The Analysis of Composts

The Analysis of Composts

The term compost has been defined by Zucconi and Bertoldi (1987) as ‘the

stabilized and sanitized product of composting which is beneficial to plant

growth. It has undergone an initial, rapid stage of decomposition and is in

the process of humification.' The initial thermophilic stage of decomposition

is the means of self-sanitizing and removing pathogens. If the compost is insufficiently

humified, it is immature, and the wide C:N ratio causes it to immobilize

soil nitrogen as it continues to actively decompose in the soil. If

sufficiently sanitized and humified, the compost is said to be biomature. The

development of globally accepted criteria for compost specifications is still at

an early stage, so some scientists have proposed biomaturity tests (Mathur et

al., 1993).

Methods on-line

The United States Environmental Protection Agency (EPA) has a website where

physical and chemical test methods for evaluating solid wastes may be downloaded

as pdf files:

http://www.epa.gov/sw-846/main.htm

We understand here by compost a marketed product of an organic based

material derived from a variety of sources. These might be treated municipal

waste, spent mushroom compost, a bracken- or seaweed-based compost, agricultural

and food processing wastes etc., which might be put to agricultural

use. Composts are often very heterogeneous, which makes it difficult to prepare

a sufficiently homogeneous sample. The high humus content makes them

similar to peat soils, where organic matter can exceed 95%, which can affect

not only the analytical method, but also the interpretation of the results in

making fertilizer recommendations.

Typical specifications

Typical parameters and nutrient levels for assessment of compost quality are

shown in Table 5.2. These are combined values from a variety of sources,

including Bertoldi et al. (1987), and are merely intended to help in setting up