All plots were fertilized with a total of 350 lbs N/ac except for the low- and high-rate ESN treatments at emergence. 50 lbs of the total N was applied to the entire trial as ammonium polyphosphate (11-37-0;30 N) at planting and MAP (11-52-0; 20 N) broadcast just prior to hilling. Growers’ practice is 75 lbs N/ac as urea broadcast and incorporated at hilling followed by nine fertigation applications of 25 lbs N/ac each; ESN full rate, ESN low rate, and ESN high rate are broadcast and incorporated at hilling; the low and high-rate ESN treatments were 350 lbs N/ac plus or minus 8% in 2018 and 15% in 2019; ESN + fertigation is 75% of total N (225 lbs N/ac) or 50% of total N (150 lbs N/ac) as ESN broadcast and incorporated at hilling followed by the remainder in three or six, respectively, fertigation applications of 25 lbs N/ac each. Source: Miller Research, Burley, ID.
Potatoes require careful management of relatively high nitrogen (N) rates. They are a shallow-rooted crop often grown under irrigation on sandy soils with potential for nitrogen leaching beyond the root zone. Typical N management usually includes multiple in-season applications to assure proper timing and amounts of N. ESN has repeatedly been shown to produce greater potato yields with fewer applications, reduce N leaching, and increase profits. This Idaho study demonstrates ESN’s value and flexibility in saving applications while producing top yields and profits.
ESN maintained top yields and profits with fewer applications either as a single application or when combined with fertigation.
One ESN application at emergence produced yields comparable to the standard fertigation program.
Combinations of ESN with in-season fertigation produced yields similar to one-time ESN application and the standard fertigation program.
Combination of 50% of N as ESN with fertigation produced the greatest grower profit, which was $24/acre greater than the standard fertigation program based on a typical grower contract.
