Effect of placement of fertilizer and sprinkler irrigation on the development of spring cereals on the basis of root investigations

Authors

• Jorma Kähäri University of Helsinki, Department of Agricultural Chemistry
• Paavo Elonen University of Helsinki, Department of Agricultural Chemistry

DOI: https://doi.org/10.23986/afsci.71729

Abstract

In 1967, two large field trials were performed on clay soil in South Finland in order to obtain detailed information on the effect of fertilizer placement and sprinkler irrigation on spring cereals. In the present paper the results of the root investigations, carried out in connection with these trials, are reported. Fifty-six root samples were taken on four dates during the growing season. The roots in the soil blocks, taken perpendicularly to the fertilizer and seed rows, retained their original distribution during washing and drying. The growth of the roots was stronger than the growth of the shoots of plants in the early part of the summer, but at the end of the summer, when the main yield above ground developed, the weight of the roots no longer increased, in fact it had decreased. There was a close correlation between the weights of roots and the weights of the shoots of plants during the whole growing season. A particularly high correlation was found between the root system and the grain yield. Fertilizer placement and irrigation increased both the growth of roots and the growth of shoots of plants. The relative increases produced by the placement of fertilizer were equal in the weights of roots and in the weights of aerial parts, but irrigation increased the weight of aerial parts to a relatively greater extent than the weight of roots. The distribution of the roots in the top soil was somewhat unexpected. A part of the roots reached the subsoil quite early in the growing season. On the other hand, the main part of the root system in the ploughed layer lay, during the whole growing season, immediately beneath the sowing depth, or at a depth of 4—10 cm. The topmost layer, i.e. the layer above the sowing depth, contained very few roots during the entire growing season, and the main part of these roots consisted of buttress roots, whose capacity for taking up nutrients may be very slight. Irrigation had only a slight effect on the distribution of the root system, while the effect of fertilizer placement was very distinct. The roots clearly sought their way to the fertilized rows, also in cases where the distance between fertilized and sowing rows was remarkably great. On the basis of the results it was concluded that it is important to place the fertilizer at a convenient depth, 5—10 cm, when spring cereals are in question. The horizontal distance between seed rows and fertilized rows appeared to be of less importance.