Statistical Optimization of Organic Fertilizer Blending From Animal Waste

Thesis Title: Statistical Optimization of Organic Fertilizer Blending From Animal Waste

Student’s Name: SIMON MAGERO SIMIYU

Supervisors’ Names:

1. DR. LINDA OUMA
2. DR. FRANCIS MAINGI

ABSTRACT:

Animal wastes specifically livestock and poultry waste are gaining mileage as an alternative to commercial nitrogenous fertilizers. Livestock and poultry manure however vary in the composition of macro and micro-nutrients, pH, and absorptivity. There was therefore need to combine different manure types for optimal plant growth because optimization of animal manure mixing ratios is among the methods of improving manure efficiency. However, optimization procedures are considered sophisticated by farmers and researchers. For instance, determination of optimal ratios by optimizing one factor while holding the others constant (one factor at a time) could be used by researchers to determine the optimum dosage. However, from reported research works it has been found to be tedious and time-consuming since it requires a large number of runs and cannot effectively account for interactive effects. To overcome these challenges, there is need for simultaneous optimization. This study sought to determine the nutrient content of cattle, goat, poultry and swine manures and assess the interactive effects of cattle, goat, poultry and swine manure on macronutrient concentrations and vegetable growth parameters. Determining the optimal animal manure mixing ratios for enhanced plant responses were also investigated. Lastly mathematical models for each factor’s effect on the individual responses were developed using response surface methodology (RSM). The findings of the study are useful in solving the challenge of production of low quality kales as result of over dosage and under dosage of animal waste on kales. DUMAS method was used in measuring amount of nitrogen in the samples while XRF techniques were employed in determining Ca, P and K levels in the samples. Response Surface Methodology (RSM) specifically the Central Composite Design (CCD) was employed to design the animal manure ratios. In total there were thirty actual experiments and six control runs. Kales were planted using CRBD. Plant height was measured using a string and a metre rule. Vernier calipers measured stem diameter. Leaf length and width were measured using a metre rule and findings used to determine leaf area. Chlorophyll contents in kales was measured using Uv- Vis instrumental analytical technique at 653 nm wavelength. RSM was used as a statistical tool to analyse the data. Regression coefficients and Response surface plots showed whether the interaction was synergistic or antagonistic. It was established that goat manure contains the highest calcium, potassium and phosphorus content. While poultry manure was established to be rich in nitrogen. Blending cattle, goat, poultry and swine manure showed synergistic as well as antagonistic effects on plant growth parameters. However synergistic effects superseded antagonistic effects. For instance, in the effective animal waste mixtures obtained: Optimal Ca was 11.963 %, N 1.2084 %, P 2.064% and K was 12.189%. Optimum plant height was 36.07cm, stem diameter was 29.5858mm, number of leaves was 51, and leaf area was 280.879cm² and finally at optimum, chlorophyll content was 25.44gcm^-2. The study therefore concluded that combining cattle, goat poultry and swine manure at varied levels enhances the nutrient content in the manure mixture and promote the quality of kale in terms of plant height, stem diameter, leaf numbers, leaf area and chlorophyll content.   Optimization of cattle, goat, poultry and swine manure that can enhance the quality of fruity plants should be a future focus.