The Status of Available Phosphorus in Several Nebraska Soils: Correlation Between ‘A’ Values and Chemical Tests for Phosphorus

Phosphorus is one of the primary elements essential for plant growth. Recently, Fried and Dean have proposed the “’A’ value concept” which relates the percentage of phosphorus in the plant from the applied fertilizer to the available phosphorus of the soil. The ‘A’ value concept has been used in connection with both field and green house experiments. Since field experiments are costly as well as time consuming, a greenhouse experiment was conducted to study the available phosphorus in several agricultural soils in Nebraska using this concept. The soils selected included typical Prairie, Chernozem and Chestnut soils as well as some intrazonal and azonal soils in Nebraska. The soils represent a wide range in soil conditions: acid to calcareous, sandy to clayey, and high to low in soluble phosphorus and organic matter. The efficacy of ‘A’ values is not altered by this range in soil properties; whereas, many chemical methods for determining available phosphorus are not equally applicable over this entire range. As a consequence, ‘A’ values should provide an excellent means for the calibration of chemical testing methods over this great diversity of soil conditions. Advisor: R. A. Olso