THE EFFECT OF COMPOST AND NPK FERTILIZER ON THE GROWTH AND YIELD OF MAIZE (A CASE STUDY OF MAIZE FARMERS IN ZARIA LOCAL GOVERNMENT AREA, KADUNA STATE)

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Maize is among the most important cereals grown in Nigeria, and demand for it is far greater than supply. A report by the News Agency of Nigeria in 2025 put the country's annual maize requirement at about 21 million metric tonnes, against a reported output of around 10.5 million tonnes (AllAfrica, 2025). Closing a gap of that size requires more land under maize, higher yields, or both, and for the smallholders who produce most of the crop, higher yields depend in large part on soil nutrients.

The soils of the northern savannas, where much of the maize is grown, are not well supplied with them. Tofa et al. (2022) point out that the soils of the Nigerian savannas are particularly low in nitrogen and phosphorus, and that this depresses maize productivity. Kareem et al. (2017) likewise describe savanna soils as low in plant nutrients and note that farmers depend on organic and inorganic manure to sustain yields. Tofa et al. (2022) worked at Zaria itself, in the northern Guinea savanna, and found that when phosphorus was applied at 13 kg/ha, plant nitrogen uptake rose by 51 and 57 per cent at nitrogen rates of 60 and 120 kg/ha respectively, compared with no nitrogen. The practical message of their study is that nutrients applied together can do more than the same nutrients applied singly.

Mineral fertiliser is the route to quick and substantial yield gains, but it has become costly. A BusinessDay market survey found that the average price of a 50 kg bag of NPK fertiliser rose from about N43,000 to about N60,500 within a year, an increase of 41 per cent (Okojie-Okeiyi, 2025). Farmers interviewed by the News Agency of Nigeria said that they were dropping maize because fertiliser had become too expensive relative to the price of the grain (AllAfrica, 2025). A farmer who cannot afford the full rate of NPK faces a choice between applying less, applying none, or finding another source of nutrients.

Organic sources are the usual alternative. In a panel survey of maize farmers in north-west Nigeria, animal manure had the highest rate of adoption among soil conservation practices, at 76 per cent in the 2016 season and 69 per cent in 2017; the commonest pattern was a combination of two practices, and the commonest pair was animal manure with crop residue retention (Oladimeji, 2020). The same study found that adoption was influenced by livestock ownership, access to credit, the use of inorganic fertiliser and other factors. Organic materials thus already feature in the practice of many northern maize farmers, and they interact with the use of mineral fertiliser rather than simply replacing it.

Trials in different parts of Nigeria show that organic materials can raise maize yield and that combining them with mineral fertiliser can do better than either alone. Kareem et al. (2017) found that poultry manure at 5 t/ha significantly improved all the growth and yield parameters they measured on maize, and Onwubiko (2026) found that poultry manure at 10 t/ha gave the best leaf number and leaf width in local maize varieties at Nsukka. Compost, which is made on the farm from crop residues, animal waste and other farm waste, has been compared with NPK 15:15:15 and with urea in maize trials: Okhumata and Idowu (2022) tested a compost–mineral fertiliser against NPK and urea and examined the time at which the compost–mineral fertiliser should be applied. The principle that organic and mineral nutrients can complement each other is also supported by work on a vegetable crop at Umuahia, where poultry manure combined with NPK gave a better yield of amaranth than NPK alone (Akinmutimi & Okoroji, 2024).

Zaria Local Government Area is in the northern Guinea savanna and is one of three local government areas in Kaduna State that have adopted villages of the National Agricultural Extension and Research Liaison Services (NAERLS); it has seven such villages with 1,225 registered farmers (Abubakar et al., 2022). Maize farmers in the area thus live close to research and extension institutions and may be more exposed than most to advice on fertiliser and organic amendments. What is not known is what they actually do. Some farmers may use compost alone, some NPK alone, some both and some neither; some may apply them at planting and others later; and the growth and yield they report under each pattern has not been gathered in the literature reviewed for this chapter.

A questionnaire survey is the appropriate way of collecting this information. It can show how many farmers follow each pattern of use, how much compost and NPK they apply, how they describe the growth and yield of their maize, and what limits their use of each input. It cannot isolate the effect of compost or NPK from the effects of soil, rainfall and management, which only controlled trials can do, but it can show whether the farmers' own experience points in the same direction as trial results, and where practice and evidence diverge.

1.2 Statement of the Problem

Maize farmers in Zaria need nutrients to obtain acceptable yields from soils that are naturally low in nitrogen and phosphorus (Tofa et al., 2022), but the main source of those nutrients, NPK fertiliser, has become expensive (Okojie-Okeiyi, 2025), and farmers are reported to be cutting back on maize because of it (AllAfrica, 2025). Compost, which costs labour rather than cash, is a possible partial substitute and a possible complement, and organic materials are already widely used by maize farmers in the north-west (Oladimeji, 2020).

The trial evidence on organic and mineral fertilisers comes mainly from research plots and uses materials and rates that farmers may not use (Kareem et al., 2017; Okhumata & Idowu, 2022). Compost varies greatly in composition, farmers may apply it in local containers rather than by weight, and they may not follow fixed ratios with NPK. No evidence was found on which combinations of compost and NPK the maize farmers of Zaria actually use, in what quantities and at what times, or on the growth and yield they report from them.

The effects of this gap are practical. Extension agents cannot say whether farmers' combinations are balanced or skewed towards one input. Farmers cannot compare their results with those of others who use different patterns. Researchers and policy makers who wish to promote compost or to design fertiliser-support programmes have no description of current practice from which to start, and so may recommend what farmers cannot or will not do.

The problem addressed by this study is therefore the absence of farmer-level evidence, for Zaria Local Government Area, on the patterns of compost and NPK use among maize farmers and on the growth and yield they report under each pattern.

1.3 Objectives of the Study

The main objective is to assess the effect of compost and NPK fertiliser on the growth and yield of maize as reported by farmers in Zaria Local Government Area. The specific objectives are to:

1. describe the socio-economic and farm characteristics of maize farmers in the area;

2. identify the patterns of compost and NPK use among the farmers (compost only, NPK only, both, or neither);

3. determine the quantities and times of application of compost and NPK used by the farmers;

4. determine the growth and yield that the farmers report under each pattern;

5. determine the relationship between the pattern of fertiliser use and reported yield; and

6. identify the constraints to the use of compost and NPK fertiliser.

1.4 Research Questions

(i) What are the characteristics of maize farmers in Zaria Local Government Area?

(ii) How many farmers use compost only, NPK only, both, or neither?

(iii) What quantities of compost and NPK do the farmers apply, and when?

(iv) What growth and yield do the farmers report under each pattern?

(v) Does the reported yield differ between the patterns?

(vi) What constraints limit the use of compost and NPK fertiliser?

1.5 Research Hypotheses

Stated in null form, the hypotheses to be tested at the 5% level of significance are:

H0₁: There is no significant difference in the maize yield reported by farmers using compost only, NPK only, both, or neither.

H0₂: There is no significant relationship between the quantity of NPK applied and the yield reported by farmers.

H0₃: The socio-economic characteristics of farmers (age, sex, education, farm size, farming experience and livestock ownership) have no significant relationship with their pattern of fertiliser use.

1.6 Significance of the Study

• To farmers: a view of how others combine compost and NPK, and what they report from it, in a season of high fertiliser prices.

• To extension agents: evidence on whether farmers' combinations are balanced or skewed towards one input, which shows where advice is most needed.

• To researchers: farmer-level data from Zaria to complement trial results from research farms, and a description of current practice from which to design realistic on-farm trials.

• To policy makers: information on the constraints that limit the use of compost and NPK, which can inform fertiliser-support and compost-promotion programmes in Kaduna State.

1.7 Scope and Delimitation of the Study

The study is limited to maize farmers in Zaria Local Government Area of Kaduna State and to the most recent cropping season. It uses a cross-sectional survey with a structured questionnaire. It covers compost (made from crop residues, animal waste or other farm waste) and NPK compound fertiliser, the quantities and times of their application, and farmers' reports of maize growth and yield. It does not cover urea, organic manure used without composting, varieties, pest control or the marketing of maize.

1.8 Limitations of the Study

1. Farmers' estimates of yield and of the quantities of compost applied may be imprecise, because compost is measured in local containers and maize is often sold or consumed before it is weighed.

2. Compost varies widely in composition, so two farmers' "compost" may differ greatly in nutrient content.

3. The survey can show association but cannot isolate the effect of compost or NPK from soil, variety, rainfall and management.

4. Time and funds limit the number of respondents and communities.

1.9 Definition of Terms

Compost: decomposed organic material prepared by farmers from crop residues, animal waste or other farm waste and applied to the soil to supply nutrients and organic matter.

NPK fertiliser: is a compound mineral fertiliser supplying nitrogen, phosphorus and potassium, commonly sold as NPK 15:15:15.

Growth: refers to the development of the maize plant (height, leaf colour and vigour) as reported by the farmer.

Yield: is the weight of maize grain harvested per unit area, as reported by the farmer.

Pattern of fertiliser use is the combination of compost and NPK, including neither, that a farmer applied in the season.

References

Abubakar, M. I., Idrisa, Y. L., & Pur, J. T. (2022). Preference of extension delivery methods used in the adopted villages of the National Agricultural Extension and Research Liaison Services in Kaduna State, Nigeria. Nigerian Journal of Rural Sociology, 22(1), 16–21.

Akinmutimi, A. L., & Okoroji, M. C. (2024). Effects of organic and inorganic fertilizers on soil chemical properties and the yield of Amaranthus species in a continuously cropped Ultisol. International Journal of Agriculture and Environmental Research, 10(1), 64–74. https://doi.org/10.51193/IJAER.2024.10105

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

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

Okhumata, D. S., & Idowu, E. R. (2022). Comparative effects of compost–mineral, NPK and urea fertilizer and time of application of compost–mineral fertilizer on the yield of maize. Journal of Wastes and Biomass Management, 4(2), 64–67.

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

Oladimeji, T. E. (2020). Effect of soil conservation on productivity and food security on maize farmers in northwest Nigeria [Thesis record]. IITA Research Repository. https://biblio1.iita.org/handle/20.500.12478/7854

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

Tofa, A., Kamara, A., Babaji, B. A., Aliyu, K. T., Ademulegun, T., & Bebeley, J. F. (2022). Maize yield as affected by the interaction of fertilizer nitrogen and phosphorus in the Guinea savanna of Nigeria. Heliyon, 8(11).