Cost-Effective Farming: Advantages of Variable Rate Applications

Variable rate technology is becoming more commonplace in the ag community, yet the adoption rate is still relatively slow. Farmers and agronomists are realizing that a soil-based foundation layer like SWAT MAPS is critical for success. As a result, the industry is seeing a transition from square grid-based sampling to more accurate soil-based zone sampling that matches the actual field landscape variability.

Understanding Variable Rate Applications
Variable rate refers to the practice of adjusting the rate of input applications based on specific variables such as soil type, soil nutrient supply, and crop nutrient requirements. By mapping and understanding the variability of these attributes within your field, you can take advantage of the technology to apply inputs at the right rate and in the right place.

SWAT MAPS provides the framework to collect data about a field which is used by an agronomist to determine the optimal rate of seed and fertilizer for each area of a field. This targeted approach ensures that resources are used efficiently and reduces the risk of over- or under-application.

The SWAT MAPS Difference
Soil, Water, and Topography (SWAT) MAPS are high-resolution soil foundation maps used to execute variable rate fertilizer, seed, soil amendment, pesticide, or precision water management. They are created using a patented process and each map is made up of ten different management zones, called SWAT zones. Using SWAT MAPS gives you the ability to address variations in soil nutrient levels and plant available water across your fields. By adjusting the rate of seed and fertilizer application based on these variations, you can ensure that each area of the field receives the necessary nutrients for optimal crop growth. These precise resource allocations can lead to improved crop yields and reduced environmental impact.

Optimized Input Allocation
These days, farm input prices are very high, so it is becoming even more critical to not waste them. By applying these inputs in varying amounts based on soil, water, and topography characteristics, you can optimize your input allocation (see Figure 1). This leads to increased efficiency, reduced waste, and cost savings, making it an essential tool for economic and environmental sustainability.
For example, in figure 1, populations are based on the soils’ ability to support a given corn population due to varying water holding capacity. Nutrients like potash, phosphate, and zinc are applied at higher rates in zones 1 to 4 where the soil supply is low. Nitrogen rates are highest in zones 3-6 where expected yield is high and soil N supply is expected to be relatively low.

Figure 1. SWAT MAPS recommendation report showing different seed and fertilizer rates for different zones. Multiple applications are shown on a single report for demonstration purpose.

Soil Potential + Genetic Potential
Matching corn populations to the soil potential – a combination of nutrient supplying power and water availability – is a powerful tool to make the most of your hybrids’ genetics. There’s no value in pushing high populations in a part of the landscape that can’t support it, but in areas that can…take advantage of that potential!

In beans, matching populations to expected growth habits can proactively help manage diseases like white mold. Populations can be reduced in high growth potential zones to mitigate excessive canopy cover, and increased in areas where they struggle with row closure!

Environmental Sustainability
Excessive application of nutrients can lead to nutrient runoff in water bodies, causing harmful algal blooms and negatively impacting aquatic ecosystems. However, by implementing variable rate applications, you can ensure that your fertilizer is only applied to the necessary SWAT zones and at the right rates, reducing the risk of nutrient runoff and minimizing environmental impact.

SWAT MAPS products can also help conserve water resources. By analyzing soil moisture data and adjusting irrigation scheduling accordingly, you can optimize irrigation water use using variable rate irrigation technology.

If you would like to further discuss how variable rate might benefit your farm specifically, please connect with us at support@swatmaps.com.

How Do I Choose the Right Variable Rate Program?

Chris Hawkins
Director of Sales – Farmer Services

In agriculture today where risk is high and profit margins can become quite thin, variable rate (VR) application programs have emerged as indispensable tools. They allow farmers to optimize input use, enhance crop yields, and maximize profitability, while at the same time minimizing environmental impact. However, with many VR programs and service providers available, farmers face the challenge of selecting the right system for their unique needs.

Here are some essential factors that farmers should consider before deciding on a VR program and service provider:

1. Establish Your Objective: There are many reasons why farmers utilize VR application. Increased yield, better pesticide application timing, and improved harvestability are just a few. Decide what problem you are attempting to solve with VR on your farm and find a service provider who will work with you to accomplish that.

2. Hardware Compatibility: Of course, you will need to make sure your own equipment is capable of, and ready to, apply VR prescriptions. Check with your equipment dealer on that. If it is “ready”, make sure your service provider can write prescriptions that will be compatible with your hardware because prescription files often need to be written specifically to match various types of controllers.

3. Field Variability (Zones): Many factors can influence variability within a field, and we have tools today to make field zone maps based on ALL of those factors at once (ie. satellite imagery, yield monitors, etc). Generally, these are a good view of “what” variability exists at a specific time (both spatial and temporal variability). However, great VR programs build zone maps based primarily on spatial factors such as soil, water dynamics, and topography (see figure 1). These stable characteristics are an ideal foundation for understanding “why” variability exists in any season.

Figure 1. SWAT MAP built primarily from spatial field characteristics.

4. Ground Truthing and Zone Sampling: Make sure your service provider incorporates ground truthing when building the zone maps for your VR program. Ground truthing is the process of comparing what an agronomist sees in a field with their own eyes to the field data that was collected. In this way, the most accurate map possible is chosen as a template for soil sampling. A proper variable rate program includes soil analysis from the same points each year by zone so the agronomist can make precise recommendations based on nutrient changes from year to year.

5. Scalability: Consider whether the VR service provider can scale with your operation as it grows. The best service providers are innovative and grow with you as they develop and incorporate new technology into their existing programs making their clients even more profitable. In figure 2 below you can see just one example of such technology. SWAT CAM can help to significantly reduce pesticide costs.

Figure 2. SWAT CAM crop and weed imaging system. Photo: Croptimistic Technology Inc.

6. Ease of Use: Development of a good variable rate program can be quite complex, however for the farmer, it should be relatively easy to use. The service provider should handle the complexity so you can focus on other aspects of your farm.

7. Support and Training: Assess the level of support and training provided by the service provider to ensure successful implementation and troubleshooting. Support should be accessible especially in the peak seasons of work. The company should have both live people to speak with as well as online support.

Figure 3. SWAT SUPPORT portal for learning and support.

8. Cost/Benefit: When analysing cost/benefit of a variable rate program, look beyond just one year. Sometimes the upfront cost of VR systems may be higher in the first year, but significantly lower in the following years. Further to that, Return on Investment (ROI) is tricky to measure because it is farm specific. It's easy to look at yield alone because that's tangible. However, yield is influenced by many different factors so it should not be the sole measuring stick for the value of a VR program. There are other intrinsic benefits to consider, such as operational efficiency and grain quality. It's very difficult to measure the value of spraying your fungicide at just the right time, or minimizing lodging, but the value needs to be acknowledged.

9. Reputation: Look for a system that offers high accuracy and precision in data collection, analysis, and application. Research the reputation and track record of the service provider, including their experience in the precision agriculture industry. Seek recommendations from other farmers or agricultural professionals to gain insights into their experiences with the system and service provider.

10. Regulatory Compliance: Ensure the program complies with local regulations regarding pesticide and fertilizer application, data privacy, and environmental concerns.

In conclusion, choosing the right variable rate program and service provider is an important decision that can significantly impact the success of your farm. By carefully considering factors such as map development and soil sampling process, scalability, ease of use, support and training, cost/benefit, reputation, and regulatory compliance, you can make informed choices that align with your goals and objectives.

If you would like to learn more about our VR program which uses SWAT MAPS technology, or any of our new innovations (such as SWAT CAM), please connect with us at sales@swatmaps.com. Or you can find more information on our website at SWATMAPS.com.

SWAT Partner Announcement: Midplains Ag

Midplains Ag, a full-service precision ag consultation and risk management group located in Northeast Nebraska, has recently joined the SWAT MAPS service provider network to offer the world’s premier soil foundation map.

The company was founded in 1983 and has been building a network of farmers located in Antelope, Boone, Holt, Howard, Merrick, Greeley, and Wheeler Counties in Nebraska. Owner Richard Uhrenholdt believes that offering SWAT services that base management zones on soils and topography is the right approach that will allow clients to invest in a long-term plan for soil health.

“We understand the issues that farms face daily and we work closely with our clients to ensure we are collecting and analyzing valuable data that will greatly affect how they make decisions,” said Uhrenholdt. “Utilizing the SWAT ECOSYSTEM will allow us to confidently recommend the next best steps based on what we see happening in the soil.”

The SWAT service offerings will be an addition to Midplains Ag current full spectrum precision ag offerings that include drone aerial imagery, crop spraying, cover cropping, scouting, soil and crop analysis, irrigation analysis, and yield data.

Join us in welcoming Midplains Ag to our elite network of SWAT MAPS Service Providers by visiting their website and following them on social media:
Website - https://midplainsag.com/
Facebook - www.facebook.com/midplainsag
Richard Uhrenholdt LinkedIn - https://www.linkedin.com/in/richard-uhrenholdt-a8689772/

How to Implement the SWAT MAPS Yield Potential Program to Maximize Your Potential and Cut Costs

Hana Ruf
Regional Manager, East Central SK
hana@swatmaps.com

SWAT MAPS variable rate technology is the first step in maximizing efficiency and productivity through fertilizer, seed, and soil amendments. Once a farm has been fully mapped and the client and their agronomist feel they have a solid fertility plan, they might be wondering what else they can do to improve their practices. The Yield Potential Program (YPP) is for SWAT MAPS clients who want to take their VR potential to the next level. Included in the YPP are unlimited in-season prescriptions, yield analysis, and SWAT CAM.

Unlimited In-Season Prescriptions

Unlimited in-season prescriptions can be made using the SWAT MAP itself, SWAT CAM maps, or NDVI satellite imagery. There are many uses for in-season prescriptions such as on/off or VR fungicides, herbicides, insecticides, plant growth regulators, top dressing, and desiccation/pre-harvest.

Figure 1 is an example of an on/off fungicide prescription that was applied by a ground sprayer using an NDVI map. In this case, areas of the field had minimal crop growth due to dry conditions and sandy soil, and in other areas due to high salinity. The fungicide was turned off in these areas (zones 8-10 on the NDVI map), saving the client $538 on this 150 acre field. If these in-season prescriptions were used across 5,000 acres and fungicide was turned off 20% of the time, in places where it is not needed, the savings alone would pay for the cost of the YPP subscription ($2/ac).

Figure 1. In-season prescription for on/off fungicide for a 150 acre canola field. Prescription is on the left, and resulting application map is on the right.

SWAT CAM

SWAT CAM maps are most often used for top-dressing and herbicide applications. One example of an easy way to save money using SWAT CAM is to target kochia with products such as Authority® (sulfentrazone) or Edge® (ethalfluralin). Figure 2 demonstrates a prescription that was used for an on/off Edge application based on both the SWAT MAP and the kochia map. The Edge is turned on in zones 7-10 on the SWAT MAP, as well as in any places where the SWAT CAM identified kochia plants to ensure good coverage. The Edge was turned off for 74.7% of this 160 acre field, saving $3935.

The SWAT CAM is also very useful for helping identify issues in a field such as nutrient deficiencies or drill issues. It is a useful tool for directing scouting efforts and checking on “problem” areas of a field. A quick reference to a SWAT CAM photo in a saline zone 10 can indicate how well the crop is growing there, and if you should adjust your seed or fertilizer rates there in future. The SWAT CAM provides clients and agronomists with unbiased, high resolution plant stand counts for canola, corn, soybeans, and potatoes. Future adjustments to seed rates can be made based on these plant stand counts.

Yield Data

As agronomists, we consider many factors when deciding what fertilizer rates to apply in each zone on a field. We use the SWAT MAP, soil tests, and general knowledge about the field and region to ensure we are not over or under applying seed or fertilizer. As a result, we see many benefits such as increased fertilizer efficiency, reduced lodging, more evenly maturing fields, and increased profitability. However, we are missing an important piece of the puzzle by not knowing exactly how our decisions within a field are affecting yield and ROI. At the end of the season, we don’t get a “report card” to know where the highs and lows were in a field or on a farm. In the YPP, client yield data is cleaned, analyzed, and used to fine tune our decisions going forward.

YPP provides useful data for each field such as actual yield by zone, yield vs. farm average by zone, multi-year yield % of average by zone, stability maps, and profitability maps and graphs. We have been successfully using these tools to identify where we are both overestimating and underestimating yield potential, whether on a zone scale or entire field scale.

Figure 3 shows a field where we were continuously underestimating the yield potential of the entire field, especially in zones 1, 2, and 10. This was a common trend on this entire farm, so in 2024 we adjusted the yield goals (Table 1.) and fertilizer rates to try and achieve even greater yield in these areas. After a few years of doing this, we can gain confidence in just how much we can push these yields and know what our potential really is. This will allow us to maximize ROI by aiming for our maximum yield potential without overapplying fertilizer to achieve it.

Figure 3. Yield % of Average by zone; 2022 canola actual yields versus target yields by zone.

Table 1. Canola yield goal, actual yield, and adjusted yield goal for example field.

Zone	Acres	Yield goal 2022	Actual Yield 2022	Yield Goal 2024
1	6.9	30	53	55
2	41.8	35	60	60
3	85.3	40	62	60
4	95.3	45	63	65
5	106.7	50	63	65
6	122.3	50	62	65
7	156.9	50	61	60
8	99.4	50	58	60
9	26.6	45	52	55
10	8.6	35	51	50

We might also identify fields or zones in which we are overestimating the yield potential. The field in Figure 4 is a poor yielding field historically and has a very sandy zone 1 and 2. When we looked at the actual vs. target yield for each year, we were always well below our target in these zones and on the field average. We knew the yield was poor in zones 1 and 2 and did adjust the yield goals and fertility for that, but we were still overestimating the yield potential even in years with adequate rainfall. Looking at the yield vs. farm average by zone and seeing how poor this field performs compared to the rest of the farm, we decided since this is a higher risk field we might be better off scaling back the fertilizer and yield goals and allocating that budget to better performing areas on the farm. This will help mitigate the risk and manage inputs properly.

Figure 4. A poor performing field with very sandy zones 1 and 2 that consistently yield lower than the farm average.

Clients can provide their input costs and selling prices to attain profitability maps and analysis through the YPP. This can help us improve margins and increase profitability both in good producing zones and troublesome zones. Zones 6 and 7 in the field in Figure 5 are at 32% of the profit margin (profit margin = profit/income). The yield data analysis provides this information, and then the client and agronomist can determine the “why.” We might be able to use SWAT CAM images to provide us with more information. We can then decide if there is a way to increase these margins. Is the solution in the seed or fertilizer rates? Do we need better drainage? If the profit margin in zones 6 and 7 can be increased by 2%, that would be an additional $30/ac. At 160 acres, that is $4800.

Figure 5. Profit Margin Analysis by Zone for a 160 acre field.

Summary

There are many use cases for the Yield Potential Program. Unlimited in-season prescriptions provide clients with an efficient and cost reducing alternative for applying pesticides. SWAT CAM provides options for directing scouting efforts, diagnosing and assessing issues in a field, and unbiased plant stand counts. The yield analysis component has many benefits which all help to fine-tune seed and fertilizer management and improve profitability.

For more information or to sign up for the Yield Potential Program, call 1-800-421-4099 today!

Using SWAT MAPS to optimize fertility recommendations, reduce crop Inputs, and save $$$

Sean Barath
Precision Agronomist
sean.barath@swatmaps.com

Introduction
Every fertilizer recommendation should start with soil test data. Without soil test data you would basically be making blind recommendations, based on yield goals and crop uptake/removal tables. This is not an ideal method of nutrient planning as you could either over or under apply certain nutrients.

Soil Testing
Composite soil testing (Table 1) can be a good starting point for making fertilizer recommendations for flat rate applications; however, it only captures soil nutrient levels in the mid-slope areas of fields, leaving out important information on soil nutrient levels in depressions or hilltops. Implementing zone-based soil sampling (Table 2) along with the use of SWAT MAPS variable rate seed and fertilizer can help producers get their best ROI on inputs and save money.

Table 1. Example of composite soil sampling test results.

Table 2. Example of zone-based soil sampling test results.

Right away, the zone soil test results in Table 2 show some potential cut back on nitrogen and phosphorus rates in upper and lower SWAT MAPS zones. Zones 1-2 are hilltops where the yield is most limited by low moisture levels, whereas zones 7-10 start getting into yield-limiting levels of salinity. There are already higher soil nitrate and phosphate levels in these areas which will also influence the recommendation for these zones. The zone soil test also sheds some light on other soil factors that the composite sample does not show. The pH levels are elevated in zones 1-2 and 7-10, OM differences between zones are significant and sulfur and zinc levels in zone 1-4 are lower.

Fertility Recommendations

The process of making fertility recommendations based on a SWAT MAP is simply not a button to hit that gives a recommendation. Agronomists are in contact with the farmer early in the fall to discuss any fall fertilizer passes, and then again in the winter for spring plans. In some cases, the grower has a set fertilizer budget to work with, while other growers want a fertility plan more aligned with yield goals and soil test results. Once agronomists have the grower's intended fertility plan, VR recommendations can begin.

Soil test results (Table 2) are the main tool to determine crop demand for a certain yield goal. The soil test is also very useful in determining the soil N supply, including left-over nitrates, organic matter credits, and N credits for cases like previous pulse crops, broken up hay/alfalfa land or previous manure applications. A critical soil test N level of 20 lbs/ac is used. If levels are below this threshold at year end, the crop was potentially starved. If levels are higher than 20 lbs/ac, the crop was supplied with too much N, other factors limited yield and nutrient uptake, or the soil mineralized more nitrate in season that the crop didn't use. When making recommendations, the crop is supplied with enough N for the yield goal while maintaining the 20 lb/ac level at year end. N credits can be tricky as there aren't absolute numbers for the mineralization rate and amount of N coming from the organic matter, pulse crop residue, old hay residue, or manure applications. Organic matter credits can range from 6-8 lbs of N per % OM but can be unpredictable in terms of the above-mentioned practices. When making zone-based recommendations with N credits, the size of credit given can also be based on the landscape position of the field. Zones 1-2 usually have the lowest N credit per % OM as these areas tend to be driest, resulting in less mineralization. In Zones 3-8, credits gradually increase due to higher mineralization potential in lower landscape areas as soil moisture and organic matter content increases. Zones 9-10 can have the highest N credit unless poor health limits microbial activity.

**Figure 1. Nitrogen Recommendation for a 45 bu/ac average canola crop.**

The example SWAT MAPS Field in Figure 1 has soil nitrate levels of 15 lbs to 104 lbs. The zone trend is common, especially after drought years where the zone 1-2's (hills) and zone 7-10's (saline areas) both have high soil nitrate levels where the crop use was low. The organic matter levels range from 4.6 to 6%. The average canola yield goal for this field is 45 bu/ac; however, yield goals per zone do vary based on zone characteristics that limit yield potential. Canola is a heavy user of N, using roughly 3 lbs N per bushel of grain produced. Using the yield goals from Figure 1 would result in crop demand ranging from 105 lbs actual N to 150 lbs actual N. Crop demand is an easy starting point to begin making the recommendation. Total soil supply includes residual nitrates plus N credits from organic matter, minus any losses that may happen and minus the 20 lb/ac year end critical level. Losses are hard to predict but N losses in lower, saturated areas within a field due to denitrification are more likely to happen. There can be leaching losses in sandy areas as well with very wet conditions. Once soil supply is determined, this amount is subtracted from crop demand and the remaining fertilizer requirements are made into a VR report.

In a SWAT MAPS recommendation for P, 15 ppm Olden-P generally is the critical level. Less than 15 ppm is low and zone(s) testing low will receive higher P rates to increase the soil test P level to above 15 ppm. If the soil test level is higher than 15 ppm, maintenance rates are applied to the zone(s) to maintain the soil test levels above 15 ppm. If soil test levels are high, to a point where they become an environmental concern, lower P rates are applied to allow the crop to mine the excess P from the soil. In the SWAT MAPS field example, the soil test in Table 2 shows zones 3-6 are well below the critical level of 15 ppm. These areas are the focus for the VR phosphate application. Zones 1-2 and 7-10 soil test levels are above the critical level and will receive maintenance rates. Depending on yield limiting factors, lower P rates may be applied to allow the crop to mine from the soil. Saline areas and fields that have had excessive manure applications in the past are some examples of where mining soil P instead of maintaining the levels would occur. Table 3 has recommended application rates from AGVISE Laboratories for P based on soil test levels and yield goals. Canola is a heavy user of P, removing roughly 0.9 lbs of P₂O₅ per bushel of canola grown and this needs to be taken into consideration when making P recommendations for canola. The soil test results for the example field in Figure 2 are showing soil P levels down to 8 ppm. According to this recommendation chart and the yield goal, it would need to be 40-45 lbs of actual P₂O₅ just to maintain this soil test level; however, applying higher rates to build the soil P level is a good idea.

Table 3. Phosphorus fertilizer recommendation guide from Agvise Laboratories.

Figure 2 shows an example VR report of the N & P recommendations for the example field. As you can see, the fertility rates do vary significantly depending on zones, soil test data and the overall crop demand.

**Figure 2. Example VR report for SWAT MAPS field.**

Variable rate vs. Flat Rate Applications
You might be wondering how variable rate will give you the best ROI on your inputs and possibly save you some money. The soil test results from Table 1 and Table 2 would result in very different fertilizer applications. A recommendation based on the composite soil test would result in high application rates being applied to the whole field. The zone-based soil test is telling a different story, where there is opportunity to rely on residual N and P levels to supply the crop with part of the fertility demand along with accounting for yield limiting factors like the salinity in Zones 7-10. In Figures 3 and 4, variable rate vs flat rate urea comparison shows how effective SWAT MAPS can be at saving product from over application in areas of the field that don't need the extra fertility.

**Figure 3. Urea VR vs FR comparison for the example field.**

**Figure 4. Phosphorus VR vs. FR comparison for the example field.**

Conclusion
Composite soil testing is a good start when making fertilizer recommendations; however, this sampling method misses important details within areas of a field like nutrient levels, pH differences, salinity, organic matter, etc. Zone-based soil sampling and SWAT MAPS Variable Rate is the most effective way to capture all the variability within a field. In the variable rate vs. flat rate example, the grower would save 37,875 lbs of urea and 19,144 lbs of MAP just by using SWAT MAPS on this field. That is a large amount of product saved and can result in product reallocated to other fields or saved money that can be invested into other areas on the farm. Talk to your SWAT MAPS service provider about how they can help you get the best return on your crop inputs and save money with SWAT MAPS Variable Rate.