Nitrogen Release Dynamics of Erythrina Abyssinica 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. The processes depends in the chemical composition of the litter and soil properties as well. Not only the initial chemical composition of litter such as lignin, ADF, cellulose and total polyphenol content controls decomposition of the litter but also the ratios of lignin, ADF, cellulose and total polyphenol has a role in the processes.  To measure the effect of chemical composition of Erythrina abyssinica and Erythrina brucei incorporated in to Luvisol an incubation pot experiment, in complete randomized design in replication, were conducted. The nutrient release dynamics was measured in terms of their capacity to release ammonium and nitrate in the mineralization process. The samples of Erythrina abyssinica and Erythrina brucei were ground and incorporated with Luvisol in pots. Erythrina abyssinica has an average of 4.05%, 9.7% and 2.04% total nitrogen, lignin and total polyphenol content respectively. Erythrina brucei   has also an average of 3.05 %, 12.63 % and 1.05 % content of Total Nitrogen, lignin and total polyphenol. Treated and control Samples were collected and analyzed on weekly basis to determine the amount of ammonium and nitrate released. The result showed that the lignin and total polyphenol content significantly, positively correlated with the release of ammonium, while the nitrate showed significant negative correlations with the release of ammonium. From the experiment, the Erythrina abyssinica 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 ammonium and nitrate 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. Erythrina abyssinica and Erythrina brucei shows fast mineralization; as a result they can be used for fast-term correction of crop nutrient demand. Furthermore, intensive field experiment on the effect of Erythrina abyssinica and Erythrina brucei biomass on yields and capacity to amend soil quality shall be studied in depth.

Keywords: Incubation, Lignin, Luvisol, Total Polyphenol, Nitrate.