Nitrogen testing and management are important for small grain production. Soil tests are conducted prior to planting, and plant tissues should be monitored during the growing season. Extension Specialists at the University of Arizona have established guidelines for nutrient levels and fertilizer applications. Soil Sampling and Analysis and Fertilizing Small Grains in Arizona are two excellent publications that address these issues.
For a more visual perspective, the following video from the UA, CALS-Cooperative Extension Field Crops program illustrates soil sampling procedures for field crops including small grains: http://youtu.be/QG3-ttTKDZQ.
Reference Strips can be used effectively for N Management in winter grains. The UA CALS-Cooperative Extension publication AZ1571, An Introduction to the Use of Reference Strips for N Management in Durum Wheat explains how the system works. In short, the system uses both N-Rich Strips and Ramp Calibration Strips. The N-Rich Strips are strips with a high rate of pre-plant N fertilizer across the length of the field. During the growing season, if wheat plants in the rest of the field grow similar to N-Rich Strips, no N application is necessary. Otherwise, N fertilizer should be applied during the next irrigation.
Ramp Calibration Strips include a few small plots with low to high pre-plant N rates placed in a sequence in the field. For example, the strips could consist of plots from 10 to 100 lb/acre of pre-plant N with 10 lb N/acre increases every 10 feet. During the growing season, one can walk the strips from the low rate to high rate until the crop in next plot does not appear greener. The N rate in the plot is the recommended N rate in next irrigation.
Please contact me if you want some help setting up N Strips in your field.
Happy Thanksgiving to Everyone!