Losses of Soil Potassium
Potassium losses are caused by:
1. Crop removal
Fixation and leaching are not serious problems for Nebraska soils. As was previously discussed, fixation can result in temporary “tie-up” of potassium. Over a period of time, however, potassium eventually becomes available. Leaching is not a problem on silt and loam soils, but can be a problem on sandy soils.
By far, crop removal accounts for the largest loss of potassium from soil. In general, potassium content of grain is less than straw or stover. Corn cut for silage would remove about 195 pounds of potassium per acre. Much of this could be returned in the form of animal manure applications from the livestock operation. Corn harvested for grain would leave the stover in the field; and, since potassium is water soluble, it would be quickly returned to the soil. Table 6.3 shows rates of potassium removal for common crops grown in Nebraska.
|Crop||Yield||K2O Removed (pounds/acre)|
|Grain stover||6300 bushels/acre||160|
|Grain straw||5000 bushels/acre||90|
Table 6.3. Average Removal of Potassium by Crop Production