Reclaiming Sodium Affected Soil: The Potential of Organic Amendments

Abstract

A study was conducted to evaluate the potential of organic amendments in managing sodic soils for crop production. In doing this, a pot experiment was conducted in which saw dust biochar (SDB), palm fiber biochar (PFB), poultry manure biochar (PMB) and poultry manure (PM) were applied to sodic soil sampled from an industrial area in Cape Coast, Ghana. Gypsum amendment and a control were included for the purpose of comparing results. All amendments were applied at the rate of 4.78 t ha-1 which was the full gypsum requirement rate for the soil. Amended soils were incubated and weekly sampled for 6-weeks (week 3 to 8) for laboratory analysis. Periodic watering was done to keep soils moisture at field capacity. From the results, organic based amendments marginally reduced soil pH and electrical conductivity (EC). Same amendments significantly (P = 0.05) increased soil Ca+2 and Mg+2, with SDB registering the highest increase. The increases in the levels of Na+ and K+ were marginal and statistically insignificant (P = 0.05). PFB recorded the highest cation exchange capacity (CEC) at week 8 and SDB and PFB reduced soil sodicity below the minimum threshold of exchangeable sodium percentage (ESP) 15. All organic based amendments recorded marginal increase in soil organic carbon (OC) but SDB recorded the highest value for OC at week 8. PMB released the highest amount of available P, with peak availability observed in week 6 Insignificant (P = 0.05) increases were also observed for soil NH4+-N and NO3--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 amendment.