The effect of different NPK levels (poor, satisfactory, excessive, toxic) and their combinations on the mineral composition, nutrient uptake and specific clement contents of the sunflower hybrid Koflor-2 was studied on a loamy chernozem soil with lime deposits. It was also hoped to check the limit concentrations used in leaf analysis by the extension service. The ploughed layer of the experimental site contained around 5% CaC<3j, 3% humus and 20% clay, and had a pH(Ka) of 7.3. The soil analysis showed the original soil to be poorly supplied with P and Zn and moderately supplied with N and K. The mineral fertilisation experiment consisted of 4N×4P×4K = 64 treatments, or nutritional levels, in two replications, giving a total of 128 plots. The N levels were 0,100,200 and 300 kg/ha/ycar and the PK levels 0,1000,2000 and 3000 kg P2O5 or K2O/ha/9 years in the form of calcium ammonium nitrate, superphosphate and 50% potassium chloride. The plot size was 6x6=36 m2 and the forccrop was sugarbcct. The main conclusions were as follows: On this humus-rich loamy soil satisfactory clement supplies to sunflower can be characterised by concentrations of 3-4% N, 0.4-0.6% P and 5-6% K in the air-dry 6-8-Ieaf shoot, or 2.5-3.5% N, 0.3-0.5% P and 3-4% K in the leaf below the inflorescence at the beginning of flowering. The ratios calculated from the optimum contents, which reflect a balanced nutrient status, were as follows: 8-15 K/P, 5-10 N/P, 0.5-0.8 N/K in air-dry leafy shoots, and 6-13 K/P, 5-12 N/P, 0.6-1.2 N/K in the air-dry leaf below the head at the beginning of flowering. An improvement in soil N reserves increased the N and Mn contents, improved K supplies the K% and increasing P supplies the Ca, Na and P concentrations in the plant organs. There was evidence of K-Mg, P-Zn and P-Cu antagonism. The P-Zn antagonism and to a certain extent the P-Cu antagonism appears to have induced latent Zn and Cu deficiencies, judging by the Zn and Cu contents and the P/Zn and P/Cu ratios. Depending on the treatments, 90-180 kg N, 31-80 kg P2O5, 144-360 kg K2O, 70-112 kg CaO and 35-78 kg MgO accumulated in the 3.1 t/ha achcnc + 1.7 t/ha head + 3.1 t/ha stalk, i.e. 7.9 t/ha total air-dry abovcground yield. The mean specific (l t achcnc + by-product) clement requirements were found to be 42 kg N, 19 kg P205, 82 kg K2O, 30 kg CaO and 18 kg MgO. The specific index of 30 kg P2O5 recommended by the Hungarian extension service leads to over-fertilisation. The 3.1 t seed yield contains an average of 88 kg N, 45 kg P2O5,35 kg K20, 8 kg CaO and 16 kg MgO. When a combine harvester is used and the by-products remain in the field, the K, Ca and Mg losses become insignificant, and on heavy soils rich in K the application of these nutrients can be omitted temporarily, or permanently in a crop rotation. Instead of being a soil-depleting crop capable of extreme K uptake, sunflower becomes a crop with a moderate demand for K if only the seed yield is harvested.
|Number of pages||11|
|Publication status||Published - Dec 1 2001|
ASJC Scopus subject areas
- Agronomy and Crop Science