Start Date

30-11-2000 12:00 AM

Description

The Iowa soil-test interpretations and fertilizer recommendations for phosphorus (P) and potassium (K) were last updated in 1996 and 1999. The 1996 update involved the most important changes compared with previous recommendations. New soil-test P ;:tnd K interpretation classes (very low, low, optimum, high, and very high) were developed to classify soil-test values into two sets corresponding to Iowa soils with either low or high subsoil P and K levels. This classification recognized research results suggesting that less topsoil P or K was needed when subsoil nutrient levels were comparatively higher. The probability of yield response to fertilization in the optimum class was considered small, and only maintenance fertilization based on nutrient removal was recommended for this class. No fertilization was recommended for soils testing in the high or very high classes, except for starter fertilization for corn under specific conditions.

DOI

https://doi.org/10.31274/icm-180809-742

Share

COinS
 
Nov 30th, 12:00 AM

Revised Iowa P and K Recommendations: New Soil-Test K Interpretations and Support for a New Soil P Test

The Iowa soil-test interpretations and fertilizer recommendations for phosphorus (P) and potassium (K) were last updated in 1996 and 1999. The 1996 update involved the most important changes compared with previous recommendations. New soil-test P ;:tnd K interpretation classes (very low, low, optimum, high, and very high) were developed to classify soil-test values into two sets corresponding to Iowa soils with either low or high subsoil P and K levels. This classification recognized research results suggesting that less topsoil P or K was needed when subsoil nutrient levels were comparatively higher. The probability of yield response to fertilization in the optimum class was considered small, and only maintenance fertilization based on nutrient removal was recommended for this class. No fertilization was recommended for soils testing in the high or very high classes, except for starter fertilization for corn under specific conditions.

 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.