Agri-Brief: GETTING MORE FROM SOIL TEST DATA

AGRI-BRIEFS
AGRONOMIC NEWS ITEMS

From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Winter 2004, No. 4

GETTING MORE FROM SOIL TEST DATA

Soil test results: we spend time and money collecting the samples and getting them analyzed. So how can we get the most out of the information they provide?

What are appropriate uses of soil test data?

• Examine changes in fertility over time

• Predict long-term probability of response to fertilization

• Determine nutrient rates to apply

More frequent soil sampling leads to more rapid assessments of fertility programs over time. Sampling a few test areas annually can help hasten evaluations. If soil tests are building more slowly than planned, it may be time to increase application rates. Conversely, if soil tests are declining more slowly than desired, rate decreases may be in order.

Very low and low soil tests predict good chances that the crops to be grown will respond profitably to fresh nutrient applications in the short term. Soil tests kept close to critical build levels may not respond as much in the year of a nutrient application, but are expected to sustain higher production levels over time, providing positive returns to longer-term fertilizer investments.

It’s important to remember that soil tests are snapshots of soil fertility status and are used for planning nutrient applications. In most cases, soils are sampled every few years. In the interim, nutrients are applied and two or more crops are grown. In such cases, the soil test represents only an initial assessment for a string of subsequent management decisions. Sampling more frequently can help keep a better tab on how soil fertility is responding to management.

For more information on examining soil test changes over time, visit >www.ppi-ppic.org<. Under “Features”, select “Toolbox Resources”.

—TSM—

For more information, contact Dr. T. Scott Murrell, Northcentral Director, PPI, 3579 Commonwealth Road, Woodbury, MN 55125. Phone: (651) 264-1936. E-mail: smurrell@ppi-far.org