Frequently Asked Questions: Organic Soils Section

Soil Health:

• Why are organic farmers concerned with soil health?
• What are the main goals of organic soil management?
• What is the best way to maintain an active soil biological community?
• Is soil erosion due to mechanical tillage a problem on organic farms?
• Is summerfallow permitted in organic agriculture?
  

Why are organic farmers concerned with soil health?
In organic farming, a healthy soil is one which, through its biological activity and inherent fertility, can grow high quality crops and remain productive over long periods of time without large quantities of inputs from outside the system. Soil structure and soil fertility are integral components of a healthy soil. Soil structure creates a necessary environment for soil micro and macro-organisms to thrive and permits healthy root growth and water infiltration. Similarly soil fertility provides necessary nutrients for plant and soil organism growth. Soil organic matter and soil organisms play key roles in the development and stabilization of soil structure in building soil fertility, and in nutrient cycling. Most organic farming practices (crop rotation, composting, green manuring, rotational grazing) attempt to increase soil organic matter content, keep the soil covered, conserve and recycle nutrients, and stimulate soil biological activity (see article on soil amendments). This promotes the development of a well-structured soil which remains fertile and productive over the long term.

What are the main goals of organic soil management?
The main goals of soil management are:
· Develop and maintain optimum soil structure and soil fertility
· Recycle nutrients and organic matter through the activities of soil organisms
· Minimize nutrient losses, both across and within the boundaries of the farm system
· Mineral fertilizers are a supplement to, not a replacement for, nutrient cycling on the farm
· Tillage is used to control weeds, incorporate crop residues and amendments, and create optimal conditions for seed germination and the growth of the crop
· Maximize the conservation of topsoil and soil moisture

What is the best way to maintain an active soil biological community?
Because organic matter is the primary source of energy and nutrients for the soil food web, adding organic matter to the soil is the best way to increase the numbers and types of soil organisms, and thereby increase the resilience and stability of the soil ecosystem.

Is soil erosion due to mechanical tillage a problem on organic farms?
Mechanical cultivation is the primary means of weed control on most organic farms but this does not necessarily mean that soil erosion is a problem. Organic farming practices that protect against soil erosion include:

• keeping the soil covered with living vegetation or stubble;
• reducing the momentum of wind and water by creating obstacles to slow them down (living vegetation or stubble, residue, soil ridges, contours, or terraces);
• and maintaining SOM with regular organic matter inputs to maintain high levels of SOM and soil biological activity; both of these contribute to the development of a stable soil structure.

Organic farmers have also been pioneers in creating and adopting minimal tillage techniques, and some recently are attempting direct seeding systems without the use of herbicides (see article on conservation tillage). Organic producers have been extremely innovative in using practices such as the use of living or killed mulches for weed suppression and soil conservation. In cereal grains and some row crops, organic producers are using mechanical weeders (rotary hoe and finger weeder) that require less horsepower and only cause minimal disturbance to the soil surface (see article on mechanical weeding)

Is summerfallow permitted in organic agriculture?
The practice of using tillage to maintain a vegetation free soil to accumulate moisture and reduce weed populations is not accepted by most certifying bodies. Summerfallowing can lead to soil erosion, salinization, organic matter and N depletion.