Nitrogen Release Dynamics of Erythrina abyssinian and Erythrina brucei litters as Influenced by Polyphenol, Lignin and Nitrogen Contents

Abstract

Litter mineralization is a crucial process in providing nutrients through decomposition to plants, which also depends in the chemical composition of the litter and soil properties as well. Decomposition rate of Erythrina abyssinian and Erythrina brucei in Luvisol was investigated in relation to their nutrient release dynamics such as NH4+ and NO3- in relation to their initial concentrations of lignin, ADF, cellulose and total polyphenol content and their ratios. The dynamic was followed in an incubation pot experiment, CRD design in replication. Erythrina abyssinian has an average of 4.05%, 9.7% and 2.04% TN, lignin and total polyphenol content respectively. Erythrina brucei has also an average of 3.05 %, 12.63 % and 1.05 % content of TN, lignin and total polyphenol respectively. The samples of Erythrina abyssinian and Erythrina brucei were ground and incorporated with Luvisol in pots. Each treatment and control were sampled and analyzed on weekly basses to determine the amount of ammonium and nitrate released. The lignin and total polyphenol was significantly positively correlated with the release of NH4+, while the NO3- showed significant negative correlations with the release of ammonium. From the experiment it was observed that the Erythrina abyssinian with lower content of lignin and high in TN has released the nutrients faster where as Erythrina brucei with high lignin and low total polyphenol content released slowly. In general, these leguminous trees released NH4+and NO3- easily because of their high total nitrogen content and low lignin, ADF, cellulose and total polyphenol content. They attained their half-life within 2–3 weeks. Therefore, Erythrina abyssinica and Erythrina brucei bears fast mineralization as a result they can be used for fast-term correction of crop nutrient demand. However, more detailed researches are needed to synchronize and verify laboratory results with field measurements of their effect on crop production and synchronization of soil nutrient availability and crop demand in different agro ecology and soil types.