Early Growth of Crotalaria (Crotalaria juncea), Tithonia (Tithonia diversifolia), and Maize (Zea mays) as Affected by Soil Fertility and Phosphorus Fertilizer under Pot and Field Conditions

Green manures are important in tropical cropping systems and are planted in degraded soils, thus affecting early growth. Pot and field experiments evaluated the impact of soil fertility on early growth of two important tropical green manures (Crotalaria juncea and Tithonia diversifolia) when compared to that of maize (Zea mays) with high and low levels of phosphorus fertilizer. Growth of tithonia was not affected by soil fertility level irrespective of phosphorus fertilizer, indicating its suitability for degraded soils. Crotalaria was affected by soil fertility (root growth was stimulated by phosphorus), indicating its potential for soils with some degree of fertility. Maize was significantly affected by soil fertility and phosphorus fertilizers, indicating the requirement of fertile soils for the successful development of a good root and shoot system. The importance of field studies in the tropics is also presented as the diverse field conditions reduces significant effects found in pot studies.