| Popis: |
Acid cheese whey, made using phosphoric acid, contains up to 1200 mg total P kg–1 whey, and cultured cheese or sweet wheys contain up to 500 mg total P kg–1 whey. Much of the 32 ×106 m3 of whey produced in the United States each year is applied to soil. Whey P mobility has not been documented for calcareous or sodic soils. This study was conducted to determine the ratio between ortho- and the more soluble organic P forms in freshly produced cheese whey, and to determine ortho- and organic P concentrations by depth within calcareous and sodic soils within one to two years of different whey rates and time of the year applications. Applications of up to 1050 kg P ha–1 in acid whey were applied to a sodic soil (in green house lysimeters) and up to 750 kg P ha–1 in sweet whey were applied to calcareous soils (field plots). Bicarbonate-extractable ortho-P did not move below 0.3 m in the sodic Freedom silt loam (fine-silty, mixed, mesic, Xerollic Calciorthid) soil by the end of one growing season. Neither bicarbonate-extractable nor saturation extract ortho- or organic P moved below 0.6 m in the calcareous Portneuf silt loam (coarse-silty, mixed, mesic, Durixerollic Calciorthid) soil after three growing seasons or below 0.3 m in the calcareous Nibley silty clay loam (fine, mixed, mesic Aquic Argiustolls) soil after two growing seasons. Even though the wheys contained up to 42% organic P, these soils retained the applied ortho- and organic P against leaching. The winter-applied whey-P did not move deeper into the soil than that applied during the growing season. |
