Last year we had tremendous rainfall totals, and to date this year, we are still running above normal. Many forage stands were damaged during the winter with heaving and saturated soils.
Although we are still trying to get cereal grain crops planted, forage harvesting is upon on us and some fields have been harvested. Several have reported that forage stands are poor this spring.
Hay supplies were tight this winter and spring and much of what was harvested last year was low quality.
Many livestock producers need forages to feed now and are eager to get into fields. So, the big question is if we harvest as soon as possible on wet soils what are the consequences?
Penetrometer
Soil compaction can be measured using a penetrometer, which is a device that has a cone tipped rod attached to a gauge that is pushed into the soil. This can be done manually, or some units are mounted to equipment and are mechanically driven into the ground.
A more technical method is to measure bulk density, which is the mass of soil per unit volume. Using this measurement of compaction can then be used to calculate the porosity of the soils. Ideally, we would like to have soils that are half solid and half pore space.
If you don’t have the equipment to measure compaction, we can often see the damaged areas by observing areas that have reduced plant growth, poor drainage, ponding or excessive runoff.
Commonly, we see the most damaged areas in the head rows of fields and load-out areas.
Regardless of soil conditions wheel traffic alone can cause yield reductions in forages. Although soil conditions and soil types will vary in the extent of damage caused.
The type of forage will also vary in damage due to wheel traffic.
Legumes are generally affected more due to crown spitting or breaking, which open stems allowing diseases to enter.
Yield loss
Dan Undersander, Extension forage agronomist with University Wisconsin-Madison, conducted a study demonstrating yield loss due to wheel traffic in alfalfa. The greater length in time between mowing and when the field is driven across, the greater yield loss occurs.
In this study, yield loss was about 22% with traffic five days after mowing which generally means 4 to 6 percent yield loss per day after mowing.
Since we have no control of the weather there are some things we can do to help reduce losses. Harvest your forages that are higher in grasses first.
Grasses can be permanently damaged, just not as much as legumes in soft soils. Smaller equipment will help reduce compaction, but larger equipment will reduce the number of trips across the field.
Using duals on tractors may not necessarily reduce compaction, however, this will often reduce ruts.
Merging swaths into large windrows will help reduce baler traffic. Harvesting bailage or haylage also helps enabling you to remove the crop from the field faster compared to hay.
The past several months have been long, wet and frustrating to say the least. Forage inventories are extremely low and straw supply this summer will probably be in short supply.
Scouting and managing your forages and pastures to minimize losses for long-term production will be critical. Anything you can do to reduce traffic, drying time and getting the forages off the field will help increase yields.
