Not only are soybeans turning yellow in Manitoba, but corn is as well. So how do you confirm a nutrient deficiency is causing the yellowing?
John Lee of AGVISE Laboratories provided MAFRD staff last year (2013) with the below information on how to properly determine if nutrient deficiencies are playing a role in the ‘yellowing’ corn seen across Manitoba. It is a great article so thank you to John Lee!
Using Tissue and Soil Analysis to Confirm Nutrient Deficiency in Corn
A cool, cloudy spring with excessive moisture has affected many areas. One effect of these conditions has been yellow corn from Manitoba to South Dakota. Using plant tissue analysis along with soil analysis can help determine if the yellow corn is a result of sulfur or nitrogen deficiency.
AGVISE staff recently worked with a local grower to help him determine why one of his corn fields was yellow while the adjacent neighbor’s field was dark green. Tissue and soil samples were collected from the yellow corn field and also from the adjacent corn field planted the same day. The concentration of sulfur in the plant tissue from the yellow corn field was well below the sufficiency range established for sulfur at this stage of growth. The nitrogen concentration in the yellow corn was good and in the middle of the sufficiency range for this stage of growth. A tissue sample from the adjacent corn field with dark green color was also tested and found to have sulfur and nitrogen levels well within the sufficiency ranges (see tissue and soil test results and pictures of corn at http://www.agvise.com/wp-content/uploads/2013/06/S-defcorn-AGVISEExample20132.pdf). There were also a large difference in the soil nitrate and sulfate sulfur levels in the soil samples from the yellow field and the adjacent green field.
The soil type in these fields is a sandy loam which is subject to leaching of sulfur and nitrogen with excessive rainfall like this spring. The yellow field did not have sulfur fertilizer applied this spring while the adjacent dark green corn did have sulfur fertilizer broadcast and tilled in before planting. The grower was planning on sidedressing the yellow corn with nitrogen fertilizer, but but now with the additional information from the tissue and soil tests, he is going to include some sulfur fertilizer in the sidedress application as well on this sandy loam soil.
This is just one example of how using tissue analysis along with soil analysis in season can help figure out if symptoms are being caused by a nutrient deficiency and which nutrient is the main cause of the symptoms.
Note: If agronomists/producers send suspected nutrient deficiencies to MAFRD’s Crop Diagnostic Lab, please send samples for tissue and soil analysis simultaneously to an appropriate laboratory. Then follow up with Crop Diagnostic Lab on the results from the tissue and soil analysis.