There is growing evidence of excessive use of phosphate fertilizer and high residual soil phosphate levels in arable cropping systems in Japan. However, there is a lack of regional-scale information on the current status of soil-available phosphate as well as its impacts on a potato (Solanum tuberosum L.) cropping system. Although phosphorus is an essential nutrient, there have been confounding reports about the effects of excessive soil-available phosphate on potato tuber yields. This study was conducted in Hokkaido, Japan, to determine the current status of phosphate fertilizer application rate and soil-available phosphate levels, and their effects on tuber yield. In two contrasting soil types varying in phosphate absorption coefficient (PAC), soil and potato tuber samples were collected from 90 and 80 grower fields in Tokachi and Kamikawa districts, respectively, in the 2013 and 2014 growing seasons. The soil samples were analyzed for PAC, available phosphate by the Truog method, and total phosphate along with total carbon and acid-oxalate extractable aluminum. The tuber samples were collected at the harvesting stage for the calculation of yields. This study revealed (1) ongoing excessive phosphate fertilization regardless of high soil-available phosphate levels in potato-producing fields of Hokkaido, (2) no positive impacts of excess soil-available phosphate on tuber yields, and (3) no yield response from the applied phosphate fertilizer in excess of the recommended rate in two contrasting soil types. In conclusion, excess phosphate fertilizer was an unnecessary cost to the growers and could also be a potential harm to the environment, and changes are urgently needed to optimize the input-output balance of phosphate in this agricultural system.
Improvement of yield and quality on processing potato (Solanum tuberosum L.) by understanding the interactive effects of soil characteristics and plant nutrient management in Hokkaido, Japan
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.