Yearly variation of root distribution with depth in relation to nutrient uptake and corn yield

Abstract

Root length and root distribution in the soil profile is important in determining the amount of nutrients and water taken up by the plant. Data about year to year variation of corn (Zea mays L.) root growth and its relation to nutrient uptake are limited. An evaluation of the importance of root system size and distribution on P and K uptake and corn yield was made from samples taken annually from a long‐term fertility experiment on Raub silt loam, fine silty, mixed, mesic Aquic Argiudolls. Root density varied with soil depth among years, whereas P and K fertilizer treatment had no measureable influence on total root length. Ear leaf P concentration was highly correlated with the amount of roots in the 0 to 15 cm layer which contained most of the available P. Since P was not appreciably limiting corn yield, no significant relation was found between yield and P content of the ear leaf. Yields on K deficient plots were positively correlated with root density in the topsoil. Correlations of root densities in the deeper soil layers with both yield and ear leaf nutrient concentration became increasingly smaller with depth in the soil profile. The results indicate that root length plus root distribution in the soil may influence year to year variation in yield particularily on soils having low available nutrient levels. This variation in root growth may be responsible for differences among years in the response of crops to applied P and/or K.