Soil Properties, Growth, Fruit Yield, Mineral, Lycopene and Vitamin C Contents of Tomato (Lycopersicon esculentum Mill) Grown with Green Manures and NPK Fertilizer
Green manures as an alternative to inorganic fertilizer offer considerable potential as a source of plant nutrients and organic matter. Hence, field experiments were carried out during 2015 and 2016 cropping seasons to compare impacts of green manures (GM) and NPK 15-15-15 fertilizer on soil properties, growth, fruit yield, mineral, lycopene and vitamin C contents of tomato (Lycopersicon esculentum Mill). The GM from green tender stems and leaves of: Pawpaw (Carica papaya L.), Neem (Azadirachta indica A. Juss.), Moringa (Moringa oleifera Lam.) and Gliricidia (Gliricidia sepium (Jacq.) Kunth ex Walp.) were applied at 5 t ha-1, and the NPK fertilizer was applied at 300 kg ha-1. Plots without fertilizer were used as a control. Application of GMs reduced soil bulk density and increased soil organic matter (OM), N, P, K, Ca, Mg, growth and fruit yield of tomato compared with the control. The NPK fertilizer had no effect on soil bulk density and soil OM, and increased soil N, P, K, Ca, Mg, growth and fruit yield of tomato compared with the control. Gliricidia increased growth and fruit yield of tomato compared with NPK fertilizer and other GMs. The GMs and NPK fertilizer increased mineral, lycopene and vitamin C contents in the tomato fruits compared with the control. Moringa produced higher K, Ca, Fe, Zn, Cu, lycopene and vitamin C contents compared with other GMs and NPK fertilizer. Use of GM has potential to improve soil properties, and growth, fruit yield and nutritional contents of tomato than does NPK fertilizer. The Gliricidia treatment best improved soil properties and tomato productivity as indicated by the benefit-cost ratio. For those growing tomato for fruit quantity Gliricidia is recommended as green manure. For those that desire fruit quality Moringa is recommended as green manure
