By: Ken Panchuk, PAg, Provincial Specialist, Soils
When field scouting in late June and early July, you may see poor performing patches within fields. If there is no obvious cause the complete comparative tissue plus soil test can be used to indicate if a nutrient deficiency is the issue.
The complete comparative tissue plus soil test involves collecting a representative soil and tissue sample from both the affected area and a nearby healthy area within the same field. The soil sample should consist of 15 to 20 cores per sample from each the affected and nearby healthy area. Take care to avoid cross contamination during sample collections and clearly label the samples. Contact your lab for specific plant tissue and soil sampling procedures.
The lab will provide an analysis of the macronutrients and micronutrients, as well as soil characteristics such as pH and salinity. The patch of crop may be performing poorly due to a nutrient(s) deficiency or another soil problem, such as salinity. If a nutrient deficiency is identified, you can take action to correct the deficiency by applying the appropriate product and rate. If a nutrient is a mobile macronutrient like nitrogen and/or sulphur or a micronutrient, you can take corrective action immediately by applying an appropriate amount of a plant-available form of that nutrient.
Nutrients added at full to late flowering or early filling stage may not result in an improvement in yield and may also not be economic. Follow label directions when applying micronutrients. Also, it is a good idea to leave an untreated check strip to see if the corrective action resulted in a vegetative improvement and, later, a yield or quality improvement.
If the cause is not found to be the soil or a nutrient, samples can be submitted to the Crop Protection Lab for diagnosis. For sampling procedure and Lab forms, visit the Ministry’s Crop Protection Lab information page.