Last year’s record rainfall not only stressed the crop and farmers, but it also has an impact on soil. All that water has longer-term implications for fields, as a lot of acres weren’t seeded or, worse yet, were mudded in.
Unseeded acres will have very little water used and will have water-soluble nutrients either washed away or leached into the soil. This will include some forms of nitrogen, sulphur, boron and chloride. Under saturated conditions, nutrients like phosphate, zinc and potassium will become unavailable. The clay in the soil will swell and when it dries out will trap the nutrients either physically or chemically with the excess calcium or magnesium in the soil.
This is true whether the land had a crop on it or not. Soil testing is going to be a must this year. A two-depth soil test would be a wise investment — the deeper test will show how deep the nutrients leached, and this will aid long-term planning. A relatively shallow test will be required for a nutrient plan in the coming year.
IMPLICATIONS AT SEEDING
If seeding was done with saturated soils, especially with wider openers, there will be a smear zone of compaction at the depth of seeding. Under moist conditions, the openers do not clean themselves and the clay particles in the soil will create a plow layer of compaction. The compaction layer will be a problem with root development and could potentially result in a seedling establishment issue.
Seed with high vigour and low seed-borne disease is a must. The only way to find out is to have your seed tested for both germination and vigour. A seed-borne disease test would also be good to have.
Seed treatments will likely offer a good return on investment this coming year. A good seed treater pays for itself quickly. A Graham Seed Treater is an investment that will pay for itself the first year simply because of the even treatment distribution on the seed, which is key to seed treating. Over-applying seed treatment is not only a waste of money but may even reduce the germination due to toxicity. And if some is over-applied, some will be missed. Using a good treating system will increase seed treatment efficacy.
The advantage we have over a lot of other parts of the world is our winter. Believe it or not, the fact of the soils freezing over winter will counteract some of the shallow compaction problems. Frost developing deep in the soil profile was actually pushed quite late this year, especially in east-central Saskatchewan, as late-season rains and then a snow pack kept soils warmer than normal. The natural process of soil reset is going to be reduced.
WHAT CAN YOU DO?
Obtaining soil conditions more favourable for crop production will take some management. Here are some options: 1) Using vertical tillage machines such as Salford’s RTS to create fissures in the hardpan works well. The coulters cut through the soil, allowing channels for roots to grow through.
2) Including an aggressive tap-rooted crop in rotation also works well. Sunflowers and tillage radish are used in areas with persistent hard pans. If you cannot seed on time this spring, tillage radishes can be seeded later as a cover crop. It can then be used as a grazing crop, plow down or as a cover crop for a fall-seeded crop. Sunflowers should be seeded early June and will require very little fertilizer. Both have a deep tap root and will recycle nutrients from deeper in the profile.
3) Another strategy would be to seed down some perennial forage such as alfalfa. Even if there is no market for the hay, by allowing the alfalfa to establish and grow biomass, when the residue is returned to the soil, it is better than a fertilizer application. Because it is plant material being returned, it will rot quickly and release plant available nutrients. Plus the root of the alfalfa will create root channels for accessing deep nutrients and allow water to drain into the profile. The other advantage is alfalfa will use water and dry out the soil.
Soil salinity may be a problem in the next couple of years. When the water comes to the surface and evaporates, it leaves the salt on the surface. By using the water before it evaporates from the surface, salts remain deeper in the soil profile.
Ruts are more obvious than wheel track compaction. Ruts are going to have to be dealt with and because of the physical change of the soil and mixing of the deep soil profile, future yields will be reduced in those areas. There will be more calcium in those areas, aeration will be reduced and there will be reduced rooting by the plants.
In wheel tracks where equipment travelled when the soils are saturated, there will be similar problems as ruts, but this problem won’t be as obvious. Once again, getting the roots growing into those areas will loosen up the soil, and hopefully you will get some frost action to break up the shallow compaction.
THE PLAN FOR 2011
Soil testing and cleaning up last year’s ruts are going to be the first priorities for this spring. Crops like canola are going to be expensive to grow because most fields are going to be low in available nutrients. Saturated soils are going to have a higher incidence of disease and slower root development. Choosing seed with low seed-borne disease levels and high vigour is going to be important.
In the meantime, if you are budgeting, pencil in higher fertilizer requirements and lower yields than the last couple of years. Watch soil compaction issues and look at using a seed treatment, applied properly, as good risk management.