Soil conservation and soil health
April 9, 2012:
There's real progress in Ontario soil management says extension leader Adam Hayes
It wasn't until the late 70s and early 80s that soil erosion became severe enough to make soil conservation a priority for government and other organizations. Soil at Risk acknowledged the problem at a national scale. Staff was hired and funding programs put in place to address the issue. By the mid 90's budgets were tight and programs were scaled back or cut. Fortunately, significant momentum was generated in the 90's so that large gains in soil conservation continued to be made.
Landscapes were gradually transformed. More and more fields were covered with crop residues. Crop rotations improved; grassed waterways, windbreaks and other erosion control measures were installed. Less soil was moving off fields and water courses carried less sediment. Significant progress had been made.
A large part of that success was due to the adoption of no-till practices and the innovative farmers who made it work on the farm. No-till significantly reduced soil erosion reduced the need for or size of erosion control structures. We have seen no-till increase yields on the sandy soils and greatly improve the soil structure of clay soils. In the clay plains in southwestern Ontario, an area which has been out of livestock and into row crops the longest, the improvement in the soil has been amazing. Once intensively tilled, these soils now drain better, crust less and produce more uniform crops.
As far as we have come, soil erosion is still a concern. Less snow cover and more intense storms are predicted as the climate changes. This past winter snow cover was well below normal in a number of areas. A few winters ago a local conservation authority recorded three "one-in-fifty" year storms over a period of five months during the winter and spring resulting in significant soil erosion. Most erosion control structures are designed for "one-in-ten" year storms. If more intense storms are anticipated we must be more diligent in our efforts to protect the soil.
Soil conservation practices are only one part of good soil management. Healthy soils are more resilient, cycle nutrients better and are more productive. Soil health is a reflection of how management has influenced the physical, chemical and biological components of the soil. The physical refers to soil structure, bulk density and available water capacity to name a few. Chemical components are the primary, secondary and micronutrients as well as pH. Organic matter, soil life and carbon and nutrient cycling make up the biological component. With so many components involved it takes a systems approach to make real improvements in soil health.
I have seen the benefits of a systems approach to soil health. There is a farm where they practice good crop rotation, use cover crops, keep tillage to a minimum and make the best use of the limited amount of manure that is available. They have very good yields each year and the crops withstand adverse weather better than the neighboring fields. The results from nitrogen rate testing showed that maximum corn yields could be achieved with 30 to 60 kg/ha of nitrogen. This operation is reaping multiple benefits from this approach such as increased yields, lower nitrogen inputs, improved nutrient cycling and increased water holding capacity.
Putting it all together in a systems approach involves consideration of the three areas of soil health and the management practices to enhance them.
Physical properties. The physical properties can be significantly improved with changes in tillage and by managing soil compaction. Tillage action breaks down soil structure and it moves soil down the slope. On sloping landscapes over the years tillage has moved more soil than water. The most aggressive implements move the most soil. Tillage also speeds up the loss of organic matter, another reason to keep tillage to a minimum. If you have to till, do as little as possible to prepare a seedbed. Managing residue at harvest and making improvements to the planter or drill can go a long way to reducing the amount of tillage required.
Biological component. The biological component of soil health is the most important and the most complex. Supporting an active and diverse soil life can be a challenge but it will be rewarded with increased productivity. The organisms in the soil need to be fed and watered similar to livestock. Crop residues provide food as well as do manures, compost and other organic amendments. Providing one of these sources is good but supplying a variety is better. It is also important to have living roots in the soil. A corn-soybean rotation has living roots in the soil only 33 percent of the two year period. Adding winter wheat under seeded to red clover more than doubles that to 77 percent over the three year period. It also increases the number of species of roots to four. Cover crops are another excellent way to increase the time living roots are in the soil.
Chemical component. The chemical component of soil health is relatively easy to ensure it is where it needs to be. Regular soil testing of soil nutrients and pH will help keep fertility levels where they need to be. Managing to maintain or improve each of the three components will help to keep your soil healthy.
Making soil a priority
Going forward managing our soils well and preserving our prime agricultural land have to be a priority for agriculture and society. Agriculture will not be able to continue as major part of to the economy if our soils become degraded. Research to develop and refine soil best management practices and technology transfer to take those practices to the farm is vital to improving soil health. Consideration has to be given to improving our soil databases, soil information and monitoring of the soil resource.
And finally, the human resources must be available to do the research and support soil management programs. We have come a long way in the last 25 years so let's work together to keep the momentum going.