WISCONSIN DELLS, Wis. – Protecting the landscape to reduce soil and nutrient loss has gained importance in recent years among farmers who are concerned about conserving and bettering both soil and water quality on their farms. Eric Cooley, the co-director of Discovery Farms, spoke about the data that has been collected through the group’s research regarding how cover crops and crop rotations have affected issues caused by run-off at the Discovery Farms Conference Dec. 11, 2019, in Wisconsin Dells.
    “If we can stop that water from coming off the landscape, we can really do a lot for both our soil and our water,” Cooley said. “The fact is that runoff is going to occur in all systems. The big question is how we can minimize both soil and nutrient loss.”
    Of the crops Discovery Farms studies have been working with, alfalfa has had the highest amount of runoff.
    “If you have tried taking soil samples from alfalfa fields, you know it’s really tough to get that probe in sometimes,” Cooley said.
    According to Cooley, working to avoid crop ground sitting bare is a priority in protecting it from soil and nutrient loss.
    “What can we do to protect these landscapes, especially in the spring periods of the year when the soils are bare, until we can get that crop canopy established?” Cooley said.
    Cooley said Discovery Farms’ data shows corn silage ground has the highest potential for soil loss followed by fields of new alfalfa seeding.
    “Traditionally as we come in to the seeding year of alfalfa, we make multiple passes to really flatten that field out to make harvest easier,” Cooley said of the potential for soil loss in newly seeded alfalfa fields. “We can really see when we destroy that soil structure. And, when we get the wrong conditions, there is traumatic soil loss when we come in and beat up those soils.”
    Cooley said farmers can try and reduce the potential for traumatic soil loss in newly seeded alfalfa by drilling the seed in and mixing other forage varieties with the alfalfa to allow for quicker establishment of a cover.
    The greatest soil loss from these fields typically occurs in the months of May and June during times of spring tillage and planting. That loss can be reduced by reducing tillage or utilizing no-till systems.
    The type of tillage system used plays a role in preserving the structure of the soil. Cooley said a dramatic difference is noted in the amount of soil lost between fields that have been conventionally tilled and fields that have been no-tilled.
    “If we are really trying to stop soil loss, no-till may be one of the predominant tools that we have to mitigate soil loss,” Cooley said.
    Planting alternative forage crops into crop rotations, using cover crops so planting is done into a green cover and retaining crop residues on soil surfaces are all ways to help lessen the potential for soil loss during the spring.
    “Letting that established cover stay until the time of planting and planting green helps reduce soil loss,” Cooley said. “We can see a dramatic difference in the soil loss on fields with corn stover left on the field as well.”
     While soil loss is a major concern of farmers, another important aspect to consider is nutrient loss. In contrast to soil loss, Cooley said the greatest phosphorous loss occurs in the wintertime months with frozen soils.
    “When that soil is frozen, we are seeing predominantly all the phosphorous leaving those landscapes in the dissolved form,” Cooley said. “We are seeing just the opposite once those soils thaw. In that May and June time period, most of the loss occurs in the particulate form.”
    Incorporation of manure into the soil will help to reduce particulate phosphorous loss in addition to methods used to reduce soil losses.
    “Really getting that manure under the soil, incorporated into the soil, we’ve seen a reduction of particulate phosphorous loss in our research data,” Cooley said.
    In contrast to reducing particulate phosphorous loss, Cooley said research data shows that no-till ground may have more dissolved phosphorous losses in the winter months than fields with reduced tillage methods. Slightly higher levels of dissolved phosphorous losses also occur with cover crops that are established in the fall and from crop residues retained on the soil surface.
    “When we have those situations, we have seen quite a bit of dissolved phosphorous as water is flowing over those soils with that residue on the surface,” Cooley said.
    Timing and incorporation of manure and phosphorous fertilizers are important factors in alleviating loss of dissolved phosphorous along with maintaining proper soil test phosphorous levels, particularly in the upper surfaces of the soil profile.
    “From a nitrogen perspective, we really aren’t seeing a lot of losses, especially in our forage crops, from nitrogen on the surface,” Cooley said. “Where we are seeing the challenges is in our tile drainage. Where we really see this is when we are making the manure applications right after a previous crop of corn silage.”
    Cooley said reducing nitrogen loss requires syncing the timing of manure or fertilizer application with the needs of the crop. Utilizing cover crops and alternative crops in rotation are also useful in reducing nitrogen loss.
    “Nitrogen specifically is where cover crops are going to have some of the biggest benefits,” Cooley said. “When applying fall manure it is going to be critical to try and get a cover crop established to try and reduce nitrogen losses through the late fall, winter and early spring.”
    Cooley urges farmers to look for different forage alternatives to use in their crop rotations to make more use of the nitrogen in the late fall especially after corn silage.