Influence of Organic and Inorganic Sources of Fertilizer on Growth and Leaf Yield of Kale (Brassica oleraceae Var. Acephala D.C.)

Abstract

Brassica oleraceae var. Acephala D.C. (kale, sukuma wiki) is the most important vegetable in Kenya but its production is hampered by low soil fertility particularly Nitrogen and Phosphorus. Most small holder farmers do not utilize inorganic fertilizers and the use of organic sources alone may have higher labour requirements for its application. The use of two organic sources Tithonia diversifolia (Tithonia) leaves and farmyard manure and two inorganic fertilizers Diammonium Phosphate (DAP) and Calcium Ammonium Nitrate (CAN) for improved soil fertility and kale yields was investigated on nitrogen limiting soil in Western Kenya, Maseno University. An experiment was carried out twice between January 1999 and April 2000 to evaluate the effect of Tithonia diversifolia, farmyard manure and inorganic sources of fertilizer on growth and leaf yield of kale. The treatments included: T₁ - control, T₂ - Tithonia leaf biomass incorporated 5 tons per hectare (dry matter), T₃ - tithonia leaf biomass incorporated (4.5 tons per hectare (dry matter) in combination with Diammonium phosphate (DAP) T₄ – DAP (200kg per hectare in combination with Calcium Ammonium nitrate (CAN) 500 kg per hectare), T₅ - Farmyard manure, 15 tons per hectare. Leaf yield was assessed by both cumulative leaf weight per given plant and leaf number, plant height was also taken. Both organic and inorganic sources of fertilizer significantly increased growth and leaf yield of kale. Tithonia leaf biomass on its own or in combination with an inorganic fertilizer gave leaf yields comparable to those applied with exclusively inorganic sources of fertilizer. With the prices of inorganic fertilizers increasing and becoming unaffordable to most farmers in Kenya, organic sources like tithonia leaves that are locally available to the farmers can be alternative sources of fertilizer to increase the yields and production of kale.

Journal of Agriculture, Science and Technology Vol.4(1) 2002: 38-51