Results from a recent Purdue University study suggests that modern corn hybrids not only take up more nitrogen, but may also require replacement of micro-nutrients taken up and stored in the grain at harvest. For many years, growers have concentrated on the big three -- nitrogen, phosphate and potassium. But researchers at Purdue now believe an increased focus on micro-nutrients could improve yields.
Thus far, most Midwestern soils have had sufficient amounts of micro-nutrients like iron, zinc, manganese and copper to satisfy crop needs. But as cropping intensifies, those nutrients may eventually run thin, forcing growers to include them in regular fertilizer applications.
Nutrient availability is related as much to the individual plant's ability to uptake nutrients as it is to soil concentrations, and the report notes that plant population had little effect on micronutrient uptake. During the study, as nitrogen rates increased, yields rose and plants acquired larger amounts of micro-nutrients suggesting that N rates can have an impact on uptake.
The study notes that at 42,000 plants per acre and an N rate at 200lbsN/acre, 58% of the zinc taken up made it to the grain, 31% copper, 18% iron and 15% of manganese. Zinc was taken up throughout the growing season and stored in the stem during the vegetative phase. Iron went to the leaves and copper and manganese were distributed to both leaves and stem, mostly prior to flowering.
The study suggests growers can prevent deficiencies by adding zinc to phosphate applications. Manganese can be provided by foliar applications, and current levels of iron and copper in most soils are considered sufficient for crop growth.
With more intense cropping comes increased nutrient removal, not just for the big three -- NPK -- but also for micro-nutrients which may one day soon have to be replaced in the soil.
Click here for the full article Published in the Agronomy Journal by Tony Vyn and Ignacio Ciampitti.