While you won’t hear crops complain during their growth spurts, they still need the right supply of nutrients to match their demands for growth and development.
Most grain or fruiting crops have distinct peak periods of nutrient uptake that correspond to their growth pattern. Crops such as grasses and forage have a more consistent pattern of nutrient uptake through the growing season.
One of the fundamental principles of 4R Nutrient Stewardship is making certain that the proper nutrients are in the root zone at the time plants need them. This “Right Time” approach needs to be adjusted for different nutrients and individual crops.
In general, it is best to apply nutrients as close to the time of uptake as practical. Nutrients such as P, K, Ca, and Mg are slow to move in the soil and can be applied several months ahead of when the plants will need them. For nutrients that readily move in the soil (such as nitrate and sulfate), it is best to apply them as close to the time for uptake as possible. This reduces the potential for nutrient loss from leaching or denitrification.
When the nutrient supply in the soil cannot match the plant’s demand, crop growth slows and a portion of the final yield is lost each day. Nutrient shortages often cause plant stress and yield loss far earlier than when deficiency symptoms become visible, a deficit known as “hidden hunger.”
It is important to understand when the peak demand periods occur for the specific crops you work with. This allows the “Right Time” component of the 4R’s to support crop yields to their full potential. A few examples of various crops are shown here to highlight some of the differences in total seasonal accumulation or daily nutrient uptake rate.
Maize: Nitrogen and K uptake follow a traditional S-shaped pattern during the growing season, with two-thirds of the total nutrient requirement acquired by the silking stage (VT/R1). However more than half of the total P uptake occurs after the VT/R1 stage, indicating the need for a continual supply of P from the soil throughout the season until crop maturity.
|N and P accumulation in maize (Better Crops, 2013).|
|Accumulation patterns of soybeans|
Better Crops, 2013
|Daily nutrient accumulation rates of potatoes,|
Hermiston, Oregon (Better Crops, 2008)
Sugar beets: High yielding sugar beets produce very large amount of biomass. During the growing season, the total nutrient accumulation in Idaho was approximately 240 lb N/A, 60 lb P/A, and 470 lb K/A. In addition to large amount of nutrients taken up, there were distinct peak periods where the daily N accumulation exceeded 4 lb N/A and the daily K accumulation reached 10 lb K/A.
|Accumulation patterns of N, P,|
and K in sugar beets
(Mriganka et al. 2018)
Link to the pdf version of this article is here: