I've been working on our soil sampling to yield data and I have a few observations that I have questions on.

The soil data was taken on 2.5 ac grids and the samples were sent to Midwest labs. I've taken the maps and had the program (SMS basic) make zones based on the soil data and cut through the layers of the yield map from last season.

This is one field of soybeans
pH to yield
7ph - 38.41 bu/ac - 3.4ac
6.6ph - 43.15 bu/ac - 17.9ac
6 ph - 49.35 bu/ac - 28.54ac
5.5ph - 54.81 bu/ac - 22.9ac
5.1ph - 52.7 bu/ac - 9.96ac

K to yield
235 ppm - 49.70bu/ac - 10ac
176.5 ppm - 54.21bu/ac - 27.5ac
142 ppm - 47.6 bu/ac - 33.45ac
114ppm - 43.89 bu/ac - 11ac

p1 to yield
63ppm - 54.78 bu/ac - 35.27ac
39.5 ppm - 48.21 bu/ac - 12.67ac
29.9 ppm - 46.57 bu/ac - 22.37ac
23 ppm - 41.1bu/ac - 12.5ac

p2 to yield
115ppm - 40 bu/ac - 3ac
85ppm - 56.57 bu/ac - 19ac
61ppm - 52.68 bu/ac - 20 ac
37 ppm - 45.34 bu/ac - 40 ac

After doing this analysis I am having a hard time seeing the coorelation between the optimum pH for soybeans (6.5-6.8) based on this fields data. The p1, p2, and k readings and yield are nice to see the coorelation because we are trying to get our soil levels up. Based on University of Wisconsin's rec's our p1 levels are excessive. They say you want your p1 to 25 ppm and anything over you won't see a yield increase. Well based on this we need to double that 25 to 50 ppm.

The same results are coming out of the corn fields also. Soing lower pH's having higher yields and p1 levels over 40 ppm showing much higher yields than the 25 ppm yields.

So basically how important is lime and getting your pH in the so called ideal range? When you look at your phos and K levels where do you want them for high quality crops that are looking to push yields? These soils are around 10-12 CEC about 65% cal, 25% mag and 3% K.