Zinc fractions in soil and uptake by wheat as affected by different preceding crops

Abstract

Zinc (Zn) deficiency is widespread in alkaline and calcareous soils. Limited information is available on the effect of preceding crops on the distribution of Zn in soil solid phase. This field study was conducted to investigate the changes in Zn chemical forms in soil solid phase as affected by four preceding crops [Sunflower (Heilianthus annuus L. cv. Allstar), Sorghum (Sorghum bicolor L. cv. Speed Feed), Clover (Trifolium pratense L.) and Safflower (Carthamus tinctorius L. cv. Koseh-e-Isfahan)] in a calcareous soil. A control treatment with no preceding crop (fallow) was also used. Our results showed that the preceding crops increased Zn concentration in exchangeable fraction (EXCH-Zn), the organically bound zinc form (ORG-Zn) and zinc bound to iron and manganese oxides (FeMnOX-Zn) while decreased carbonates bound-zinc (CAR-Zn) and residual zinc forms (RES-Zn). However, the changes in Zn fractions were dependent on the preceding crop type. The EXCH-Zn and ORG-Zn pools can be considered labile pools that play significant roles in supplying Zn for plants. Among the preceding crops used in this experiment, clover (Clo) had the highest effect on transforming CAR-Zn form to EXCH-Zn and ORG-Zn labile forms and thus resulted in the highest Zn accumulation in tissues of the target wheat (Triticumaestivum L. cv. Back Cross). Although the changes in chemical forms of Zn in the soil solid phase are complex and dependent on various factors, our findings showed that the preceding crops significantly increased the concentration of Zn in exchangeable and organic matter pools and in turn resulted in higher uptake of Zn by the target wheat.

Chemical Fractions and Availability of Zn in a Calcareous Soil in Response to Biochar Amendments

“…In addition, the increases in the Fe-MnOx-Zn in B200 treatments might be due to an increase in ligand adsorption. Ligand adsorption usually suggests a negative charge is being conveyed onto the oxide surfaces, thus increasing Zn adsorption by Fe and Mn oxides in calcareous soil (Norouzi et al 2014). Similar results were also reported by Zahedifar (2017) in calcareous soils treated with wheat straw biochar.…”

“…Moreover, processing crop residues to biochar and applying it to calcareous soil are recognized as a better way for disposal of crop residue and improvement of soil quality (e.g., Beheshti et al 2018;Khadem and Raiesi). Hence, application of soil organic amendments such as biochar may help to increase soil organic matter and can subsequently increase availability and distribution of Zn fractions in calcareous soils (Khoshgoftarmanesh et al 2018;Norouzi et al 2014).…”

Influence of Different Rates and Frequencies of Zn Application to Maize–Wheat Cropping on Crop Productivity and Zn Use Efficiency

“…These findings are in accordance with the observation of Zhang et al [64], who reported that Zn application could increase Zn uptake by plants. Similar results were also reported in different crops by Harris et al [65], Norouzi et al [66], and Kumari et al [67].…”

Quantify the Requirements to Achieve Grain Zn Biofortification of High-yield Wheat on Calcareous Soils

“…Zn is often relatively low (< 0.5 mg kg -1 ), developing high-Zn-distribution cultivars should be 213 combined with agronomic measures like Zn fertilization to promote Zn uptake. For instance, in Iran 214 rainfed drylands with soil available Zn of 0.2 mg kg -1 (Norouzi et al, 2014), the tested wheat 215 cultivars exhibited high yield of 6.6 t ha -1 and shoot Zn uptake of 174 g ha -1 . Even if the Zn.c of 17.0 216 mg kg -1 was increased to the Zn.a of 26.4 mg kg -1 by introducing new cultivars, there was still a large 217 gap to Zn.t which needed to be closed by increasing Zn uptake.…”