THE EFFECT OF ORGANIC MANURE ON THE GROWTH AND YIELD OF MAIZE (A CASE STUDY OF MAIZE FARMERS IN IKWUANO LOCAL GOVERNMENT AREA, ABIA STATE)

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

For a smallholder maize farmer in southern Nigeria, the decision to fertilise is now largely a decision about money. A market survey reported by BusinessDay found that the average price of a 50 kg bag of NPK fertiliser rose from about N43,000 to about N60,500 within a single year, an increase of 41 per cent (Okojie-Okeiyi, 2025). In the same season, farmers interviewed by the News Agency of Nigeria complained that a bag of urea cost about as much as, or more than, a bag of maize, and some said they were abandoning maize for crops that need little fertiliser (AllAfrica, 2025). The same report put Nigeria's annual maize requirement at about 21 million metric tonnes, against a reported output of around 10.5 million tonnes. When the price of the inorganic input climbs faster than the price of the grain, cheaper sources of plant nutrients become more than an environmental preference.

Organic manure is the obvious candidate. Livestock and poultry droppings, compost and crop residues are available on or near most farms, and they supply nutrients while also adding organic matter to the soil. Rayne and Aula (2020) reviewed the effects of livestock manure on soil health, and the principle behind their review is well established in Nigerian agronomy: low-input farmers in the savanna and forest zones rely on organic and inorganic manure because the soils are low in plant nutrients (Kareem et al., 2017). Onwubiko (2026) makes the same point for the south-east, noting that poor soil fertility is a major reason for low maize yields across Africa.

Field and pot studies show that maize responds to manure, but the size and shape of the response vary with source, rate and variety. At the University of Nigeria, Nsukka, Onwubiko (2026) tested poultry manure at 5, 10 and 15 t/ha against a control on white and yellow maize and found that 10 t/ha gave the best growth in leaf number and leaf width, with yellow maize responding more strongly. At the Niger Delta University, Diri and Kedoneojo (2024) compared three types of poultry manure and swine manure, alone and in combination, at 0, 10 and 20 t/ha; layer manure and the swine-plus-layer combination at 20 t/ha gave the best soil and maize growth results. In Pakistan, a pot experiment by Rasool et al. (2023) found that poultry manure improved available phosphorus and organic matter and raised the yield of two maize varieties at 50 and 75 g per pot. Kareem et al. (2017) found significant improvements in all measured growth and yield parameters when 5 t/ha of poultry manure was applied, and they judged 2.5 t/ha adequate for optimum yield under their conditions. Other Nigerian studies have compared manure sources on degraded land (Denton et al., 2020) and examined organic manure on maize at Ishiagu, Ebonyi State (Okoroafor et al., 2013), while Jjagwe et al. (2020) compared organic fertilisers for maize growth, yield and economic results in Uganda.

What this literature does not settle is what a farmer in Ikwuano should do. Recommended rates range from 2.5 to 20 t/ha, the experiments were mostly carried out on research farms, in greenhouses or in pots, and the manure used was usually well characterised. Ikwuano Local Government Area is the home of the Michael Okpara University of Agriculture and the National Root Crops Research Institute at Umudike, so agricultural research is close at hand, yet evidence on how organic manure performs on the plots of ordinary maize farmers in the area is thin. This study was designed to supply it.

1.2 Statement of the Problem

Maize farmers in Ikwuano face a squeeze. Inorganic fertiliser has become costly (Okojie-Okeiyi, 2025), the soils they farm are not fertile enough to give good yields without added nutrients (Kareem et al., 2017; Onwubiko, 2026), and national maize output is reported to fall well short of national demand (AllAfrica, 2025). Many farmers already use manure, but they do so by habit, in unmeasured quantities, and without evidence of what each quantity returns.

The research that could guide them is scattered across locations, manure sources and rates, and most of it was not done on farmers' fields. Without local, field-based evidence, extension officers cannot give a confident rate, and farmers cannot tell whether more manure is worth the cost of collecting and applying it. The problem this study addresses is therefore the absence of rate-specific evidence on the growth and yield response of maize to organic manure under the conditions of farmers in Ikwuano Local Government Area.

1.3 Objectives of the Study

The general objective is to determine the effect of organic manure on the growth and yield of maize in Ikwuano Local Government Area, Abia State. The specific objectives are to:

(i) determine the effect of different rates of organic manure on the growth of maize (plant height, number of leaves, leaf area and stem girth);

(ii) determine the effect of different rates of organic manure on the yield and yield components of maize (cob length, number of grains per cob, 100-grain weight and grain yield per hectare);

(iii) identify the rate of organic manure that gives the best growth and yield under the conditions of the study area; and

(iv) compare the performance of manured plots with that of unmanured plots and with the farmers' own practice.

1.4 Research Questions

1. How do different rates of organic manure affect the growth of maize?

2. How do different rates of organic manure affect the yield and yield components of maize?

3. Which rate of organic manure gives the best growth and yield in the study area?

4. How does the performance of manured plots compare with that of unmanured plots and with the farmers' own practice?

1.5 Research Hypotheses

The following null hypotheses will be tested at the 5% level of significance:

H0₁: Different rates of organic manure have no significant effect on the growth parameters of maize.

H0₂: Different rates of organic manure have no significant effect on the yield and yield components of maize.

H0₃: There is no significant difference between the growth and yield of manured maize and that of unmanured maize.

1.6 Significance of the Study

The first beneficiaries are the farmers who took part. They will see for themselves, on their own land, what a measured rate of manure returns, and they will be able to set that return against the price of fertiliser. Extension agents in the Abia State Agricultural Development Programme and the wider extension system will receive a field-tested rate for the area instead of a figure borrowed from another zone.

The findings also bear on policy. If manure at a given rate gives yields close enough to those of inorganic fertiliser, it can be promoted as a lower-cost option at a time when fertiliser prices are high. For researchers and students, the study adds a farmer-field data point to a literature that rests heavily on station and pot experiments.

1.7 Scope and Delimitation of the Study

The study is limited to maize grown by farmers in Ikwuano Local Government Area of Abia State, using on-farm plots managed with the participation of the farmers. It considers one source of organic manure at several rates and measures growth and yield only; it does not cover soil microbiology, nutrient losses or the economics of transporting manure, although the cost of manure will be recorded for later comparison. The study covers a single cropping season.

1.8 Limitations of the Study

Results from one season cannot show how the effect of manure varies with rainfall from year to year. Manure is a variable material, and its nutrient content depends on the animal, the feed and the storage; although samples will be analysed, the findings will apply most closely to manure of similar quality. On-farm plots differ in soil and management more than station plots do, which adds variability that the experimental design can reduce but not remove. Time and funds limit the number of farms and the number of manure rates.

1.9 Definition of Terms

Organic manure: Plant or animal material, such as poultry droppings, that is applied to soil to supply nutrients and organic matter.

Growth: The increase in size of the maize plant, measured in this study by plant height, number of leaves, leaf area and stem girth.

Yield: The quantity of maize grain harvested per unit area, expressed in tonnes per hectare.

Rate of application: The quantity of manure applied per hectare, expressed in tonnes per hectare.

Farmers' practice: The way the participating farmer would normally fertilise (or not fertilise) the crop, used as a comparison.

References

AllAfrica. (2025, July 22). Nigeria: High fertiliser cost – Farmers dump rice, maize cultivation. https://allafrica.com/stories/202507220646.html

Denton, O. A., Fademi, I. O., Are, K. S., Ojo, A. O., & Adeoyolanu, O. D. (2020). Effect of different manure sources on soil chemical properties, performance and yield of maize on a degraded land. International Journal of Plant & Soil Science, 32(13), 48–58. https://doi.org/10.9734/IJPSS/2020/v32i1330358

Diri, K. H., & Kedoneojo, A. T. (2024). Evaluating the impact of poultry manure variants and swine manure on soil chemical properties and growth of maize (Zea mays). Asian Journal of Agriculture, 8(1). https://doi.org/10.13057/asianjagric/g080101

Jjagwe, J., Chelimo, K., Karungi, J., Komakech, A. J., & Lederer, J. (2020). Comparative performance of organic fertilizers in maize (Zea mays L.) growth, yield, and economic results. Agronomy, 10(1), 69. https://doi.org/10.3390/agronomy10010069

Kareem, I., Jawando, O. B., Eifediyi, E. K., Bello, W. B., & Oladosu, Y. (2017). Improvement of growth and yield of maize (Zea mays L.) by poultry manure, maize variety and plant population. Cercetări Agronomice în Moldova, 4(172), 51–64. https://doi.org/10.1515/cerce-2017-0035

Okojie-Okeiyi, J. (2025, September 10). Farmers shift to cash crops as fertiliser cost jumps 41%. BusinessDay. https://premium.businessday.ng/article/top-story/Farmers-shift-to-cash-crops-as-fertiliser-cost-jumps-41

Okoroafor, I., Okelola, E., Edeh, O., Nemehute, V., Onu, C., Nwaneri, T., & Chinaka, G. (2013). Effect of organic manure on the growth and yield performance of maize in Ishiagu, Ebonyi State, Nigeria. IOSR Journal of Agriculture and Veterinary Science, 5, 28–31. https://doi.org/10.9790/2380-0542831

Onwubiko, G. N. (2026). Comparative assessment of the morphological traits of local maize (Zea mays L.) varieties upon exposure to varying rates of poultry manure. Current Research in Agricultural Sciences, 13(1), 104–113. https://doi.org/10.18488/cras.v13i1.4944

Rasool, A., Ghani, A., Nawaz, R., Ahmad, S., Shahzad, K., Rebi, A., Ali, B., Zhou, J., Ahmad, M. I., Tahir, M. F., Alwahibi, M. S., Elshikh, M. S., & Ercisli, S. (2023). Effects of poultry manure on the growth, physiology, yield, and yield-related traits of maize varieties. ACS Omega, 8(29), 25766–25779. https://doi.org/10.1021/acsomega.3c00880

Rayne, N., & Aula, L. (2020). Livestock manure and the impacts on soil health: A review. Soil Systems, 4(4), 64. https://doi.org/10.3390/soilsystems4040064