Use of cattle manure, calcium ammonium nitrate and diammonium phosphate in watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) production increases fruit quality and maximize small holder farmers net returns and profits

Abstract

Watermelon is a vegetable crop grown by small-holder farmers for both subsistence and commercial purposes in Kenya.2 Watermelon consumption is higher than that of the other cucurbit family members.3 Watermelon accounts for 7% of the world area devoted to vegetable production.4,5 Several of these cultivars have been recommended for the Kenyan climate and they include Sugarbaby, Crimson Sweet, Charleston Gray, Chilean Black, Congo, Fairfax and Tom Watson.6 However, among these cultivars, only the first three are available in Kenyan market, with Sugarbaby being the most popular because of its sugary taste, small size, earlier maturity and higher yields.7 The average world production of watermelon is 98.6 million metric tonnes, while Africa produces 4.4 million metric tonnes.3 It can also be used for making jams and jelly, and flavoring drinks and smoothies. The demand for watermelon in Kenya is higher than its production, resulting in the fruit being very expensive6,7 and only affordable to the rich class. With local demand for watermelon unsatisfied, its potential for export cannot be realized even though the export market is available.8 To meet the local demand and have some surplus for export, production of watermelon in Kenya needs to be increased.9 One of the major challenges currently facing watermelon farmers in Kenya is poor growth and low yields due to either nutrient deficiency or excessive application of nutrients especially with nitrogen and phosphorus.7 The current recommended fertilizers are calcium ammonium nitrate (CAN) at the rate of 80kgNha-1 and triple super phosphate (TSP) at the rate of 100kg P2O5ha -18 Many farmers have however complained of excessive vegetative growth, low yield and poor quality of fruit upon use of the recommended fertilizer rates.10 The average yield and quality of watermelon upon use of the national recommended