Soil biological health - what is it and how can we improve it?

SOIL BIOLOGICAL HEALTH is a topic of great interest to sugarcane growers, although there is confusion as to what constitutes soil health. Many growers and consultants are unaware that beneficial organisms, rather than pathogens and pests, dominate the biological community in a healthy soil. Considering the vast diversity of soil organisms and their complex interactions, it is unsurprising that there is limited knowledge about how farming practices precisely impact on soil biological health, and how biological health can be achieved. The former Sugar Yield Decline Joint Venture (SYDJV) and subsequent activities have demonstrated that soil biological health represents a significant production constraint. The modern farming system (MFS), with controlled traffic, permanent beds, minimum tillage, legume break crops and crop residue retention, aims to overcome soil constraints, including soil biological health, by minimising problems arising from soil compaction, continuous monoculture and low levels of soil organic matter. In this paper we discuss key organisms that inhabit soils under sugarcane production and how soil biology responds to management practices. We highlight biological indicators of soil health, and their usefulness to growers for quantifying soil responses to changed farming practices. We outline research needs to advance the industry’s ability to manipulate soil biological health.