1.0    INTRODUCTION

Soybean (Glycine max (L) Merrill) is a member of the Leguminosae family and subfamily

Papilinoideae. Soybean is an annual herbaceous legume that originated from North-eastern

China and has been cultivated for the past three millennia (Simmondet al., 1999). The crop is

now cultivated throughout the world with the largest production in the United State of

America, Brazil, China and Argentina (Javaheri and Baudoin, 2001).

Soybean which is popularly known as golden bean has become a miracle crop of the 21st

century because it is widely cultivated throughout the world. The world production figure for

soybean as at 2013 is about 283millions tonnes. While Nigeria production is 58 tonnes.

Soybean is an excellent health food crop, containing 40-44% protein, which is more than in

other food crops and common vegetable sources in Nigeria (Thakareet al., 2006). The protein

yield of soybean on dry matter basis is about twice that of meat and most beans and nuts and

four times that of milk (Dalleyet al., 2004). Soybean seed contains about 20% oils on dry

matter basis and it is 85% unsaturated and cholesterol-free. It also contains 20% carbohydrate

and 0.69% phosphorous (Oyekan, 1987). The seed is used in making soymilk (Kanaseet al.,

2006). The crop has been described as the world cheap source of edible vegetable oil and

protein in livestock feeds (Dalleyet al., 2004). It is a primary source vegetable of oil in local

and international markets. It has the capability to fix 45-60kg/ha atmospheric nitrogen in the

root nodules and adds about 0.5-1.5 t/ha organic matter through leaf fall (Kurehet al., 2005).

Soybean cultivation has expanded as a result of its nutritional and economic importance and

diverse domestic uses.

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1.1 Production and Economic Importance

Soybean is among the major industrial and food crops grown in every continent of the world.

The crop can be successfully grown in many states in Nigeria using low agricultural inputs

(Dugje, 2009. Soybean cultivation in Nigeria has expanded as a result of its nutritive and

economic importance and the diverse domestic uses (Omoigui, 2009). The crop is also an

excellent source of vegetable oil in the international market.

Soybean is an annual grain legume crop that provides about one –quarter of the world dietary

protein. According to Ezedinma, (1994), soybean and other leguminous crops are essential

sources of plant protein for about 700 million people. About 35-40% of the total dry matter

content of the whole soybean is protein. It compares favourably with animal protein sources

and contains the most essential amino acids required by man. It has digestible nutrients of

about 92%, which makes it a good source of energy (Mijindadi, 1987).

Soybean contributes to the improvement of soil fertility by fixing 60-70 kg-N-ha

atmospheric nitrogen in the soil for the subsequent crop (Khan et al., 2005). The crop has an

average protein content of 40% and is more protein –rich than any of the common vegetable

crops or animal food sources found in Nigeria (Dugje et al., 2009). The crop can be used as

soy-milk and vegetable oil. Soybean seed contains about 20% oil on a dry matter basis,

which is 85% unsaturated and cholesterol- free (Kanase et al., 2006)

1.2 Weed Infestation and Control in Soybean

Reduction in soybean yield due to weed infestation varies from 27-77%, (Fletcher et al.,

1992) depending on the type of weeds and weed infestation intensity, soil type and rainfall

pattern. It was reported that yield declined by as much as 84% as a result of weed infestation

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(Mijindadi, 1987) .Weed infestation removed 21.4 kg N and 3.4 kg P per hectare in soybean

(Hailu, et al., 2010).

It was reported that two hand hoeing was very effective in suppressing weeds and increasing

soybean seed yield (Ahmed et al., 2001). The conventional methods of weeding such as

hoeing and hand pulling are expensive, laborious and the labour is not available during peak

period of weeding (Khan et al., 2001). Presently, there is a