By Rachel Milliron
Without living cover in the field, nutrients applied after fall applications are vulnerable to losses. We can reduce some of the potential losses and water quality concerns by planting cover crops.
This late in the fall, you may be wondering “What can I plant?”
Winter rye is a top performer when it comes to late cover crop establishment. Although we are beyond the recommended planting dates for many cover crops including rye, it is the hardiest of cover crops and can germinate when temperatures are as low as 38°F.
Triticale and wheat are not quite as hardy as cereal rye, but they are still contenders this late in the game.
Winter rye and other small grains are known to be nutrient scavengers that can reduce soil nitrate levels, phosphorous losses, and nitrate leaching. With adequate growth in the fall and spring, a two year study found that rye reduced soil nitrate levels by 32 and 67% compared to no cover crop.
A winter small grain will not only reduce nutrient losses after a fall manure application, but can supply approximately 40-50% of the total manure nitrogen for the following summer annual crop.
The Agronomy Guide, Table 1.2-15 provides manure nitrogen availability factors based on the time of manure application, with a cover crop or double cropped small grain, and application management. Additional benefits of these small grains include erosion control, weed suppression, and harvesting it as an additional forage crop.
While you can still plant these cover crops late into the fall for fall-winter nutrient scavenging, it is better to ensure establishment by planning to plant cover crops early in the fall. If applying manure after harvesting, don’t delay cover crop planting. Plant cover crops first and then apply manure. A study out of Minnesota found that delaying cover crop planting later can affect the capacity of winter rye to reduce nutrient leaching compared to an early planting.