The Pre-Sidedress Nitrogen Soil Test for Field Corn

 PSNT Quick Guide for Farmers


For most benefit doní»t apply N fertilizer at planting.

The need for a pre-sidedress N test is because there is no accurate way to predict N release from manure and crop residues. Nitrogen in the form of nitrate is extremely soluble and moves freely with soil water as it drains.  Over-application of N from fertilizer and manure can result in N loss throughout the growing season, and especially after crop harvest in the fall, increasing production costs.

Sampling Procedure for Nitrogen Soil Test

1) Sample soil when the corn is approx. 10 to 12 inches tall.

2) Collect 15 and 20 cores per field area to a depth of 12".  If you can't get to 12", sample as deep as you can. Take samples between rows, avoid starter fertilizer bands or areas where manure was piled or were an application was unusually heavy or light.

3) Mix together completely all the cores for each field, then dry on the same day a subsample to stabilize the nitrate.  Samples can be air dried if spread out thinly on a nonabsorbent material. A fan will reduce drying time. Do not put wet samples on absorbent paper because the paper will absorb some nitrate.

4) Send soil sample (up to one cup of dried soil) to the: Soil Testing Lab, West Experiment Station at UMASS-Amherst, MA 01003 (ph. 413-545-2311).  Include with soil sample your name, address, phone number, sample number or field identification together with $6.00 per sample.

The Sidedress N recommendation will be mailed to you from the UMass testing lab within one or two days after sample receipt.


Stephen J. Herbert and Masoud Hashemi

Dept. of Plant & Soil Sciences

University of Massachusetts Amherst

UMass Extension and s319 Nonpoint Source Pollution

CDL Pub 01-3                                                                                                                                  

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Last updated: 11/11/02.