Bruce Anderson, University of Nebraska Extension forage specialist, offers the following tips on spring cultivation of established alfalfa, as well as fertilization advice.
- Anderson says some Great Plains alfalfa growers periodically cultivate their alfalfa stands. It’s usually done to control weeds like mustards and downy brome, but sometimes light tillage is used to incorporate fertilizer, smooth rough spots, or lessen compaction.
Some folks believe such tillage increases production by splitting crowns into two or more plants. Anderson says tillage generally does stimulate early alfalfa growth by blackening the soil and maybe improving water infiltration, but most research shows that spring tillage aggressive enough to provide useful weed control also damages alfalfa stands and yields. Likewise, light tillage that doesn’t harm stands also usually fails to control many weeds.
The down side to alfalfa tillage is that by cutting open some of the crowns, diseases can enter and start injuring the plant. These crown and root diseases usually take a while to show much damage, so if the field will be rotated to another crop in a year or two, losses will be slight if any. But, if you want to keep that stand for a longer time, don’t till or diseases might start to thin your stands earlier than normal.
The bottom line is that spring tillage before alfalfa greens up and when soils are dry does little immediate harm to alfalfa, but it also does little good.
- How much fertilizer should you apply to alfalfa? One can always guess, but with increasing fertilizer costs, the smart answer is to first get a soil test.
Soil tests tell you the amount of each nutrient your soil can provide to your alfalfa plants. From that, you can determine how much more fertilizer, if any, should be applied for maximum profits.
Remember that alfalfa gets most of its nitrogen from the air if the plant roots are well-nodulated. Thus, usually you’re just wasting money if you fertilize with nitrogen. However, all other nutrients must come from the soil or from fertilizer.
Collect soil samples as soon as frost is gone from existing alfalfa fields and also from fields you expect to plant to alfalfa this spring and next fall. Send the samples to a lab for analyses of phosphorus and soil pH. If your field is sandy, eroded or highly weathered, also test for potassium and sulfur.
Most important of all, use the results of these soil tests, with advice from your Extension educator and fertilizer dealer, to develop an alfalfa fertilizer program designed for your conditions.