Decomposition of soil organic matter by microorganisms is a major process governing the carbon balance between soil and atmosphere which needs to be fully understood. Extracellular enzyme activity is often the limiting factor for microbial utilization of soil organic matter. Contrary to expectations, we observed that enzymatic activity rises at increasing temperatures in soils and sediments. Current climatic change will induce the increase of global mean temperatures, frequency of extreme heat events and soil temperatures during the next decades. The relevance of the increase in activity at high temperature is dependent on Latitude. At Latitudes around and below 40° a significant number of days per year present high temperatures. Results suggest that the hydrolytic activity of microbial extracellular enzymes is currently underestimated mainly at medium and low Latitudes where soil temperatures frequently reach high values (often above 40oC). This report contributes to understand (1) the hydrolysis of soil organic matter within a Latitude-dependent scenario of global warming and (2) the role of microorganisms in processing soil organic matter and their influence in carbon cycling.

This work optimises the collection of solar energy within the period of its availability in order to increase its utilisation and also to enhance performance of heating systems that depend on it through appropriate determination of optimum solar collector tilt angles. Buoyancy-induced flow equation in solar collector pipe was established by continuity, energy and Navier–Stokes equations in cylindrical coordinates. Fundamental solar radiation equations were programmed to determine optimum tilt angles in locations within Latitudes 1o and 14o. A set of data recorded from a pryanometer located on Latitude 6.45o north of the equator was used to generate average monthly radiation over the Latitudes. Graphs obtained from Latitude 6o and 13o data were analysed to investigate solar radiation on some tilt angles. The optimum tilt angles for solar heating for periodic tracking of the sun in the region within Latitudes 1° and 14° were predicted as Æ+25° for November, December and January, Æ+15o for February, September and October, Æ-15o for August, Æ-25o for May, June and July, and Æ for March and April. The results of this work confirmed that solar radiation on tilted surface increases with Latitude.

In this paper, the solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers were assessed. The KT solar radiation model was coded in the MATLAB-based environment to compute the monthly solar radiation values. Seven-year data of monthly average daily solar radiation on a horizontal surface in Bangi, Malaysia (Latitude=3oN) were adopted as input in the simulation programme and the results were compared with the local optimum tilt angle at solar noon and other solar radiation model. The contour mappings of solar irradiation at various orientations in 12 months were presented.Results showed that the surface tilted £20o could intercept a relatively high solar intensity, which was less sensitive to the variation of azimuths with average solar insolation deviation of 11.82%. The monthly optimum tilt angle altered throughout the year, ranging from -24o (in equator direction) to +22o (in north direction). The estimated annual optimum slope, 1.4o facing to the equator, was close to local Latitude. Based on the seasonal analysis, the northfacing surface was able to intercept higher daily average solar radiation energy compared to south-facing plane. The optimum angles for seasonal south- and north-facing surfaces were found to be 14.4o and 14.8o, respectively, with a tolerable slope deviation of ±5o from the optimal values in the present work.

Temperature is a key factor in yield, crop water requirement, and then virtual water content of various agricultural products. Therefore, it is necessary to investigate the effect of Latitude as one of the most effective factors on the average temperature and consequently on the variation of virtual water of agricultural products, considering the major share of this sector in water consumption (about 90%). In this research, the virtual water content of nine major plants including wheat, barley, alfalfa, sugar beet, corn, watermelon, tomato, onion and potato in four eastern provinces (including 56 cities) of Iran was calculated based on 20-year statistical data. Then, the average virtual water of each plant was calculated in different Latitudes from to N at intervals using ArcGIS software. The regression between the average virtual water with crop water requirement and yield of the products revealed a positive correlation between virtual water and crop water requirement (r=0. 65) and a negative correlation between virtual water and yield (r=-0. 74). The average virtual water from the lowest to the highest was 0. 19, 0. 38, 0. 45, 0. 46, 0. 53, 0. 57, 1. 59, 1. 69, and 1. 80 thousand cubic meters per ton for corn, sugar beet, onion, watermelon, tomato, potato, alfalfa, barley, and wheat, respectively. The results showed that the variation pattern of virtual water of the studied products across different Latitude was Gaussian. Despite the different maximum values of virtual water, they occurred in the Latitude range of to N and by moving away from the mentioned range to higher or lower Latitude, the virtual water content of all products decreases. The results of the present study can be used in national plans for agricultural land-use planning and agro-climate zoning.

In this paper, the solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers were assessed. The KT solar radiation model was coded in the MATLAB-based environment to compute the monthly solar radiation values. Seven years data of monthly average daily solar radiation on a horizontal surface in Bangi, Malaysia (Latitude=3oN) was adopted as input in the simulation programme, and the results were compared with the local optimum tilt angle at solar noon and other solar radiation model. The contour mappings of solar irradiation at various orientations in 12 months were presented. Results showed that the surface tilted at£20o could intercept a relatively high solar intensity, which was less sensitive to the variation of azimuths with average insolation deviation of 11.82%. The monthly optimum tilt angle altered throughout the year, ranging from-24o (in equator direction) to+22o (in north direction). The estimated annual optimum slope, 1.4o facing to the equator, was close to local Latitude. Based on the seasonal analysis, the north-facing surface was able to intercept higher daily average solar radiation energy compared to south-facing plane. The optimum angles for seasonal south- and north-facing surfaces were found to be 14.4o and 14.8o, respectively, with a tolerable slope deviation of ±5o from the optimal values in the present work.