A field, laboratory, and greenhouse study of secondary effects of hill fertilization was made using several different soils as follows: Carrington loam, Webster silt loam, Grundy silt loam, Knox silt loam, Marion silt loam, and Buckner coarse sand. The effect of hill fertilization on the root development of the corn plant was also investigated.
Acid phosphate was found to have a more pronounced effect on the hydrogen ion concentration of the soil solution than either ammonium sulfate or potassium chloride. In most cases the first effect of acid phosphate was to increase the acidity of the soil solution. In poorly buffered soils, such as sands or sandy loams, this increased acidity may persist for some time. In other soils the acidity is neutralized very quickly, and sometimes a less acid solution than that of the untreated soil may be produced.
The effect of hill fertilization on carbon dioxide production was found to be slight on a loam and silt loam, while a decreased occurred on a sandy soil.
Harper, Horace J.
"A study of the secondary effects of hill fertilization,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 6
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol6/iss87/1