2018 Volume 89 Issue 2 Pages 95-107
Potassium and phosphoric acid fertilization and planting density analyses were conducted across 31 fields in Tokachi District, Hokkaido, in 1990. The three test plots were arranged side-by-side in the same field, each with an area of 15 m2 and designed in a fully randomized method, with no repetition. Seven levels of potassium fertilization [range, 0–249 kg-K ha−1 (0–300 kg-K2O ha−1)], six levels of phosphoric acid fertilization [0–273 kg-P ha−1 (0–625 kg-P2O5 ha−1)], and planting density [50,000–90,000 plants ha−1] were examined. To quantify the effect of fertilization and planting density on the yield and quality of sugar beet, these factors were varied, and linear regression coefficients were calculated for each studied field. Next, the correlation between these regression coefficients and soil analysis values was examined. Some significant correlation was found between these variables, and these signs of significant correlations were opposite between potassium and phosphoric acid fertilizations. A negative significant correlation was found between regression coefficients of potassium and phosphoric acid fertilization effects on the root weight and sugar yield.
The effect of potassium and phosphoric acid fertilization can be classified into the following three groups: group A, strong effect of potassium; group B, strong effect of phosphoric acid; and group C, strong effect of both potassium and phosphoric acid. Hierarchical cluster analysis was performed for the regression coefficients of potassium and phosphoric acid fertilization effects on the sugar yield. Therefore, we investigated a method to classify cultivation fields into the abovementioned groups using canonical discriminant analysis for soil parameters and developed a prototype for automatic calculation using Microsoft Excel.
This model is a field discrimination model derived from the field test of sugar beet, but it seems to be helpful in estimating the potassium and phosphate acidic characteristics of the field including other crops.
