Nutrient uptake of winter barley (Hordeum vulgare L.) on calcareous chernozem soil

The effect of different levels of N, P and K supplies (poor, medium, satisf actory, excessive) and their combinations was investigated on the macro- an d microelement uptake of winter barley (variety Mv 35) grown on calcareous loamy chernozem soil, as a function of vegetation period and NPK supplies. The specific element contents were also determined. The ploughed layer cont ained 5 % CaCO3, 3 % humus and 20-25 % clay, and had a pH of 7.3 PH(KCl).Th e groundwater depth was 15 m. Soil analysis showed the original soil to be poorly supplied with P and Zn, moderately well supplied with N and K, and w ell supplied with Fe, Mn and Cu. The mineral fertilisation experiment invol ved 4Nx4Px4K = 64 treatments, or nutritional situations, in two replication s, giving a total of 128 plots. The N levels were 0, 100, 200 and 300 kg/ha /year N. Replenishment fertilisation with P and K was carried out when the experiment was set up in autumn 1973 with rates of 0, 500, 1000 and 1500 kg /ha/10 years P2O5 and K2O. The fertilisers were applied in the form of calc ium ammonium nitrate, superphosphate and 50 % potassium chloride. In the 6( th) year of the experiment, in 1979, the second half of the vegetation peri od of winter barley, from spring onwards, was very dry. The plot size was 6 x6=36 m(2) and the forecrop was potato. The main conclusions were as follow s: 1. NxP interactions were dominant in element uptake (as in the formation of dry matter and in changes in the plant composition). The element uptake re corded on the unfertilised control plot generally increased by an order of magnitude as the result of a joint excess of N and P in shoots at the end o f tillering or at heading. The fertiliser effects later declined and the di fference was 1.5-3.5 times at harvest, depending on the elements. In was th e only exception. Maximum Zn uptake was observed at the N1P1 level, while i n the N3P3 treatment there was a reduction of some 30 % due to P-Zn ion ant agonism. 2. The incorporation of the elements generally preceded dry matter accumula tion, especially in the case of plentiful NP supplies. Maximum absorption i n the shoots was recorded at heading for N, P and K and at flowering for Ca , Mg and Na. Between this period and maturity the winter barley lost 1/3 of the N, 1/2 of the Ca, Mg and Na and approx. 60% of the K in plots with an excess of N and P, partly due to the withering of the foliage. On P-deficie nt soil this phenomenon was only observed to a moderate extent for K. In th e case of microelements the accumulation was pronounced right up to maturit y on the P control soil (and for Fe in the NP treatments, too), while the m aximum quantity of Mn, Zn and Cu absorbed was much the same at flowering an d harvest in the NP treatments. 3. With an improvement in the NPK supplies (with an excess of NP) the uptak e of other elements accelerated in the early developmental stages, which co uld lead to a change in the dynamics of uptake and in the specific element contents. On the NP plots with maximum yield the specific N, P, K and Na va lues were 20%, 30%. 30% and 100% greater than the control, while the Mg and Zn values were 30% and 45% lower. 4. The specific element content of winter barley, i.e. that of 1 t grain the relevant by-products, was as follows, depending on the nutrient supplie s in the soil: N 24-30 kg, K2O 14-19 kg, CaO 6-7 kg, P2O5 8-11 kg, MgO 3-4 kg, Na2O 2-4 kg, Fe 170-200 g, Mn 50-60 g, Zn 24-42 g, Cu 5-6 g. The values of 27 kg N, 10 kg P2O5 and 3 kg MgO recommended by the Hungarian extension service are in good agreement with these results, while the 26 kg K2O and the 10 kg CaO are 35-40% too high. 5. If the crop is harvested with a combine which only removes the grain yie ld from the field, the K and Ca requirements are reduced to a minimum. A to tal of only 10 kg Ca and 30 kg K2O would be lost per hectare for an average yield of 5 t/ha, which is not substantial even on acidic or K-deficient so il. On heavier soils rich in lime and K this loss is negligible.