Lessons (Ghosts) of Droughts Past

From Alberta to Iowa, the region has experienced everything from abnormally dry soil conditions to exceptional drought. In some places, the drought started in 2020 and has continued through 2021. Considering lower than expected crop yields, we expect that residual soil nitrate-nitrogen levels will be much higher than normal in many wheat, canola, and corn fields this fall. There was reduced crop nitrogen uptake and little to no soil nitrogen losses to leaching or denitrification through the growing season, which should result in higher soil test nitrate-N remaining in the soil profile.

In major drought years, high residual nitrate levels are a normal phenomenon. In 1988, the average soil nitrate test following wheat across the region was a staggering 107 lb/acre nitrate-N (0-24 inch soil profile). This is considerably higher than the long-term average around 30-45 lb/acre nitrate-N (0-24 inch soil profile). The 1988 drought was extreme, and 2021 has rivaled that in some locations. Based on previous drought years, it will be no surprise to find wheat fields with 80-100 lb/acre nitrate-N (0-24 inch soil profile) or even higher.

Past experience also shows us that drought can create greater crop yield variability across fields. Some zones in the field with better water holding capacity and soil organic matter may have produced a decent crop yield, and these will have lower residual soil nitrate-N. Yet, other zones may have had very poor crop growth and yield, leaving very high amounts of soil nitrate-N remaining.

Zone soil sampling is always a good idea, but it is especially important in drought years. Soil sampling based on productivity zones is the only way to determine the correct amount of nitrogen fertilizer in each zone across the field. To create good productivity zones for soil sampling, it is best to use multiple data layers such as satellite imagery, crop yield maps, topography, or electrical conductivity (Veris or EM38).

This fall, we expect residual soil nitrate-N to be higher than normal, but there will be exceptions to the rule. Last spring, there was a lot of broadcast urea fertilizer applied without incorporation. If no rain was received for several weeks after application, much of the nitrogen could have been lost to ammonia volatilization. This means some fields will seem out of place with lower residual soil nitrate-nitrogen because fertilizer nitrogen was lost last spring.

For fields with more than 150 lb/acre nitrate-N (0-24 inch soil profile), the crop nitrogen requirement for next year may not call for much, if any, nitrogen fertilizer. We must remember that drought creates variability within a field and even within large productivity zones. This is why we always suggest applying a base amount of nitrogen fertilizer to address the variability, even if the soil nitrate test is more than 150 lb/acre nitrate-N. A base nitrogen fertilizer rate (maybe 20 to 40 lb/acre N) should address most of the field variability and provide a fast start to the next year’s crop. In 1988, we learned the tough lesson that applying no nitrogen fertilizer on fields testing very high for nitrate-N was a mistake, and the best producing parts of fields had early-season nitrogen deficiencies. A modest base nitrogen fertilizer rate was the right decision to cover field variability.

Three Simple Lessons from Droughts Past

  1. Soil test all fields for residual soil nitrate-N. There will be considerable variability from field to field and even zone to zone.
  2. The residual soil nitrate-N test allows you to reduce nitrogen fertilizer rates for next year, saving money on crop inputs for 2022.
  3. Remember to apply a modest base nitrogen fertilizer rate on fields testing very high in nitrate-N to address field variability. You will want to get next year’s crop started right.

Save Time and Avoid Mistakes by Using AGVISOR to Submit Soil Samples Online

AGVISE Laboratories is always trying to make soil sampling easier. Since 2011, AGVISE customers have enjoyed submitting soil samples online through our AGVISOR platform. AGVISOR is the online platform that allows you to submit soil samples (conventional, grid/zone, and soybean cyst nematode samples); save grower and field information (so you don’t have to fill it in by hand on paper forms); and set default crop fertilizer guidelines. With online submission, you simply submit the sample information online and print barcode reference number stickers to place on each soil sample bag (like below). There is no more handwriting on soil sample bags or forms anymore!

Picture of samples with online sticker labels for AGVISOR article

With the online AGVISOR platform, organizing your sampling operation is easy. You can save time by submitting soil samples ahead of time and printing reference number stickers before the fall soil sampling rush begins. If you are working with a third-party sampler, you can submit samples online and then email a PDF of the barcode reference stickers to the sampler, allowing them to print the stickers at their location.

In addition to submitting samples online, the AGVISOR platform allows you to view, print, and save soil test reports. This means you can save soil test reports and send them as PDFs to growers. AGVISOR also allows you to change crop choice, yield goal, and fertilizer guideline type (broadcast vs. band). The flexibility of the platform makes it easy to keep up with changes that inevitably happen in farming.

If you have any questions on how to access AGVISOR or need help navigating the online submission and results platform, please give one of our Laboratories (Northwood 701-587-6010; Benson 320-843-4109) a call and our technical staff will be happy to help you.

How Much AMS Does Your Spray Water Need?

AGVISE Laboratories Spray Water Analysis

Hard water is a fact of life for those of us in the northern Great Plains and Prairie Provinces. It is why our homes have water softeners, why our well water tastes funny (or delicious), and one reason we need to add AMS (ammonium sulfate) or UAN to our spray tanks to optimize weed control.

When we talk about conditioning “hard water” for herbicide applications, we are preventing dissolved salts (calcium, magnesium, sodium, potassium, and iron) in water from antagonizing, or binding, the pesticide we’re putting in the tank. Dissolved salts bind to weak-acid, salt-formulated pesticides and reduce their efficacy (e.g. glyphosate [RoundUp], growth regulators, ACCase inhibitors [Select, Axial, etc.], ALS inhibitors [Pursuit, Express, etc.], HPPD inhibitors [Callisto etc.], and glufosinate [Liberty]).

A water conditioner like AMS prevents salts in spray water from binding to pesticides. AMS is most often recommended at rates from 8.5 to 17 lb/100 gal spray volume on herbicide labels. This is a wide window, however, and handling dry AMS can be a pain. So, how do you know how much AMS you should add to the tank to overcome antagonism?

A spray water analysis!

An example of an AGVISE Laboratories spray water report

AGVISE Laboratories provides fast and convenient analysis of spray water used for pesticide applications. The Spray Water Analysis package includes calcium, magnesium, sodium, iron, pH, salt, hardness, and SAR (sodium adsorption ratio). The spray water report uses NDSU data to determine the recommended amount of AMS required per 100 gallons of water to overcome antagonism. You will want to test each water source you use for pesticide applications. This information can help avoid problems throughout the spraying season.

Give us a call in either Benson, MN, or Northwood, ND and we will send you a water sample kit. Each kit contains a water collection jar and a sample information sheet. Water sample tests are completed within a week and results are emailed to you, so you have information on your water source right away.

Don’t let salts take away from your weed control this summer – get your spray water tested!

2021 Plant Nutrient Deficiency Troubleshooting Project

Plant analysis is a valuable tool for managing plant nutrients and troubleshooting agronomic problems. Being certain that a specific plant nutrient is causing deficiency symptoms is difficult with visual symptoms alone. Many causal agents unrelated to soil fertility can cause symptoms that appear to be nutrient-related. There are also some plant nutrient deficiencies that are impossible to determine visually so we call them a “hidden hunger.” For troubleshooting situations, you will need a pair of good and bad plant samples, along with good and bad soil samples, to discover the real answer to what is happening in the field (nutrient deficiency or something else).

To help you troubleshoot problem areas and get familiar with plant analysis, AGVISE Laboratories is sponsoring the Plant Nutrient Deficiency Troubleshooting Project in 2021. We are looking to work with 50 to 100 customers this summer who see apparent nutrient deficiency symptoms in one of their fields and want to be involved in this educational project. Volunteering in this project will help you figure out if a problem area in a field is caused by a plant nutrient deficiency or something else. If you want to volunteer, contact one of our agronomists or soil scientists in Northwood (701-587-6010) or Benson (320-843-4109) as soon as you have a problem area you want to troubleshoot for this project. Immediacy is key for good data. The results may be inconclusive if you wait to take plant samples 7 to 10 days after symptoms first appear because new problems can arise.

Once you have spoken with one of our staff and described the problem in your field, we will send you the supplies packet to submit good and bad plant samples, as well as good and bad soil samples (0- 6 inch). If you can provide us with good photographs to aid in the problem diagnosis, we will cover the soil and plant analysis fees (two complete tissue analyses and two complete soil analyses; $151.20 USD retail value).

It is important to catch plant nutrient deficiencies early while you still have time to make a rescue fertilizer application. Take advantage of the AGVISE Plant Nutrient Deficiency Troubleshooting Project and solve those problems the right way… right away.

New Address for AGVISE Laboratories Canada Receiving Facility

The AGVISE Laboratories Canadian Receiving Facility has moved across the street from its former location in Winkler, Manitoba. What this means for customers sending samples to our Canadian Receiving Facility:

  • The new address is 380 Kimberly Rd Winkler, MB R6W 0H7
  • If you’ve dropped off samples at the receiving shed in Winkler, the shed is now across the street in the Winkler Construction parking lot
  • We will be changing the address on all future printings of AGVISE documents, such as Purolator shipping labels
  • If you have pre-printed Purolator shipping labels that have the old address (375 Kimberly Rd), you can still use these. The Purolator delivery professional knows where the shed has been moved to. 

If you have any questions, please give us a call at 701-587-6010.

Soil Testing and 4R Nutrient Stewardship

Each year, farmers aim to increase agricultural production and profitability while conserving our land resources for the next generation. These tandem goals drive sustainable soil fertility and crop nutrition decisions on cropland across the world.

In 2005, global fertilizer industry and environmental stakeholders began developing a standard theme to emphasize science-based stewardship in soil fertility and crop nutrition. The theme eventually became known as 4R Nutrient Stewardship, where each “R” referred to the “right” way to manage nutrients for crop production. The 4Rs are summarized as managing crop nutrition with the 1) Right Source, 2) Right Rate, 3) Right Time, and 4) Right Place.

To successfully implement 4R Nutrient Stewardship, you must start with a high-quality soil sample and an informative soil test. To begin, the fertilizer need and amount is determined through soil testing, which is based on regionally calibrated soil test levels for each crop. If you do not have a soil test, how do you know what the Right Rate is? Using crop removal rates or simply guessing without soil testing often leads to overapplication of fertilizer, cutting into profit.

A conventional whole-field composite soil sample (one soil sample per field) is certainly better than no soil sample. It gets you in the ballpark, but it does not detect variation in soil nutrient levels across the field. You might underapply fertilizer on high yielding parts and overapply fertilizer on low yielding parts. To get the Right Rate applied in the Right Place, precision soil sampling, either grid or zone, is the best way to determine the appropriate fertilizer rate and where to apply it in each field. Precision soil sampling is a proven tool to reduce over- and under-fertilization across fields, thus optimizing crop yield and profitability while reducing the potential risk of soil nutrient loss to the environment.

When you start soil sampling and making soil fertility plans for next year, keep 4R Nutrient Stewardship in mind. AGVISE Laboratories is a proud 4R Partner. To learn more about the 4Rs or become a 4R Partner, visit the 4R Nutrient Stewardship website.

Soil Salinity Analysis: Which method to choose?

This submission is courtesy of Dr. Heather Matthees, Research Soil Scientist, USDA-ARS, Morris, MN. It was originally published in the AGVISE Newsletter Fall 2017.

Salt-affected soils are a major problem for agricultural producers, resulting in $12 billion annual losses in crop production across the world. In the northern Great Plains and Canadian Prairies, soil salinity has always existed in some soils of the region, but the problem has become more widespread and severe since a hydrological wet period began in the 1990s.

Salinity is the overall abundance of soluble salts, which compete with plant water uptake and reduce crop productivity. The soluble salts pull soil water toward themselves in the soil solution, which leaves less soil water available for plant uptake. This causes an apparent drought stress, reducing crop productivity and sometimes may kill the plant. Soluble salts are naturally occurring and a product of regional geology in the northern Great Plains and Canadian Prairies. Since the 1990s, the hydrological wet period has raised the groundwater level and allowed saline groundwater to rise toward the soil surface, causing soil salinization. Saline soils are often called “salty,” “sour”, or “white alkali.”

The severity of soil salinity will control which plant species are suitable for crop or forage production. Some crop species like dry bean and soybean are very sensitive to salinity, whereas other crop species like barley and sunflower have good tolerance to salinity. For soils with very high salinity, the only practical forage option may be salt-tolerant perennial grasses. To assess soil salinity, there are two soil analysis methods: saturated paste extraction and routine 1:1 soil water methods.

Saturated Paste Extraction Method

The gold standard in soil salinity research is the saturated paste extraction method. The method requires a trained laboratory technician to mix soil and water into a paste, just reaching the saturation point, which is about the consistency of pudding. The saturated paste rests overnight to dissolve the soluble salts. It is then is placed under vacuum to draw the saturated paste extract. Soil salinity is then determined by measuring the electrical conductivity (EC) of the saturated paste extract.

The saturated paste extraction method is fairly straightforward, but it requires a trained technician, specialized equipment, and over 24 hours to complete the procedure. The procedure is labor intensive and difficult to automate, so it is considered a special analysis service in commercial soil testing. Therefore, it is more expensive than routine soil testing methods. Among soil salinity determination methods, it is considered the most accurate because the soil:water ratio at saturation controls for differences in soil texture and water holding capacity.

Routine 1:1 Soil:Water Method

The routine method for soil salinity assessment is the 1:1 soil:water method, which mixes standard mass of soil (10 g) and volume of water (10 mL) in a soil-water slurry. Soil salinity is then determined by measuring the electrical conductivity (EC) of the soil-water slurry. It is most commonly abbreviated EC1:1.

The method is fast and inexpensive (only 5-10% of saturated paste extraction cost). The low cost per soil sample allows a person to collect more soil samples from various soil depths and multiple locations within a field (e.g. zone soil sampling), which can create a more comprehensive and detailed soil salinity map to evaluate soil salinity presence, severity, and variability. Since soil salinity is so intimately related to soil water movement across the landscape, the soil salinity map also provides information about soil water accumulation and leaching, soil nutrient movement (e.g. chloride, nitrate-nitrogen, sulfate-sulfur), and crop productivity potential.

A general caveat about the 1:1 soil:water method is that the reported values will be lower than the saturated paste extraction method. Fortunately, the two methods are highly correlated. AGVISE Laboratories worked with soil science researchers at North Dakota State University and South Dakota State University to validate the correlation between the two methods using over 2,300 soil samples from the northern Great Plains. You can convert the two methods by multiplying the 1:1 soil:water result by 2.26 to estimate the saturated paste extraction result (Figure 1).

The simple method conversion enables you to quickly and cheaply monitor soil salinity using the 1:1 soil:water method and still utilize the historical soil salinity interpretation criteria based on the saturated paste extraction method.

Figure 1. Soil salinity method conversion between saturated paste extraction and 1:1 soil:water methods.


Matthees, H. L., He, Y., Owen, R. K., Hopkins, D., Deutsch, B., Lee, J., Clay, D. E., Reese, C., Malo, D. D., & DeSutter, T. M. 2017. Predicting soil electrical conductivity of the saturation extract from a 1:1 soil to water ratio. Communications in Soil Science and Plant Analysis, 48(18), 2148–2154.

Quality Control is First Priority for AGVISE

When you receive a soil test report from AGVISE you should expect the best. Since our start in 1976, our first priority has been providing you with the most accurate soil test data. Ensuring proper quality control and quality assurance (QC/QA) takes extra care and dedication from everyone at AGVISE to provide you with the best data possible.

for quality control article

Quality control in sample identification

Quality control in soil testing begins with a unique reference number/barcode on every sample bag. AGVISE will never ask you to write information on your soil sample bags. Deciphering unreadable handwriting is the first place mistakes happen. With the barcoded reference number on each sample bag, we track samples from the moment they arrive, through the analysis process, and when results are entered into AGVISOR, our online soil reporting system. AGVISE has used barcode reference numbers to identify soil samples for over 30 years. Since 2010, we have also offered online soil sample submission. The online submission system is another way to reduce errors because the customer can send the correct data directly to the laboratory. With online submission, there is no worry of misreading handwritten information!

When your soil samples arrive, we scan the barcode sticker and record its unique reference number, confirming it has reached the laboratory. Soil samples are dried overnight and ground the next morning. It is important to homogenize the soil sample through grinding and blending to ensure that what is analyzed represents the entire field, zone, or grid that was sampled.

Quality control in the laboratory

Soil analysis requires skilled technicians and calibrated instrumentation.  Each soil analysis is done following accepted methods for soils in our region and supported by university soil test calibration research.  When a soil test is performed (e.g. nitrate-nitrogen), quality control samples or “check samples” are tested along with customer samples to ensure accuracy and precision. The “check soil” has verified nutrient levels so we know what test value to expect every time. If a check soil value is outside the accepted range, all analysis from that group of samples is retested after the issue is corrected.  A check soil is tested after every ten customer samples. Therefore, ten percent of all soil tests done in the laboratory each day are quality control samples!  This past year, AGVISE used over 2,000 pounds of check soil in our quality control program to ensure you are receiving accurate data to make soil fertility decisions with.

Quality control – Laboratory proficiency and certification programs

AGVISE Laboratories in Northwood, ND and Benson, MN participate in three proficiency testing programs: the National Proficiency Testing program (NAPT), the Agriculture Laboratory Proficiency (ALP) program, and the Minnesota Department of Agriculture Manure Analysis Proficiency program. Our laboratories are also approved by the NAPT-Performance Assessment Program (PAP) and are certified soil and manure testing laboratories by the Minnesota Department of Agriculture. The Benson, MN laboratory is also an Iowa Department of Agriculture certified soil testing laboratory.

The proficiency programs send double-blind samples throughout the year to AGVISE. The samples are tested and results are evaluated by the proficiency programs for accuracy. Approval from PAP means that AGIVSE uses PAP approved methods to conduct soil analyses, which are required for NRCS programs. AGVISE has been involved with the NAPT proficiency testing program since it started in 1983.  As a longtime participant, AGVISE has had committee representatives on the NAPT Oversight Board for many years, striving to make the program better each year.

Quality control has been and will continue to be a priority for AGVISE Laboratories. When you receive a soil test report from AGVISE, you can be sure you are receiving the most accurate data possible.

More information about soil test certification and proficiency programs:

Agricultural Laboratory Proficiency Program (ALP)

Iowa Department of Agriculture Certified Soil Testing Laboratories

Minnesota Department of Agriculture Certified Manure Testing Laboratories

Minnesota Department of Agriculture Certified Soil Testing Laboratories

North American Proficiency Testing Program (NAPT)

Performance Assessment Program (PAP)






Phosphorus and the 4Rs: The progress we have made

The year 2019 marked the 350th anniversary of discovering phosphorus, an element required for all life on Earth and an essential plant nutrient in crop production. Over the years, we have fallen in and out of love with phosphorus as a necessary crop input and an unwanted water pollutant. Through improved knowledge and technologies, we have made great progress in phosphorus management in crop production. Let’s take a look at our accomplishments!

Right Rate

Phosphorus fertilizer need and amount is determined through soil testing, based on regionally calibrated soil test levels for each crop. Soils with low soil test phosphorus require more fertilizer to optimize crop production, whereas soils with excess soil test phosphorus may only require a starter rate. Across the upper Midwest and northern Great Plains, soil testing shows that our crops generally need MORE phosphorus to optimize crop yield (Figure 1), particularly as crop yield and crop phosphorus removal in grain has increased. Since plant-available phosphorus varies across any field, precision soil sampling (grid or zone) allows us to vary fertilizer rates to better meet crop phosphorus requirements in different parts of the field.

For phosphorus and the 4Rs article

Figure 1. Soil samples with soil test phosphorus below 15 ppm critical level (Olsen P) across the upper Midwest and northern Great Plains in 2019.

Right Source

Nearly all phosphorus fertilizer materials sold in the upper Midwest and northern Great Plains are some ammoniated phosphate source, which has better plant availability in calcareous soils. Monoammonium phosphate (MAP, 11-52-0) is the most common dry source and convenient as a broadcast or seed-placed fertilizer. Some new phosphate products also include sulfur and micronutrients in the fertilizer granule, helping improve nutrient distribution and handling. The most common fluid source is ammonium polyphosphate (APP, 10-34-0), which usually contains about 75% polyphosphate and 25% orthophosphate that is available for immediate plant uptake. Liquid polyphosphate has the impressive ability to carry 2% zinc in solution, whereas pure orthophosphate can only carry 0.05% zinc. Such fertilizer product synergies help optimize phosphorus and micronutrient use efficiency.

Right Time

Soils of the northern Great Plains are often cold in spring, and early season plant phosphorus uptake can be limited to new seedlings and their small root systems. We apply phosphorus before or at planting to ensure adequate plant-available phosphorus to young plants and foster strong plant development. In-season phosphorus is rarely effective as a preventive or corrective strategy.

Right Place

Proper phosphorus placement depends on your system and goals. Broadcasting phosphorus fertilizer followed by incorporation allows quick application and uniform distribution of high phosphorus rates. This strategy works well if you are building soil test phosphorus in conventional till systems. In no-till systems, broadcast phosphorus without incorporation is not ideal because soluble phosphorus left on the surface can move with runoff to water bodies.

In no-till systems, subsurface banded phosphorus is more popular because phosphorus is placed below the soil surface, thus less vulnerable to runoff losses. In general, banded phosphorus is more efficient than broadcast phosphorus. In the concentrated fertilizer band, less soil reacts with the fertilizer granules, thus reducing phosphorus fixation, allowing improved plant phosphorus uptake. Some planting equipment configurations have the ability to place fertilizer near or with seed, which further optimizes fertilizer placement and timing for young plants.

For more information on 4R phosphorus management, please read this excellent open-access review article: Grant, C.A., and D.N. Flaten. 2019. J. Environ. Qual. 48(5):1356–1369.

AGVISE Laboratories: Trusted by University and Industry Researchers

While you may know AGVISE Laboratories for the soil and plant analysis services we provide you and your producers, AGVISE also has a long history of supporting university and industry research. For the past 30 years, many university-operated soil testing laboratories have closed in the region. This has left a gap in the on- and off-campus research capacities at some institutions. To help bridge the gap, AGVISE partners with university and industry researchers to provide the laboratory analysis services they need to further research in soil fertility, plant nutrition, nutrient use efficiency, and many other areas. Researchers choose AGVISE for their research projects because of our reliability, consistence, and standard of excellence.

Each year, AGVISE analyzes thousands of soil and plant samples for researchers across the United States and Canada. You may have even heard of some recent research projects for which we provided the analysis services. A unique collaborative project was the Public–Industry Partnership for Enhancing Corn Nitrogen Research, which included eight land-grant universities and USDA-ARS. AGVISE analyzed thousands of soil and plant samples for researchers from the University of Illinois, Purdue University (Indiana), Iowa State University, University of Minnesota, University of Missouri, University of Nebraska, North Dakota State University, and University of Wisconsin. We are proud of our small part in support of this research that provided critical information to corn producers and helping them improve nitrogen management. You can read more about the project in the links below.

Another research project that AGVISE is helping with is the Potato Soil Health Project, supported by USDA-NIFA Specialty Crop Research Initiative (SCRI) and spearheaded by the potato industry. The research project includes eight potato-growing states across a range of diverse soils. In addition to soil fertility analysis, AGVISE is also helping evaluate soil health using biological activity (24-h CO2 respiration), active carbon (POXC), bioavailable nitrogen (ACE), and soil aggregate stability. AGVISE Laboratories is a strong supporter of soil health research, and we are excited to have been chosen to provide soil health analyses for the research project.

In addition to these large research projects, AGVISE also provides analysis services for many research organizations and universities throughout the region, including Agriculture and Agri-Food Canada, University of Manitoba, Montana State University, University of Saskatchewan, and South Dakota State University.

The next time you send your soil or plant samples to AGVISE Laboratories, you can be confident that you will be receiving the highest quality analyses and service, just like we provide to researchers across the United States and Canada.

Some open-access articles from AGVISE-supported university research projects

A Public-Industry Partnership for Enhancing Corn Nitrogen Research and Datasets: Project Description, Methodology, and Outcomes

When to Use a Single or Split Application of Nitrogen Fertilizer in Corn

Which Recommendation Tools Are Best for Achieving the Economically Optimal Nitrogen Rate?

The Potato Soil Health Project funded through USDA-NIFA SCRI