A second concern with the current P application rates may be that the P application rate is too low for the higher grain yields being produced. When this occurs constantly, the soil test P values will decline over time.
How are the application rates of K stacking up to the soil maintenance K value determined by your crop yields? Frequently, the manure doesn’t have enough K to maintain soil test K values. To correct this problem, add a liquid application of 1-3-30 (manure special) in a fall dribble band to correct the K deficiency. This added nitrogen and phosphorus in the 1-3-30 fertilizer will enhance root growth in the zone of application. This greater root growth, in the application zone, will enhance K uptake in the plant.
In most instances, the hog manure will supply some sulfur, but additional sulfur should be applied to the crop. However, there exists a need for added zinc and boron for the crop. The 1 lb. zinc and .2 lb. boron per acre, and whatever level of sulfur required, could be added to the 1-3-30 dribble band application, to a liquid N (32%) solution as a weed & feed application in the spring or the zinc could be added to the starter fertilizer (note: B should not be applied with the starter fertilizers).
Here are two thoughts dealing with N management and manures. First, Instinct should be added to all liquid manure at the time of application. The use rate for Instinct is 35 oz./A. By adding Instinct to the manure, increased corn yields will be achieved in most instances. Secondly, a weed & feed broadcast application of 30 to 50 lbs. N per acre in the spring is highly recommended. This broadcast application will place N in the rooting zone of the newly developing corn plant and give the new plant improved early N status.