Effect of nitrogen fertilization, grass species and cultivar on sod production on Valkeasuo peat bog - a case study

Abstract

As part of a research project concerning the agricultural utilization of cut-away peat bogs, a sod production experiment was conducted at Valkeasuo, Tohmajärvi, in 1990-1993. The aim of the experiment was to study the effect of nitrogen and choice of cultivar on sod production and sod quality on peat bogs. The N fertilization rates were 50, 100 and 150kg ha-1. The Poa pratensis cultivars were ‘Conni’, ‘Cynthia’, ‘Haga’ and ‘Julia’, the Festuca rubra cultivars were ‘Center’, ‘Juliska’, ‘Koket’ and ‘Näpsä’ and the Agrostis capillaris cultivar was ‘Rasti’. Two mixtures of P. pratensis/F. rubra and one of A. capillaris/F. rubra imitated commercial sod products. Increasing of N fertilization from 50 kg up to 150 kg ha-1 a had positive effect on general the quality of sod as well as on the green cover before and after transplanting. It increased the thatch formation. The positive effect of N on the number of tillers and green cover in the year following transplanting was dependent on the species and the cultivar. Species and cultivar affected all measured variables excluding thatch formation. Generally, the P. pratensis cultivars tested suited better for sod production than cultivars of F. rubra, but there were clear differences between cultivars within species as well. Although the soil was infertile, the contents of Ca, K, Mg, P, Cu, Fe, Mn, Mo and Zn in the herbage samples were within normal range. The botanical purity was high, which supports the hypothesis that the absence of seed bank of weeds on peat bogs immediately after harvesting the peat can be utilized.