Adenosine Triphosphate

A phosphorus containing compound which stores energy (and which is created in the light dependent (first) stage of photosynthesis) and transports it to where metabolic activity is taking place. There are three component parts to this compound: Adenine (which is a nitrogen base), ribose sugar (a carbohydrate), and a chain of three-phosphate groups. It is often referred to as ATP. Energy is released when the bond between one of the phosphate groups (the outer one) is broken. The loss of this group leaves two phosphate groups behind resulting in a new compound called adenosine diphosphate.

  Adhesion

The force of attraction between two different substances. In the transpiration stream process this is a feature of water molecules interacting with the cell wall of the xylem vessel.

  Adjuvant

A substance which is added to a pesticide to improve the effectiveness of the pesticide. Examples include to improve the ability to stay on a grass leaf reducing its ability of being washed off by rainfall, or improve its ability to penetrate into, or be taken up by, a plant. An adjuvant is not harmful to the target organism. Water is a ‘medium for a pesticide’ not an adjuvant.

  Adsorption

The attachment, or adhering, of elements such as water or dissolved nutrient molecules, to another surface. Most fertilisers, once dissolved, will have many of their nutrients adsorbed by the surface of clay particles and organic matter as part of the process of cation (and anion) exchange.

  Aerobic [1]

In general terms this is a situation in which oxygen, or air, is present, so a healthy soil is an aerobic one.

  Aerobic [2]

Micro-organisms within the soil which require free oxygen for their survival, these organisms are called aerobes.

  Aerobic [3]

Processes which occur during aerobic conditions, such as decomposition of organic matter, or aerobic respiration, in contrast to anaerobic respiration.

  Aerobic Respiration

A metabolic process that occurs in the presence of oxygen and is essential for plant growth with the conversion of glucose (produced by photosynthesis), via glycolysis, into pyruvic acid. These pyruvate molecules are then transported into the mitochondria as part of the Kerbs cycle (also called the citric acid cycle) resulting in energy (ATP molecules) released for plant growth, as well as carbon dioxide and water vapour being released to the atmosphere. The energy molecules are also used in various biochemical pathways, including the synthesis of proteins, nucleic acids, photosynthesis, a

Continue reading about this

  Aggregation

The coming together of individual parts, for example, the aggregation of soil particles into structural units.

  Aggressive Cut

This is where the cutting edge of a bottom blade is located slightly forward of the central axis of a cylinder, on a cylinder mower. This results in a less upright grass blade being cut at the point of being sheared by the cylinder and bottom blade edge coming together. The nearer the cutting edge of the bottom blade is located vertically beneath the central axis of the cylinder, the less aggressive the cut: The cutting action is being carried out on a more upright grass blade.