Effects of Cu and Zn Coated Urea on Eh, pH and Solubility of Cu and Zn in Rice Soils

Abstract

The concentration of Cu (Copper) and Zn (Zinc) decreases upon flooded conditions of rice soil. To assess the effects of flooding and application of Cu and Zn coated urea on changes in Eh, pH and solubility of Cu and Zn, a glasshouse experiment was conducted at Universiti Putra Malaysia. Rice plants (30 days old seedlings of type MR-219) on two soils (riverine and alluvium and marine alluvium) were transplanted. Nine treatments with variable rates and combinations of Cu and Zn coated urea were applied. The sources of fertilizers were copper sulfate and zinc sulfate. Eh values decreased with flooding time in both soils. The changes of Eh values were more negative in control treatments and stabilized after 3 weeks of submergence. The Eh variation was not observed affectively in the treated soils however, soil pH increased with flooding time. During the 3rd week of submergence, pH was neutral (pH 7.0). In both soils, Cu and Zn treated soil showed lower Eh and higher pH values as compared to untreated soil. Concentration of Cu and Zn in soil solution decreased with flooding. The higher Cu and Zn contents in soil were recorded in treated soils. Reduced solubility of Cu and Zn in control soils was related to larger changes in Eh and pH values. Mean comparison with Tukey’s HSD (Honest Significant Difference) test showed that Cu and Zn solubility decreased with decreased Eh and increased pH in the soil solution (p < 0.05%).

Effect of Zn Applied with or Without Palm Stearin Coated Urea on The Growth and Mineral Element Concentration of Maize (Zea mays L.)

“…Babar et al (2019) reported that using controlled-release urea (CRU) in the form of encapsulated urea for wheat during the winter growing season significantly increased N-availability in soil and improved yield by 40.5%. A similar observation was also reported previously by Babar et al in 2018 where they applied coated urea; used palm stearin as a binder which was enriched with Cu and Zn (urease inhibitors) observed a positive effect on all the growth parameters and N-contents along with the chlorophyll contents in rice plants under acidic soil conditions of Malaysia. They have documented a 40% increase over control in rice yield.…”

Improving crop productivity and nitrogen use efficiency using sulfur and zinc-coated urea: A review

“…Zinc-coated urea decreases the pH of the soil, thus, it increases zinc availability in the rhizosphere. Babar et al (2018) observed the positive effect of Zn-coated urea in controlling the fluctuation of pH ranging from 6.0 to 6.5 in submerged paddy soils. Hence, Zn-coated urea as a mineralcoated fertilizer significantly maintains the soil pH around the optimal plant value of 6.5.…”

“…The rate of breakdown of coated urea fertilizers containing Zn is mostly determined by soil temperature and density of soil microflora, and the duration is also determined by the activity of soil microbes (Yang et al, 2018). Zinc-coated urea reduces the rate of urea hydrolysis and serves as a urease inhibitor which increases crop growth and yield (Babar et al, 2018).…”