Some places in our trade area experienced heavy rainfall in the weeks following planting and it is likely that nitrogen was lost in these saturated areas. Plant color has improved overall but some of the stressed areas might benefit from additional nitrogen applied later in the season to help finish the corn crop. Extended dry weather after crop establishment in some of our trade will improve the soil retention of nitrogen and may reduce plant availability.
Plant tissue sampling up until 2 weeks past tasseling can help monitor the condition of the crop and indicate when plants are struggling to access needed nutrients to support the rapid growth phase of development. When interpreting plant tissue data, it is important to remember this reveals a snapshot in time and does not offer predictive value of future condition of the plants. Soil nutrient levels and future weather conditions have a large impact on late season nitrogen availability.
When paired with soil nitrate and ammonium levels, a better picture of the overall conditions will become apparent. Given the current cost of Y-drop UAN applications, UAN fertigation, and urea top dress treatments these two testing methods will help guide these in-season decisions. For more information on using soil test nitrate and ammonium to determine late season nitrogen applications see our blog post.
Please contact your ALGL agronomist for assistance with mid-season nitrogen testing.