As harvest attracts in close proximity to, farmers are also looking ahead to the 2022 crop calendar year. With that will come selections about nitrogen prices for corn. Exactly where drought-diminished corn yields, there are concerns on nitrogen carryover where by 2022 corn will follow 2021 corn. I will begin by conversing about nitrogen prices exactly where there is a reasonably ordinary 2021 corn harvest, or in which 2022 corn will abide by soybean and then address potential nitrogen carryover.
An exceptional resource to assistance farmers make nitrogen selections is the Iowa Condition University Corn Nitrogen Price Calculator. The person tells the instrument the area place, the rate of nitrogen fertilizer and the value of bought corn, and the resource responds with the most rewarding rate of nitrogen to utilize calendar year-in and year-out it will also offer a assortment of nitrogen premiums that will be within $1 for each acre of the most rewarding level. The Iowa calculation is centered on hundreds of nitrogen price reaction trials finished at many locations more than numerous years.
Iowans will note that they can pick remaining in southeast Iowa or getting in the rest of the point out. Investigation showed that on the poorly and very badly drained soils in southeast Iowa, slightly greater nitrogen rates are needed when when compared to the relaxation of Iowa. Those in southeast Iowa with better-drained soils could want to use the rates advisable for the remainder of Iowa. Additional element is in the ISU article Nitrogen Use in Corn Creation.
Generally, farmers will know the value of nitrogen but not the marketing rate of corn, so there is the skill to use numerous rates. An software at a amount where the worthwhile ranges overlap will supply income within $1 for every acre of maximum gain from nitrogen fertilizer, irrespective of corn value at the finish of the time.
Charge without a gain
There is a temptation to implement further nitrogen “as insurance coverage,” in case the early expanding period is specially wet, and nitrogen is missing. In most yrs, that extra nitrogen is a price tag without the need of a reward and serves only to incorporate nitrate to h2o jogging down the Mississippi River. Perform by John Sawyer at Iowa State College indicates that checking complete rainfall by means of the months of April, May well, and June (in all but southeast Iowa) will offer steering for supplemental nitrogen conclusions. If the whole rainfall for that three-month interval exceeds 15.5 inches, farmers must think about including about 50 models of supplemental nitrogen fertilizer in extremely early July and if rainfall quantities are much less than 15.5 inches, enough nitrogen should continue being in the soil. Following that guideline will be the right training course of action just about 80% of the time. The remaining 20% of the time is divided practically evenly amongst placing on nitrogen when it is really not desired, and not putting on nitrogen when it would have been valuable. For southeast Iowa, the “set off” is 17.8 inches of rainfall throughout the 4 months of March, April, May possibly and June.
Farmers who are worried about nitrogen losses may want to use the Late Spring Soil Nitrate Take a look at to validate either the existence or absence of enough nitrogen for the crop. The LSNT is taken when plants are 6 to 12 inches large at the whorl. If the examination demonstrates that nitrogen is lacking, a sidedress software can be produced. Specifics can be located in Use of the Late-Spring Soil Nitrate Test in Iowa Corn Production.
If the corn yield was dramatically affected by drought ailments, then nitrogen uptake was lowered and unused nitrate-N could be accounted for in deciding the nitrogen fertilization charge for the 2022 corn crop pursuing a 2021 corn crop. Even so, don’t forget that if tumble and/or spring precipitation is effectively over usual, or if soils are coarse, carryover nitrate is unlikely.
Estimating carryover nitrogen
There are two methods to estimate carryover nitrogen in the drop. The direct process is to sample the soil profile just after harvest and measure the nitrate-N focus. The next method is to estimate carryover nitrate-N based mostly on 2021 corn grain yield. However, Sawyer and Antonio Mallarino propose constantly applying a minimal of 50 models of nitrogen for each acre.
Spring soil profile sampling for nitrate-N is an possibility that removes some of the decline fears following the tumble and wintertime. Details on these methods can be discovered in this ISU report by Sawyer and Mallarino.
In the long run, the most rewarding use of nitrogen fertilizer can be reached by applying the Corn Nitrogen Amount Calculator and then using the Late Spring Soil Nitrate Exam and monitoring spring rainfall amounts to determine if supplemental nitrogen should be utilized. Where 2022 corn will adhere to a drought-diminished 2021 corn crop, residual nitrate may well lessen nitrogen software needs if slide and spring rainfall is usual or down below-ordinary.
Schmitt is an Iowa Point out College Extension subject agronomist.