Low prescribed nitrogen rates? Dry weather and occasional rain are an opportunity to reduce nitrogen costs
How to understand the rates prescribed by SCAN.AI in FieldApex in 2018
Do the nitrogen rates prescribed by FieldApex’s SCAN.AI seem low to you? It’s normal! Past and future weather is among the key parameters that affect the economically optimal nitrogen rate. The algorithm that prescribes sidedress nitrogen considers the actual rainfalls on your field over the past 15 days as well as forecast weather trends for the next 15 days. It is based on the Abundant and Well-distributed Rainfall (AWDR) parameter.
Low and erratic precipitation in 2018
I’m not telling you anything new when I say that the 2018 season is characterized by low and erratic precipitations. Thus, the AWDR parameter is unusually low this season. This significantly lowers the nitrogen rates required to come closer to the economically optimal rate, which is the rate that allows you to achieve maximum profits from your cornfields.
Here is the cumulative rainfall over the past 15 days in different territories (as of June 14):
- Ottawa, Ontario: 58 mm
- London, Ontario: 31 mm
- Beauport (Québec City), Quebec: 64 mm
- Sainte-Anne-de-Bellevue, Quebec: 40 mm
This volume is exceptionally low and irregularly distributed, with rainfall concentrated over two- or three-day periods. As for expected precipitation in the foreseeable future, Environment Canada anticipates that it will be low.
Save nitrogen this year to better invest in the years when it matters
Given these weather conditions, 2018 is particularly appropriate to start keeping your fertilization costs under control by considering the impact of seasonal weather.
« The dry weather in 2018 could save you a lot by reducing your need for nitrogen fertilizer. »
To reduce nitrogen consumption, two aspects are key. To begin with, use a sidedressing approach. Next, use an artificial intelligence algorithm such as FieldApex’s SCAN.AI. This method is far more effective than using slow-release fertilizer that consider a single weather standard regardless of actual precipitation. In addition, quantities applied in excess are lost to the environment at the end of the season.
However, an algorithm like FieldApex’s SCAN.AI helps maximize the chances of optimizing gains, because it adapts to the reality of each farmer in Ontario and Quebec. For example, in the current seasonal context, the AWDR parameter alone can make the nitrogen rate vary by up to 100 lbs/acre. However, for more safety, the algorithm includes a factor that restricts extreme rate variations from year to year.
Is it normal to have a rate that is 70 lbs/acre lower than the usual rate?
Did FieldApex recommend a rate much lower than usual, possibly about 70 lbs/acre less? It’s possible! Many myths remain surrounding the management of nitrogen. For a long time, rates were established according to the nitrogen balance, considering the input minus the output, or by aiming at maximum crop yields.
However, only a fraction of the nitrogen present in the soil remains available for the plants. Rather than considering the nitrogen balance, it is more appropriate to consider nitrogen availability. SCAN.AI precisely plays this role, namely to calculate the quantity of nitrogen to be applied according to the seasonal and agronomic particularities of each of your fields. As for crop yield, remember: FieldApex is not about achieving maximum yield, but rather about achieving maximum profit.
Adopting a progressive approach
FieldApex’s SCAN.AI algorithm gets close to the in-season economically optimal nitrogen rate without necessarily reaching it altogether. The algorithm does a good job, but you would better adopt a progressive approach in case of significant deviation from your usual practice. For example, if SCAN.AI prescribes a rate that is 70 lbs/acre lower than your usual rate, it would be appropriate, as part of a first use of FieldApex in this field, to give you a little extra safety margin, for example by reducing the rate by 35 lbs/ha instead of 70 lbs/acre. However, beware! If your safety margin is too high, you will also limit your potential for economical gain. Success comes by using the algorithm on several fields, because it is on average that SCAN.AI performs best and not so much with a single field.
Different prescriptions for different conditions
The economically optimal rate varies based on the season and the field. For example, next year, FieldApex SCAN.AI may prescribe a rate higher than your usual rate, if the season is very rainy, and precipitation is constant from day to day. Some soils with poor aggregate structures, compaction or excess water could in other cases cause SCAN.AI to prescribe insufficient nitrogen rates, because it takes a good soil condition for granted. In this respect, the imagery provided by FieldApex is a valuable tool that will allow you to better understand your fields and make the necessary corrections. We had a few delays in implementing the imagery in FieldApex, but no worries, it will arrive in June.
Agronomists and farmers at the core of the decision-making process
FieldApex’s SCAN.AI is an exceptional tool for adapting nitrogen rates to your corn fields. It can be immensely useful in helping you understand the needs of your fields over the years. However, agronomists and farmers should use their own judgement regarding the recommended rates. Like all other methods, the algorithm may recommend excessive or insufficient fertilization. Nevertheless, FieldApex remains the only validated, easy-to-use tool to come ever closer to the economically optimal rate over the years.
Validating the optimal nitrogen rate based on your actual yields at the end of the season
At the end of the season, FieldApex will provide a small calculator so that you can validate the most profitable rate based on your actual yields. Remember, FieldApex’s SCAN.AI aims to reach not so much maximum yield as maximum profits.
Have a great 2018 season,
Nicos Keable-Vézina, Agr. MBA
Director, Precision Agriculture