Determining nutrient needs for a soil’s fertility can be compared to a hay mow, where all summer you add hay supply, while feeding some of that hay to the cows. But then, when the growing season is over and hay making comes to a close, the cows do not stop needing to be fed. The key here is to have enough hay supply to get through the winter-feeding of the cows.
The same plays out for farm fields. Daniel Andersen, Iowa State University assistant professor who authors “The Manure Scoop” blog, explains this “mass balance” approach in his April 7 edition.
Andersen looks at the “ins” and “outs,” specifically phosphorous, which is added to the soil via manure and commercial fertilizers (MAP, DAP, triple phosphate). Phosphorous leaves soils in the grain and crop residues as we harvest, the loss of soil particles and attached phosphorous through erosion, or any dissolved phosphorous flowing from the field in surface runoff. Andersen looks at the importance of keeping the ins and outs in balance to maintain productivity of our soils.
Andersen also explains the dose-response concept of maintaining soil nutrients. The dose is the amount of a substance that an organism receives and the response is the effect the organism has from the introduction of that substance.
Log on to read this full blog, as well as previous blogs by Andersen to get “The Manure Scoop.”
