The effect of different N, P and K supply levels (poor, medium, satisfactory, excessive) and their combinations was examined on the yield, starch yield and cooking quality of the potato variety Desiré grown on calcareous loamy chernozem soil, and on the element contents of the plots (analysed using various methods). The ploughed layer contained 5% CaCO3, 3% humus and 20-25% clay, and had a pH(KCl) of 7.3. The original soil was poorly supplied with P and Zn and moderately supplied with N and K according to soil analyses. The mineral fertilisation experiment involved 4N × 4P × 4K = 64 treatments or nutritional combinations in 2 replications, giving a total of 128 plots. The N levels were 0, 100, 200 and 300 kg/ha/year, and the PK levels 0, 500, 1000 and 1500 kg/ha/10 years P2O5 and K2O in the form of calcium ammonium nitrate, superphosphate and 50% potassium chloride. The replenishment with P and K fertiliser took place when the experiment was set up in autumn 1973. The plot size was 6 × 6 = 36 m2 and the forecrop over 2 years was maize. The groundwater level was at a depth of 15 m. The main conclusions were as follows: 1. The development of the foliage was stimulated to the greatest extent by combined NK fertilisation, while the dominance of P fertilisation accelerated foliage aging and the appearance of Alternaria infection, counteracting the opposite effect of NK fertilisers. As the NK supplies improved there was a 50% increase in the number of tubers and a 25-30% rise in the mean mass of the tubers, while the tuber yield per hectare was almost doubled. K fertilisation led to a 1.5% increase in the starch %. 2. Cooking quality parameters (raw grey and brown discoloration; brown discoloration during frying, grey discoloration during boiling; brown discoloration during frying, grey discoloration during boiling of over-ready chips; grittiness, water content, consistency and flavour) exhibited no significant change as a function of plant nutrition, retaining the favourable characteristics of the variety. Nor could any difference between the treatments be demonstrated for the shrinkage losses recorded during 190 days of storage. 3. According to the soil analyses "satisfactory" P supplies for potato could be achieved with 110-120 ppm AL-soluble P2O5 or 25-30 ppm NaHCO3-soluble P2O5 "Satisfactory" K supplies were reached at a concentration of 150-200 ppm AL-K2O or NH4-acetate-K2O, at which point the K effects disappeared. The analysis of I:50 aqueous extracts indicated that 10-20 ppm P2O5 and 50-60 ppm K2O content in the ploughed layer could be regarded as "satisfactory". The total of EUF fractions I-VII showed that the following concentrations resulted in "satisfactory" supplies: EUF-P2O5 20-30 ppm, EUF-K2O 130-140 ppm.
|Number of pages||16|
|Publication status||Published - Jun 1 2000|
ASJC Scopus subject areas
- Agronomy and Crop Science