A weekly report prepared by the staff of the Ministry of Agriculture and Food (OMAF) and the Ministry of Rural Affairs (MRA). For more information, call the Elora Resource Centre at 519-846-0941 between 8:30am and 5pm. For technical information, call the Agricultural Information Contact Centre at 1-877-424-1300 or visit the OMAF website: www.ontario.ca/omaf and/or the MRA website: www.ontario.ca/mra
IS YOUR SOIL IN GOOD PHYSICAL SHAPE?
Soil health is broken down in to three components: physical, biological and chemical.
Each is important, but the physical component is one that can have a significant impact on yield. Physical aspects of soil have two main areas: soil structure, including aggregate stability, and available water capacity.
Aggregate stability measures how well clumps of soil stay together when they are subjected to a water test or simulated rainfall. Soil aggregates with good stability will stay intact for the most part when exposed to the test. Soils with poor stability will break down into particles.
Soil with poor aggregate stability is prone to water erosion. When raindrops hit the soil the individual particles are easily broken away and washed down the slope and potentially off the field.
The same is true for wind erosion. It also increases the incidence of crusting. The rain hits the surface breaking the aggregates apart and spreading them across the soil surface filling in the soil pores. When the soil dries, it is a solid layer slowing water movement into the soil making it difficult for the crop to emerge.
Soil structure refers to the way in which soil particles cling together to form aggregates. When individual soil particles are aggregated, they form larger, relatively stable primary structures.
Structure also encompasses how soil particles are bound together and the spaces or pores in between. Structure has a significant effect on soil water properties and the ability to resist erosion. Good soil structure increases porosity, aeration, drainage and permits easier root penetration, all of which are important in those with limited internal drainage, such as clays.
Poor soil structure in the topsoil produces hard, massive clods, which makes a poor seedbed for germinating crops. Poor structure in the subsoil results in dense, compact properties which limit root and moisture penetration.
Clay particles cling tightly together and resist separation more than sand particles. As organic matter decomposes to humus, a variety of compounds are released which “glue” soil particles together. Soil structure is formed through the actions of:
–drying and wetting or shrinking and swelling, this creates cracks and planes of weakness for roots
–freezing and thawing roots through the removal of water, root exudates or organic materials that bind soil particles and the formation of root channels
–soil animals like worms and beetles, moving soils, mixing and releasing organic materials
–microorganisms breaking down plant and animal residues
–tillage reduces the size of aggregates, an artificial way of creating structure in some soils, but not long lived.
Tillage breaks down soil structure, so minimum or no tillage is the best. Increasing organic matter in the soil using manure, other organic materials such as compost, a diverse crop rotation and cover crops, will improve soil structure.
Soil compaction is a part of the soil profile that has poor structure, making it difficult for roots to grow through, and for air and water to move. Keeping axel loads below five tonnes per axel, reducing traffic in the field, making sure the soil is fit, using radial tires and reduced tire pressure, will help prevent the problem.
Plant growth depends on water stored in the soil. Water capacity is a measure of the soil water that is available to the plant. Water is stored in the soil in the pores and in organic matter. Adding manure and compost, is a good way to improve water holding capacity.
Soil in good physical shape will have good structure. A well-structured soil will allow water to move through the soil, and air to enter. It will not crust and will favour good root growth. Minimizing tillage and compaction, using a multi-crop rotation including cover crops and adding organic materials such as manure and composts, will greatly improve the structure.
EXCELLENCE AWARD FOR AGRICULTURE STUDENTS NOW OPEN
Farm Management Canada (FMC) and the Canadian Association of Diploma in Agriculture Programs (CADAP) have joined forces to offer an award designed to encourage students to improve their communication and leadership skills through a national video competition. FMC and CADAP are collecting submissions from agricultural students across Canada and will award three winners with $1,000 towards furthering their education in agriculture.
Students are asked to submit videos, responding to the following questions: What key skills has your educational institution taught you about farm management that will be most useful in your career? Please explain why these are important?
Applications must be received no later than May 9. For more information, please visit: www.fmc-gac.com/excellence-award.
COMING EVENTS
May 9: Grower Pesticide Course, OMAF and MRA Boardroom, Elora. To register, call the Ontario Pesticide Education Program at: 1-800-652-8573 or visit website at: www.opep.ca or email: opep@opep.ca.
