My main source is KSO4, minor source is chicken litter. I can get dairy manure on 1 farm so that is the main source for that farm as it is a lot higher in K than the litter. The KSO4 is banded at planting for corn & soybeans. Manure is spread preplant. I also do a little broadcasting KSO4 for low testing soils. I like to keep 3-4% K so that is about 100 - 300 ppm on my soils on the Midwest Labs test When acquiring a new farm I have observed excessive K levels from the guys that worshiped at the co-op to severely deficient from guys that don't know what fertilizer is. After a couple years, I feel it is fairly easy to manage the K level in the soil at 3-4%. I just started tissue testing last year, so I don't have much to go on. I was running good on K early, but ran low late into the season. Could have been dry weather, or anything else. I need more years to compare tissue tests. I have observed drastic yield increases when K changed from 2% to above 3%. I do not VRT. I usually do 20-40 acres / sample. I have not done any K trials. I am 80% confident in my current program, but am always looking for better or more efficient ways to fertilize. |