System analysis of ³⁵sulphur kinetics in pastures grazed by sheep.

Abstract

A mathematical model representing the S cycle in a grazed pasture was programmed on to an analogue computer to simulate the results of a field experiment in which observations were made on the incorporation of radioactivity into wool following a single application of [³⁵S] gypsum to pasture. The results showed that the specific activity of wool was consistent with a closed-system recycling process involving c 60% of the total S in the system, and that up to 90% of the cycling S was probably held in organic residues in forms not directly available to plants.

Key words

• analysis
• cycling
• gypsum
• incorporation
• kinetics
• mathematical models
• pastures
• radioactivity
• recycling
• residues
• wool