Managing Sodic Soils: The Role of Organic Amendments

Abstract

A study was conducted to evaluate the potential of organic amendments in managing sodic soils for crop production. Soils sampled from Cape Coast industrial area, opposite Ameen Sangari Industries Limited, were used in the study. In preliminary studies, wastewater discharged from the soap making industry contained pH of 11.2, EC of 4.37 dS m-1 and ESP of 60.4. Soil used in the study had the following properties: pH of 8.7, EC of 3.7dS m'1 and ESP of 18.0. A pot experiment was then conducted in which saw dust biochar (SDB), palm fiber biochar (PFB), poultry manure biochar (PMB) and poultry manure (PM) were applied to the sodic soil. Gypsum amendment and a control (soil only) were included for the purpose of comparing results. All amendments were applied at the rate of 4.78 t ha-1. Amended soils were incubated at room temperature. The incubated soil was weekly sampled for 6-weeks for laboratory analysis. From the results, organic based amendments reduced soil pH and electrical conductivity (EC). The same amendments significantly (P = 0.05) increased soil Ca+2 and Mg+2, with SDB registering the highest increase. Increases soil Na+ and K+ were marginal and statistically insignificant (P = 0.05). PFB recorded the highest CEC at week 6. SDB and PFB reduced soil sodicity below the minimum threshold of ESP 15. SDB recorded the highest OC increase at week 6. PMB released the highest amount of available P. Insignificant (P = 0.05) increases were observed for soil NH4+-N and NO3乙N. SDB and PFB recorded 90 % and 80 % maize seed germination and also, 10.1 t ha'1 and 8.7 t ha'1 dry matter yields respectively. No maize seed however germinated in the control and all other amendments.