Effect of the use of Bio-Fertiliser on growth and yield of Onions (Allium cepa. L) in comparison with NPK and Manure 2021

Abstract

Soil infertility due to soil organic matter depletion, soil nutrient depletion and loss of soil biodiversity is considered as a cause of declining agricultural productivity in Uganda. Using bio-waste such as crop residues, which are produced in large quantities and currently disposed of indiscriminately for fertiliser production, is encouraged for replenishment of soil fertility and also for reduction of environmental problems such as ground and surface water pollution, spread of disease vectors from open and uncovered dump sites, and emission of greenhouse gases including methane. The main objective of this research was to compare the performance of bio-fertilisers in relation with organic manure and inorganic fertilizer (NPK), on red creole onions. The study was conducted in 2019-2020 at Mairye in Wakiso district in central Uganda. A completely randomised design (CRD) was used and the field was divided into 16 plots with each treatment having four replicates applied at rates of Bio-fertiliser (4 kg), manure (4.5 kg) and NPK (0.1 kg) per plot of area 18m2. Soil sampling and laboratory analyses was conducted before planting and after harvesting to determine the residual effect of the amendments on selected soil chemical properties. After the first soil sampling and testing, onions were established in the plots to evaluate response to the soil amendments. The growth parameters studied included: plant height, number of leaves, leaf length and width and bulb yield. The data collected were subjected to ANOVA using Genstat statistical package 14th edition. Significant means were separated using Fischer’s LSD at 5% level of significance. pH(6.0±0.37-6.4±0.37 ) obtained were within a suitable pH range( 5.5-6.5), Organic matter(1.8±0.22-2.6±0.22)% was below the recommended value 3%, total nitrogen(0.1±0.03-0.2±0.03)%, available phosphorus(2.6±0.71-5.99±0.71)ppm and exchangeable potassium(0.344±0.08-0.652±0.08)cmolkg-1 were within recommended range of >0.3cmolkg-1. Plant height(34.7±0.28-46.3±0.28)cm was below the highest height 76cm expected from an onion plant, leaf length(32±0.3-39.7±0.3)cm, leaf width(0.5±0.04-0.83±0.04)cm and number of leaves(7±0.46-9±0.46) was below 13 leaves of the perfect onion. Yield analysed(10.25tonha-1) was below the highest yield expected(15tonha-1). Chemical parameters analysed for tissues included Nitrogen (4.060±0.14-0.1423±0.14)%, Phosphorus(2.988±0.17-0.463±0.17)% and Potassium(0.646±0.01-0.256±0.01)%.The results obtained indicated a positive response with the use of NPK during the first stages of growth, Bio-fertilisers and manure showed the highest response on yield and uptake by the onion tissues, this also had the highest nutrient composition in the soil residual. This implies that use of NPK has a short term effect in the soil and can only be applied repeatedly for proper onion growth and yield whereas Bio-fertiliser had a long term effect in the soil therefore improving the soil structure, promoting sustainable agriculture and reducing on the costs for repeated addition of the fertiliser.