Soil temperature varies seasonally and daily which may result from changes in radiant energy and energy changes taking place through the soil surface. It governs the soil physiochemical and biological processes and also influences the interspheric processes of gas exchange between the atmosphere and the soil. Environmental factors affect soil temperature by either controlling the amount of heat supplied to the soil surface and the amount of heat dissipated from the soil surface down the profile. Soil temperature alters the rate of organic matter decomposition and mineralization of different organic materials. It also affects soil water content, its conductivity and availability to plants. The paper introduced soil temperature as a major determinant of the processes that takes place in the soil which are necessary for plant growth.

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The effects of organic mulching material on soil surface evaporation were studied in Abia State. The objective of the study was to compare impact of mulch materials on saturated hydraulic conductivity and surface evaporation. The organic mulch materials were composted and non-composted Calapogonuim, Chromolena and Panicum spp. The design was randomized complete block design (RCBD). Data generated were statistically analysed. Analysis of variance was used to compare the influence of mulch materials on the measured soil properties and significant means were separated using least significant differences at 5% level of probability. Line graph was used to represent the impact of mulch materials on the surface evaporation. Results showed that saturated hydraulic conductivity of the soils increased significantly (P ≤ 0.05) with the application of the mulch materials. Soil applied with non-composted Chromolena spp. mulch material had the highest saturated hydraulic conductivity (73.00 cm hr-1). Soil surface evaporation varied with both composted and non-composted mulch materials at 3rd and 9th day. The volume of soil moisture lost to the atmosphere was lower in non-composted Calapogonuim mulch material compared with the other mulch materials under study (3rd to 9th day, 3.9 to 11.0 cm3 respectively). Composted and non-composted Panicum mulch was observed to be a more efficient physical barrier to prevent the loss of moisture to the atmosphere as compared to other mulch materials studied. From the present study, it was evident that application of mulch reduced the actual evaporation rates in the initial days after irrigation (coinciding with early periods of plant growth). The water was thus conserved and could be used by the crop subsequently during the later period of its growth.

Information about spatial distribution of soil qualities in a given area is a fundamental piece of land surface prerequisites for ecological purposes, agriculture and other land use systems. The utilization of numerical methods to portray soil properties and upgrade objectivity in soil-related decision making, was applied to soil samples collected from soil under the land use systems; excavation site (EX), refuse dump site (RD), forest land (FL), continuously cultivated land (CC) and 4-year bush fallow (4-BF) along Umuahia South LGA of Abia State in south eastern Nigeria. Geostatistical technique was applied to estimate the spatial distribution and produce soil maps for each selected soil properties. Results revealed that excavation site (1.70 Mg m-3) recorded a high bulk density, while the other land use systems had a moderate bulk density. The results showed that refuse dump site had a neutral soil reaction (7.02), slightly acidic reaction was recorded under 4-year bush fallow (6.00) and forest land (5.71). Continuously cultivated land had a moderately acidic soil reaction (5.41) and organic carbon content (1.48%). The result also revealed that forestland (2.97%) and refuse dump site (3.20%) had very high organic carbon content, while excavation site (0.38%) had very low organic carbon content. This study will help land owners/users in terms of choice and adoption of land for different uses in the area.

An in-depth knowledge on the soil thermal properties under different soil solarization techniques is essential for soil treatment against soil-borne pathogens. This paper presents an investigation on effects of different soil solarization materials on soil thermal properties, organic matter and aggregate stability under field conditions. This study evaluates three materials: translucent whitish plastic (TWP), transparent nylon (TN) and black nylon (BN) each at three thickness levels (0.05, 0.10 and 0.15 mm) and control (bare soil). The parameters investigated in this study included soil temperature, organic matter, bulk density, volumetric moisture content, thermal conductivity, volumetric heat capacity, heat flux, thermal diffusivity and thermal effusivity. The results showed that the soil solarization materials varying in thickness influenced the soil heat energy transfer and had a significant effect on soil bulk density and volumetric moisture content. The results revealed that transparent nylon at a thickness of 0.05 mm recorded the highest soil temperature (62 o C) and was significantly higher than black nylon at a thickness of 0.15 mm (44 o C) and the bare soil (41 o C). Transparent nylon at a thickness of 0.05 mm also recorded the highest organic matter content (19.60 g kg -1 ). The bulk density of the bare soil (1.57 Mg m -3 ) was significantly higher than the bulk densities of soils covered with solarization materials. Transparent nylon at thickness of 0.05 mm had the highest volumetric moisture content (0.116 m 3 m -3 ) while translucent whitish plastic at a thickness of 0.15 mm recorded the lowest (0.401 m 3 m -3 ). Transparent nylon at a thickness of 0.05 mm transmitted the highest quantity of heat through a unit length of soil per unit cross-sectional area (2.50 W mk -1 ). The variation in volumetric heat capacity between the solarization materials was highly noted in transparent nylon (TN) at a thickness of 0.05 mm (2.65 J (m 3 K) -1 ) and less in bare soil (control) with a value of (1.65 J (m 3 K) -1 ). Transparent nylon with thickness of 0.05 mm transferred the highest heat per unit area of soil (42338.25 W.m -2 ), while bare soil transferred the lowest. The highest thermal diffusivity (1.35 m 2 s -1 ) was recorded in the soil with no solarization material. The soil under transparent nylon with thickness of 0.05 mm recorded the highest exchange of thermal energy (2.57 Jm -2 K -1 S -1/2 ) with the environment and was significantly higher than other solarization materials. The transparent nylon had the highest soil macro aggregate stability. This study will help farmers in terms of choice and adoption of affordable conservation methods in treating the soil against soil-borne pathogens.