Soluble salt concentrations and properties of mound tilled degraded soil amended with fresh and decomposed rice mill waste and effects on maize (Zea mays L) grain yields in Abakaliki, southeast Nigeria

ABSTRACT

A two-year field experiment was carried out in 2019 and 2020 cropping seasons to investigate the effects of applying fresh and decomposed rice mill waste on soil properties, pollution potential in terms of concentrations of soluble salts (sodium adsorption ratio (SAR), % exchangeable sodium (ESP), % exchangeable potassium (EPP) and soil nitrate (NO₃⁻)) and on the yield of maize (Zea mays L). The experiment was arranged as randomised complete block design with four treatments and five replications. The treatments were a) control (no amendment, C); b) 5 t ha⁻¹ fresh rice mill waste (FRMW); c) 5 t ha⁻¹ rice mill waste decomposed with 2.5 t ha⁻¹ poultry droppings (PDMW); and d) 5 t ha⁻¹ rice mill waste decomposed with 2.5 t ha⁻¹ cow dung (CDMW). The results showed significant (p < 0.05) decreases in soil bulk density and increases in aggregate stability in soil amended with fresh or decomposed rice mill waste, relative to the control. Significant increases in available P, total N, organic carbon and pH were observed in the amended soils, compared with the control. ESP, SAR, EPP and NO₃ in the soil were also increased in amended soils, but they were still at levels lower than the threshold considered as detrimental in soils. Application of fresh and decomposed rice mill wastes significantly increased maize grain yields relative to the control. These findings suggested that the use of both fresh and decomposed rice mill waste can enhance soil fertility in the area.

KEYWORDS:

• Decomposition
• soil fertility
• soil structure
• tropical soils
• ultisol

Acknowledgments

The authors hereby acknowledge the laboratory staff of the Department of Soil Science and Environmental Management, Ebonyi State University, Abakaliki.

Disclosure statement

No potential conflict of interest was reported by the authors.