Saran's Learn Microbiology

  CHEMICAL CHARACTERISTICS OF SOIL 1. Macroelements in Soil ·        Macroelements are the most important nutrients for plants. ·        Macroelements occur naturally in the soil to some extent and can be supplemented with fertilizers, manure and compost. ·        Macroelements are Calcium (Ca), Magnesium (Mg), Potassium (K), Sulphur (S), Phosphate (P), Nitrogen (N) and Sodium (Na). 2. Microelements in Soil ·        Trace elements are nutrients that plants need in small doses. ·        The trace elements are Boron (B), Copper (Cu), Manganese (Mn), Cobalt (Co), Silicon (Si), Zinc (Zn), Iron (Fe) and Molybdenum (Mo). ·        Signs of shortage occur when the disappearance of trace elements through the crops is not compensated adequately with supplements by means of fertilizer, manure or compost, or when the availability of certain elements is limited by the pH or mineral imbalance in the soil. ·        Crop analyses can help to trace an acute shortage and to solve it at plant level.   3.

  PHYSICAL CHARACTERISTICS OF SOIL 1. Soil Texture ·        Non-technically, Soil texture is defined as “How the soil feels to the touch”. ·        Technically, Soil texture is defined as “The proportions of sand, silt and clay in the soil”. ·        Soil texture refers to the proportion of the soil “separates” that make up the mineral component of soil. These separates are called Sand, Silt and Clay. a)     Sand ü   Sand particles are the largest in the soil, ranging in size from 0.05 mm to 2.00 mm. ü   Soil with high sand content feels gritty and doesn’t hold well in a ball. ü   Sand particles are highly inactive and play less role in Physicochemical activities but when coated with clay, the sand particles take very active part in chemical reactions. b)     Slit ü   Silt particles are moderate size particles and range from 0.002 mm to 0.05 mm. ü   Silt, when wet, feels plastic but in dry state feels like flour or talcum. ü   Silt soil has got larger exposed su