Soil productivity improving attributes of Mexican sunflower (Tithonia diversifolia) and siam weed (Chromolaena odorata)

In the present investigation, soils fallowed to Mexican sunflower (Tithonia diversifolia), siam weed (Chromolaena odorata), spear grass (Imperata cylindrica) and soil cropped to cassava were chemically analysed. Soil physical properties such as bulk density, total porosity and moisture content were also determined. The soils were also used to grow maize in screen house. Soils fallowed to Tithonia and Chromolaena had higher mineral values like nitrogen, phosphorus, potassium, calcium, magnesium and also organic matter. The plant morphological paramters like maize height, girth and leaf area were also found higher than cropped land and soil fallowed to spear grass. Soils under Tithonia and Chromolaena had more favorable physical properties compared with soils under cassava and spear grass as indicated by lower bulk density and higher total porosity. This can be adduced to the ability of the Tithonia and Chromolaena weeds to protect the soil, proliferate surface soil with their roots, and attract fungi, increase biomass and organic matter.