Soil testing is a necessity to reap the benefits of growing alfalfa for hay, said Dirk Philipp, assistant professor with the University of Arkansas System Division of Agriculture.
"Modern production of alfalfa depends on improved varieties, well-defined harvesting schedules, and precise fertilization practices," he said. The last-named is key because alfalfa grown as hay can remove substantial amounts of nutrients from the soil.
Published research shows that removed amount to be as much as 14 pounds of phosphate, 58 pounds of potash and 30 pounds of calcium per ton of dry matter of alfalfa.
The precision is worth the effort. Alfalfa has many advantages to hay producers, or livestock owners, including fixing nitrogen, improving the soil structure and producing high-quality forage for beef or dairy or haying operations. Alfalfa requires phosphorus and potassium in relatively high amounts. The phosphorus is needed for photosynthesis, energy transfer and creation and of carbohydrates and protein. The potassium is needed for enzyme activation, and opening and closing of the stomata, or leaf pores, and other essential activities.
Keeping nutrients in balance is important because "research has shown that nutrient imbalances may affect yield much more than no fertilization at all," Philipp said.
A current soil test is critical to know what nutrients to add. Philipp recommends the following for annual fertilizer replacements:
- Fertilizer should be applied after the first and third harvest.
- Apply fertilizer immediately before regrowth sets in to avoid damaging the alfalfa crowns.
- Stand winter hardiness may be increased by fertilizing later in the growing season -- early to late September based on latitude.
- Don’t apply at times when soil is too soft and physical damage to plants may be likely.
- Split the application if large amounts of fertilizer are required. This split can is can be avoided by keeping track of soil fertility status over time.
- Keep in mind that soil test reports are provided for free by the University of Arkansas.
- Monitoring soil fertility including liming requirements will safe costs in the long run and keep high-intensity crops such as alfalfa in optimum conditions.
Source: University of Arkansas Cooperative Extension Service