Characterisation of selected organic inputs for carbon, nitrogen and lignin for improved soil management in tropics

Abstract

Organic materials remain a very important input in most of the Sub-Saharan Africa because majority of the farmers cannot afford inorganic inputs. A study was conducted to find out the extent to which these materials can influence soil nitrogen and organic carbon levels. Basing on the physiochemical characteristics (determined by lab analytical methods) and decay pattern (determined by the single model equationMt = Mo {exp (-kt)}) of the materials. It was found that the materials contribute differently to soil carbon and nitrogen, with bio char being the most suited for soil organic carbon build up, and Sesbania sesban being the fastest decaying material.The carbon levels were as follows; biochar 75.39%,Maize stovers 32.1%,compost 15.43%, Calliandra calothyrsus 49.63% and Sesbania sesban 41.16%.The half-life 9in days) of the different materials, using the above model equation was such as; biochar 173.3, maize stovers 74.53, Sesbania sesban 16,Calliandra calothyrsus 57.76 and Mucuna pruriens 30.1. Most of these materials require constant addition into the soil so that as they are broken down, the nutrient stocks are not depleted, thus improved yields over time. All of these materials have capacity to improve soil nutrient stocks, and are readily available to farmers, and thus are very important for soil carbon sequestration and fertility management.