Critical value of soil Olsen-P for potato production systems in volcanic soils of Chile

Abstract

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.

Critical Value of Soil Potassium for Potato Crops in Volcanic Soils

“…For example, for phosphorus (P), critical values of soil Olsen-P have been defined for several crop species (Johnston et al 1986;Bollons and Barraclough 1999;Mallarino and Atia 2005;Colomb et al 2007). Recently, Sandaña et al (2018) found a critical value of 33 mg P kg −1 for potatoes grown in volcanic soils. Different critical values of soil Olsen-P for diverse sites could be related to differences in soil properties, such as soil texture (Redulla et al 2002;Johnston et al 2013;Sandaña et al 2018).…”

“…Recently, Sandaña et al (2018) found a critical value of 33 mg P kg −1 for potatoes grown in volcanic soils. Different critical values of soil Olsen-P for diverse sites could be related to differences in soil properties, such as soil texture (Redulla et al 2002;Johnston et al 2013;Sandaña et al 2018). Regarding K, Li et al (2015) analysed a high number of trials assessing two rates of K in experiments conducted in Inner Mongolia, Gansu, Qinghai and Ningxia provinces, the main potato production regions in northwest China.…”

“…These authors found that the critical level of soil exchangeable K (extracted by ammonium acetate) was 105 mg kg −1 , which could be a reference for K fertilization practices in potato crops grown in this region. Nevertheless, this value could vary depending on soil properties, such as soil texture, as it was highlighted by Sandaña et al (2018) for critical soil P.…”

“…Recently, in a study by Li et al (2015), the relationship between relative yield and soil exchangeable K was described by a quadratic model. Other models, such as the linear-plateau and Mitscherlich models, have been successfully used to assess the relationship between relative yield and initial soil nutrient concentration (Allison et al 2001;Colomb et al 2007;Tang et al 2009;Bai et al 2013;Sucunza et al 2018;Sandaña et al 2018). However, contrary to the Mitscherlich and quadratic models, the linear-plateau model does not require an arbitrary relative yield value to find the critical value of a soil nutrient (Colomb et al 2007;Tang et al 2009;Sandaña et al 2018).…”

“…Other models, such as the linear-plateau and Mitscherlich models, have been successfully used to assess the relationship between relative yield and initial soil nutrient concentration (Allison et al 2001;Colomb et al 2007;Tang et al 2009;Bai et al 2013;Sucunza et al 2018;Sandaña et al 2018). However, contrary to the Mitscherlich and quadratic models, the linear-plateau model does not require an arbitrary relative yield value to find the critical value of a soil nutrient (Colomb et al 2007;Tang et al 2009;Sandaña et al 2018). To the best of our knowledge, the critical soil exchangeable K value has not yet been determined for potato crops cultivated in volcanic soils such as those in southern Chile, which are characterized by a high organic matter content (< 25% of organic carbon), low bulk density (≤ 0.9 Mg m −3 ), low pH (5.0-6.5) and high P adsorption capacity (> 85%) (Valle and Carrasco 2018).…”