The Vertical Distribution of Total and Dilute Acid‐soluble Phosphorus in Twelve Iowa Soil Profiles¹

Available and inorganic forms of phosphorus in selected Alfisols and Mollisols

“…Within the same climatic region and under the influence of the same natural vegetation, the soils formed in loess (Weller, Pershing and Tama) show higher values of the total IP fractions than the soils formed in Gary till (Hayden, Lester and Clarion). This is expected since the loess soils have higher amounts of total and dilute acid soluble P than till soils ( Pearson et al, 1940). The loess derived soils contained an average of about 500 to 700 ppm of total phosphorus as compared to about 300 ppm in the till derived soils.…”

Soil, location, and climatic factors influencing available phosphorus level with depth in subsoil horizons of Iowa soils

“…The influence of weathering on soil development and inorganic P compounds (discussed previously) not only affects extractable-P distributions but also soil pH and clay distributions in relation to genetic soil horizons. The min-tTmmi subsoil F level has occurred in the lower  to upper B horizon and the Tna-v-fîniTm level has generally occurred in the lower B or upper C horizon (Pearson et al, 1940;Mausbach, 1969;Tembhare, 1973;Birchett, 1974). Salih (1979) found that the soil test P level in the shallow 30-51 cm layer was significantly affected by the genetic horizon present in that layer; this effect was modified by interactions with other vari ables.…”

“…Many investigators have reported that biosequence (prairie to transition to forest) had a dominant effect on soil test P in the subsoil (Pearson et al, 1940;Fenton et al, 1967;Mausbach, 1969;Tembhare, 1973;Birchett, 1974). The forest-derived soils had higher subsoil P levels and more marked sigmoid distributions with depth than the prairie soils.…”

“…Several investigators have studied the distributions of extractable P in Iowa soils (Pearson et al, 1940;Riecken, 1954, 1957;Mausbach, 1969;Tembhare, 1973;Birchett, 1974). Their results and those of others (Drs.…”

“…Several researchers reported that the loess-derived soils contained higher total P and plant-available P in their profiles than the till-derived soils (Pearson et al, 1940;Mausbach, 1969;Tembhare, 1973). Dumenil (1978) reported that subsoil P levels varied among the soils derived from deep loess, till, colluvium, and alluvium in southwestern and southern Iowa.…”