Critical Value of Soil Potassium for Potato Crops in Volcanic Soils
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ORIGINAL PAPER
Critical Value of Soil Potassium for Potato Crops in Volcanic Soils Patricio Sandaña 1
&
Sandra Orena 2 & José Santos Rojas 2 & Julio Kalazich 2 & Marco Uribe 2
Received: 12 November 2019 / Accepted: 17 February 2020 # Sociedad Chilena de la Ciencia del Suelo 2020
Abstract The critical value of soil exchangeable potassium (K) (mg K kg−1) is a valuable tool for an efficient K fertilization management in potato production systems. The aim of the present study was to determine the critical value of soil exchangeable K for potato crops grown in different environments and differing availabilities of initial exchangeable K. The data used in this study were taken from 34 experiments on K fertilization conducted in southern Chile from 1977 to 2017 by the National Potato Center at the Instituto de Investigaciones Agropecuarias (INIA). Yield responses to K fertilization rates were assessed with linear-plateau and Mitscherlich models in order to determine the critical soil exchangeable K across environments. Across experiments, the average fresh tuber yield ranged between 18 and 91 Mg ha−1. Fresh tuber yields decreased by up to 70% when no K fertilization was applied. Yield reduction was concentrated around 25% in response to K deficiency. Relative yields were described as significant by both linear-plateau and Mitscherlich models. However, relative yields were better described by the linear-plateau model (p < 0.01, R2 = 0.62; SEE = 0.11). The critical soil exchangeable K value identified with the linear-plateau model was 224 mg K kg−1. This critical K value will be useful for potato farmers that produce their crops in volcanic soils, such as Andisols. Moreover, this critical K value will help to increase K use efficiency through better K fertilization management strategies aimed at building and/or maintaining K levels in soils. Keywords Tuber yield . K deficiency . Exchangeable K . Relative tuber yield
1 Introduction Potatoes (Solanum tuberosum L) are an important staple crop in most parts of the world. They have high nutrient requirements, among which potassium (K) is required in higher concentrations than both nitrogen and phosphorus (Fernandes et al. 2017; Job et al. 2019). Fernandes et al. (2017), when comparing five potato cultivars under different phosphorus supplies, showed that the N, P and K in the whole plant dry matter varied between 1.58–2.16, 0.18–0.26 and 2.93–3.78%, respectively. K has proved to play an important role in the carbon and nitrogen balance through several physiological mechanisms in other species (Ali et al. 2020). Therefore, a
* Patricio Sandaña [email protected] 1
Institute of Plant Production and Protection, Universidad Austral de Chile, Campus Isla Teja, Valdivia, Chile
2
Instituto de Investigaciones Agropecuarias, INIA-Remehue, Ruta 5, km 8 Norte, Osorno, Chile
high amount of K fertilizers is usually required to obtain high potato crop yields probably due to the low nutrient uptake efficiency of potato crops due to their small root systems (Iwama 2008; Sandaña
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