It’s important to note that soil sampling and testing are excellent tools to assess nutrient levels in your fields. That information sets the stage for smarter fertilizer planning in the spring. It’s also relevant that fewer than 20 per cent of fields in Western Canada are sampled each year. To me, that’s a huge missed opportunity to understand your soil and build a solid fertilizer plan.

When to soil sample

Ideally, sampling in early spring gives the most accurate measurement of soil nutrient status for spring-seeded crops. However, springtime is often too short and rushed to allow proper analysis and developing your fertilizer plans. So, if soils are moist, late fall (after soil temperature has dropped to 5-7 C) is often the most practical time. If soils are very dry, sampling in early fall is fine.

Nitrogen, phosphorus and sulphur levels can fluctuate from fall to spring, especially in moist soils with warmer-than-normal winters. Variations in nutrient levels from fall to spring are more likely in the Chinook regions of the southern Prairies. I don’t recommend sampling frozen soils during the winter simply because of the difficulty in obtaining representative sampling depths.

Further, I encourage farmers to go out with the person doing the soil sampling on their farm. It allows you to develop a good sense of how soils vary across fields and to see where samples are taken to ensure representative sampling. When you are with the sampler, you know where and how the samples were taken.

What are the options for sampling?

Many fields across the Prairies have moderately rolling topography, resulting in soil variability across the landscape. This can pose a challenge in deciding how to take representative soil samples. Samples must be representative of the field or each soil/crop management zone of a field. Work with your fertilizer dealer or agronomist to help you decide how to sample each field.

Briefly, here are a few ways fields can be soil sampled:

Random sampling of a whole field: Works best in fields with relatively uniform soil and topography. It involves taking representative soil samples throughout the entire field, but make sure to avoid unusual areas.

Sampling soil/crop management zones: Works best in fields with variable soil and topography. Uniquely different zones are mapped based on soil characteristics, topography, and/or crop yield potential. Representative soil samples are taken within each management zone. This method works well in fields with variable soil. Each management zone can be randomly sampled or benchmark sampled (see point 3). Work with an experienced agronomist to map each soil/crop management zone carefully.

Benchmark soil sampling: Involves sampling a one-to-two-acre area that is representative of most of the field or soil/crop management zone. Each year, the same area is soil sampled. When a field is variable in soil or topography, three or more benchmark locations may be needed to account for that variability.

When selecting soil/crop management zones with your agronomist, make use of crop yield maps, aerial photos, topographic maps, soil salinity maps and/or satellite imagery information. Also, use your personal field knowledge and observations of crop growth differences (crop establishment, vigour, colour, and growth) and landscape/topography of each field to identify where different soil types occur.

Number of sampling sites

I suggest taking samples from a minimum of 20 sites for each field, soil/crop management zone or benchmark area. Les Henry used to suggest 30 sites, which is even better. The more sampling sites taken, the more representative your samples will be of the field.

A common mistake is only taking six or seven soil cores from a field or management zone, which is not enough and may result in unreliable information for your fields and the development of inaccurate fertilizer recommendations. Why? Typically, each soil sample sent to a soil testing lab weighs about two lbs. One acre of land, six inches deep, weighs about 2,000,000 lbs. If a 160-acre field is soil sampled to a six-inch depth, a two-lb. soil sample must represent about 320 million pounds of soil. The soil sample would represent less than one-millionth of the field. So, it is critically important that an adequate number of soil cores be taken!

Choosing depth increments

There are various recommendations for sampling depth. My preference is to separate each soil core into depth intervals of zero-to-six, six-to-12 and 12-to-24 inches (0-15, 15-30 and 30-60 cm) and place the three sampling depths into three clean plastic pails. Do not use metal pails! Do this at each site sampled. Many agronomists suggest zero-to-six- and six-to-24-inch (0-15 and 15-60 cm) depths, which is easier and faster but does not give as useful information on nutrient stratification.

Most research on nitrate and sulphur in Western Canada’s annual crops has been based on sampling to 24 inches. Sampling in three depth increments gives a clearer picture of how these nutrients are distributed through the soil profile.

Phosphorus and potassium are less mobile, so keep the zero- to six-inch depth sample separate.

After the 20-plus soil cores are taken, thoroughly mix each composite sample and lay out the soil samples to completely air dry to stop nutrient changes. If moist soil samples are sent directly to the lab in sealed bags, soil microbes can alter the levels of plant-available nitrogen, phosphorus and sulphur, causing incorrect estimates of soil nutrient levels. If samples are sent directly to the lab in a moist condition, they must be shipped in coolers and kept below 5 C and arrive at the lab the next day for drying.

Sample analysis

The key macronutrients to test for are nitrogen (N), phosphorus (P), potassium (K), and sulphur (S). Measure N, P, K, and S in the zero-to-six- and six-to-12-inch depths, and N and S in the 12-to-24-inch depth. For most soils in Western Canada, testing for calcium (Ca) or magnesium (Mg) isn’t usually necessary, since these nutrients are rarely deficient.

It is a wise idea every few years to check levels of soil micronutrients copper, iron, manganese and zinc. Testing for micronutrients every year is only necessary if one or more micronutrients are in the marginal or low range; otherwise, testing every few years is fine.

It is important to note the tests for boron and chloride are not reliable, so I do not recommend testing for them. The problem is with the soil test methodology and critical levels used, which often result in unnecessary fertilizer recommendations.

Checking organic matter, pH and soil salinity is worthwhile for keeping an eye on your soil. Other tests, like cation exchange capacity, base saturation, or base cation saturation ratios, generally aren’t useful for planning fertilizer. CEC doesn’t change much because it depends on clay content, and base saturation mainly flags soil problems such as sodic soils. Research shows that BCSR adds little value in Western Canada, so you can skip the cost.

Finally, make sure the soil testing lab that does your soil analysis uses the correct soil test methods. For Alberta farmers, all soil test P calibration has been with the Modified Kelowna method since 1990 by Alberta Agriculture. It is also the recommended P method by Saskatchewan Agriculture. Soil samples from Alberta and Saskatchewan should be sent to a lab that uses the modified Kelowna method for the best 4R interpretation and fertilizer recommendations.

For Manitoba farmers, all soil test P calibration has been with the Olsen method (also referred to as the bicarb method), so use a lab that uses the Olsen method. Other soil test P methods, such as the Bray method, have never been calibrated to Western Canada’s soils. I do not recommend methods that have not been calibrated for western Canadian soils.

Next, interpret your soil tests. Make sure you seek the advice of several agronomists when developing your fertilizer plans for next spring.

The post Soil sampling for Prairie farmers: How to test for nutrients and avoid common mistakes appeared first on Grainews.

Nutriscan is a hand-held piece of technology that aims to change that.

“When it comes to tissue sampling, most times in our industry we see an issue, we tissue-sample, we send it away, we wait a week and then conditions substantially change,” says Ben Sherk, regional account manager with ATP Nutrition.

“So for us as agronomists, and everyone in the industry alike, if we can learn right then and there what is wrong with our crop, I believe it’s going to make our industry better to make informed decisions.”

READ MORE: Taking the mystery out of soil and tissue tests

Designed by ATP Nutrition, Nutriscan uses a near-infrared sensor to measure a range of macro- and micronutrients, such as nitrogen, phosphorus, potassium, calcium, copper and zinc — the essentials for growing healthy crops.

After a leaf tissue sample is measured, the results are sent to an app called AgroCares on a user’s smartphone, on which they can see and assess where any nutrient deficiencies may lie.

“Having real-time results, especially with tissue and soil in-season, will help a farm, or a retail consultant, make better decisions for our industry,” Sherk adds.

The Nutriscan device is now programmed to identify nutrient deficiencies in corn, soybeans, wheat and canola crops. Other crops such as potatoes and some fruits are being planned for future consideration in its database, Sherk adds.

At Manitoba Ag Days in January, ATP Nutrition was awarded first prize in agronomics in the farm show’s Innovation Showcase. At the Western Canadian Crop Production Show, held in Saskatoon in January, ATP claimed top prize in that farm show’s Innovation Award program.

The post Hand-held device detects nutrient deficiencies in leaf tissue appeared first on Grainews.

1. Ride along when your fields are being soil sampled. If the person doing your sampling is your agronomist or fertilizer dealer, who has soil science training, this is an excellent opportunity to see the locations in your fields being sampled.

As cores are pulled up, the agronomist can show you and explain the depths of the topsoil and depth to the subsoil in the various areas of each field. The changes in soil characteristics can be explained, such as soil texture or parent material on which the soils have formed. This is an excellent learning opportunity to understand soil variability in your fields. As you develop a greater understanding of the soils and variability on your farm, soil management zone maps will make more sense and provide greater value to your farm management.

2. Take at least the minimum number of soil sampling sites. In uniform fields that are randomly soil sampled, at least 20 to 25 sites should be sampled. In fields with different soil management zones, it remains important to have at least 20 sampling sites. The fewer the number of sites sampled, the greater the probability of inaccurate assessments of soil nutrient levels, which in turn will affect fertilizer recommendations. Not taking enough soil samples in your fields can be a costly mistake.

3. Understand sampling depths. I prefer sampling depths of zero to six, six to 12 and 12 to 24 inches. Most soil phosphorus and potassium fertilizer recommendations for most crops in each province have been based on calibration with the zero- to six-inch depth. Most nitrogen recommendations are based on the full, 24-inch soil depth and sulphur is based on both the zero- to six- and full, 24-inch depths. More recently, some agronomists and researchers have been sampling the zero- to three- and three- to six-inch depths separately in no-till fields to develop a better knowledge of nutrient stratification and changing characteristics, such as soil pH.

4. How to handle soil samples. Soil samples should be placed in a cooler in the field and at the end of each day shipped in the cooler to the laboratory overnight. If this is not possible, samples should be carefully laid out in plastic or aluminum trays in a clean environment to air dry and then repackaged and sent to the laboratory. If moist soil samples are left in bags in a warm environment, there is potential for nutrient change. Always make sure your soil samples are properly handled to ensure accuracy.

5. Know the details around laboratory analysis. Be sure to ask your agronomist which soil testing lab will do the analyses. Then, ask what analyses will be conducted and why for greater understanding. For example, for Alberta and Saskatchewan farmers, the modified Kelowna-P method is the recommended method to determine plant-available phosphorus levels, which are used to develop phosphate fertilizer recommendations. Some companies do not want to pay for a slightly more expensive test and may opt for a less expensive and less accurate test.

For Manitoba farmers, the recommended method is the sodium bicarbonate (Olsen-P) method due to the more calcareous character of their soils. The Olsen-P method works well on high pH soils but poorly on soils with a pH of less than 6.5. The Bray-P method is used by some laboratories but has never been calibrated to western Canadian soils and is not a recommended method. It should never be used on higher pH soils to make phosphate fertilizer recommendations.

If the same sites are soil sampled on your farm each year, there is no need to pay to determine characteristics such as cation exchange capacity or base saturation, which do not change from year to year. This is simply a waste of money. Be sure to have a good chat with your agronomist to understand the analytical tests that will be done to plan your fertilizer program and soil management on your farm next year.

These are a few issues to keep in mind when your fields are soil sampled and analyzed this fall.

The post Soil sampling time is here again appeared first on Grainews.

Poor plant growth leads to reduced nutrient uptake, which leaves more residual nutrients, especially nitrogen, in the soil. Drought also causes important chemical and biological processes, like denitrification and assimilation, to slow down or stop altogether. As a result, much of the applied fertilizer may remain unused, and nutrients applied on the surface may also be stranded due to lack of rainfall.

According to Farmers Edge agronomist Thom Weir, what this means is a general increase in soil nutrient levels — which may persist for years. Nutrient levels will typically also vary widely across a field, which can have a significant effect on a farmer’s fall fertility plans.

Weir says the drier a soil is, the more variability you’ll likely see in a field. That’s because drought accentuates differences in soil texture and moisture as well as in crop growth and nutrient uptake. To get the clearest picture of nutrient levels in their fields, Weir believes farmers considering a fall fertilizer application should test their soils first.

“Before anybody starts putting anything down in the fall, and especially in coming off of a dry year, they should do soil testing. You don’t know what’s left,” he says.

John Heard is a soil fertility extension specialist with Manitoba Agriculture. Like Weir, he believes if dry conditions persist on the Prairies, fall soil testing can benefit farmers by helping them determine the right fertilizer application rates.

“A great advantage we have in the Canadian Prairies is the fall soil test works, and so what we measure in the fall is a very good reflection of what we end up with in the spring for the next growing crop,” Heard says. “It’s a very important tool to use to assess any residual nitrogen.”

Benefits of zone sampling

Weir maintains when it comes to sampling soil in the fall after a dry year, it’s important for farmers to have a clear objective in mind. If farmers’ goals are to maximize the efficiency of their fall fertilizer applications, he suggests zone soil testing is the best way to go.

Weir says when he talks to growers about zone sampling, there are three questions he asks them about their fall fertilization goals:

• Do you want to get more yield from the same amount of fertilizer?
• Do you want to get the same yield by using less fertilizer?
• Do you want to improve crop quality?

“From there, you can develop your fertilizer plan based on those needs,” he says.

The most common form of soil testing is composite sampling, which involves taking samples in a random pattern across a field, while avoiding unusual or problem areas. For zone sampling, fields are divided up into different sectors or zones — examples would be areas with contrasting soil types, or areas with below-average, average or above-average yields.

Weir says by sampling soils in similar areas that make up a zone, this factors in wide variations in nutrient levels, which can occur in drought conditions, and can provide farmers with a better understanding of what their fall fertilizer plans should look like.

“If you go to a provider that is able to provide mapping of the field and zone delineation, you then can go in and say (there are) eight zones in this field that are acting similar,” he says. “We’ll take our samples out of those eight zones and come up with a more focused view of what’s happening on that field.”

Zone sampling and variable-rate applications

Weir believes zone soil sampling in the fall is also an excellent opportunity for producers considering variable-rate nutrient applications for their farms.

For best results, Weir says at least 15 soil samples should be taken per zone. He suggests in a dry year, it’s not a bad idea to increase the number of samples in each zone, which will account for high variability and provide a better assessment of nutrient needs.

Weir notes because there’s less biological activity in dry soil, it may be possible to start soil sampling fields a bit earlier than usual. He cautions, though, test results could be skewed if there’s any rain before the soil temperature falls below 10 C, since this can cause the nitrogen in anhydrous ammonia to be converted to other forms and be lost.

Soil mapping: An art and a science

Soil mapping technology and sample analysis have come a long way in recent times. Weir, whose business is among those companies offering these services to western Canadian farmers, says the way most providers go about creating zone soil maps for guiding fall fertility is to combine yield maps from the previous year with satellite images of the current crop.

“Each one has (its) own special ‘11 herbs and spices’ recipe. But for the most part, those are the two things most commonly used,” he says.

Weir doesn’t view zone soil mapping as an exact science, and he feels producers should be part of the process since most will have a good feel for the land, especially if they’ve farmed it for many years.

“It’s not (like) you can put (data) into the computer and hit the button and come up with the answer. It has to be a collaboration (with) the farmer,” says Weir.

“Creating a zone map is a combination of art and science. And, for the most part, guys with grey beards and (who) have been around for a while probably have more experience and could put more into the art, and then balance it with the science.”

Weir notes if farmers are unsure of anything they see in a zone soil map, it might make sense to head to the field to ground proof those areas.

“My challenge would be for farmers to make sure they’re involved,” he says. “If they’re getting zone maps done … (try to) dedicate a half day to the provider and spend time with them and make sure you’re comfortable with those maps.”

The post The benefits of zone soil sampling after a dry season appeared first on Grainews.

Bennie Dunhin is the agronomy manager at Cavalier Agrow, an ag retailer based in north-western Saskatchewan. Dunhin, who originally hails from South Africa, holds an MSc. in plant pathology and is “obsessed” with plant nutrition.

He’s also a fan of precision farming, but said farmers have a long list of complaints with satellite imagery. Part of the answer, he told farmers during a farm forum in Glaslyn, Sask, is grid soil sampling.

“I’m surprised that not a lot of people are looking into soil samples. I think everybody thinks that soil samples are labour intensive, cost too much,” said Dunhin during a coffee break interview. But by sampling the soil, agronomists can better predict what will happen in that spot, he added.

Cavalier Agrow has finished two years of intensive soil sampling as part of a precision ag program they’ve dubbed iFARM. When a farmer brings a new field into the program, Dunhin and his team sample five acre blocks using a customized soil-sampling truck.

In years two through four, they sample 40-acre blocks to check nitrogen levels, he said. They’ll resample five-acre blocks in the fifth year. Soil sample data is used to create maps and nutrient prescriptions.

Soil sampling is the most expensive part of the program, Dunhin said. But they get a break on lab fees, he added.

“If we had to pay normal lab fees, there’s no way that we could do this program. No way. Nobody can pay that.”

Since unrolling the program in 2014, Cavalier Agrow has sampled about 120 fields belong to 42 farmers. “We’ve punched over 47,000 holes in the ground.”

Fields are located everywhere from Meadow Lake to Unity, and as far east as Spiritwood and Medstead. Dunhin said they never enrol all of a farmer’s land in the first year.

“They need to see the differences and the value of the program.”

The deficiencies

Dunhin told farmers it’s too early in the program to see any differences in nutrients such as potassium and phosphate. But they’ve seen some trends in sampled soils. For example, well over 90 per cent of the sampled soils were deficient in copper and boron.

“It’s unreal the deficiencies we had. When I show this slide to industry people that don’t live in this part of the world, they cannot believe that we have that kind of deficiency in our soils,” Dunhin told farmers.

Nearly half of sampled soils had zinc deficiencies. Just over half had pH levels lower than six. About 40 per cent had potassium deficiencies. Dunhin also noted some soils had salt issues, magnesium deficiencies, or organic matter topping 10 per cent.

Typically zinc levels can vary through the field, Dunhin said. But he noted fields with a history of hog manure application don’t have any zinc deficiencies. Farmers need to be aware of how and where to apply hog manure, he cautioned.

“But if you have zinc problems, hog manure is a pretty good thing to do.”

Nutrient deficiencies favour certain weeds, Dunhin told farmers. For example, sow thistle prefers soils with low calcium, low potassium, high magnesium, high moisture, and low microbial activity. Soil maps can tell farmers where to scout for certain weeds. Dunhin also hopes to train agronomists to make nutrient recommendations to help manage weeds.

“If we can more effectively control weeds just by changing the nutrition on the field, that’s a win-win for every-body.”

Dunhin also showed farmers how yield maps can be correlated with soil sampling maps. For example, if high iron levels are correlated to lower yields in a specific field, that probably means iron levels are too high in the field.

If there’s a strong correlation between higher calcium levels and higher yield, this points to calcium-deficient soils, he said. Dunhin cautioned these examples are field-specific and don’t apply to all soils.

Dunhin hopes to add correlation services to the iFARM platform.

When it comes to precision farming, variable rate prescription maps and a nutrition plan aren’t enough, said Dunhin. In the near future, Cavalier Agrow also plans to offer everything from variable rate seeding maps to yield map analysis to farm business planning services, he said.

“This is intelligent farming. And this is how we need to think about the future and go forward with what we want to do on the farm.”

The post Grid soil sampling best for prediction appeared first on Grainews.

Morgan Cott, field agronomist for Manitoba Corn Growers Association, says that corn has two major fertility needs, nitrogen and phosphorous, and that generous application is required to get high yields. “What each field needs depends on the soil type. Lighter soils will tend to leach nitrogen more if conditions are right,” she explains. “However, over-applying in a dry year will just cost the grower more money. Nitrogen is very mobile in the soil and corn doesn’t need the bulk of its requirements until V4 to V8 staging, so over-applying nitrogen early on will just lead to losses.” (V4 refers to the fourth Vegetative Growth Stage, the point where the collar of the fourth leaf is visible. At Vegetative Growth Stage 8, the collar of the eighth leaf is visible.)

Cott also says that corn benefits from a complete blend of fertilizer, including potassium and sulfur, and soil sampling should be done to assess the soil’s needs. “Corn also loves micronutrients, but you need to sample for these to know if they are needed or not,” she says.

According to John Heard, crop nutrition specialist for Manitoba Agriculture, Food and Rural Development, and recipient of this year’s International Certified Crop Advisor (CCA) of the year award from the American Society of Agronomy, farmers should be “spoon-feeding” the crop at the rate it requires, but also managing time of application. If farmers apply fertilizer at the wrong time, they’ll need to bump the rate of application to account for possible losses. It’s a tricky balance, and one that growers have to figure out for themselves.

“In each individual situation I hope the farmers are getting good advice and experience and will tailor rate based on the equipment they have for whatever time and placement system they have,” he says.

New types of fertilizer application

Cott says Manitoba farmers are adapting to new methods of fertilizer application. “It used to be that all the fertilizer went down at the same time, but now we have the ability to do split applications of nitrogen, or add fertilizer safeners such as ESN, a nitrogen product, so that it can be placed in larger amounts and closer to the seed without burning,” she says.

One common problem she’s noticed with fertilizer application, Cott says, is that growers sometimes float on the fertilizer before incorporating it, or they apply the fertilizer with an air seeder drill and plant afterward. “The concerns I have with these methods are that they require multiple passes over the field, and that there may be too much fertilizer-to-seed contact and create burn,” she explains.

Cott is also concerned about farmers who may be over-fertilizing. “Are you capable of getting 150 bushel yields, or just 110? Sometimes we push for a yield that just isn’t possible for our area that we farm in, so don’t be fertilizing for a pipe dream — it’s a waste of money,” says Cott. “On the flip side, if you can get 150 plus bushels, you need to be fertilizing for that capability. Don’t skimp and expect to get those yields year after year because you’ll end up mining the soil and wind up spending more in the long run.”

If farmers wish to self-assess the appropriateness of their fertilizer application, they can take the corn stock nitrate test, says Heard. While it will be too late to make fertilizer changes for the current year, it will give farmers valuable information for future years.

Zero-tillers need less N

This summer, North Dakota State University unveiled a new set of corn fertility recommendations, this time with separate suggestions for no-till soil. According to the North Dakota experts, farmers who have been continuously no-till for six years or longer require 40 to 50 pounds less nitrogen per acre than growers with tilled fields.

David Franzen, North Dakota State University extension soil specialist, led the effort to develop the recommendations. “I was able to run a statistical analysis to determine whether the responses of corn to nitrogen were the same in both tillage systems. They were not,” he emphasizes. “The response curve of the no-till sites was flatter (less response to nitrogen) and the economic optimum for long-term no-till was about 50 pounds of nitrogen per acre less than for conventional tillage.”

The difference, he says, is similar to that seen in 2010’s North Dakota spring wheat and durum recalibration project.

Franzen’s theory is that in long-term no-till soil, the diversity of biology takes up a large percentage of nitrogen and uses it to increase population multiplication and residue decomposition. “The nitrogen is excreted as intermediate nitrogen containing compounds that seem to act like a natural slow release nitrogen. Conventional tillage systems do not have this type of biology, or at least not nearly as much, and so the nitrogen is much more exposed to losses to leaching/denitrification,” he says.

Manitoba’s John Heard cautions that the new recommendations should be taken with a grain of salt, especially for farmesr who have only been zero tilling for a short time. “The zero-till corn function does not always have a lower nitrogen recommendation,” he says of the NDSU’s fertility calculator. “For the first five years the zero-till corn needs more nitrogen, presumably to deal with nitrogen immobilization by crop residue until an new nitrogen cycle equilibrium is established,” he explains. “Then the nitrogen rate is reduced.”

The new recommendations out of North Dakota will only be of passing interest to Prairie growers, who have by and large not yet adopted zero-till farming, according to both Cott and Heard. However, the results are highly applicable to Manitoba growing conditions. “Nine of the Manitoba Corn Grower Association sponsored studies conducted by myself during the last decade were included in the NDSU dataset to develop the calculator,” he says.

Heard also points to another study led by Curtis Cavers of Agriculture and Agri-Food Canada based in Portage la Prairie which is analyzing nitrogen management in corn at three sites for the next three years. “The study looks at different nitrogen rates, sources such as urea, ESN and UAN, timings, both pre-plant and in-crop, and placement, including broadcast and incorporated, surface broadcast and side dress injected. This data should help us validate the guidelines published by NDSU,” says Heard.

The post Higher corn yields through fertility appeared first on Grainews.

“The reality of the situation is if you don’t know what you have to start with, you won’t know how much or what to fertilize with,” says Ray Dowbenko, senior specialist, agronomic services at Agrium. “You will, in fact, be flying blind.”

John Heard, crop nutrition specialist with Manitoba Agriculture, Food and Rural Development, agrees with Dowbenko. “The real value of soil testing is not just to determine how much fertilizer to buy,” says Heard. “It’s an important audit tool to track the nutrients in your soil and the effectiveness of your fertility program.”

Soil testing is an important tool used to gauge soil fertility and plan a suitable fertilizer regime to maximize the yield potential of the crop. But the results are only as good as the sample.

“The reality of soil testing is that most farmers are not doing it themselves,” explains Heard. “Most now are using the services of independent agronomists or a fertilizer company or supplier. These professionals are properly equipped with truck-mounted samplers, and as a result, if a grower has consistency in his service provider for both sampling and testing, he will reap the benefit of long-term tracking of his fertility program.”

• More Grainews: Soil testing with the PRS probe

Soil sample timing and placement

“Fall is a good time to soil test,” says Dowbenko. “In spring, most growers deal with some serious time crunches and if test results are delayed, or fertilizer supply is interrupted, there is little time to get a comprehensive fertility plan in place.” Heard agrees. “Farmers have to differentiate between the best time to soil test and the most practical time to soil test,” he says. “Just before the crop is about to use the nutrients in the soil might be the best time to test, but it’s certainly not practical. Fall testing in cool soils gives the grower time to formulate a comprehensive fertility program, as well as take advantage of both fall buying and application opportunities.”

Soil samples are best taken when soil temperature has dropped to 10 C or lower. “Right after combining, and before any fall tillage operations, is a good time to take soil samples,” says Dowbenko. “The soil has usually cooled sufficiently that any changes due to bacterial activity and mineralization are at a minimum.”

Farmers can work with local agronomists or fertilizer dealers to draw up a sampling plan to ensure soil samples are taken in sufficient volume in enough areas of the field to produce a representative view of the field’s fertility status. It’s very important that the person most familiar with the topography has input into the sampling plan. “The key is to know where to avoid sampling,” says Heard. “For example, a saline area might reveal very high levels nutrients like sulphur simply because crops won’t grow there very well, if at all. A sample like this can easily taint an otherwise good soil testing program.” Heard advises to leave out problems areas or sample them separately.

• More Grainews: Crop rotations and soil science

Lab tests

The laboratory will conduct a soil test based on your instructions. Generally, a typical soil test package will include tests for nitrate-nitrogen, available phosphorus and potassium and extractable sulphur, as well as pH and salinity. Additionally, a micronutrient scan can be requested to determine levels of elements such as copper, zinc or boron, amongst others. “Farmers should stick with a lab once they find one they are happy with,” says Heard. “Different labs can conduct tests using different methods which would make long term monitoring more difficult. It’s the apples to apples analogy.”

“Understanding and interpreting soil test recommendations is very important to designing the fertilizer management plan for your farm,” says Dowbenko. “Think of the recommendations as a guideline — a starting point with which to engage your advisor or local dealer in a discussion on your fertilizer plan for the upcoming season. The laboratory does not know how you farm, the moisture levels you typically experience or what your growing season is like.”

Heard recommends using a “rotational fertilization strategy.”

“Farmers have been achieving very high yields, and we know some of our crops in particular are greedy phosphorus users, especially canola and soybeans,” says Heard. “We are exporting more phosphorus generally than we are applying, so it’s important farmers take into consideration both the soil test values and the yields they are achieving now.” Many farmers have been scaling up their fertilizer programs, but modern seeding equipment does not always allow the full recommended or desired rate of phosphorus to be applied with the seed for seed safety reasons. “A rotational fertilization strategy comes into play in a situation like this,” explains Heard. “Some nutrients can be applied in excess of the needs of the current crop, for instance wheat, but remain available for a canola, soybean or flax crop in a following year.”

The post Add soil sampling to the fall “to do” list appeared first on Grainews.