The effect of irrigation depth on root growth of some pasture species

Summary Within the limits of the experiment,i.e. 60 cm, the depth of rooting of three pasture species in a sandy loam soil was found to be directly affected by the depth to which irrigation water penetrated the soil. Some practical implications for irrigation farming are discussed.The species reacted differently to the deeper wetting treatments; white clover produced a larger weight of roots, subterranean clover a lesser weight, and there was no difference in the weight of roots with perennial ryegrass. However, the weight of roots relative to the total weight of the plant decreased with increase in the wetting depth in all three species. The effect of growth of roots on the total growth of the plants is discussed and it is suggested that root growth is not a determinate of total production when the supply of nutrients is not limiting.The vertical distribution of the roots is discussed.