Soil Management for Conservation and Sustainable Rice Production in an Irrigated Area of Eastern Nigeria

Abstract

An comparison of soilmanagement techniques In the different irrigation zones of Lower Anambra Irrigation Project (LAIP) In eastern Nigeria showed that heavy use of machinery led to Increases In bulk density and decreases In field water Infiltration rate. The relative proportion of clay In the irrigated fields Increased as a result of Irrigation, suggesting that mobilized clay from uncemented main and distribution canals Is carried and deposited In the rice fields. Both Irrigation and the use of machinery have had substantial negative effects on soli nutrient levels, and there is a danger of this process continuing. Soli management for sustainable production in the area should centre on applying organic matter in combination with inorganic fertilizers, monitoring the soli properties on yearly basis before the cropping season for fertilizer and lime recommendations, and varying the depth of tillage to Increase or maintain the effective soli depth.

Land-use intensification and environmental degradation: empirical evidence from irrigated and rain-fed farms in south eastern Nigeria

“…Each plot measures 0.5 ha. descriptors such as topography and vegetation cover before the inception of irrigation (WADSCO, 1981;Asadu, 1996;Asadu et al, 1997). The WADSCO (1981) study involved detailed analyses of a random sample of soils from all farm plots in the river basin to assess the physical and financial feasibility of the soils of the river basin for irrigated agriculture.…”

“…This was subsequently followed up by a pilot survey of 80 farm plots (40 from each group) exploring the potentials and limitations of the methodology. Because the soils of the river basin were highly homogenous prior to the introduction of irrigation (see WADSCO, 1981;Asadu, 1996;Asadu et al, 1997), two soil sampling points were randomly chosen in each of the farm plots studied for soil sample collection using the standard auger method. Soil samples were taken from the surface soil (down to 40 cm depth) only.…”

“…Soil fertility indicators were selected based on a review of the literature and expert advice (Asadu, 1996;Wilson and Maliszewska-Kordybach, 1997;Carter and Stewart, 1996;Ball et al, 1997Ball et al, , 2000Dexter, 1988;Birnie et al, 2002). Laboratory analysis of soil samples collected from the survey was carried out in the University of Nigeria.…”

“…For example bulk density, infiltration rate and hydraulic conductivity are directly related and relate to other chemical and biological indicators (Wilson and Maliszewska-Kordybach, 1997). Organic matter content often relates to aggregate stability and water holding capacity (Asadu, 1996). Of all these indicators, measurement of soil organic matter content is the most important as it relates strongly to loss of soil quality assessed by measurement of physical and chemical properties, in addition to threats of a more direct biological nature, such as reduced soil microbial activity and reduced biological diversity (Wilson and Maliszewska-Kordybach, 1997).…”

“…However, to avoid possible errors inherent in two-point data analysis such as presented above, the study also examined the trends in selected key indicators of soil fertility (bulk density, percentage organic matter and percentage nitrogen) in the study area since the introduction of irrigation, using data collated from relevant databases and studies (WADSCO, 1981;Asadu, 1996;Asadu et al, 1997;Urama, 1999;Urama, 2003). The results of the analysis of trend in bulk density of soils of the irrigated and rain-fed farms are presented in Fig.…”