/ha), probably due to soil shading caused by the plants themselves. Curiously, the roots of plants placed at a denser spacing (4 to 6.000 plants/ha), when irrigated, deepened their root system (around 0.5 m). This could be explained by the decreased volume of lateral roots competing for the same soil space at high densities. The implications of this fact would be related not only to water availability
but also to nutrients.