Introduction

Development of four softwares applied in agricultural and environmental sciences Including:  Soil Cation Exchange Capacity Estimator (CEC-App), Soil Bulk Density Estimator (BD-App), Erosion Modeling System (EMS), Land Evaluation System (LES), which have been listed and explained in continue...

1. Soil Cation Exchange Capacity Estimator (CEC-App)

Introduction

The soil cation exchange capacity (CEC) is the total exchangeable cations which may be hold in soil by electrostatic forces at a specific pH level. It is one of the most important chemical characteristics of soil. The CEC influences the stability of soil structure, nutrient availability, nutrient retention capacity, soil pH and the soil's reaction to fertilizers and other ameliorants, as well, it provides a buffer against soil acidification. Usually, heavy clay soils present higher magnitudes of CEC, expressing the higher availability of nutrients in these soils. CEC is usually measured on the fine soil fraction (clay particles lower than 2 mm in size). In coarse textured soils, the effective of soil CEC is diluted, and if only the clay fraction is analyzed, the obtained CEC values will be higher than the actual values of CEC. Measuring CEC includes washing the soil for removing excess salts and using an "index ion" for determining the total positive charge in the original soil mass. This resulted in predetermined pH level of soil before analyzing.

Description...

2. Soil Bulk Density Estimator (BD-App)

Introduction

Soil bulk density (BD) is defined as the dry weight of soil per soil volume (which includes the soil particles as well as the soil pores). It is an important factor in land drainage and reclamation because it is an indicator of drainage characteristics and determines whether there are impermeable barriers in the soil, which can deteriorate the drainage and root penetration conditions. In irrigation scheduling, BD can be utilized to estimate the soil volumetric water content which is an important parameter for controlling optimum irrigation. BD is also an essential factor for assessing soil carbon and nutrient stock, determining pollutant mass balance in soil, and determining the soils' packing structure in soil classification issues. It also affects the soil biomass productivity and environment quality. Bulk density reflects the soil's ability to function for structural support, water and solute movement, and soil aeration. Bulk density is also used to convert between weight and volume of soil. It is used to express soil physical, chemical and biological measurements on a volumetric basis for soil quality assessment and comparisons between management systems.

Description...

3. Erosion Modeling System (EMS)

Introduction

Soil erosion is a global threat to the natural resources and is particularly responsible for reduction in crop yield due to reduction in land productivity and storage capacity of multipurpose reservoirs due to continuous siltation. Accelerated soil erosion has adverse economic and ecological impacts. Estimating soil losses, sediment production and the assessment of the risk of soil erosion can be helpful for land evaluation in the region where soil erosion is the major threat to sustained agriculture, as the soil is the basis of agricultural production. Erosion models are used to predict soil erosion. Soil erosion modeling can consider many of the complex interactions that influence rates of erosion by simulating erosion processes in the watershed. Most of these models need information related to soil type, land use, landform, climate and topography to estimate soil loss. The models which have been introduced in the Soil Erosion Estimator (SEE) software includes:

• USLE (Universal Soil loss Equation model)
• MUSLE (Modified Universal Soil Loss Equation)
• EPM (Erosion Potential Method)
• PSIAC (Pacific Southwest Inter Agency Committee)
• WEPP (Water Erosion Prediction Project)
• FAO (Erosion Risk Evaluation)

Description...

4. Parametric Land Evaluation System (PLES)

Introduction:

Making effective decisions regarding agricultural land suitability problems are vital to achieve optimum land productivity and to ensure environmental sustainability (Kurtener et al., 2004). Land evaluation procedures focus increasingly on the use of quantitative procedures to enhance the qualitative interpretation of land resource surveys. Crucial to the estimation of land suitability is the matching of land characteristics with the requirements of envisaged land utilization types. Land evaluation results from a complex interaction of physical, chemical and bioclimatic processes and evaluation models are reliable enough to predict accurately the behavior of land (Held et al., 2003; Ball and De la Rosa, 2006). Land evaluation is carried out to estimate the suitability of land for a specific use such as arable farming or irrigated agriculture. Land evaluation can be carried out on the basis of biophysical parameters and/or socio-economic conditions of an area (FAO, 1976). Biophysical factors tend to remain stable, whereas socio-economic factors that are affected by social, economic and political performances (Dent and Young, 1981; Triantafilis et al., 2001). Thus, physical land suitability evaluation is a prerequisite for land-use planning and development (Sys, 1985; Van Ranst et al., 1996). It provides information on the constraints and opportunities for the use of the land and therefore guides decisions on optimal utilization of land resources (FAO, 1984). The FAO (1976) provided a general framework for land suitability classification. In this framework, doesn't have been proposed a specific method for doing this classification. In later years, the collection of methods was presented based on the above framework (FAO 1984, 2007). From the variation of these methods can be pointed to parametric approaches. A qualitative land evaluation considers two key elements, the soil qualities/characteristics, and the crop soil and climate requirements (FAO, 1976). The latter refers to "a set of land characteristics that can determine the production and management conditions of a kind of land use". The outcome of the suitability assessment for a particular crop which is the final result of a land assessment depends on whether the land characteristics match with the crop requirements. In parametric method, a quantitative classification is allocated to each characteristic of land. If a characteristic of land for a specific crop is completely desired and provide optimum conditions for that, maximum degree of 100 would give to that characteristic and if it has limitation, the lower degrees between 0 to 100 will be given to it. Then the obtained values for each land quality/characteristics are combined by a formula to allocate the land suitability index value to each study point. In parametric approach different classes of land suitability are defined as completely separate and discrete groups and are separated from each other by distinguished and consistent range. The methodology adopted based on FAO guidelines on land evaluation involves most aspects of climatic requirements (the maximum, minimum and the average of temperature and precipitation during various phenological stages of the plant growth), land terrains (elevation levels, slope degree and aspect, drainage condition and erosion hazard) and soil quality/characteristics (soil physical, chemical and fertility properties such as soil texture, soil depth, coarse fragments, calcium carbonate and gypsum percent, the percent of organic carbon, soil reaction (pH), apparent cation exchange capacity (CEC_app), total equivalent bases (TEB), soil salinity (EC_e) and alkalinity (ESP)) (Sys et al., 1991a, 1991b, 1993).

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