Humus is decomposed vegetable and animal material. It is capable of holding large amounts of moisture and plant nutrients which, makes the soil good plant life.  High readings indicate soils that are preferable for agricultural and green house plants.

Calcium is a main component of plant cell walls.  High levels maintain optimum pH levels by neutralizing acids.  Low levels in clay or organic soils indicate calcium has been replace by hydrogen or other ions increasing alkaline or acidic soil levels.

Magnesium  atoms are incorporated into each chlorophyll molecule of all greenhouse plants.  Photosynthesis is dependent on the magnesium to make the chlorophyll molecules complete.  Low levels also result in higher acidity.

Sulfur is important to various aspects of plant metabolism, especially protein formation and the production of chlorophyll.  Ions of sulfur are easily leached in alkaline soils.  Deficient soils result in pale green leaves with thin reedy stems.

Aluminum in high amounts is poor for plant growth because it leads to soil acidity. Acidic soil is bad for plants because it kills the microorganisms that provide nitrogen for the soil that plants need to oxygen.

Chlorides in high amounts will poison plants although, small amounts of chlorine are beneficial for growing plants.

Acidic soils contain high amounts of iron. A soil may be abundant in iron but only soluble iron can be used by plants. Ferric iron is a test to determine the soluble iron in the soil. Too much iron is toxic and too little results in chlorosis.

Nitrate Nitrogen is produced from the decomposition of organic matter.  It is an important factor in amino acids, nucleic acids, enzymes, vitamins, and chlorophyll.  Excess nitrogen can have a very negative effect on plant growth.  It is found in small amounts in well drained and aerated soils.  Excessive nitrites are toxic to plants.  High nitrite readings may be encountered in soils with large amounts of nitrates.

Potassium is a basic meal present in most soils.  Usually sandy soils have little potassium present.  It enhances disease resistance, activates enzymes, strengthens the cuticle and chlorophyll.

Phosphorus when not present retards growth and lowers tone and vigor.  The phosphorus is necessary for the growth of the plant because it encourages root strength, and increases resistance to disease.  An excess of phosphorus has no harmful effects on plants.

pH is the level of acidity that can be found in soil.  Plants grow the best in soils with a medium to high pH(alkaline).  If soils became acidic and the soil microbes become reduced.  If the pH becomes too high the micro-nutrients could become threatened.

Ammonia Nitrogen  is expected to be low in fertile soil.  In forest soils ammonia is the most abundant available form of nitrogen.  If there is a satisfactory rate of nitrogen transformation,  the humus layers of a forest soil will produce very high concentrations of ammonia nitrogen.

Manganese is an essential element in the enzyme system of plants, manganese plays a role in metabolic reactions affecting germination, photosynthesis, and other vital aspects of plant development.  Any positive test reading, even a very low reading, generally indicates the presence of sufficient available manganese to meet plant requirements.