CROP SCENE INVESTIGATION - 5

The mystery of the uneven corn stand – Solved

It turned out that fertilizer burn described in the October issue of Better Farming was the problem which wreaked havoc with Jim’s attempt at another record-setting corn crop.

Even though Jim applied fertilizer within the recommended rates, the treatments are to blame for the injury. In most years, it wouldn’t be a problem, but the dry weather for several weeks around planting meant that there wasn’t enough water to dissolve and dilute the broadcast and starter fertilizers. The high concentration of nutrients caused a salt effect – water moved out of the plant cells and into the soil. The result was loss of moisture from the young root tissue and potential injury or death from fertilizer burn.

This diagnosis was confirmed by clues left at the end of the field and at the end of rows. They had run out of fertilizer on the last pass at the end of the field. As well, the planter had been pulled up near the end of the rows leaving fertilizer on top of the furrow. The low concentration of fertilizer in these areas allowed the corn plants in these areas to thrive.

Jim’s crop grew out of the injury, but it didn’t have a chance to set any record yields. He’ll try again next year and will be extra cautious with his fertilizer program. We discussed using lower rates as well as starter nitrogen sources other than urea, which converts to ammonia and can be toxic to young corn seedlings.

Other options I suggested were to apply a side-dressing of nitrogen later in the season, when roots are more developed, or to use fall applications of potash. 

Be thorough in your analysis when diagnosing fertilizer injury. Check the roots of affected plants, review fertilizer application rates, soil type and weather conditions.

Congratulations to Allan Spicer, Port Burwell, for his correct answer. BF

Shawn Brenneman, CCA, is a field agronomist for NK® Brand, Syngenta Seeds. He is based near Tillsonburg.