application rates and timing
Using this information in Nitrogen nutrition of crops
exploiting the products
Compost that has been produced from passing through the three stages outlined can be used for:
Using this compost as a summer or autumn mulch will both feed and enliven your soil. It will help to suppress weeds and will aid in moisture conservation. With regular applications the soil will respond and consume ever larger quantities. If the chemical composition is known then it is possible to calculate the medium and long-term benefits of the compost and to integrate this into fertiliser programmes.
Liquid feed can be produced by immersing compost in a greater volume of water, giving it a good mix, leaving it for a day and draining the liquid off. Used undiluted as a general feed this rather crude but effective method will extract a reasonable proportion of the soluble nutrient content. Unfortunately without detailed information it is impossible to calculate the precise nutrient content of the material and even if this is known it may not reflect the soluble content. Add to this the influence of the pH, temperature, dissolution rates, etc, etc, and any attempt to give averages are more likely to mislead than inform.
Within the literature there is much said and many conflicting results about the bio-control properties of compost. Whilst some composts have been shown to have pathogen suppressing properties, others have been shown to be disease conducive. Such a case can only come about if the conditions or materials under consideration are not consistent. One of the problems with studies into the bio-control properties of compost is that we cannot decide what compost is. As a consequence insufficient consideration is often given to the origin, processing or the age of the material. The evidence suggests that this property is an expression of the activities of specific groups at specific stages of the process and that different properties exercise control over different organism. The effect is dependent on the right control or combination of organisms being present. Precisely how this suppression works is unknown but it has been proposed that it is as a result of either one or a combination of :
Antibiosis (suppression as a result of antibiotic action)
Induced systemic resistance (ISR) (Induction of a host defence mechanism by a non parasitic organism in the absence or in advance of a specific attack from a parasitic organism) (Lievens, Vaes et al. 2001).
Free Cultural Works (CC-BY-NC-SA) Malcolm McEwen 2011