Asian Soil Research Journal

A field experiment was conducted in 2015 and 2016 to evaluate the effects of in-situ moisture conservation using tied-ridging and conventional flatbed tillage practices combined with five sulfur fertilizer rates (0, 10, 20, 30 and 40 kg ha^-1). The experiment was lied out in a split plot design with three replications under rain-fed conditions. A newly released improved variety of sesame“Setit 1” was used as a test crop. Most of the agronomic data were collected at harvest. The collected data were analyzed using GenStat16 EdSP. The marginal rate of return was also estimated from the total revenue and total variable cost. Results show that there was a significant (P < 0.05) difference due to the combined effects of tied ridges and sulfur fertilizer rates on grain yield, days to 90% maturity, number of branches per plant, plant height, and number of capsules per plant except the days to 50% flowering in 2015. But, in 2016 there was no significant (P > 0.05) difference by the combined effect. The highest grain yield of 889.3 kg ha^-1 as well as the corresponding highest net revenue of 14,239.4 Ethiopian Birr was recorded at 40 kg S ha^-1 under tied ridges, but this was statistically not significant (P > 0.05) with the grain yield of 857.6 kg ha^-1obtained using 30 kg S ha^-1combined with tied ridges in 2015. However, in 2016 the significant difference resulted were due sulfur fertilizer but not due to the combined effect of tillage practices and sulfur fertilizer, hence calculating partial budget analysis is not necessary for statistically non-significant results. Therefore, sulfur fertilizer rate at 30 kg ha^-1combined with tied ridges is most economically feasible technologies for the farmers to increase sesame productivity at Kafta Humera district.

The experiment was conducted to assess the influence of grass mulch on some soil physical attributes of a luvisol and water requirement of cowpea in the transition zone of Ghana at the University of Education, Winneba, Mampong campus. A Randomized Complete Block Design (RCBD) was used. The grass mulch rates were; 1 t ha^-1, 3 t ha^-1, 5 t ha^-1 and control (no mulch) with four replications. The grass mulch was applied evenly on the soil surface under a cultivated cowpea. Parameters assessed were soil aggregate stability, bulk density, soil porosity, soil gravimetric and volumetric moisture contents, cumulative infiltration, sorptivity, organic matter content and cowpea seed yield. The study showed that mulching improved cowpea seed yield, soil gravimetric moisture content, soil volumetric moisture content, cumulative infiltration amount, infiltration rate, sorptivity and soil residual moisture. The soil physical parameters measured in both the minor and major seasons were higher on the 5 t ha^-1 plots but lower on the control (no mulch) plots. There was a significant (P = .05, r = 0.61) positive correlation between the cowpea seed yield and soil gravimetric moisture content. Estimation of water requirement of cowpea using the Blaney-Criddle method produced higher values in 2010 (629.70 mm season^-1), 2011 (619.60 mm season^-1) than the field graphical estimated values in 2010 (399.00 mm season^-1), 2011 (357.0 mm season^-1) and improvised evaporation pan values in 2010 (347.90 mm season^-1), 2011 (136.11 mm season^-1) seasons Although cowpea is tolerant to water deficit to some extent, the use of 5 t ha^-1 mulch for sustainable soil moisture management would be important in areas of erratic and inadequate rainfall.

The sustainable soil management necessary to maintain soil quality depends on the understanding of how the soil responds to agricultural practices over time. This paper reports the changes in physicochemical properties that resulted from different cropping systems on a soil in Ado Ekiti, Nigeria. Soil samples were collected from sole maize plot (1.0 ha), sole cowpea plot (1.0ha) and cassava/maize intercrop plot (0.6ha) on a land that was previously under fallow. The sand, silt and clay contents of the soil and some selected chemical parameters varied considerably within the study area (different cropping zones). The soil was generally sandy loam and was found to vary from slightly acidic to slightly alkaline and generally low in Soil Organic Matter (SOM) and Available P (Av. P) with no salinity problem. High magnitude of variability was observed for Electrical Conductivity (EC), Av. P and SOM while pH had the least magnitude. A geostatistical evaluation of the soil chemical properties showed moderate to strong spatial dependence. The geospatial maps clearly revealed the heterogeneity of the soil chemical properties across the field. Both classical statistics and geo-statistical analyses of the soil of the area provided a better understanding of the spatial variability of soil chemical properties and the influence that such could have on crop performance. The results indicated that the soil pH is slightly acidic and contained low amounts of both SOM and Av. P. It is suggested that planting of cover crops, minimum tillage and controlled application of phosphate fertilizer should be done so as to increase the SOM, improve Av. P and maintain the soil pH. Further studies should be conducted to include other soil chemical properties such that robust site specific management programme could be effected.

Aims: The study was aimed to determine the edaphic qualities of two Long-Term Ecological Research (LTER) sites in Mindanao; Mt Apo in Cotabato and Mt. Hamiguitan in Davao Oriental, the Philippines

Study Design: Random soil sampling within the plots

Place and Duration of Study: Analyses of the soil samples collected from each site were performed at Soil and Plant Analysis Laboratory (SPAL), Central Mindanao University, Musuan, Bukidnon, the Philippines from October, 2012 to December 2013.

Methodology: One hectare permanent plot was established in each site. Soil profile description was done in a pit measuring 1m wide, 1.5m long and 1m deep in each site. Soil samples for physicochemical characterization were collected within the plot. Soil physical properties included bulk density, particle density, soil texture and water holding capacity while the chemical properties included soil pH, organic matter, extractable P and exchangeable K contents using the methods employed at SPAL.

Results: Results showed that the soils in Mt. Apo were extremely to very strongly acidic, had very high organic matter contents, slightly deficient to very deficient in extractable P, low to very high exchangeable K content, low particle and bulk density values, high porosity, moderate water holding capacity and moderately coarse to moderately fine-textured soils belonging to loamy textural class. On the other hand, the soils in Mt. Hamiguitan were slightly to very strongly acidic, contained adequate organic matter content, low extractable P, low exchangeable K, low particle and bulk density values, high porosity, moderate water holding capacity and are moderately fine to fine-textured belonging to loamy and clay textural classes. Generally, soils in Mt. Apo were more acidic but with relatively higher fertility status and comparable physical make-up with the soils in Mt. Hamiguitan.

Conclusion: It was found that both sites have some soil constraints, particularly in terms of soil acidity and low nutrient availability to plants. Information obtained on this study revealed that identification of soil constraints are indispensable in formulating proper land use and conservation program.

Soil compaction affects soil fertility through increasing bulk density and soil strength. It also decreases infiltration rate, total porosity and amount of water stored in the root zone for crop use. In this study, we evaluated the optimum moisture contents (OMC) in relation to maximum dry density (MDD) and compaction of cultivated and uncultivated soils. The study was carried out on four land use types viz: uncultivated: Velvet tamarind (Dialium quineese), rubber plantation (Hevea brasiliensis) and cultivated: 5-year fallow and 10-year continuous cultivated soil to maize crop. Proctor test for the maximum dry density-moisture content relationship was carried out, including some hydraulic and structural properties of the soil, and their effect soil compaction. Results showed that optimum moisture content (OMC) for compaction relate to the maximum dry density (MDD).  In which case, dry density increased with water content to a maximum and decrease as moisture content increased above the optimum. Soil organic matter (SOM) content and particle size distribution highly affected the MDD and OMC. The MDD and OMC were: 1.92 g cm^-3 and 10.4%, 1.95 g cm^-3 and 11.2%, 1.91 g cm^-3 and 12.3%, and 1.87 g cm^-3 and 12.8% for velvet tamarind, 5-year fallow, CC and rubber plantation soils respectively, at 0-15 cm depth. Changes in field bulk densities at similar depths were in the order of velvet tamarind < rubber < 5-year fallow < CC. There were highly significant (p < 0.01) relationships between MDD, total porosity, Ksat and SOM and negative relationships between these parameters and OMC. Thus, continuous cultivation increased MDD and reduced OMC for compaction. Two- season fallow periods with legume could improve soil hydraulic properties and maintain the MDD of sandy soils at minimum.