Zinc and copper interactions under variable soil phosphorus and moisture conditions in selected Saskatchewan soils

Abstract

This study evaluates the influence of phosphorus (P) fertilization (without and with added P fertilizer) and soil moisture (stress and no-stress) on efficacy, fate, and transformation of soil applied micronutrients such as copper (Cu), zinc (Zn), and Cu + Zn in a wheat and pea cropping sequence. Wheat was grown as first crop under controlled environment conditions in which micronutrient fertilizer treatments were applied, whereas pea was grown as following crop with recommended macronutrient fertilizers to understand the residual effects of micronutrient fertilization. The high-P fertilizer application and no-stress moisture condition produced the highest grain and straw yield of wheat. Without P fertilization, there were significant negative effects of a combined application of Cu and Zn on wheat yield in a Dark Gray Chernozem. Yield of the following pea crop did not show response to residual Cu and Zn. Micronutrient fertilization increased the Cu and Zn concentration in wheat and pea grain and straw and resulted in increased after-harvest availability and supply in soils. Apart from the increased concentration in labile fraction, a considerable amount of added Cu and Zn was occluded with organic matter and oxyhydroxide species, respectively. Molecular speciation analyses revealed that carbonate associated was the dominant form of Cu and Zn in the soils. Additional Cu species such as Cu-acetate and methoxide, and Zn species including Zn-sorbed montmorillonite species were identified. Insoluble Cu-phosphate and Zn-phosphate complexes were not identified by speciation analyses and do not appear to be a significant factor controlling Cu and Zn availability in these soils.

Keywords:

• micronutrient fertilization
• moisture stress
• nutrient interaction
• speciation
• yield response

Acknowledgments

We extend our sincere thanks to Ning Chen and Weifeng Chen, for technical assistance at the Hard X-ray MicroAnalysis (HXMA) beamlines during data collection at Canadian Light Source. We also greatly appreciate the reviewers for their time spent on reviewing this manuscript and their insightful comments helping us improving the article.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was financially supported by the Western Grains Research Foundation and Agriculture and Agri-Food Canada Agri- Innovation Program.