2024 Volume 95 Issue 5 Pages 276-284
In Hokkaido, the planted area and production of potatoes for processing are increasing. The fertility of phosphates, which aids in the early growth of crops, is deemed crucial in upland fields where Andosols are widely distributed. Despite the increase in fertilization, no studies have confirmed the reduction of phosphate fertilizer. Hence, we carried out field experiments on the reduction and application rate of phosphate fertilizer at growers’ fields where processing potatoes were grown to explore the potential for fertilizer reduction. Experiments were conducted in the Tokachi and Kamikawa districts at growers’ fields, where the phosphate fertilizer applied was half the standard rate, and the amount varied between 0 and 250 kg-P2O5 ha−1. Comprehensive cultivation experiments were also performed at the experimental fields of Obihiro University of Agriculture and Veterinary Medicine, where the phosphate fertilizer applied was halved. The results of these experiments showed that the halved fertilizer plots yielded equal or higher than the standard plot, irrespective of the region or year. The application rate experiments revealed that the amount of phosphate fertilizer applied did not influence the yield of processing potatoes and that applying fertilizers beyond the standard fertilization rate decreased yield. To maintain yield levels and phosphorus fertility, it is advisable to apply phosphate fertilizer at a rate of 50 to 100 kg-P2O5 ha−1. In comprehensive experiments, reduced fertilization plots with a 50％ fertilization rate yielded equal or higher yields than those in standard plots. It is essential to challenge the outdated notion that “phosphorus deficiency is a problem for crop production in Andosols fields” and update our understanding of soil science.
