Heterotroph

An organism which cannot make its own food (unlike an autotroph) and needs to consume materials (which may be living or dead / decaying organic matter) that have been produced by others. Animals and fungi are common heterotrophs, along with many bacteria species, although there are also many bacteria species which are autotrophs.

  Heterotrophic

The need of an organism for using complex organic compounds that have not been self-produced for healthy growth and development. Fungi are heterotrophic organisms.

  Hide-bound Turf

An old-fashioned term, dating from at least as far back as the 1930s, which means a compacted soil in need of significant and regular aeration work. Turf surfaces in those days would often contain relatively high amounts of clay particles and when dry conditions persisted would often bake and form a hard-capped surface layer.

  Humate

This is dried humic acid, which has become a solidified organic material from drying.

  Humic Acid

The part of humus which is soluble in water. It is typically dark brown to blackish in colour. Humic acid can be extracted, with a solution of sodium hydroxide, from any material containing well-decomposed organic matter, such as compost. This extractant helps to dissolve most of the organic matter. The solution is then acidified to a pH of about 2, which flocculates the organic material from the liquid portion to create humic acid. It is very resistant to any further breakdown. The remainder in solution is fulvic acid.

  Humification

The process of decomposition of organic matter to form humus.

  Humification Coefficient

The ratio of carbon from returned clippings and organic matter which remains in a soil profile at the end of a year. High rates of decomposition result in a low ratio of humification coefficient, which is typically around 0.25 for grass leaves. This can still add up to a significant build-up of organic matter within a turf surface, hence the need for appropriate maintenance practices to reduce any residual build-up.

  Humin

The part of humus which is not soluble in water. It is typically black in colour.

  Humus

Decomposed organic matter which contributes to increased soil nutrient availability and retention in a soil, as well as improved soil structure. It consists of Fulvic acids, Humic acids, and Humin. Humus is also termed Humified Organic Matter. It can also be categorised as Mor, Moder, or Mull.

  Hybrid

A plant resulting from cross-pollination and breeding of two different species or cultivars, with the resultant plant being called an F1 hybrid and these are often sterile plants. The aim is to improve one or more features within a plant. For example, to improve disease resistance, or to improve wear tolerance.