NUTRIENT-UPTAKE IN OATS IN THE COURSE OF THE VEGETATION PERIOD

In an 8-year, smalt-plot, field NPK fertilisation experiment on cherno zem loam with lime deposits, studies were made on the element uptake ( N, P, K, Ca, Mg, Fe, Mn, Zn, Cu) of spring oats as a function df the m ajor phenophases and the NPK supplies. The soil of the growing site wa s originally supplied well with Mn, satisfactorily with Mg and Cu, mod erately well with N and K, and poorly with P and Zn. The ploughed laye r contained 5% CaCO3 and 3% humus. The experiment involved 4Nx4Px4K=64 treatments in 2 replications, giving a total of 128 plots. Plant samp les were taken at the end of tillering and at shooting, heading and ha rvest (grain, straw) from 4 running metres on each occasion. The resul ts of the examinations can be summarised as follows: 1. Intensive accu mulation occurred during the shooting stage for N, P, K, Ca, Mg, Mn an d Zn, in the heading stage for Fe and during ripening (in the generati ve phase) for Cu. 2. At harvest an average of 76% of the N, 61% of the P, 16% of the K, 11% of the Ca, 46% of the Mg, 55% of the Fe, 26% of the Mn, 80% of the Zn and 74% of the Cu was found in the grain. It can thus be seen that N, P, Zn and Cu accumulated chiefly in the grain an d K and Ca in the by-products, while Fe and Mg are divided approximate ly equally between the main and by-products. In the case of combine ha rvesting, when the straw remains in the field, the soil is chiefly dep leted of N and P during the cultivation of oats. 3. At a grain yield l evel of 5-6 t/ha, plus the relevant straw yield, oats can be expected to absorb a maximum of 150-160 kg N, 150-170 kg K (180-200 kg K2O), 30 -40 kg P (70-90 kg P2O5), 30-40 kg Ca, 15-18 kg Mg, 1.2-1.4 kg Fe, 1.1 -1.4 kg Mn, 110-120 g Zn and 100-110 g Cu. 4. When determining the nut rient (fertiliser) requirements of the planned yield, 25-30 kg N, 25-3 0 kg K2O, 10-15 kg P2O5, 5-6 kg Ca and 2-3 kg Mg should be calculated for each ton of grain yield + straw. The specific microelement require ments are around 200 g for Fe and Mn and around 20 g for Zn and Cu. Th e specific contents may vary over a wide range of values as the result of the ion antagonisms and synergisms which modify supplies and uptak e.