By Adam Hayes OMAFRA
Nov. 10, 2015, Ontario - As crop harvest nears completion, Adam Hayes, OMAFRA's soil management specialist, reminders producers it is important to consider what cover the soil has heading into the winter. Soil erosion continues to be a problem and sediment carried off fields into surface water can be a significant contributor to phosphorus in the Great Lakes. A lot of attention has been focused on the algal blooms in the lakes and agriculture is expected to help reduce the amount of phosphorus entering surface water. Farmers should do what they can to minimize the loss of phosphorus from fields. Keeping the soil covered and installing erosion control measures will greatly reduce the sediment contribution of phosphorus.
Leaving at least 50 per cent soil cover going into the winter will provide sufficient protection to the soil and should result in at least 30 per cent cover after planting. For soybean or edible bean residue this means doing little or no tillage. One pass with vertical tillage is about all that could be done. Of course, fields planted into winter wheat already have a “cover crop” to help protect the soil over the winter. Leaving corn and cereal residue will provide the most protection but if some tillage must be done a chisel plow, disc or vertical tillage are a few options. Avoid too much tillage so at least 50 per cent residue is left on the surface. Keep in mind implements that move a lot of soil like chisel plows or other plows contribute to tillage erosion.
Some cover crops were planted early and have very good growth. Others were planted late or did not receive much rainfall so they do not have much growth. Residue from cover crops with good growth can be left untouched over winter depending on crop species, soil type and the amount of growth. Most cover crops do not leave an excessive amount of residue on the soil by spring and can be planted into with little or no tillage. Cover crops with poor growth this fall, depending on the amount of crop residue, can be left untouched to keep the ground covered. Most fields where red clover was seeded had excellent stands and growth. Leaving these stands until the end of October before termination provides the maximum nitrogen credit, biomass accumulation and soil improving benefits.
Phosphorus also enters surface water in runoff. Phosphorus in runoff largely comes from fertilizer and manure applications. Phosphorus fertilizer and manure applications this fall should not be left on the soil surface, especially on sloping land. If applied to the soil surface it should be worked in immediately. Alternatively it should be banded in the soil.