The critical value of soil Olsen-P (mg Olsen-P kg -1 ) is the value of soil Olsen-P above which the probability of crop response to P fertilization is small or null. The aim of the present study was to determine the critical value of soil Olsen-P for potato tuber yield in volcanic soils. The data used in this study were taken from 41 experiments of P fertilization conducted in southern Chile from 1977 to 2015 by the National Potato Center at the Instituto de Investigaciones Agropecuarias (INIA). To identify the critical values of soil Olsen-P, relationships between relative yields and initial soil P-Olsen were assessed using three models (linear-plateau, boundary and Mitscherlich function). Across experiments, the average fresh tuber yield was 41.9 Mg ha -1 and varied between 4 and 89 Mg ha -1 . Fresh tuber yield decreased up to 92% by P deficiency; however, yield reduction was concentrated between 20 and 40%. The critical Olsen P values determined were 41, 33 and 11 mg Olsen-P kg -1 obtained (P < 0.01) with linear-plateau, boundary function and Mitscherlich function, respectively. However, linear-plateau and Mitscherlich functions showed lower coefficient of determinations (R 2 = 0.23-0.31) than the boundary function (R 2 = 0.97). Therefore, we suggest that the critical Olsen-P value of 33 mg P kg -1 determined with the boundary function is more appropriate for potato growers than the critical value determined with the other models. This information will be valuable for optimizing strategies for P fertilizer management in potato production systems aimed at achieving optimal crop yield and minimizing potential environmental risk.
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Sandaña, P., Orena, S., Rojas, J. S., Kalazich, J., & Uribe, M. (2018). Critical value of soil Olsen-P for potato production systems in volcanic soils of Chile. Journal of Soil Science and Plant Nutrition, 18(4), 965–976. https://doi.org/10.4067/S0718-95162018005002801