THE EFFECT OF MULCHING MATERIALS ON SOIL MOISTURE AND THE GROWTH OF OKRA (A CASE STUDY OF OKRA FARMERS IN UDI LOCAL GOVERNMENT AREA, ENUGU STATE)

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Okra (Abelmoschus esculentus L. Moench) belongs to the family Malvaceae and is a widely grown fruit vegetable in tropical and subtropical regions. The immature pods are eaten fresh or dried and are valued in Nigerian soups and sauces for their mucilage, and they supply fibre, vitamins and minerals to the diet. The crop is relatively quick to mature and can be harvested repeatedly over several weeks, which makes it attractive to smallholder farmers who depend on regular small incomes from the market.

Okra production in sub-Saharan Africa is largely rainfed, and rainfall is erratic. Obi et al. (2024) note that rainfed okra is exposed either to moderate or severe drought or to excessive wetness that lowers soil temperature. Water shortage affects germination, leaf expansion, flowering and pod set, and in derived-savannah environments, soils that dry out quickly may leave the crop short of water for much of the dry spells that interrupt the rainy season. Soil moisture is therefore one of the most important factors in the growth of okra, and practices that conserve it deserve close attention.

Mulching is one such practice. It involves covering the soil surface with organic materials, such as dry grass, straw, sawdust or crop residues, or with synthetic materials such as black polythene film. In a review of mulching as a water-saving technique in dryland agriculture, Kader et al. (2019) describe its value in preserving soil moisture, moderating soil temperature and limiting evaporation, with effects on crop yield, and they discuss both organic and plastic materials. Demo and Asefa Bogale (2024) likewise report that mulching reduces soil water loss, erosion and weed growth in dryland agriculture. Organic mulches also decompose to add organic matter to the soil, whereas plastic mulches last longer but cost more and can pose disposal problems.

Studies close to the study area illustrate how mulch performance can vary. Researchers at the University of Nigeria, Nsukka, tested dry-grass, sawdust and black polythene mulch on okra in droughty derived-savannah soils. Black polythene gave better growth than sawdust, but mulch material alone did not change flowering, fruiting or fruit yield, and the highest yield (2.93 t/ha) came from black polythene combined with close spacing (Obi et al., 2024). In another study, Okorie et al. (2024) examined what they call bio-economic mulching in droughty tropical agroecosystems, applying dry-grass mulch at 0, 2, 4 and 6 t/ha on sandy-loam Ultisols. They found that mulch-induced differences in soil moisture over time were associated with okra plant height (r² = 0.85) and total fresh fruit yield (r² = 0.69), which suggests that soil moisture is the main route through which mulch influences okra performance.

These findings show that mulching can benefit okra, but they also show that the response depends on the mulching material, the rate of application, the soil and the season. Materials that are cheap and available locally are of special interest to smallholders, who often cannot afford plastic film or large quantities of imported inputs.

Udi Local Government Area is in Enugu State, where okra is cultivated by smallholder farmers largely under rainfed conditions. The area lies in the same state as the Nsukka-based studies cited above, but farmers in Udi cultivate under their own soil and management conditions. This study was therefore designed to examine the effect of mulching materials on soil moisture and the growth of okra among farmers in Udi Local Government Area.

1.2 Statement of the Problem

Okra farmers in Udi Local Government Area depend largely on rainfall, and short dry spells during the growing season reduce soil moisture, slow plant growth and may reduce pod yield. Mulching can help to reduce these losses, but farmers do not have local information on which mulching materials work best. Results from the literature also differ: in one study from the Nsukka area, growth responded to mulch material while fruit yield did not (Obi et al., 2024), and in another, the benefit of dry-grass mulch depended on the rate of application and was linked to changes in soil moisture (Okorie et al., 2024).

Many mulching studies also compare plastic film with organic materials under experimental conditions (Kader et al., 2019), whereas smallholder farmers usually have only cheap, locally available residues such as dry grass or sawdust. The literature consulted for this study did not reveal an investigation of the effect of locally available mulching materials on soil moisture and okra growth carried out with farmers in Udi.

Without this information, farmers may leave the soil bare and lose water by evaporation, or may use materials that give little benefit. Extension agents also lack local data for advising farmers. This study was undertaken to provide evidence on the effect of mulching materials on soil moisture and growth of okra in Udi Local Government Area.

1.3 Objectives of the Study

The main objective of the study was to determine the effect of mulching materials on soil moisture and the growth of okra in Udi Local Government Area, Enugu State. The specific objectives were to:

(i) measure soil moisture content under different mulching materials and under bare soil;

(ii) compare the growth of okra (plant height, number of leaves and stem girth) under the mulching treatments;

(iii) determine the relationship between soil moisture and okra growth; and

(iv) identify the mulching material that performs best under local conditions.

1.4 Research Questions

The following research questions guided the study:

(i) How do different mulching materials affect soil moisture?

(ii) How do they affect the growth of okra?

(iii) What is the relationship between soil moisture and okra growth?

(iv) Which mulching material is most suitable for okra production in Udi?

1.5 Research Hypotheses

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

H01: Mulching materials have no significant effect on soil moisture.

H02: Mulching materials have no significant effect on the growth of okra.

1.6 Significance of the Study

The findings will help okra farmers in Udi to choose mulching materials that conserve moisture and improve growth. Extension agents will have data to cite when advising farmers.

The study will also add another site in the Enugu agro-ecology to the existing literature on mulching.

1.7 Scope and Limitations of the Study

The study covers okra farmers in Udi Local Government Area, Enugu State, and is limited to the effect of selected mulching materials on soil moisture and growth. Pod quality and economic returns are outside its scope.

Limitations include the short study period, the limited number of mulching materials tested and variation in rainfall during the season. Findings apply most directly to Udi and environments that resemble it.

1.8 Definition of Terms

Mulch: material spread over the soil surface to conserve moisture, regulate temperature and suppress weeds.

Soil moisture: the quantity of water held in the soil.

Organic mulch: mulch made from plant material, such as dry grass or sawdust.

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

Rainfed: crop production that depends on rainfall without irrigation.

REFERENCES

Demo, A. H., & Asefa Bogale, G. (2024). Enhancing crop yield and conserving soil moisture through mulching practices in dryland agriculture. Frontiers in Agronomy, 6, Article 1361697. https://doi.org/10.3389/fagro.2024.1361697

Kader, M. A., Singha, A., Begum, M. A., Jewel, A., Khan, F. H., & Khan, N. I. (2019). Mulching as water-saving technique in dryland agriculture: Review article. Bulletin of the National Research Centre, 43, Article 147. https://doi.org/10.1186/s42269-019-0186-7

Obi, J. O., Onah, C. J., Nnadi, A. L., Osadebe, V. O., Akubue, J. C., Amuji, C. F., & Obalum, S. E. (2024). Sensitivity of rainfed okra (Abelmoschus esculentus L. Moench) to mulch material and plant spacing in drought-prone tropical soils. Agroindustrial Science, 14(2), 97–106. https://doi.org/10.17268/agroind.sci.2024.02.02

Okorie, B. O., Obi, J. O., Chioke, G. U., Obalum, S. E., Onah, C. J., Nnadi, A. L., Igwe, C. A., & Obi, M. E. (2024). The concept of bio-economic mulching in droughty tropical agroecosystems and its trans-season effects on soil hydro-thermal regime and okra performance. Sains Tanah – Journal of Soil Science and Agroclimatology, 21(2), 165–178. https://doi.org/10.20961/stjssa.v21i2.83285