Development And Performance Evaluation Of Rice Destoning Machine

CHAPTER TWO
2.    LITERATURE REVIEW
2.1    De-Stoning of Rice
De-stoning is separation of stones mixed with milled rice. Separation of agricultural products can be done by using one of these methods or by the combination of the following methods: screening, shelling, sorting and grading. Many researcher’s effort were made to solve this problem with different levels of success, among them is Oguomaet al., (2002) established that the separation of sand and stones from rice can be achieved by exploiting the difference in the dimensional features of rice and stone.
2.2        Rice production in Nigeria
 Accordingto Hardcastle (Hardcastle, 1959) rice production started in Nigeria in1500 BC with the low-yielding indigenous red grain speciesO.glaberrimaSteud and then widely grown in the NigerDelta area. West Africa Rice Development Association (WARDA 1996) reported about the high-yieldingwhite grain O. SativaL. introduced in 1890, and by 1960 itaccounted for more than 60 percent of the rice grown in thecountry. Also, the chart below shows the trend of rice productionin Nigeria since 1968 through 2008 (four-decade) study.Rice production remained at low level from 1968 to 1978 perhaps due to dietary idiosyncrasy for tubers. WARDA (1996) reported that paddy rice production had risen from 13400 to 344000 tons in 1970 and area was cultivated from 156,000 to255,000ha. Since then, paddy rice production has been on the increase. Tremendous increases in area planted, output, and productivity in paddy rice production were achieved over the last two decades and now stand at 1.09million tons. More so, the     production continued to rise higher from 1978 and since 1980. Nigeria has become the highest rice productions country in West Africa and the third largest in Africa, after Egypt and Madagascar (WARDA 1996).The production reached the peak in 1990 in which the countrywas producing 3.4 million tons of rice from about 1.2 million tons (ImolehinandWada,2000) before it slightly fluctuated down the slope in 1993.
However, the production soared up from 1993 to 2006 where the production remains 3.8 million metric tons. The graph shows that as years increased the production also increased; thismay be due to increase in population growth as well as increase in consumption trend of rice in the country. This healthy production trend would have been sustained but for the unsteady government policy on rice imports. Increased production over the last two decades could be attributed to the ban imposed on rice imports in 1985 and if this restriction had been maintained, Nigerian rice farmers would have risen to the challenge of meeting the domestic demand for the commodity. This has not been the case; however, as the government slackened rice import restrictionin 1997, the resultant effect was that foreign rice flooded back onto Nigeria markets. Restrictions on rice imports were reintroduced later in 1997, and local production has increased in response to the attractive prices offered (Emodi and Madukwe,2008). For rice production to be boosted, Nigerian government introduced institutions to monitor production and distribution of local rice. As the years went by, the indigenous production of rice could not meet the demand for rice. Therefore, Nigeria started importing rice into the country. This shows clearly the rice importation figures as reported by United State Department of Agriculture (2014). This importation of rice did not follow a regular pattern but it is observed from the figure that rice importation was not up to 1 million metric ton per year since 1983–1998. However, from 2006 upwards, the importation figure soared yearly to reach the peak in 2013 with 3.5 million metric tons. The major reason is the preference of foreign to indigenous rice which has a low level of processing technology (Akande, 2003).
          Furthermore, figure2.2 shows the importation yearly rice growth rate from 1983 to 2013. It is observed that growth rate is irregular and in some years there is no growth at all in rice importation business. From this, the growth rate is counted when the curves are upward ones and no growth rate occurs when curves are downward ones. This growth rate implies that the higher the growth rate is, the higher the country depends on importation of rice and the less the production of local rice is. This means that in 1997 Nigeria depended heavily on imported rice to feed its populace. This had negative consequence on the economy.