Rice Scheme Research Articles

Water use in rice schemes in the Senegal river Delta and Valley

The water use of rice schemes was derived from field measurements made during the 1991 and 1992 season at 13 irrigation schemes situated in the delta and valley of the Senegal river. The seasonal water consumption, as well as the water distribution throughout the season and the operation of the pumping stations were evaluated. The water consumption was compared with standards which ranged from 16,650 to 21,100 m3 ha−1 depending on the season and the location of the scheme. Half of the analyzed schemes used more water than required. Analysis of the water distribution throughout the season revealed that in general the supply follows the demand. In small-scale schemes however, the fit between supply and demand is often lacking, resulting in crop stress and yield reduction. Furthermore, the study shows that the capacity of half of the pumping stations are under-used as a result of a long stretched saturation period and/or the irrigation of only a small fraction of the total area of the scheme.

Evaluating an insect pest management system in an irrigated rice environment

AbstractThe efficiency and profitability of an integrated pest management system consisting of a phytosanitary survey and threshold interventions (based on levels of insect damage) was tested at the Vallée du Kou irrigated rice scheme in Burkina Faso, for two consecutive crop seasons in 1987. There was a considerable advantage in cost, number of insecticidal applications and yield of a threshold intervention-based system over arbitrary or routine insecticidal application methods. The proposed method is considered to be environmentally friendly.

Optimal control theory approach to enhancement of HgAr photodissociation

Practical application of the Tannor—Rice scheme for selective photochemistry requires that the effects of changes in the laser temporal pulse shapes must be understood. We report the results of a study of the effects of pulse shaping, within the Tannor—Rice scheme, applied to a simple diatomic molecule, namely the van der Waals complex HgAr. Optimal control theory is used to generate pulse shapes which provide enhanced reaction yield. The best yields are found by the method of simulated annealing using Gaussian pulse shapes.

Schistosomiasis mansoni and paddy-rice growing in Uganda: an emerging new problem.

In Eastern Uganda, paddy-rice growing, which has only become popular in recent years, seems to be associated with the emergence of schistosomiasis mansoni as a new problem in public health. To estimate the magnitude of this problem, a cross-sectional, baseline survey was carried out in six villages of the Kibimba Rice Scheme. The overall prevalence of Schistosoma mansoni infection was found to be 20%. The highest prevalences and intensities of infection were seen in those aged 5-29 years, with more males infected than females. An attempt was then made to identify the important factors in the aetiology of S. mansoni in this area. Odds ratios indicated that working regularly in the rice paddies, fishing with baskets, and being male were statistically associated with an increased risk of S. mansoni infection. It is clear that schistosomiasis mansoni which is emerging as a new health problem in the study area is closely linked to working in the rice paddies. Encouraging the rice farmers to wear knee-high, waterproof boots while in the fields may help control the disease.

Productivity of Cotton Following Rice

The continuous cotton (Gossypium hirsutum L.) culture practices of the Mississippi Delta tend to deplete soil organic matter and maximize soil losses. Conversely, rice (Oryza sativa L.) production in the Mississippi Delta produces considerable amounts of dry matter which offers the possibility of increases in soil organic matter and reduction of soil erosion during the winter. Experiments were conducted over 4-yr, 1984 to 1987, at the Delta Branch Experiment Station, Stoneville, MS, on a mixed Bosket (fine-loamy, mixed, thermic Mollic Hapludalf) and Beulah (coarse-loamy, mixed, thermic Typic Dystrochrepts) very fine sandy loam to evaluate the effects of rice and cotton rotation schemes on cotton yield, growth, and soil parameters in subsequent years. In 1986, penetrometer data revealed increased soil compaction in plots previously grown to rice for 2 yr prior to cotton when compared with continuous cotton. These differences in soil compaction were not found in 1987. When compared with continuous cotton, cotton heights in 1986 were reduced following 2 yr of rice. In 1987, seed cotton yields following two cycles of a 1:1 rotation with rice were slightly lower than continuous cotton. In 1987 soil test Ca was lower in rice plots following a 1:1 rice-cotton rotation than continuous cotton. Results indicated that continuous cotton was of equal productivity with rice and cotton rotations.

Struggles over crop rights and labour within contract farming households in a Gambian irrigated rice project

Contract farming schemes based on smallholders are expanding in Africa. Peasant household production is being restructured by the process. Research carried out in the Jahaly Pacharr irrigated rice scheme in The Gambia examines the changes that developed with the genesis of ‘contract farming of the dietary staple, rice. The production routine generated conflicts and struggles within project households over access to and control of female labor. These have led to new labor processes in the project area, which are shaping producers’ abilities to comply with contract farming production strictures.

Mosquitoes of the Kano Plain, Kenya. II. Results of outdoor collections in irrigated and nonirrigated areas using human and animal bait and light traps.

The results of catches of exophilic mosquitoes using light traps and human and animal bait confirmed our earlier observations on the Kano Plain that irrigation has had a marked effect on the local mosquito fauna. Monks Wood light traps placed under the outside eaves of houses and away from areas of human settlement caught large numbers of Anopheles gambiae s.l., An. ziemanni , and An. pharoensis on the Ahero Pilot Rice Scheme, while on the nonirrigated Kano Plain catches were predominantly Mansonia uniformis and Ma. africana . The major species taken on animal bait at Ahero was Culex poicilipes , while on the Kano Plain Ma. uniformis again made up the bulk of the catch. The use of a human-baited drop net out-of-doors enabled us to determine the outdoor biting activities of the common species of the Kano Plain. A series of 98 twelve-hr Monks Wood light trap catches made under the eaves of houses gave information on flight activities and has enabled us to suggest in this paper that, in the case of An. gambiae s.l., An. funestus and An. pharoensis , flight activity is followed by a period of quiescence before the mosquitoes begin to bite; in most of the other common mosquitoes of the area, flight and biting activity follow each other closely.

Mosquitoes of the Kano Plain, Kenya. I. Results of indoor collections in irrigated and nonirrigated areas using human bait and light traps

The preliminary entomological results from a nonirrigated area of the Kano Plain and from the irrigated Pilot Rice Scheme at Ahero, Kenya, are used to demonstrate that irrigation has had a marked effect on the mosquito fauna. Catches inside houses using human bait and modified CDC light traps indicated that in the rice field environments numbers of the main malaria vectors of the area were higher than in nonirrigated areas, and that their breeding extended over some 6 months of the year. Abundance of these mosquitoes in dwellings was closely linked to the conditions in nearby rice fields, and the 2 main population peaks of A. gambiae were connected with hand transplanting of young rice from nurseries to the main fields. On the nonirrigated plain, prevalence of the major anopheline species followed a more classical pattern, being closely linked to local rainfall, and the predominant mosquito species were found to be those breeding in semipermanent swamps and water holes. The combined results of a series of human-bait catches gave a series of biting activity curves very similar to those found by other workers in Africa.

The Response to Planned Change: a Study of the Rice Scheme in Chief Mwambo's Area (Lake Chilwa, Zomba, Malawi).

stereotype that peasant farmers, be it in Malawi or else? where, are resistant to changes and that this is a result of their being conservative. Such statements, which in the Third world have become cliches, are often used by unsuccessful planners and initiators of various rural development schemes to transfer blame for failure from themselves to, in this case, farmers. Much of the failure of such schemes can be explained in terms of the planners' ignorance of conditions conducive to acceptance of the planned change. Our premise is that when these conditions for success are met partially or wholly the doubt on the 'universal'