Unless your head has been buried in the proverbial manure pit, you already know that fertilizer prices hit the roof in December, busted through in January, and are currently somewhere in the ionosphere.  The reasons are numerous, but now we have to deal with realities.  First, if you prepaid in December it may be the best and most profitable decision you make all year.   Second, a good set of soil tests will be worth their weight in gold as you try to decide where cuts can and should be made and where they can’t, regardless of fertilizer price.  For alfalfa, the focus immediately turns to potassium (K), as it’s the nutrient removed in the greatest amount (60 lbs. per ton of dry matter removed) and the one most often needing to be applied on an annual basis. 

        So why is a GOOD soil test analysis valuable?  If you can say with certainty that soil K levels are in the high range, fertilizer rates can be cut in half without impacting yield.  That’s a savings of about $75 per acre if the per unit K price is $0.50 per pound.  Even larger savings can be made if K soil levels are in the very high or excessively high ranges (more common to see this with phosphorus levels than with K).  Again, all of these savings are contingent on the accuracy of the soil test. 

        What are the ramifications of cutting K rates at high soil test levels?  From a yield standpoint, there are none; however, if this is done over a period of years the soil test level will drop to the optimum range or below.  So at some point in the future, the full complement of fertilizer will need to be applied. 

        Research is conclusive that it simply doesn’t matter whether fertilizer is topdressed after first cutting, after the last cutting, or split between the two.  If you’ve already paid for your fertilizer, the timing is a moot issue.  If you haven’t paid for your fertilizer, then there remains the option of waiting until fall when there is less demand and hope that price and availability conditions improve.  Of course there is no guarantee that will happen.  Some reports say that it will, while others indicate it could get worse. 

What about manure?

        The value of manure is obviously at an all-time high from a nutrient perspective.  Applying manure to alfalfa SOON after each harvest is a practice that is not uncommon, but is also not without risk.  It has to be applied in relatively small quantities (5,000 to 7,000 gallons per acre) and it’s difficult to meet total K needs unless soil test levels are already in the high range.  Further, there is always the risk of field compaction damage and plant salt burn (especially if the plants have started to green-up).  Odor can also be a problem as there is no means of soil incorporation.  Nevertheless, there may still be situations where the cost savings justifies the risk, especially on older fields. 

        Another strategy is load fields up with manure prior to seeding alfalfa.  The advantage to this practice is that relatively high amounts of manure can be applied that will supply enough K for multiple years without the addition of purchased fertilizer.  The disadvantage to this strategy is that the nitrogen content of the manure essentially goes unutilized for the N-fixing alfalfa crop (actually the alfalfa will use the N supplied rather than fix its own).  As a total nutrient supplying package, manure is probably best utilized for corn.