THE EFFECT OF ORGANIC AND INORGANIC FERTILIZERS ON THE GROWTH AND YIELD OF TOMATO (A CASE STUDY OF TOMATO FARMERS IN OGOJA LOCAL GOVERNMENT AREA, CROSS RIVER STATE)

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Tomato (Solanum lycopersicum L., synonym Lycopersicon esculentum Mill.) belongs to the family Solanaceae and is one of the most widely cultivated fruit vegetables in the world. Its fruits are eaten fresh in salads and are cooked in soups, stews and sauces, and they are also processed into paste, puree and juice. Tomato fruits supply vitamins, minerals and antioxidant compounds such as lycopene, and in many Nigerian households tomato is a daily ingredient, so that demand remains high throughout the year.

Tomato is a heavy feeder. It produces a large quantity of foliage and fruit in a short cycle, and fruiting continues over several weeks, so the crop requires a steady supply of nitrogen, phosphorus, potassium and other nutrients from transplanting through harvest. Many soils in the humid and sub-humid tropics are low in organic matter and inherently low in fertility because of leaching and rapid mineralisation, so that growth and yield of tomato depend strongly on the nutrients that the farmer adds. Fertilizer management is therefore one of the most important factors determining yield and fruit quality.

Farmers generally choose between two broad categories of nutrient source. Inorganic fertilizers such as NPK 15:15:15 supply nutrients in forms that plants can absorb quickly, but they must be purchased, their cost has risen, and repeated use may affect soil condition. Organic sources such as poultry manure, cow dung and compost are often cheaper and locally available and add organic matter that improves soil structure and microbial activity, but they release nutrients more slowly, and their nutrient content varies with the source and the way they are handled. Abebe et al. (2022) examined the growing use and impacts of chemical fertilizers in Ethiopia and assessed alternative organic fertilizer sources, and Bhunia et al. (2021) reviewed the agronomic efficiency of animal-derived organic fertilizers and their effects on the biology and fertility of soil. Both works reflect a wider search for nutrient management that is productive as well as sustainable.

Nigerian studies give further insight. Adewusi (2024) compared moringa leaf extract, poultry manure and NPK 15:15:15 on ten tomato genotypes in a pot experiment at the Federal University of Technology, Akure. NPK gave the best growth and yield, followed by poultry manure and then moringa extract, and the author concluded that moringa extract and poultry manure remain worthwhile alternatives to NPK. In a related field study on bell pepper, another Solanaceous crop, Hassan et al. (2024) tested a control, 100% NPK, three NPK–poultry manure mixtures and 100% poultry manure at the University of Ibadan, and reported that 33% NPK combined with 67% poultry manure gave taller plants, more leaves and branches, and the highest fruit yield. These results support the idea that combining organic and inorganic sources can be better than relying on one alone, although the best proportion depends on the crop, soil and environment.

Fertilizer source also influences fruit quality. Aina et al. (2019) studied how organic and inorganic sources of nutrients affected the bioactive compounds and antioxidant activity of tomato, while Stoleru et al. (2020) examined the yield and nutritional response of greenhouse-grown tomato cultivars to sustainable fertilization and irrigation management. Such studies show that the choice of fertilizer affects not only how much fruit is harvested but also its nutritional value, which is important for consumers and for the market value of the crop.

Ogoja Local Government Area is located in the northern part of Cross River State and has farmers who grow tomato as a source of food and income. Farmers there make their own decisions about whether to use organic manure, inorganic fertilizer or both, based largely on cost and availability. This study was designed to examine the effect of organic and inorganic fertilizers on the growth and yield of tomato among farmers in Ogoja Local Government Area.

1.2 Statement of the Problem

Tomato production in Nigeria is frequently limited by low soil fertility, and fertilizer decisions are among the most important decisions a tomato farmer makes. Inorganic fertilizers give quick results but are costly and may be scarce or difficult to afford for smallholders, while organic manures are cheaper and easier to find but release nutrients slowly and differ in quality. Many farmers apply one or the other, or a mixture, without clear guidance on which option gives the best return.

The studies reviewed here were mostly carried out on research stations, in pots or in other regions of the country and the world (Abebe et al., 2022; Adewusi, 2024; Hassan et al., 2024). The literature consulted for this study did not reveal a comparison of organic and inorganic fertilizers on tomato carried out with farmers in Ogoja Local Government Area. Because the response of a crop to fertilizer depends on the soil, rainfall and management of the particular location, results from other places cannot be taken as a sure guide for farmers in Ogoja.

Heavy reliance on inorganic fertilizer exposes farmers to high input costs and may reduce profit, while use of organic manure without information on its effectiveness may result in poor growth, low fruit set and low yield. Extension workers also lack local data on which to base recommendations. This study was therefore undertaken to provide locally relevant evidence on the effects of organic and inorganic fertilizers on the growth and yield of tomato.

1.3 Objectives of the Study

The main objective of the study was to determine the effect of organic and inorganic fertilizers on the growth and yield of tomato among farmers in Ogoja Local Government Area, Cross River State. The specific objectives were to:

(i) compare the effect of organic and inorganic fertilizers on the growth of tomato (plant height, number of leaves and flowering);

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

(iii) determine whether a combination of organic and inorganic fertilizers performs better than either alone; and

(iv) identify the fertilizer option most practical for farmers in the study area.

1.4 Research Questions

The following research questions guided the study:

(i) How do organic and inorganic fertilizers affect the growth of tomato?

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

(iii) Does a combination of organic and inorganic fertilizer give better results than either alone?

(iv) Which fertilizer option is most suitable for tomato farmers in Ogoja?

1.5 Research Hypotheses

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

H01: Organic and inorganic fertilizers have no significant effect on the growth of tomato.

H02: Organic and inorganic fertilizers have no significant effect on the yield of tomato.

1.6 Significance of the Study

The findings will guide tomato farmers in Ogoja on how to spend fertilizer money wisely and may help reduce production costs. Extension agents will obtain locally grounded recommendations.

The study will also provide baseline data for northern Cross River State and add to the literature for future researchers.

1.7 Scope and Limitations of the Study

The study covers tomato farmers in Ogoja Local Government Area, Cross River State, and is limited to the effect of selected organic and inorganic fertilizers on growth and yield.

Limitations include the single growing season, the limited fertilizer sources and rates tested, and variation in weather and pest pressure. Findings should not be extended to other crops or agro-ecologies without further testing.

1.8 Definition of Terms

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

Inorganic fertilizer: manufactured mineral fertilizer, such as NPK 15:15:15.

Growth: measurable development of the plant, such as height and number of leaves.

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

NPK: a fertilizer containing nitrogen (N), phosphorus (P) and potassium (K).

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

Aina, O. E., Amoo, S. O., Mugivhisa, L. L., & Olowoyo, J. O. (2019). Effect of organic and inorganic sources of nutrients on the bioactive compounds and antioxidant activity of tomato. Applied Ecology and Environmental Research, 17(2), 2773–2785.

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

Stoleru, V., Inculet, S. C., Mihalache, G., Cojocaru, A., Teliban, G. C., & Caruso, G. (2020). Yield and nutritional response of greenhouse grown tomato cultivars to sustainable fertilization and irrigation management. Plants, 9(8), 1053. https://doi.org/10.3390/plants9081053