Calibration of Potassium Soil Test Results in Some Calcareous Soils

Document Type : Research Paper

Authors

• Marzieh Barati Zanyani ¹
• Alireza Hosseinpur ²
• Mohammad Hasan Salehi ²
• Azam Jafari ³

¹ Department of Soil Sciences and Engineering. Faculty of Agriculture. Shahrekord University. Shahrekord., Iran.

² Department of Soil Sciences and Engineering. Faculty of Agriculture. Shahrekord University. Shahrekord. Iran.

³ Department of Soil Science. Faculty of Agriculture. Shahid Bahonar University of Kerman. Kerman. Iran.

Abstract

Keywords

• 'Available Potassium'
• 'Maize Plant Response'
• 'Different Extractants'
• 'Cate- Nelson'

Main Subjects

• ..

Introduction:

One of the macronutrient essential for plant growth is potassium and plays significant physiological and biochemical roles in plant yield. There are four forms of potassium in the soil, listed in order of their availability for plant uptake: soluble potassium, exchangeable potassium, non-exchangeable potassium, and structural potassium. Due to continuous cultivation and the lack of potash fertilizer usage, the available potassium in soils has decreased, and the status of available potassium should be assessed. Therefore, soil testing serves as an effective method for evaluating the potassium absorbed by plants during the growing season.The soil test program for each element, includes; the correct principles for preparing and collecting soil samples, extracting the desired element from the soil, correlation element extracted with plant indices, interpreting laboratory results and recommending appropriate fertilizers based on climatic, economic, and farm management factors. Soil testing enables farmers and researchers to identify the best soil management practices and make optimally use of fertilizer resources.

Objective:

The aim of this research was to investigate the potassium status using different extractants in Shahrekord plain farmlands and calibration of  potassium soil test results by using two-classes and three-classes Cate-Nelson models variance analysis for maize (Zea mays L.) plant in some calcareous soils.

Material and method:

 To implement the potassium soil test program for maize plant in the calcareous soils of the ShahreKord plain, 30 agricultural soil samples were collected from a depth of 30 cm. Five extractants including; 1N NH₄OAc, AB- DTPA, 0.1M barium chloride, 0.01M calcium chloride and Mehlich 1 were evaluated for extracting available potassium.

The greenhouse experiment was carried out as a factorial in the form of completely randomized design with two factor; 30 types of soil and potash fertilizer in two levels of potassium (zero and 100 mg k kg^-1) from sources of potassium sulfate with three replications. At the end of,  the vegetative period , corn plants harvested and plant indices including; dry matter weight, potassium concentration, potassium uptake, relative yield and plant response were determined. To assess the significance of treatment effects in terms of plant indicators, factorial analysis of variance was performed. Then, the soils based on potassium extracted in appropriate extractants; by using the Cate-Nelson variance analysis method grouping into two (low and high) and three groups (low, medium, and high).

Result and Discussion:

The results of the analysis of variance showed that the main effects of soil type and potassium fertilizer were significant (p<0.01) on dry matter weight, potassium concentration and uptake. However, the interaction between soil and fertilizer was not significant for dry matter weight. The results showed that different extractants, extracted varying concentrations of potassium. Based on the high correlation between potassium extracted by extractants 1N NH₄OAc, 0.1M barium chloride and 0.01M calcium chloride with relative yield and plant responses indices, these extractants can be considered appropriate for use these soils. By using two-classes model of Cate- Nelson variance analysis, the low and high class boundaries for the 1N NH₄OAc, 0.1M barium chloride and 0.01M calcium chloride extractants were 290.0, 270.25 and 69.50 mg kg^-1 respectively. By using the three-class model of Cate- Nelson variance analysis showed that the low and medium class boundaries for 1N NH₄OAc, 0.1M barium chloride and 0.01M calcium chloride extractants were 200.5, 205.5 and 33.0 mg kg^-1 respectively. The medium and high class boundaries for these extractants were 364.5, 270.5, and 69.5 mg kg^-1 respectively. Based on the two-classes model of Cate- Nelson variance analysis, in the 1N NH₄OAc, 0.1M barium chloride and 0.01M calcium chloride extractants 47, 67 and 77, of the soils are placed into the low soil test class. Also, based on the three-class model of Cate- Nelson variance analysis, in the 1N NH₄OAc, 0.1M barium chloride and 0.01M calcium chloride extractants, 13, 13 and 13 are classified in the low class and 17, 30 and 20, of the soils are placed into the high soil test class.

Author Contributions:

All authors have read and agreed to the published version of the manuscript.

Data Availability Statement:

Data is available on reasonable request from the authors.

Acknowledgements:

The authors would like to thank the Soil Science Department of the University of Shahrekord for providing equipment and facilities.

Ethical considerations:

The authors avoided data fabrication, falsification, plagiarism, and misconduct.

Conflict of interest:

The author declares no conflict of interest.