EFFECT OF DIFFERENT TILLAGE PRACTICES ON GROWTH AND YIELD RESPONSE OF SWEET POTATO (Ipomoea batatas (L) LAM) IN ISHIAGU

 

ABSTRACT

A field experiment was conducted at the project site of Federal College of Agriculture, Ishiagu during the 2022 rain fed cropping season on the ‘Yield Response of Sweet Potato (Ipomoea Batatas (L) Lam) to different Tillage Practices in Ishiagu.’ A randomized complete block design (RCBD) was used with four (4) treatment and three (3) replications. The treatments are: T1- Bed, T2- Ridge, T3 - Mound and T4 - zero tillage. Yield in kilogram was taken at harvest and was statistically analyzed. The result of the experiment shows that there were significant difference between treatments on the yield of sweet potato. Based on the results of the experiment, it was recommended that Bed and Mounds (Heap) tillage practice should be adopted by farmers in the production of sweet potato.

 

CHAPTER ONE

INTRODUCTION

1.1     Background of the Study

Tillage is the post clearing physical manipulation of soil aimed at modifying its structure, although it controls weeds. It initially improves aeration, water transmission and enhances root growth and nutrient uptake. It induces soil nutrients to be released faster (Ojeniyi, 1990, 1992). Factors responsible for farmer`s low yields are inappropriate tillage practices and lack of knowledge on the type and rate of fertilizer needed by the crop. Appropriate tillage systems improve aeration, water transmission, root growth and nutrient uptake (Ojeniyi, 1992; FAO, 2000).

For crop production, manual clearing of soil, ridging and mounding are common practices among majority small holding farmers in the humid tropics. Lal (1979) reported that in areas of Alfisols with gravel layer at shallow depth, farmers plant their crops on hillocks or mounds. Ridge cropping has also evolved as an integral component of subsistence farming and is well adapted for small, low inputs subsistence farms (Lal, 1987). Row tillage which combines the attributes of tilth formation and minimum tillage has been found (Ojeniyi, 1991, 1993) to be as effective as traditional hoe tillage in cowpea and maize production.

Any tillage or seeding system that maintains a minimum of 30% residue cover on the soil surface after planting is classified as conservation tillage (ASABE Standards, 2005). Conservation tillage has been used to reduce soil erosion and decrease production costs worldwide. Management techniques like no-tillage, which have increased yield and reduced soil and nutrient runoff, have been explored extensively to determine the impact on management of soil and cropping (Hoogmoed, 2009). Increased soil water, lower soil temperatures, and non-incorporation of residue under no-tillage may result in increased organic matter as compared to soil environmental conditions with tillage. Minimum tillage (or reduced tillage) system involves limited number of tillage passes and includes inversion and maintains a high level of surface residue.

Soil tillage by use of heavy duty equipment and implements, and even farm animals often result to soil compaction, which hardens the soil and deplete the infiltration characteristics, reduces the fertility of the soil, increase soil bulk density and penetration resistance, and reduces crop yield (Fasinmirin and Reichert, 2010). The continuous use of soil in tropical areas without recourse to conservation practices often constrained the soil ecosystems beyond their natural capacity, consequently leading to reduction in soil productivity and sustainability (Jongruaysup et al., 2003). The use of conventional tillage is inevitable during soil preparation for large scale production. To this end, there is a dire need to investigate the potential of growing sweet potato using traditional tillage, minimum/reduced and conventional tillage methods.

Sweet potato (Ipomoea batatas (L) Lam) is a tuber root bearing vegetable species grown in tropical areas for either domestic or industrial uses. Root of sweet potato is rich in vitamin A, B6, C, riboflavin, copper, pantothenic and folic acid (Abd El-Baky et al., 2009). These tubers have great food quality and an excellent source of anti-oxidants and carotenes (Woolfe, 1992). According to Berberich et al., (2005), the crop has several industrial uses, including medicinal purposes; use for treating diabetes, hookworms, ulcer and internal bleeding.

China is the highest producer of sweet potato (82,474,410 tonnes) and making Asia the leading producer of sweet potato in the world (FAO, 2012). In Africa, Nigeria (2,883,408 tonnes) ranked after Uganda while Ghana produces 90,000 tonnes on 65,000 ha area (FAOSTAT, 2006). In Nigeria, sweet potato is produced exclusively by peasant farmers. Consequently, the potential contribution of this crop toward food security in Ghana is underestimated as there is a huge gap between potential yield and the yield of peasant farmers (CRI, 2002). Farmers use various tillage methods for sweet potato production, among these small scale farmers’ plant local varieties using the flat method of tillage while farmers who have adopted improved varieties plant them on mounds or ridges. Janssens (2001) reported that mound planting provides favorable conditions for the formation of tuberous roots, therefore it can be concluded that growing on mounds is better than the growing on ridges, particularly in heavy soils. Further, Ennin et al., (2003) concluded that planting on ridges is preferable as it leads to increase in the crop`s yield due to increased plant population density which facilitate weed suppression and reduce crop-weed competition.

1.2     Statement of the Problem

Soil tillage is meant to create a loose and uniform seedbed prior to planting. The degree of loosening is closely related to soil texture, soil moisture content, and the type of tillage operation (Ismail, 2011). Tillage treatments affect crop growth and yield by altering bulk density, compaction and hydraulic properties of the soils. Desired plant growth depends on rooting ability, nutrient status and accessibility of roots to nutrients, soil aeration, and water availability. Some of soil physical properties affected by loosening are bulk density, soil strength, infiltration, water redistribution within the soil profile and the moisture retention (Osunbitan et al., 2005).

Several literatures are available on the effects of tillage on tuber and grain crops but information on the influence of tillage practices on sweet potato is very scarce, especially in the humid tropics.  Therefore the present study tends to fill in that gap by conducting an investigation into the effect of different tillage practices on the growth and yield of sweet potato

1.3     Objective of the Study

The general or broad objective of the study is to determine ‘yield response of Sweet Potato (Ipomoea Batatas (L) Lam) to different tillage practices in Ishiagu.’

Specific Objectives include:

i.                   To determine the effects of different tillage systems on the growth parameter of sweet potato.

ii.                 To determine the effect of different tillage systems on then yield of sweet potato.

1.4     Justification the Study

 Tillage treatments affect crop growth and yield by altering bulk density, compaction and hydraulic properties of the soils. The Study will able to let the farmers the best tillage practice to adopt in order to increase the growth and yield of the crop

The research work can also serve as a reference source to future researchers who might be interested in a related subject. Above all, the research work has helped in broadening the horizon or knowledge of the researcher with regards to tillage practices and its effect on crop growth and yield.