Despite a bit of rain this year’s Ag in Motion farm show (Langham, Saskatchewan) was well attended and a great display of new farming tech. Among the hubbub, an announcement was made of a new committee labelled the “Soil Champions”. They are a group of policy makers who will work as a part of the Soil Conservation Council of Canada (1). This new group has as part of its mission to champion soil health. It seems these days we can’t turn around without someone mentioning soil health and soil biology. In this week’s edition of Growing Possibilities, we decided to ask: what is soil health and how does it relate to soil biology?
Soil health is a wide-ranging topic but for the purposes of this blog we will focus on soil health (and soil microbiology) as it relates to food production. The UN’s World Soil Day page provides a functional definition of soil health: “Like us, soils need a balanced and varied supply of nutrients in appropriate amounts to be healthy. Agricultural systems lose nutrients with each harvest, and if soils are not managed sustainably, fertility is progressively lost, and soils will produce nutrient-deficient plants (2).”
In developed countries, this loss of fertility is largely compensated for using chemical fertilizer. A study out of the University of Colorado Boulder estimates that one third of the fertilizer applied to grow corn in the US each year simply compensates for ongoing lost fertility in cultivated soils. This adds up to a half billion dollars every year (3). The economic opportunity to remedy this loss of fertility through biological means has brought soil health (and soil biology) into vogue. With a slew of ag-biological companies springing up in the last few years claiming to sell natural solutions to restore your soil’s health. The idea behind these products is that intensive agricultural practices have upset the balance of the soil and by buying some ‘bugs in a jug’ you can not only restore your soil’s biology but also boost fertility and profitability.
While the effect of chemical fertilizers on native soil bacteria and fungi is not yet entirely understood, excessive use of fertilizer can disrupt existing systems in the soil. For example, if excessive nitrogen is applied to a legume crop, then nodulation will not occur because the plant will have no reason to form symbiotic relationships with the rhizobia in the soil (4). Over the long term this can lead to less active rhizobia in the soil.
Soil microbes can be affected by other factors like soil erosion. This leads to soil that is less able to hold moisture that is needed for a diverse soil biological community (5). Erosion can be remedied through practices such as no till or cover cropping. But once we have changed our physical practices how do we restore soil health? We know that manure is an effective way to restore biological activity to our soils, but manure cannot be applied on every acre of agricultural land (6). Again, the ag-biological industry has positioned itself as a solution to restoring soil biology. Soil microbes are known to have wide ranging beneficial effects including increased fertility and disease suppression. However, because of their complex nature we are only beginning to understand the relationship between these microbes, plants, and the soil food web (7).
At XiteBio Technologies, we promote a line of ag-biological products and stand behind their testing & effectiveness in real-world farm scale operations. But we always suggest exercising caution when dealing in soil biology and selecting ag-biological products to use on your farm. Products that purport to “do it all” should be viewed with skepticism. We look for products with well-known actives or proven strains that may one to three modes of action. Since the relationship between these microbes and the soil is so complex, they will not work the same in every situation. That’s why it is important to conduct field testing (if possible) or rely on measurable field efficacy trials (in similar agro-climatic regions) of these products to ensure that they work on your farm. Until next time we wish you healthier plants and better yields.