Development of the limit values of micronutrient deficiency in soil determined using Mehlich 3 extractant for Polish soil conditions. Part I. Wheat

Abstract

To implement the Mehlich 3 method in Polish agro-chemical laboratories, limit values for deficiency of B, Cu, Fe, Mn and Zn in soil for wheat were developed. The values were developed on the basis of 1921 fields with wheat, evenly distributed throughout Poland. Soil samples were collected from these fields in 2016, together with the plants growing on them, at the stage of stem elongation (BBCH 30/31). The concentration of micronutrients was determined in all soil and plant samples. In addition, pH, texture, and the content of organic carbon and available phosphorus were determined in soil samples. Moreover, grain yield after wheat harvest was estimated for all fields. Limit values were developed by two independent methods: 1) the regression equation method and 2) the so-called high yield method. In the first case, the limit microelement concentration in soil was calculated from the equation describing the relationship between the bioaccumulation factor (R/G) and a specific soil feature (n=1921). The bioaccumulation factor is the quotient of the concentration of a micronutrient in a plant (R) and its concentration in the soil (G) determined by the Mehlich 3 method. The equations were constructed using the Stagraphics program. For each micronutrient, 8 models were tested in search for the equation with the highest determination coefficient r2. Limit values were calculated after substituting the critical value of microelements in the plant (R) to the selected model and transforming the equation accordingly. The basis of the second method was to separate the “high yield group” ≥7.0 t ha−1 (n=578) from the entire data set. In this group, lower quintiles for the Mehlich 3-concentration of individual microelements in soil were calculated. The lower quintiles (QU1) were taken as limit values. It was assumed that QU1 is a good indicator of the lowest micronutrient concentration in the soil at which a yield of 7.0 t ha−1 or higher can be obtained. The comparison of the values calculated with the regression equations method and the high yield method showed their similarity, which confirmed the reliability of these values. The proposed values define the limit for low microelements concentration in soil determined with the Mehlich 3 method, below which wheat fertilization with these nutrients is recommended.

Effect of Soil and Foliar Silicon Application on the Reduction of Zinc Toxicity in Wheat

“…After the digestion, Zn was determined using the flame atomic absorption spectrometry FAAS (flame atomic absorption spectrometry) method [51]. The available Zn in the soil was determined by Mehlich 3 method [52][53][54].…”

New limit values of micronutrient deficiency in soil determined using 1 M HCl extractant for wheat and rapeseed

“…All chemical analyses were performed in accredited agro-chemical laboratories. Detailed methodology of analyses is given by Korzeniowska et al (2019) Table 2 Characteristic of soil samples Table 3 The concentration of microelements in soil samples determined by the 1 M HCl method in mg kg -1…”

“…QU1 were taken as limit values. Details of the "high yield method" was described by Korzeniowska et al (2019) and Stanisławska-Glubiak et al (2019).…”

“…9), the concentration of Mn in the soil was calculated (Mn S ). The detailed methods of calculation of the values and critical concentrations in the plant, were described in Korzeniowska et al (2019) and Stanisławska-Glubiak et al (2019).…”

“…The high correlation between the two extractants was also confirmed by Gediga et al (2015) and Korzeniowska et al (2016). This required development of limit values for Mehlich 3 extractant for Polish conditions (Korzeniowska et al, 2019;Stanislawska-Glubiak et al, 2019) and updating the "old values" for 1 M HCl that were used for 30 years in OSChR laboratories.…”