THE EFFECT OF WEEDING FREQUENCY ON THE GROWTH AND YIELD OF COWPEA (A CASE STUDY OF COWPEA FARMERS IN FUNTUA LOCAL GOVERNMENT AREA, KATSINA STATE)

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Cowpea (Vigna unguiculata L. Walp) is a leguminous crop grown mainly for its protein-rich grain, which is eaten in dishes such as beans, moin-moin and akara. The leaves are used as vegetable and the haulms are valued as livestock fodder, especially in the northern savanna. Because it fixes atmospheric nitrogen, cowpea also contributes to soil fertility. Adigun et al. (2020) note that Nigeria is the largest producer and consumer of cowpea, and the crop is central to the diet and income of many households in northern Nigeria.

Cowpea yields on farmers' fields are generally low. Adigun et al. (2020) identify weed infestation as one of the major factors responsible for the poor yield of cowpea in Nigeria and other parts of sub-Saharan Africa. Young cowpea plants grow slowly at first and are easily overtopped by weeds, which compete with the crop for light, water and nutrients, harbour pests and diseases, and lower both growth and grain yield.

The yield loss can be severe. In experiments at Abeokuta, Adeyemi et al. (2020) compared five weeding frequencies (no weeding, weed-free, hoe weeding at 3 weeks after sowing, at 3 and 6 weeks, and at 3, 6 and 9 weeks) on an extra-early cowpea variety, and found that unchecked weed infestation reduced yield by 53.10% and 49.9% in the early and late seasons respectively, compared with the maximum obtained from weed-free plots. Weeding at 3, 6 and 9 weeks after sowing gave the highest grain yield in the early-season trial, and the authors concluded that this frequency, together with 15 kg P2O5/ha, gave effective weed control and optimum grain yield.

More frequent weeding is not always better, however. Adigun et al. (2020) evaluated weeding levels and row spacing on cowpea in the forest–savanna transition zone and reported that hoe weeding twice, at 3 and 6 weeks after sowing, resulted in optimum growth and grain yield, and that an additional weeding did not improve growth and yield and was considered superfluous. They also found that a narrow row spacing of 60 cm reduced weed density by 18 to 39% and weed biomass by 17 to 27%, and raised grain yield by 67 to 109% in the early season and 24 to 56% in the late season compared with 75 and 90 cm. These results show that the best weeding frequency depends on the season, the row spacing and the other management practices used.

Weeding frequency is also a question of labour and cost. Most smallholders weed by hand or with the hoe, which is slow, tiring and expensive, and farmers must balance the cost of an extra weeding against the yield they expect to gain. Adeyemi et al. (2020) point to the persistent use of manual weeding by cowpea farmers. How many times farmers weed, when they weed, and what effect they see on growth and yield are influenced by labour availability, rainfall, the cropping system and the weed species present.

Funtua Local Government Area is in the southern part of Katsina State, where cowpea is grown by smallholders, often alongside cereals. This study therefore used a structured questionnaire to examine the weeding frequencies used by cowpea farmers in Funtua and their perceived effects on the growth and yield of cowpea.

1.2 Statement of the Problem

Cowpea farmers in Funtua Local Government Area contend with weeds throughout the rainy season, but the number and timing of weedings vary with the labour and money available and with personal experience. Studies from other parts of Nigeria show that weeds can reduce cowpea yield by about half (Adeyemi et al., 2020) and that two well-timed weedings may be enough in some conditions (Adigun et al., 2020), but it is not known how many times farmers in Funtua weed or how they judge the effect on their crop.

The studies reviewed here were carried out at research stations in south-western Nigeria (Adeyemi et al., 2020; Adigun et al., 2020), and the literature consulted for this study did not reveal a survey of weeding frequency practices and perceived effects among cowpea farmers in Funtua. Differences in rainfall, soil, weed species and cropping system mean that results from the south-west cannot be assumed to hold in Katsina State.

As a result, some farmers may weed too seldom and lose yield, while others may weed more often than necessary and waste labour and money. Extension agents also lack local information on which to base advice. This study was undertaken to provide it.

1.3 Objectives of the Study

The main objective of the study was to assess the effect of different weeding frequencies on the growth and yield of cowpea among farmers in Funtua Local Government Area, Katsina State, using a structured questionnaire. The specific objectives, each of which corresponds to a section of the questionnaire, were to:

(i) describe the socio-economic characteristics of the farmers, namely age, sex, educational level, farming experience, farm size and source of labour.

(ii) identify the weeding frequencies, timing and methods of weeding currently used by the farmers in the production of cowpea

(iii) ascertain the Farmers' perception of the effect of different weeding frequencies on the growth of cowpea ;

(iv) ascertain the respondents' perception of the effect of different weeding frequencies on the yield of cowpea ; and

(v) identify the constraints faced by the respondents in the use of different weeding frequencies and the measures they suggest for improvement .

1.4 Research Questions

The following research questions, which correspond to the sections of the questionnaire, guided the study:

(i) What are the socio-economic characteristics of the respondents?

(ii) What weeding frequencies, timing and methods of weeding do the respondents use in the production of cowpea?

(iii) How do the respondents perceive the effect of different weeding frequencies on the growth of cowpea?

(iv) How do the respondents perceive the effect of different weeding frequencies on the yield of cowpea?

(v) What constraints do the respondents face in the use of different weeding frequencies, and what improvements do they suggest?

1.5 Research Hypotheses

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

H01: There is no significant relationship between the socio-economic characteristics of the respondents and their weeding frequency.

H02: There is no significant difference in the perceived growth of cowpea among respondents who differ in their weeding frequency (once, twice or three or more times).

H03: There is no significant difference in the perceived yield of cowpea among respondents who differ in their weeding frequency (once, twice or three or more times).

1.6 Significance of the Study

The findings will give cowpea farmers in Funtua information on the weeding frequencies used by their peers and those they perceive to give better growth and yield, which may help them use labour more efficiently. Extension agents will obtain local information for advice on weed management, and the study may help agencies that support cowpea production to target their assistance.

The study will also add to the literature on cowpea production in northern Nigeria.

1.7 Scope and Limitations of the Study

The study covers cowpea farmers in Funtua Local Government Area, Katsina State. It is limited to weeding frequency and covers the respondents' socio-economic characteristics, weeding practices, perceived effects on growth and yield, and constraints. It does not include measurement of weed density or controlled field measurement of yield.

Limitations include reliance on respondents' recall and perception, seasonal differences in rainfall and weed pressure, and the limited number of respondents who could be reached. The findings should be applied with care outside the study area.

1.8 Definition of Terms

Weeding frequency: the number of times weeds are removed from the cowpea field during one cropping season.

Weed: a plant growing where it is not wanted, which competes with the crop.

Weeks after sowing (WAS): the number of weeks counted from the date of sowing.

Growth: the visible development of the cowpea plant, such as vigour, branching and ground cover, as perceived by farmers.

Yield: the quantity of cowpea grain harvested per unit area.

Questionnaire: a structured set of written questions used to collect information from respondents.

REFERENCES

Adeyemi, O. R., Ogunsola, K. O., Olorunmaiye, P. M., Azeez, J. O., & Hosu, D. O. (2020). Effect of phosphorus (P) rates and weeding frequency on the growth and grain yield of extra early cowpea (Vigna unguiculata L. Walp) in the forest–savanna transition agro-ecological zone of Southwest Nigeria. Journal of Agricultural Sciences (Belgrade), 65(1). https://doaj.org/article/3f353abc03354de7aebb37b655ac6fea

Adigun, J. A., Adeyemi, O. R., Daramola, O. S., & Olorunmaiye, P. M. (2020). Response of cowpea (Vigna unguiculata, L., Walp) to inter-row spacing and weed competition. Agricultura Tropica et Subtropica, 53(2). https://doi.org/10.2478/ats-2020-0008