Effects of fertilisers on growth and yield of tomato

Abstract

Low soil fertility impairs production of tomato (Solanum lycopersicum L.) by smallholder farmers in South Africa. Consequently, this study was designed to determine growth, yield and nutritional quality of three tomato cultivars to sole and combined applications of fertilizers including effective microorganisms (EM) (Ravivi)-enriched compost, broiler manure and inorganic (NPK) fertilizer. Field experiments were conducted at the Horticultural Skill Centre, University of Limpopo, and at Mphebatho Farm, Apel, Limpopo province, South Africa. The experiment was laid in a 7×3 split-plot design. The treatments were: control (without fertiliser application), NPK (2:3:4(30) at a rate of 200 N ha(-1), 260 P ha-1 and 257 K ha(-1), applied as N from urea, P from superphosphate and K from KCl, decomposed broiler manure (10 t ha-1), ½ NPK + ½ broiler manure rates, EM (Ravivi)-enriched compost (14 m3 ha(-1)), ½ EM compost + ½ NPK rates, and ½ EM compost + ½ broiler manure rates. Three tomato cultivars (‘Floradade’, ‘Roma’, ‘Money maker’) seedlings were transplanted using standard spacing of 30×60 cm. Chlorophyll content of leaves, biomass production, plant height, number of fruits, stem diameter and number of branches were determined six weeks after transplanting and fortnightly thereafter. Plant samples were analysed for micronutrient content. Values of plant height and number of fruits were significantly higher in soils treated with sole EM compost, NPK and broiler manure compared to control. On the farmer’s field, the highest number of fruits (6.83) at 8 WAT occurred in ½ EM+ ½ NPK and the least number of fruits of 1.83 was recorded in the control. The highest Fe content was obtained in ½ EM compost + ½ broiler manure treatment and the highest Zn content was found in ½ broiler manure+ ½ NPK. Fruit yield and micronutrient contents of tomato was better in a combination of organic (broiler or EM compost) with inorganic (NPK) fertiliser compared to sole applications.