The cost of nitrogen fertilizer has started to creep back up over the last 6-8 months, reminding many producers of the high prices they paid for nitrogen a few years ago.
The cost of nitrogen fertilizer has started to creep back up over the last 6-8 months, reminding many producers of the high prices they paid for nitrogen a few years ago. It is always a good idea to evaluate one's options well before we are forced to make a decision. One option, that takes a few years to put into place, is Legumes in pastures. Legumes are a way of bridging the gap in the production of their grass pastures since they have reduced nitrogen fertilizer inputs.
Legumes have the ability to produce their own nitrogen with the help of a bacteria that lives on their roots. This bacterium has the ability to convert nitrogen from the air into a useable form for the plant. Most of this nitrogen is taken in by the legume plant itself and is used in the production of above ground forage and for growth of its roots. Nitrogen credits attributed to legumes can be as high as 200 lbs of N per acre for white clover, 110 lbs. for red clover and 100 lbs per acre for crimson and arrowleaf clovers. The legume plant itself is using most of this N production for its own growth, while providing high quality forage to the grazing animal. Contrary to popular opinion, very little of this nitrogen leaks out from the roots and is available for grass growth. We do receive some nitrogen recycling from legumes in animal urine and manure, but about 50% of this nitrogen is lost through volatilization and is not available for forage grass uptake. In a pasture that has been in legume production for several years, there will however be decaying roots and bacteria nodules that will provide nitrogen to the soil that is available for the grass crop to use. The amount returned to the soil by this decomposition varies greatly with the previous year's production of legumes. The nitrogen credit to that soil can vary from 20 to 50 pounds of N per acre from decaying plant root material and recycled animal waste.
So, are legumes a good way of reducing the need for fertilizer inputs? The answer to that is yes, but not because it puts large amounts of N in the soil for your grass to use. What is does is replace the grass production you used to get with nitrogen fertilization with high quality legume production, which is probably better for your grazing animals in the long run. Will it reduce your cost of production? Well that depends, in order to grow legumes, your soil will have to have the proper ph, phosphorus and potassium levels in order to survive and thrive. If your pastures fertility is not in good enough shape to produce legumes and you are not willing to spend the time, money and effort to get them established properly, then don't waste your time buying expensive legume seed. Without the proper soil fertility environment, your legume stand will not survive.
Using legumes in a balanced forage system will in the long run save you on nitrogen inputs and will provide your grazing animals with high quality forage. It will take some proper management in order to work well over the long haul. Get a soil test and visit with your local county extension educator before jumping off head long into a legume forage system. They will help you pick the proper legume for your geographical location and soil type. They will also be able to provide you with the proper management plan to keep your legume pastures in healthy and productive systems.