Efficiency and residual effect of alternative potassium sources in grain crops

Rogério Peres Soratto,Amanda Prado Gilabel,Murilo de Campos,Gustavo Spadotti Amaral Castro,Jayme Ferrari Neto,Carlos Alexandre Costa Crusciol,Claudio Hideo Martins da Costa

doi:10.1590/s1678-3921.pab2021.v56.02686

Abstract

Abstract The objective of this work was to evaluate the efficiency and the residual effects of both molten and ground alkaline potassium-silicate rocks (K1) and of ground phonolite rock (K2), as sources of potassium, compared with the traditional source (KCl), in grain crop successions. Two experiments – one with the succession soybean-wheat-corn and the other with the succession corn-millet-soybean – were conducted on a Typic Haplorthox in a randomized complete block design with four replicates. The treatments consisted of three sources (KCl, K1, and K2) and four rates of K (corresponding to 0, 0.5, 1.0, and 2.0 times the recommended rates for soybean and corn). The used sources did not affect leaf K concentration in soybean, but KCl and K2 similarly increased leaf K concentration in corn. Regardless of the source, K application increased the yield of all crops. The K1 and K2 sources present agronomic efficiencies equivalent to that of KCl. K1 and K2 show a more pronounced residual effect than KCl, especially on crops grown approximately one year after their application and under K rates above those recommended for the crops.

Highlights

Potassium is essential for plant nutrition, being the second most required nutrient by most crops and the most abundant cation in the cytoplasm, contributing to maintaining the osmotic potential of plant cells (Malavolta et al, 1997; Hasanuzzaman et al, 2018)
Experiment I evaluated the annual effects of K fertilizer sources and rates applied to soybean in the summer of 2007/2008, as well as the residual effects on wheat (Triticum aestivum L.) in the winter of 2008 and on corn in the summer of 2008/2009
Experiment II assessed the annual effect of K fertilizer sources and rates when applied to corn in the summer of 2007/2008, besides the residual effects on millet [Pennisetum glaucum (L.) R

Summary

Introduction

Potassium is essential for plant nutrition, being the second most required nutrient by most crops and the most abundant cation in the cytoplasm, contributing to maintaining the osmotic potential of plant cells (Malavolta et al, 1997; Hasanuzzaman et al, 2018). The element plays a role in activating several enzymatic systems, many of which are involved in photosynthesis, respiration, protein synthesis, and photoassimilate transport by the phloem (Hasanuzzaman, et al, 2018), affecting grain yield and quality (Mancuso et al, 2014; Lima et al, 2017; Fan et al, 2021). The demands for K2O in Brazilian agriculture reached 6.7 Tg in 2019 (FAO, 2021). The Brazilian production of K2O was only of 240,000 Mg (400,000 Mg KCl), which corresponds to less than 4.0% of the domestic agricultural demand, leading Brazil to spend more than USD 3.0 billion with K2O imports (Oliveira, 2015; Kulaif & Góes, 2016; Manning, 2018; Sipert et al, 2020; FAO, 2021). The high import volume of KCl negatively affects Brazilian trade balance and shows the need of negotiating with a restricted group of supplier countries, emphasizing the importance of exploring alternatives to this fertilizer (Mancuso et al, 2014; Oliveira, 2015)

Objectives

Methods

Results