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Articles by S.T. Abu
Total Records ( 3 ) for S.T. Abu
  S.T. Abu and W.B. Malgwi
  Quantification of soil physical and chemical properties and estimation of their associated variability are essential for making site-specific decisions on soil and crop management practices. This study was conducted with the aim of determining the degree of spatial variability and variance structure of soil physical and chemical properties on about 20 ha in Kadawa Irrigation Scheme in Kano state, Nigeria, to observe changes in the variance structure caused by irrigation and to suggest future sampling designs for efficient management decisions. Forty eight soil samples were collected at 0-30 cm depth at a distance of 50 m intervals using Geographical Positioning System (GPS). The software package GS+ was used to model the variance structure of sand, silt, clay, soil bulk density, saturated hydraulic conductivity (Ks), Organic Carbon (OC), Total Nitrogen (TN), Available Phosphorus (AP), Cation Exchange Capacity (CEC), exchangeable bases, pH, Electrical Conductivity (EC), Exchangeable Sodium Percentage (ESP) and Sodium Adsorption Ratio (SAR). Results obtained revealed that the coefficient of variation ranged from 3.2% (bulk density) to 156% (exchangeable K). The semivariograms showed that the range of spatial dependence varied from 26 m (AP) to 911 m (exchangeable Na) for all measured soil properties. Cross-semivariograms showed that the particle size classes and soil hydraulic properties were spatially correlated; therefore, kriging or cokriging can be used to estimate hydraulic properties from available texture data. Correlograms with Moran’s I indicated that a distance of 391 m was adequate to generate independent samples for measured soil physical and chemical properties. The kriged contour maps showed positional similarities. These contour maps of soil properties, along with their spatial structures, can be used in making better future sampling designs and management decisions.
  W.B. Malgwi and S.T. Abu
  Physical properties of soils formed on a hilly terrain were investigated in three identified landscape positions (upper, middle and lower positions) under two land use types (Fallowed and Cultivated land). Three soil profile pits were dug randomly in each landscape position, described and samples were taken from each horizon for laboratory analysis. SAS 8.2 and SPSS 16.0 were used to analize data. Mostely in detail showed significant differences in soil properties among the land use types, landscape positions (except in clay dispersion index) and pedons. Fallowed compared to continuously cultivated land got significantly higher values of silt and clay, organic carbon, aggregate stability indices, pore size classes and water retention capacities. Significantly (p<0.0001) higher sand fraction, macroaggregate stability, BD and lower water retention capacities were recorded at the upper landscape position compared to the other positions. The lower landscape position compared to the other positions got significantly (p<0.0001) higher silt and clay fractions, microaggregate stability indices, porosity, OC and water retention characteristics. The epipedons compared to the endopedons of the soils had significantly (p<0.0001) higher organic carbon, aggregate stability indices, pore size classe and moisture retention at various capacities. Of the three factors, the distribution of pore size classes (except macroporosity), BD and water retained at various capacities were to a greater extent influenced by changes in landscape positions whereas the distribution of OC and aggregate stability of the soils were more dependant on changes in land use.
  S.T. Abu and W.B. Malgwi
  Strategies to improve water use efficiency of irrigated crops are among others deficit irrigation, precision irrigation technologies soil and water conservation practices. The study evaluates the effects of deficit irrigation regime and interval on soil chemical properties and performance of paddy rice in Sudan Savanna agroecosystem. The treatments include water application depths of 100, 85, 70, 55 and 40% of Total Available Water (TAW) capacity and 4, 8, 12 and 16 days irrigation intervals. Water was conveyed from field ditches into each basin through a pair of polyvinyl chloride pipes using surface irrigation method. Routine methods of chemical analysis were employed. Results showed that the highest organic carbon was recorded in treatments irrigated with water depth of 85% TAW at 4 days interval. Significantly higher total nitrogen, cation exchange capacity, sodium, pH (H2O) and pH (CaCl2), exchangeable sodium percentage and sodium adsorption ratio were recorded with TAW and 4 days interval treatments. Treatments irrigated at 40% TAW and 16 days interval got higher available P, Ca, Mg and potassium as well as base saturation. Treatments with 85% TAW (4772.0 kg ha-1) and 8 days interval (4442.3 kg ha-1) gave the highest yield. Based on stepwise regression analysis, potassium, organic carbon and cation exchange capacity were the major determinants of the yield. Hence, sustainable utilization of such land under irrigation requires regular application of organic matter and 85% of total available water at 8 days interval for more efficient use of irrigation water and acquisition of high paddy rice yield.
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