The effect of different levels of N, P and K supplies (poor, medium, satisfactory, excessive) and their combinations was investigated on the mineral composition, nutrient uptake and specific element contents of potato (variety Desiré) grown on calcareous loamy chernozem soil. A further aim was to check the concentration limits used by the extension service for leaf diagnosis. The ploughed layer contained 5% CaCO3, 3% humus and 20-25% clay, and had a pH of 7.3 pH(KCl). Soil analysis showed the original soil to be poorly supplied with P and Zn and moderately well supplied with N and K. The mineral fertilisation experiment involved 4N×4P×4K = 64 treatments, or nutritional situations, in two replications, giving a total of 128 plots. The N levels were 0, 100, 200 and 300 kg/ha/year N, and the PK levels were 0, 500, 1000 and 1500 kg/ha/10 years P2O5 and K2O, applied in the form of calcium ammonium nitrate, superphosphate and 50% potassium chloride. Replenishment fertilisation with P and K was carried out when the experiment was set up in autumn 1973. The plot size was 6×6 = 36 m2 and the forecrop was 2 years of maize. The groundwater depth was 15 m. The main conclusions were as follows: 1. On this relatively humus-rich loamy soil, satisfactory N levels for potato can be characterised by values of 4.5-5.0% N at the beginning of flowering, 3.5-4.0% at the end of flowering and 1.5-2.0% prior to harvesting in air-dry leaves, or 1.7-1.8% N in the tubers. Satisfactory values of P are 0.40-0.50% at the beginning of flowering, 0.25-0.30% at the end of flowering and 0.10-0.15% at harvest in the dry leaves, or 0.25-0.30% in the dry tubers. Satisfactory K supplies were reflected by K concentrations of 3.0-4.0% at the beginning of flowering, 2.0-3.0% at the end of flowering and 1.0-1.5 % at harvest in dry leaves, or 1.5-2.0% in the tubers. These data can be used as guidelines by the extension service. 2. The ratio of the major elements also gives a good reflection of the nutritional status of the plant and can thus be used for diagnostic purposes. The data suggest that the satisfactory or "normal" N/P ratio in the dry leaves is 10-12 at the beginning of flowering, and 12-15 at the end of flowering and at harvest. The K/P ratio of the foliage at flowering should be between 5 and 10. 3. The tuber yield ranged from 13.4-32.6 t/ha in the N0P0K0-N3P3K3 treatments. The quantity of elements taken up by the tubers + foliage were as follows (kg/ha): N 66-180, P2O5 25-69, K2O 55-192, CaO 46-84, MgO 27-42, Fe and Na 2-3, Mn 0.2-0.3, Zn 0.1-0.2, Cu 0.03-0.06. The specific element requirements for 1 t tubers + foliage averaged 5.5 kg N, 5.3 kg K2O, 1.9 kg P2O5,2.5 kg CaO and 1.4 kg MgO, and were in good agreement with the parameters used by the Hungarian extension service (with the exception of K2O, where a parameter of 9 kg/t is applied). 4. If the foliage remains in the field, the Ca and Mg requirements become negligible, while the specific K requirement drops to 5-6 kg/t K2O, which is half that given in the literature. The specific requirement of 9 kg/t K2O reflects luxury K uptake, which is frequent on the colloid-poor, intensively fertilised soils of North-West Europe. On average sites in Hungary this value may lead to over-fertilisation with K.
|Number of pages||12|
|Publication status||Published - Oct 2000|
ASJC Scopus subject areas
- Agronomy and Crop Science