THE EFFECT OF DIFFERENT SOURCES OF ORGANIC FERTILIZER ON THE GROWTH AND YIELD OF PEPPER (A CASE STUDY OF PEPPER FARMERS IN ILESA EAST LOCAL GOVERNMENT AREA, OSUN STATE)

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Pepper (Capsicum spp.) is a member of the family Solanaceae and is one of the most important vegetable and spice crops in Nigeria. It is grown for its fruits, which are used fresh, dried or ground to flavour soups, stews and sauces, and which are also sold in markets throughout the year. Different types are grown, including sweet or bell peppers and the hot types commonly known as tatashe, shombo and atarodo in southwestern Nigeria. Pepper is a source of vitamins, especially vitamin C, and of pigments and compounds that contribute to flavour and nutritional value, and for many smallholders it is an important source of cash income.

Pepper requires fertile, well-drained soil with adequate organic matter, and its growth and fruiting depend on a steady supply of nutrients. In many tropical soils fertility is low, and farmers must either buy mineral fertilizers or use organic materials. Because mineral fertilizers are expensive and their price rises often, there is a growing interest in organic fertilizers, which are cheaper, locally available and able to improve soil condition.

Organic fertilizer is not a single product, however. Poultry manure, cow dung, pig dung, goat droppings and compost differ in the amount of nitrogen, phosphorus and potassium that they contain, in the speed at which they decompose and release nutrients, and in the labour and cost involved in obtaining and applying them. Bhunia et al. (2021) reviewed animal-derived organic fertilizers and showed that they differ in composition and in their effects on soil biology and fertility, and Abebe et al. (2022) discussed the growing use of chemical fertilizers in Ethiopia together with alternative organic sources. It follows that the choice of organic source is likely to affect how pepper grows and yields.

Recent Nigerian trials illustrate this. Osadebe et al. (2025) tested cow dung, pig dung and poultry manure at 20 t/ha, NPK at 150 kg/ha and a control, combined with weed-management practices, on bell pepper at Nsukka. They reported that weed management influenced growth and yield more strongly than fertilizer type, and that mulch combined with poultry manure or NPK gave good growth and weed control. At the University of Ibadan, Hassan et al. (2024) found that 33% NPK combined with 67% poultry manure gave taller bell pepper plants with more leaves and branches and the highest fruit yield among the treatments tested. Adewusi (2024), working with tomato, a close relative of pepper, found that NPK performed best, followed by poultry manure and moringa leaf extract, and concluded that organic sources were a worthwhile alternative.

These studies show that organic sources can support good growth and yield of Solanaceous crops, but they also show that the outcome depends on the materials compared, the soil and the management of the crop. They provide a useful guide, yet none of them gives a direct comparison of several locally available organic sources on pepper under the conditions of the study area.

Ilesa East Local Government Area is in Osun State, in south-western Nigeria, where pepper is produced by smallholders for food and sale. Farmers in the area use whatever organic materials are available and affordable, such as poultry droppings, cattle dung and household waste. This study was designed to compare different sources of organic fertilizer on the growth and yield of pepper among farmers in Ilesa East Local Government Area.

1.2 Statement of the Problem

Pepper farmers in Ilesa East Local Government Area choose organic materials mainly on the basis of availability and price rather than on evidence of how well each source performs. The materials differ in nutrient content and rate of decomposition (Bhunia et al., 2021), so applying one rather than another may result in very different growth and yield.

The studies reviewed here were conducted in other locations, such as Nsukka and Ibadan, or on related crops (Adewusi, 2024; Hassan et al., 2024; Osadebe et al., 2025), and the literature consulted did not reveal a comparison of different organic fertilizer sources on pepper carried out within Osun State. In addition, some studies found that factors such as weed control mattered as much as fertilizer type (Osadebe et al., 2025), which means that results cannot be transferred without local testing.

As a result, farmers do not know whether the cheapest organic source is also an effective one, and they may apply materials that supply too little nutrient or that are not cost-effective. Extension workers also lack local data for advice. This study was therefore undertaken to provide evidence on the effect of different sources of organic fertilizer on the growth and yield of pepper.

1.3 Objectives of the Study

The main objective of the study was to evaluate the effect of different sources of organic fertilizer on the growth and yield of pepper among farmers in Ilesa East Local Government Area, Osun State. The specific objectives were to:

(i) compare the effect of different organic fertilizer sources on the growth of pepper (plant height, number of leaves and branches);

(ii) compare their effect on fruit number, fruit weight and total yield; and

(iii) rank the organic sources according to performance and practical suitability for smallholders.

1.4 Research Questions

The following research questions guided the study:

(i) How do different sources of organic fertilizer affect the growth of pepper?

(ii) How do they affect the yield of pepper?

(iii) Which organic source is most suitable for pepper farmers in Ilesa East?

1.5 Research Hypotheses

The following null hypotheses were tested at the 0.05 level of significance:

H01: Sources of organic fertilizer have no significant effect on the growth of pepper.

H02: Sources of organic fertilizer have no significant effect on the yield of pepper.

1.6 Significance of the Study

A clear ranking of local organic sources will help farmers lower input costs without sacrificing yield and will give extension officers an evidence base for recommendations. It may also encourage the recycling of animal waste.

The study will further contribute to the literature on organic vegetable production in Osun State.

1.7 Scope and Limitations of the Study

The study covers pepper farmers in Ilesa East Local Government Area, Osun State, and is limited to the effect of selected organic fertilizer sources on growth and yield.

It does not measure nutrient losses, long-term soil changes or fruit quality. Other limitations include the single season and the limited number of organic sources tested.

1.8 Definition of Terms

Organic fertilizer: nutrient source of plant or animal origin, such as poultry manure or cow dung.

Source of organic fertilizer: the type of organic material applied.

Growth: measurable plant development, such as height, leaf number and branching.

Yield: the weight of fruit harvested per plant or per unit area.

Poultry manure: droppings from poultry used as fertilizer.

REFERENCES

Abebe, T. G., Tamtam, M. R., Abebe, A. A., Abtemariam, K. A., Shigut, T. G., Dejen, Y. A., & Haile, E. G. (2022). Growing use and impacts of chemical fertilizers and assessing alternative organic fertilizer sources in Ethiopia. Applied and Environmental Soil Science, 2022, Article 4738416. https://doi.org/10.1155/2022/4738416

Adewusi, O. F. (2024). Comparative effect of organic and inorganic fertilizer on growth and yield of tomato genotypes, Lycopersicon esculentum (Mill.). FUDMA Journal of Sciences, 8(6), 343–348. https://doi.org/10.33003/fjs-2024-0806-3116

Bhunia, S., Bhowmik, A., Mallick, R., & Mukherjee, J. (2021). Agronomic efficiency of animal-derived organic fertilizers and their effects on biology and fertility of soil: A review. Agronomy, 11(5), 823. https://doi.org/10.3390/agronomy11050823

Hassan, O. A., Ajayi, E. O., & Babatola, L. A. (2024). Growth and yield of bell pepper as influenced by combination of poultry manure and NPK fertilizer. Technology in Horticulture, 4, Article e010. https://doi.org/10.48130/tihort-0024-0007

Osadebe, V. O., Amuji, C. F., Dauda, N., Ukwu, U. N., Unagwu, B. O., Uzoigwe, A. D., & Nwoja, A. A. (2025). Effects of weed control practices and fertilizer types on the growth and yield of bell pepper (Capsicum annum L.) in Nsukka, Nigeria. Journal of Agricultural Extension, 29(3), 57–67. https://doi.org/10.4314/jae.v29i3.6