Hay and Pasture and Potash

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Although it’s a little earlier than normal, I think it’s time to start thinking of applying spring potash (K) and phosphorus (P) fertilizer to your pasture and hay fields. For the hay fields, you will want to wait until after the first harvest, but I’ve seen a number of fields at heading (grasses) or late bud (alfalfa) which is a good time to harvest a good to excellent quality hay. For those more interested in tonnage, you’ll be holding off harvest for a few more weeks but you can still plan ahead for when your fields will be ready to fertilize with P and K and another shot of nitrogen (N). The warm weather of the past week and the period of very warm weather earlier this spring has orchardgrass and many other cool-season grasses heading out already. Early May is also, on average, a time when we have the greatest chance of a period of warm sunny weather long enough to dry hay.

Potassium or potash is a very critical element that helps plants tolerate the stresses of heat, drought, insects, and diseases that attack cool-season grasses in the summer. Although the price of K is high at the present time, the corresponding benefits of K fertilization will help you afford the cost of fertilizing with K. Many growers have chosen to either lower their K fertilization rates or eliminate them completely during the past couple of years when the price of fertilizer has been very high. If you have a current soil test, check the recommendations for how much K might be needed. If your soil test is not current you should get one as soon as possible to determine how much K you should apply or to see if the soil test levels are falling too rapidly.

In general if both P and K are needed by your hay or pasture field, add the P and half the K after the first hay harvest or in late-May or early June and then add the second half of the K recommendation in late August or early September. This timing will allow the plant to prepare for the stresses of summer and then for the stresses of winter.

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