|
Little River, TX | Bill,
I would hope the lab used Olsen chemistry. If they used Bray with a soil this acid the phosphate results will read much too low. Mehlich III is better but still marginally effective for phosphate levels.
I mentioned free lime being the major culprit for phosphate quickly becoming not available with high pH conditions. Really a surplus of any cation in the soil's available pool can and will combine with phosphate.
I mentioned high CEC values and their not all being the same. There are several clay types to attract cations. Some will also trap the cation molecules between layers of clay platelets. This is what I have. The theory is the process of drying these high shrink swell soils expose the trapped cations and give an reported fertility level above the truly available levels. In round numbers multiply the CEC value by 8 and by 10 and this is the range potassium should be to insure adequate plant K levels.
The problem with a computed CEC is with the normal variability of soil testing results. A computed CEC is derived using a magic equation of 3 to 5 cations. The problem with a measured CEC value is cost. Runs about $40/sample. For a few of us this is a good investment.
For real excitement a calcareous soil that is also a heavy clay, will make life interesting. | |
|
HIGH PH SOIL
