Start Date

30-11-1995 12:00 AM

Description

A variety of soil tests are reliable for evaluating plant available phosphorus (P) of neutral or acid soils but there is still uncertainty about appropriate soil tests and soil-test interpretations for calcareous soils. The Bray-PI is the most widely used soil-test P method by soil testing laboratories operating in Iowa, although many also offer the Olsen method. Extensive research has shown that the Bray-PI test is reliable on neutral or acid soils but that it tends to underestimate available P on many calcareous soils. The Olsen test seems more reliable for calcareous soils. Because of this problem, many soil testing laboratories base fertilizer recommendations on one or the other method depending on the pH of the sample.

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Nov 30th, 12:00 AM

Soil Test Interpretations for Iowa High Ph Soils

A variety of soil tests are reliable for evaluating plant available phosphorus (P) of neutral or acid soils but there is still uncertainty about appropriate soil tests and soil-test interpretations for calcareous soils. The Bray-PI is the most widely used soil-test P method by soil testing laboratories operating in Iowa, although many also offer the Olsen method. Extensive research has shown that the Bray-PI test is reliable on neutral or acid soils but that it tends to underestimate available P on many calcareous soils. The Olsen test seems more reliable for calcareous soils. Because of this problem, many soil testing laboratories base fertilizer recommendations on one or the other method depending on the pH of the sample.