CHANGES IN THE DRY-MATTER ACCUMULATION AN D NUTRIENT CONTENT OF OATS DURING THE VEGETATION PERIOD

In an 8-year NPK fertilisation experiment carried out on chernozem soi l with lime deposits, studies were made on the dry matter accumulation of oats and on changes in the contents of major nutrients (N, P, K, C a, Mg, Fe, Mn, Zn) as a function of time and NPK supplies. The experim ental soil initially had a high Mn content, satisfactory supplies of M g and Cu, moderate supplies of N and K and poor supplies of P and Zn, The ploughed layer contained approx. 5% CaCO3 and 3% humus. As the res ult of the treatments 4 supply levels (poor, moderate, satisfactory, h igh) were created for the three macroelements, N, P and K (4x4x4=64 tr eatments), each in 2 replications, giving a total of 128 plots. Plant samples were taken from the aboveground parts of 4 linear metres per p lot at the end of tillering and at shooting, heading and harvest (grai n, straw). The following conclusions can be drawn from the results: 1. Dry matter accumulation showed a constant increase from tillering to full maturity. It was most intensive for 5-6 weeks following heading, during which time mom than half the aboveground dry matter accumulated . The maximum grain yields (5-6 t/ha) were ensured with an annual 100 kg/ha N fertilisation and satisfactory P supplies. K fertilisation had no effect on this loamy (20% clay-containing) soil. 2. The concentrat ion of macroelements decreased in time. N and P concentrated in the gr ain, and ea and K in the straw. Mg was found in roughly equal quantiti es in the main and by-products at harvest. There was a substantial ris e in the NPK content after NPK fertilisation, while the contentrations of Ca and Mg declined as a function of the K supplies (K-Ca, K-Mg ion antagonism). 3. The drop in element concentrations in aging plant tis sues was also perceptible for the major microelements. P supplies gene rally improved the uptake of Fe and Mn, but reduced that of 2n to almo st a half However, an increase in the Id supplies was able to counterb alance the P-induced reduction in the Zn content. Plentiful N supplies also had a positive effect on the uptake and incorporation of Cu.