We undertake reviews of existing data and conduct a desktop assessment

We undertake reviews of existing data and conduct a desktop assessment. As part of the assessment, baseline soil information will be obtained from the South African land type data published with maps at a scale of 1:250 000 by the Institute for Soil, Climate and Water (ISCW) of the Agricultural Research Council (ARC). The soil survey will determine the soil type and properties (position in landscape, soil depth, texture, structure and underlying material) as well as the current land capability. The soil forms will be identified using the South African Soil Classification System namely; Soil Classification: A Taxonomic System for South Africa (Soil Classification Working Group, 1991). Representative soil samples will be taken at each of the predetermined focus areas. Survey positions will be recorded and mapped. A hand soil auger will be used to confirm the soil types and depths. The soil will be augured to the first restricting layer or a 2.0 m depth. The process of land capability (Agricultural Potential) classification is the grouping of specific areas of land in terms of their suitability for a defined land use. Soils will be classified for land suitability based on soil form, depth and drainage. A map delineating the various land suitability areas will be produced to provide a visual representation of the most suitable areas for crop production and animal production. Land capability will be determined by assessing a combination of soil, terrain and climatic features, as well as observations during the site survey. Land capability is defined by the most long-term sustainable land use under rain-fed conditions. The land will be rated into eight classes which include groups of capability units or subgroups that have the same relative degree of limitation or potential. This will involve the collation of all information, including desktop, statistical analysis of historic data (where available) and field survey findings. This information will be used to determine the Agricultural Potential and develop associated maps describing the findings.

The soil analysis reports will include the measurement, benchmarking and amelioration requirement of key soil variables like:

• Soil texture (silt, sand and clay percentage) is an important soil characteristic that influences the drainage, water holding capacity, aeration, susceptibility of soil to erosion, organic matter content, Cation Exchange Capacity (CEC) and pH buffering capacity. Well drained soils typically have good soil aeration, which is conductive to healthy root growth and thus a healthy crop with high agricultural potential. Five samples will be taken for the affected area.
• Standard soil analysis (pH, Phosphorus (P), Potassium (K), Sodium (Na), Calcium (Ca), Magnesium (Mg), exchangeable acidity, acid saturation, cation exchange capacity (CEC), Carbon (C) and Sulphur (S). A suitable sampling grid will be determined for area to be surveyed and sampled.
• Soil pH is a master variable in soil, because it controls many chemical and bio-chemical processes operating in the soil. Soil pH regulates plant nutrient availability by controlling the different forms of different essential nutrients and influences their chemical reactions. As a result, soil and crop, pasture and veld productivities are intricately linked to the soil pH value.
•  P has many important roles in agricultural, pasture and crop production and is involved with many metabolic functions. P plays in important role in energy reactions, like photosynthesis and respiration and for the general health and vigor of plants. P also plays a vital role in plant reproduction. Adequate P results in increased root growth, greater stem or stalk lengths, improved crop, pasture and veld qualities, more uniform and earlier crop, pasture and veld maturity and ultimately higher biomass production.

• Sekela Impilo Services (SES)  monitor Na levels in the soil to determine if there is a specific ion toxicity, to check if nutrient deficiencies and balances are present. High Na levels decreases the plant intake of Nitrogen (N), P, Ca, Mg, and Iron (Fe). High Na and salt levels result in reduced production, which affects both the yield and quality of the produce produced. 

• Ca, Mg and S are essential plant nutrients for crop, veld and pasture production. They are called secondary macro-nutrients, because plants require them in smaller amounts than the primary macro-nutrients, which are N, P and K. Ca and Mg both increases soil pH, but S generally decreases soil pH.  Ca is an integral part of the plant cell wall and cell walls can collapse and not remain upright if Ca is lacking in the soil and/or plant. Ca helps improve the absorption of other nutrients by roots and their translocation in plants and it can help improve disease resistance in plants. Ca improves soil structure and thereby increasing water penetration and providing a more favorable soil environment for growth of plant roots and micro-organisms. Mg is a component of the chlorophyll molecule and is essential for photosynthesis and is a major carrier in plants. If a soil has a Mg shortage, it will result in poor uptake of the macro-element P. Mg is essential for phosphate metabolism, plant respiration, and the activation of enzyme systems in plants. Some crops and plants require a greater amount of S because it is a high dry matter production crop. S is essential for protein synthesis, chlorophyll development and photosynthesis. S deficiencies are often caused by N deficiency.

• N is one of the most important and primary nutrients required for growth and development of the crop, veld and pasture production. N is a major component of amino acids, which function as the building blocks of proteins in the plant. N plays a major role in all plants is as it a major component of chlorophyll, the green pigment in plants, that is critical for photosynthesis and production. Adequate N allow the plants to reach its genetic yield potential and production potential.

• Electrical conductivity (EC) is a measure of the amounts of salts in the soil. It is an important indicator of soil health. EC affects the crop, pasture and veld yields, crop, veld and pasture suitability, plant nutrient availability, and the activity soil micro-organisms, which influences key soil processes. High EC values will result in hindered plant growth by negatively affecting the soil water balance. A suitable sampling grid will be determined for area to be surveyed and sampled.
• Ohm Resistance is a measure of the salinity of the soil. The higher the resistance, the less salts are present in the soil and vice versa. A suitable sampling grid will be determined for area to be surveyed and sampled.

Carbon (C ) and soil organic material significantly improves the soil capacity to store and supply essential nutrients like Nitrogen (N), P, K, Calcium (Ca) and Magnesium (Mg) and helps the soil to retain toxic elements so that they are not leached into the ground water and root zone. Its critical sticky components play a vital role in the formation of soil aggregates which give soil its stability against weathering and erosion, and its ability to hold water and air essential for plants and microbes.

Potassium (K) is an essential macro-element for plant and animal growth. Adequate levels of soil K enables pastures to better withstand stress from drought, diseases, insects and winter damage. K is important because it can increase root growth and development, maintains plants maintain turgidity, reduces water loss and wilting, aids in photosynthesis and food formation, reduces respiration, preventing energy losses, enhances translocation of sugars and starch, produces grain rich in starch, increases plants’ protein content and builds cellulose and reduces lodging.

Micro- or trace elements are essential plant nutrient elements, but that are only required by plants in small trace amounts for healthy growth. There are 7 essential plant nutrient elements defined as micronutrients Boron (B), Zinc (Zn), Manganese (Mn), Iron (Fe), Copper (Cu), Molybdenum (Mo) and chlorine (Cl). B is used with Calcium (Ca) in cell wall synthesis and is essential for cell division (creating new plant cells).

B requirements are much higher for reproductive growth, so it helps with pollination, fruit and seed development. Other functions include translocation of sugars and carbohydrates, nitrogen metabolism, formation of certain proteins, regulation of hormone levels and transportation of potassium to stomata (which helps regulate internal water balance). Since B helps transport sugars, its deficiency causes a reduction of exudates and sugars from plant roots, which can reduce the attraction and colonization of mycorrhizal fungi.

The function of Zn is to help the plant produce chlorophyll. Leaves discolor when the soil is deficient in Zn and plant growth is stunted. Zn deficiency causes a type of leaf discoloration called chlorosis, which causes the tissue between the veins to turn yellow while the veins remain green.

Mn is used in plants as a major contributor to various biological systems including photosynthesis, respiration, and nitrogen assimilation. Mn is also involved in pollen germination, pollen tube growth, root cell elongation and resistance to root pathogens.

Fe is involved when a plant produces chlorophyll, which gives the plant O₂ as well as its healthy green color. Fe is also necessary for some enzyme functions in many plants. Soil that is alkaline and/or has had too much lime added often causes an iron deficiency in the plants in the area.

Cu facilitates respiration and photosynthesis and is important for plant metabolism. It is a component of a variety of enzymes and plant cell walls, so it is important for plant strength.

Mo is important for both plants and animals. In plant growth, it helps in the N, O² and S cycles. The element is crucial to the functions of nitrogenase and nitrate reductase, two enzymes important for N fixing and N reduction.

Cl occurs predominantly as Cl^-1 in soil and plant. Its functions in plant growth and development include osmotic and stomatal regulation, evolution of O² in photosynthesis, and disease resistance and tolerance.

Cation Exchange Capacity (CEC) is a measure of how many cations can be retained on the soil particle surface and is negatively charged. These negative charges bind to positively charge atoms or molecules but allow these to exchange with other positively charge particles in the surrounding soil water. CEC and soil texture are intimately related. Soils with large soil particles are coarse textured (e.g., sandy soils) and have high rates of aeration, water and nutrient infiltration, but have a low CEC and nutrient and water holding capacity. However, soils with small soil particles are fine-textures (e.g., clayey soils) and can be anaerobic due to low rates of aeration, water and nutrient inflation, but have a high CEC and nutrient and water holding capacity