RESPONSE OF MAIZE (Zea mays L.) AND SELECTED SOIL PHYSICAL AND CHEMICAL PROPERTIES TO POULTRY MANURE APPLICATION AND TILLAGE PRACTICES IN AN ULTISOL

Abstract

Declining soil fertility and unsustainable land management practices remain major constraints to maize production in tropical regions, particularly in soils classified as Ultisols, which are generally acidic, nutrient-deficient, and structurally fragile. This study evaluated the response of maize (Zea mays L.) and selected soil physical and chemical properties to varying poultry manure application rates and tillage practices in an Ultisol environment. The research aimed to determine the combined influence of organic nutrient management and soil tillage methods on maize growth, yield performance, and soil quality improvement. Treatments consisted of different poultry manure rates integrated with selected tillage systems such as conventional tillage, minimum tillage, and zero tillage. Data were collected on soil bulk density, porosity, moisture retention, soil pH, organic carbon, nitrogen, phosphorus, potassium, plant height, leaf area, and grain yield. The findings indicated that poultry manure significantly enhanced soil fertility status and improved maize growth parameters, while appropriate tillage practices positively influenced soil structure and moisture conservation. The interaction between poultry manure and reduced tillage practices showed promising potential for sustainable maize production and soil restoration in degraded tropical soils. The study concluded that integrating organic nutrient sources with suitable tillage systems can improve crop productivity, enhance soil health, and support environmentally sustainable agriculture. Recommendations were made for the adoption of integrated soil fertility management strategies among smallholder farmers in Ultisol-dominated agroecological zones.

Table of Contents

Title Page
Certification
Dedication
Acknowledgements
Abstract
Table of Contents
List of Tables
List of Figures

Chapter One: Introduction

1.1 Background to the Study
1.2 Statement of the Problem
1.3 Aim and Objectives of the Study
1.4 Research Questions
1.5 Research Hypotheses
1.6 Significance of the Study
1.7 Scope of the Study
1.8 Limitations of the Study
1.9 Operational Definition of Terms

Chapter Two: Literature Review

2.1 Concept of Soil Fertility and Sustainable Crop Production
2.2 Importance of Maize in Tropical Agriculture
2.3 Characteristics and Constraints of Ultisols
2.4 Poultry Manure as an Organic Soil Amendment
2.5 Tillage Practices and Soil Productivity
2.6 Effects of Organic Manure on Soil Physical Properties
2.7 Effects of Poultry Manure on Soil Chemical Properties
2.8 Integrated Soil Fertility Management in Maize Production
2.9 Empirical Review of Related Studies
2.10 Knowledge Gap and Conceptual Framework

Chapter Three: Materials and Methods

3.1 Description of the Study Area
3.2 Experimental Design
3.3 Land Preparation and Tillage Treatments
3.4 Collection and Processing of Poultry Manure
3.5 Experimental Treatments and Field Layout
3.6 Planting Materials and Agronomic Practices
3.7 Soil Sampling and Laboratory Analysis
3.8 Data Collection Procedures
3.9 Measurement of Growth and Yield Parameters
3.10 Statistical Analysis

Chapter Four: Results and Discussion

4.1 Initial Soil Characteristics of the Experimental Site
4.2 Effect of Poultry Manure and Tillage on Soil Physical Properties
4.3 Effect of Poultry Manure and Tillage on Soil Chemical Properties
4.4 Growth Response of Maize to Treatments
4.5 Yield Performance of Maize under Different Treatments
4.6 Interaction Effects of Poultry Manure and Tillage Practices
4.7 Discussion of Findings

Chapter Five: Summary, Conclusion and Recommendations

5.1 Summary of Findings
5.2 Conclusion
5.3 Recommendations
5.4 Suggestions for Further Research

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Maize (Zea mays L.) is one of the most important cereal crops cultivated globally and serves as a major source of food, feed, and industrial raw materials. In sub-Saharan Africa, particularly in Nigeria, maize contributes significantly to household food security, livestock production, and income generation among rural farmers. The increasing demand for maize products due to rapid population growth and industrial utilization has intensified the need for sustainable production systems capable of maintaining high yields under changing environmental conditions (FAO, 2021).

Despite its economic importance, maize productivity in many tropical regions remains relatively low due to declining soil fertility, continuous cultivation, nutrient depletion, erosion, and inappropriate land management practices. Among the soil groups prevalent in southeastern and southern Nigeria are Ultisols, which are highly weathered soils characterized by low organic matter, poor nutrient reserves, high acidity, and weak structural stability (Brady & Weil, 2017). These limitations significantly reduce crop productivity and increase the vulnerability of agricultural lands to degradation.

The widespread dependence on inorganic fertilizers has raised concerns regarding soil acidification, nutrient imbalance, environmental pollution, and high production costs. Consequently, attention has shifted toward the use of environmentally friendly and sustainable soil management practices such as organic manure application and conservation tillage systems. Poultry manure has emerged as one of the most effective organic nutrient sources due to its high nitrogen, phosphorus, potassium, and organic matter content. It improves soil aggregation, microbial activity, water-holding capacity, and nutrient availability (Ayeni et al., 2018).

Tillage practices also play a crucial role in soil productivity and crop performance. Conventional tillage, though effective in seedbed preparation, often accelerates soil erosion, organic matter loss, and structural degradation. Conversely, reduced tillage and conservation tillage systems help preserve soil structure, improve moisture retention, reduce erosion, and promote long-term soil sustainability (Lal, 2015). The interaction between tillage systems and organic nutrient amendments can substantially influence soil physical and chemical properties, thereby affecting crop growth and yield.

Recent studies in sustainable agriculture emphasize the integration of organic nutrient management with suitable tillage systems as a viable strategy for improving soil quality and increasing agricultural productivity in fragile tropical soils. However, limited information exists regarding the combined effects of poultry manure and tillage practices on maize performance and soil properties in Ultisols. This study therefore seeks to evaluate the response of maize and selected soil physical and chemical properties to poultry manure application and tillage practices in an Ultisol environment.

1.2 Statement of the Problem

Soil degradation and declining fertility have become major threats to sustainable maize production in tropical agroecosystems. Continuous cultivation without adequate nutrient replenishment has led to reduced soil organic matter, poor soil structure, nutrient deficiencies, and low crop yields. In Ultisols, these challenges are more severe due to the inherently poor fertility status and susceptibility of the soils to erosion and compaction.

Many farmers rely heavily on mineral fertilizers to improve crop yield, yet the rising cost and inconsistent availability of inorganic fertilizers limit their accessibility, particularly among smallholder farmers. Furthermore, excessive dependence on chemical fertilizers may contribute to environmental degradation and declining soil health over time.

Inappropriate tillage practices also worsen soil degradation by disrupting soil aggregates, reducing moisture conservation, and increasing erosion risk. Although poultry manure and conservation tillage practices have been reported to improve soil productivity, there is inadequate empirical information on their combined effects on maize growth and soil quality in Ultisol conditions.

This research therefore addresses the need to identify sustainable soil management strategies capable of enhancing maize productivity while improving soil physical and chemical properties in degraded tropical soils.

1.3 Aim and Objectives of the Study

The main aim of this study is to evaluate the response of maize (Zea mays L.) and selected soil physical and chemical properties to poultry manure application and tillage practices in an Ultisol.

The specific objectives are to:

1. determine the effect of poultry manure application on the growth and yield of maize;
2. assess the influence of different tillage practices on selected soil physical properties;
3. evaluate the effect of poultry manure on soil chemical properties in an Ultisol;
4. examine the interaction effects of poultry manure and tillage practices on maize performance;
5. identify the most suitable soil management combination for sustainable maize production.

1.4 Research Questions

1. What effect does poultry manure application have on maize growth and yield?
2. How do different tillage practices influence soil physical properties in an Ultisol?
3. To what extent does poultry manure improve soil chemical properties?
4. What are the interaction effects of poultry manure and tillage systems on maize productivity?
5. Which treatment combination provides the best improvement in soil quality and maize yield?

1.5 Research Hypotheses

H??: Poultry manure application has no significant effect on maize growth and yield.

H??: Tillage practices have no significant effect on soil physical properties.

H??: Poultry manure application does not significantly influence soil chemical properties.

H??: There is no significant interaction effect between poultry manure application and tillage practices on maize productivity.

1.6 Significance of the Study

This study will contribute to sustainable agricultural development by providing scientific information on the combined effects of poultry manure and tillage practices on maize production and soil quality. The findings will benefit farmers, agricultural extension agents, researchers, policymakers, and environmental managers.

Farmers will gain practical knowledge on cost-effective and environmentally sustainable soil management practices capable of improving maize productivity. Agricultural extension personnel will use the findings to promote integrated soil fertility management technologies among rural farming communities.

The study will also contribute to existing literature on soil fertility management in tropical agroecosystems and serve as a reference material for future academic research in agronomy, soil science, and sustainable agriculture.

1.7 Scope of the Study

The study focuses on the evaluation of maize response and selected soil physical and chemical properties under varying poultry manure application rates and tillage practices in an Ultisol environment. Parameters assessed include maize growth performance, grain yield, soil bulk density, soil porosity, soil moisture content, pH, organic carbon, nitrogen, phosphorus, and potassium levels.

1.8 Limitations of the Study

The study may be limited by climatic variations, soil heterogeneity, financial constraints, and time available for field experimentation. Variability in poultry manure composition and environmental conditions may also influence experimental outcomes.

1.9 Operational Definition of Terms

Maize: A cereal crop scientifically known as Zea mays cultivated for food, feed, and industrial purposes.

Ultisol: A highly weathered acidic soil with low natural fertility commonly found in humid tropical regions.

Poultry Manure: Organic waste derived from poultry birds used as a soil amendment to improve soil fertility.

Tillage: Mechanical manipulation of soil for seedbed preparation and crop production.

Soil Physical Properties: Characteristics of soil related to structure, texture, porosity, bulk density, and moisture retention.

Soil Chemical Properties: Soil characteristics related to nutrient composition, pH, organic carbon, and cation exchange capacity.

Sustainable Agriculture: Farming practices that maintain productivity while conserving environmental resources for future generations.

References

Ayeni, L. S., Adeleye, E. O., & Ojeniyi, S. O. (2018). Integrated application of organic and inorganic fertilizers for sustainable maize production in Nigeria. Journal of Soil Science and Environmental Management, 9(3), 45–53.

Brady, N. C., & Weil, R. R. (2017). The Nature and Properties of Soils (15th ed.). Pearson Education.

Food and Agriculture Organization (FAO). (2021). FAOSTAT Statistical Database. Rome: FAO.

Lal, R. (2015). Restoring soil quality to mitigate soil degradation. Sustainability, 7(5), 5875–5895.

Moyin-Jesu, E. I. (2019). Comparative evaluation of organic fertilizers on soil fertility and maize performance in southwestern Nigeria. International Journal of Agricultural Research, 14(2), 65–74.

Ojeniyi, S. O., & Adejoro, S. A. (2020). Effects of tillage and organic amendments on soil properties and maize yield in tropical soils. African Journal of Agricultural Research, 15(8), 1120–1128.