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MB, Canada | I don't grow straight alfalfa but I've found that by fixing limiting nutrients (sulfur in my case), I've got some alfalfa/grass stands where the yield has been trending up after as late as year 7. My current program is basically manure and elemental sulfur every 4-5 years or so based on how much I'm exporting from the field and how heavy the manure's going on. Less manure more frequently tends to work better. Levelling mole hills tends to be more of an ongoing challenge though.
My theory on why digging up a "tired" hayfield and putting it to greenfeed works is that basically all the nutrients in the upper root zone have been exported, so by digging it up you mix together a bunch of other soil, as well as exposing the soil to a bunch of oxygen so that the soil life quickly cycles a bunch of carbon for a short-term yield bump. But's that's honestly just a guess. One thing I'm quite confident in is that when a hayfield has gotten short on phos, it's usually a problem that should have been addressed 5 years ago due to how slowly P moves through the soil.
That said, I think you're on the right track growing hay instead of greenfeed. Get a number of species of grass and legumes involved, keep the nutrients going back on at least as fast as they're leaving, and a hayfield can last as long as you want it to. | |
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Fertilizing hay land?
