Search

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 Znsorbed 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. [ABSTRACT FROM AUTHOR]

Five different cultivars each of wheat, pea, and canola were grown with and without copper (Cu), zinc (Zn), and boron (B) fertilization, respectively, in a greenhouse study to identify any crop cultivar and rhizosphere soil responses to micronutrient fertilization. The prairie agricultural surface soils (0–10 cm) used in the study were suspected to be micronutrient deficient according to soil extractable levels. Only durum wheat (CDC Fortitude) produced greater biomass from Cu fertilization compared to the other wheat cultivars. Cultivar dependent responses of pea and canola biomass yield to Zn and B fertilization were not significantly (P >.05) different. Boron concentration in whole plant canola tissue increased following fertilizer addition. Micronutrient fertilization increased concentrations and supply rates of available Cu, Zn, and B in post-harvest rhizosphere soil. Fertilizer Cu and Zn were distributed in labile soil solution-carbonate-exchangeable and oxyhydroxide fraction, whereas B was primarily found in the hot water-soluble fraction, specifically adsorbed and oxyhydroxide fractions. The composition of low molecular weight organic acids (formic, propionic, malic, and fumaric acid) in the rhizosphere soil varied among crops. Additionally, citric and tartaric acid were present in the pea and canola rhizosphere soils, respectively. The rhizosphere soil of durum wheat not fertilized with Cu contain higher levels of succinic acid compared to the other wheat cultivars. For pea and canola, there was no significant (P >.05) effect of cultivar on the amounts or forms of organic acids in the rhizosphere soils. [ABSTRACT FROM AUTHOR]