Extraction methods and availability of micronutrients for wheat under a no-till system with a surface application of lime

Abstract

Micronutrient availability can be affected by the increase of the soil pH due to surface liming. A field trial was carried out on a loamy, kaolinitic, thermic Typic Hapludox at Ponta Grossa, Paraná State, Brazil. The main objective was to evaluate the effects of surface liming and re-liming on the availability of micronutrients [copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)] for wheat (Triticum aestivum L.) cropped under a no-till system. A randomized complete block design was used in a split-plot arrangement. The main plots received surface lime applications (2, 4, and 6 Mg ha -1 ) in July 1993. In the subplots, surface lime (3 Mg ha -1 ) was applied again in June 2000. In 2003, before the wheat sowing, soil samples were taken at 0-5, 5-10, and 10-20 cm layers. Soil cationic micronutrients concentrations using different extractants (DTPA-TEA, Mehlich-1, HCl, and Mehlich-3) and solution/soil ratios were determined. Application of lime increased soil pH at 0-5, 5-10, and 10-20 cm. The increase in soil pH by liming did not affect soil organic carbon content. The Mehlich-3 solution had a greater capacity in extracting soil micronutrients. Increasing solution/soil ratio of the DTPA-TEA, Mehlich-1, and HCl solutions generally increased the extraction of Cu, Fe, Mn, and Zn. Liming and re-liming caused a decrease in Mn concentration in the wheat leaves. Leaf concentrations of Cu, Fe and Zn were not affected by liming treatments. The solutions of DTPA-TEA, Mehlich-1, HCl, and Mehlich-3 were ineffective to predict the soil cationic micronutrients availability for a wheat crop after surface application of lime.

Liming and application of micronutrients in the establishment of Tifton pasture

“…This shows that although the increase of soil pH provided by liming decreases the bioavailable fractions and increases the adsorption (Nascimento et al, 2007) by redistributing these elements into more stable fractions with higher binding energy (Brunetto et al 2014), the methods used in routine laboratories to evaluate the availability of these micronutrients are not always able to detect these changes (Fonseca et al, 2010). On the other hand, liming causes greater mineralization of organic matter by improving the soil chemical condition for microorganisms (Ernani et al, 2002), which can provide part of the micronutrients that were present in the soil organic matter.…”

<b>Effect of liming on micronutrient availability to soybean grown in soil under different lengths of time under no tillage

“…However, Caires et al (2003) observed decreases in Mn and Zn absorption by soybean plants, but only in some crops. Liming and re-liming caused a decrease in the Mn concentration in wheat leaves, but leaf concentrations of Cu, Fe and Zn were not affected by liming (Fonseca et al, 2010).…”

“…In the soil with nine years under NT, all rates applied on the surface reduced Fe content in the 0-0.05 m layer. On the other hand, Fonseca et al (2010) observed that liming caused a linear decrease in the extractable Fe content. Alleoni, Cambri, and Caires (2005) also observed a decrease in Fe concentrations extracted by DTPA at the 0.10 m depth after the application of surface liming under an NT system.…”

“…Thus, the Cu2+ solubility is soil pH dependent and decreases 100-fold for each pH unit increase (Fageria, Baligar, & Clark, 2002). In a study by Fonseca et al (2010), the soil extractable Cu decreased linearly with increasing lime application rates in a soil under NT due to the increased pH. Nachtigall, Nogueirol, and Alleoni (2007) reported that as the pH decreased, the exchangeable Cu content increased, while the amount of Cu bound to OM, oxides and residual fractions decreased.…”

“…Cultivation under no tillage (NT) increases the amount of OM in the surface layer (Thomas, Dalal, & Standley, 2007;Santiago, Quintero, & Delgado, 2008;Aziz, Mahmood, & Islam, 2013;Motschenbacher, Brye, Anders, & Gbur, 2014;Vukasinovic, Todorovic, Dordevic, & Rajkovic, 2015;Moreira, Prochnow, Kiehl, Pauletti, & Martin-Neto, 2016) as well as increases the pH when lime is applied to the surface (Caires, Blum, Barth, Garbuio, Kusman, 2003;Teixeira, Souza, Borém, & Silva, 2003;Caires et al, 2005;Fonseca, Caires, & Barth, 2010). In addition, the soil moisture increases and the temperature decreases compared with conventional tillage because organic residues Acta Scientiarum.…”