The phosphate in all soils is absolutely essential for plant growth and energy exchange. This plant nutrient is key for plant cell biochemical functions and is a component of the DNA and RNA for cell division. Phosphate is needed in large quantities for seed germination, root development and seed or fruit production.

Agricultural phosphate is mined from mineral rock and the amount available worldwide is limited. Five countries hold about 95 per cent of known P reserves — Morocco, China, South Africa, Jordan and the United States.

Phosphate fertilizer is usually available as super phosphate, monoammonium phosphate (MAP) and diammonium phosphate. Phosp­hates are extracted from rock phosphate by treating it with sulphuric acid in order to render the phosphate soluble.

Rock phosphate itself, sometimes called black gold as well as the “organic” bone meal, are very highly insoluble forms of phosphate. They are only sparingly useful in acidic soils below pH 5.5 and conditions of high rainfall. Bone meal and rock phosphate are totally unsuitable for neutral or high pH soils.

With P deficiency, plant growth is retarded, roots are stunted and leaves are usually red/purple pigmented — at this stage it’s usually too late to apply P.

When soluble P is applied to cropland it does not move very far in the soil from where it was applied. It quickly binds with aluminum, iron and micronutrients, especially at soil pH below 5. Remember, an average soil has something around five per cent of the soil weight in iron (Fe) and seven per cent of a typical soil is aluminum (Al) by weight. Since P is so easily fixed when it is applied to soil perhaps only 10–20 per cent is taken up by crop plants in the year of application. P is most readily available at pH 6.5 to neutral, and at a higher soil pH of 7.5 and up it again becomes less plant available.

In mineral soils, the total P in soils that is immediately plant available is around one per cent at any given time. In most soils, phosphorus can be found in both inorganic -P and organic -P forms.

Thus, while the majority of soil P is pretty stable, it is largely unavailable to plants. The small amount of P that is water soluble is replenished slowly during the growing season following plant uptake. This P is made available in a slow process from organic matter decomposition and by interchange with soil mycorrhiza for most crops, canola and beets excepted.

Adding P fertilizers frequently to cropland will maintain those P reserves and build up the soil P. In soils that test very low for P, the reserves will be insufficient to meet the crop demand over the growing season, resulting in lower yields and significantly delayed crop maturity.

A significant proportion of P in mineral soils is stored in the soil organic matter. This organic P is made plant available by microbial activity, providing that moisture, warm temperatures and the soil pH is suitable.

Intensification of the livestock industry in many areas of Prairie Canada has created national and regional soil P imbalances. This is particularly so with the poultry, beef, milk and hog livestock industries. Today, only a small percentage of farm-produced grain and pulse crops is fed on the farm where it is grown, very unlike the situation of 80 to 100 years ago.

This evolution in agriculture is causing a huge transfer of P from grain-producing areas to the livestock-intense areas resulting in huge P and sometimes nitrogen overloads on relatively restricted areas of cropland. The transfer of livestock manures to nearby cropland continues to add N and in particular P to be applied to this cropland, sometimes way in excess of crop needs. This leads to leaching of P, crop yield problems and significant environmental concerns leading to surface and groundwater pollution.

Where I live, west of Edmonton, I have over the years investigated sand loam cropland in particular that has received major and repeated quantities of either cattle manure, both beef and dairy, and poultry manure.

Soil analysis of the top six inches (0–15 centimetres) would often show Bicarbonate and Bray soil available P to be in the low hundreds for the Bicarbonate test, and 300 parts per million and up to over 600 parts per million for the Bray test. Organic matter would usually be five to seven per cent. Zinc, manganese and iron levels would be high to very high yet copper levels would be moderate to very low — i.e., often less than one part per million for these highly-productive soils.

In wet summers, these soils would have wheat crops that lodge badly, yield poorly, are late maturing and are adjudged to be copper deficient. Reading the literature, I believe or hypothesize that the following may be happening on these highly-manured soils. The abundance of P may be chelating the available copper and the high P levels in grain and legume crops have been shown to strongly discourage mycorrhizal associations with these crop plants.

Mycorrhizal linkage to crop plants in normal soils have been shown to supply phosphate, copper and zinc to growing crops. The discouragement of mycorrhizal association therefore may result in a failure of the crop plants to receive copper in particular, resulting in severe stem weakness, lodging and delayed maturity. Mycorrhizal failure in high P soils could be likened to growing field peas in soils high in nitrogen, resulting in nodulation failure.

I do not profess a 100 per cent accuracy but over the years and even up to now highly-manured soils and in particular the high P levels may be directly responsible for severe lodging of cereal crops with huge loss of yield and quality particularly in wet growing seasons. In dry seasons in these areas, deep rooting of the crops usually results in exceptional yields of 100 bushels or more of high-grade wheat, indicating that deeper rooting in the subsoil supplies the missing copper nutrition resulting in bumper yields.

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“In this fascinating carbon world, we’re now moving beyond just crop rotation and beyond just grazing management all the way to thinking about using spatial diversity such as intercrops,” said Entz during a presentation at an intercropping workshop in Brandon last fall.

Entz explained that crop rotation is diversity in time, meaning one year you grow soybeans, another year oats and so on. Intercropping is diversity in space. “If you think about how nature works, nature is always intercropping, there’s always more things on the land than just one thing,” said Entz. As an example, intercrops allow for plants with different root depths. “We do this in our pastures all the time. There is scientific evidence to show that some plants will actually lift water. They will not only use the water from down in the soil, but bring it up in the root and then deposit it into that upper layer of the soil where other plants can use it.”

There are many types of intercrops, like pasture mixtures, shelterbelts, cover crops and grain intercrops. These systems may help unlock yield potential as scientists and producers continue strive for more yield.

“Canola is a good example of where we have relatively low harvest indexes; there is lots of yield potential left there but with some other crops, there’s not,” said Entz. “When you have a monoculture, you risk disease because you create a lot of food for the organism that eats it, so the hypothesis now is that huge yields gains are going to come from mixtures.”

After years of experiments with intercropping, some researchers have found that the land equivalent ratio (LER) is greater with crops grown together than with crops grown individually. The LER is found by comparing yields of an intercrop by comparing monocrop yields on similar-sized land parcels. That is, does a 100-acre field of intercropped peas and canola yield more than a 50-acre field of peas and a 50-acre field of canola? If the intercrop yield is bigger than the monocrop yield, the LER is greater than one. “Canola is a very good intercrop partner, we get a lot of results where we’re harvesting more yield per unit area of land in a mixed crop environment,” said Entz.

Peas and canola is a common intercrop and has been reported to consistently over-yield by up to 21 per cent compared to either crop alone. Farmers in southern Saskatchewan have reported 120 to 130 per cent of the yields of monocrops when growing intercrops.

In-crop assistance

A lot of early intercropping research came from Scandinavia. In the 1980s Scandinavian work with barley and legumes showed that the grass roots tend to be bigger than the legume roots. “In this case, the growth rate of the barley root was about two to four times higher in the grass than the legume root,” said Entz. “That makes sense because the legume doesn’t need to build a big root system to capture nitrogen because it gets it biologically with nodules. The grass, on the other hand, has no choice but to build a big root system to go get that nitrogen.”

The same is seen in many involuntary intercrops such as canola/soybeans. Entz’s colleague, Dr. Rob Gulden has looked at these root systems and found that canola roots grow deeper to scavenge more nitrogen, while soybean roots don’t need to grow so deep. Gulden has also found that the canola and soybean roots intermingle, allowing opportunities for a synergistic relationship. “All plants exude sugars and proteins out of their roots into the rhizosphere, the area right around the root, so there is opportunity for one plant to take up what the other plant is giving.”

Not only are the roots intermingling, they are getting some help through something called the common mycorrhizal network (CMN), says Entz. Mycorrhizal fungi live in the soil as spores. When a plant sends a seed out, the spores will germinate. The fungi send a thread and infect that plant to get carbon from the plant. Then the fungi will bring nutrients to the plant — it’s a symbiotic relationship.

Entz cited a study that showed that in an intercrop of flax and sorghum, the sorghum increased flax growth by 46 per cent by shifting nutrients from its root system to the flax roots via the mycorrhizal network, costing the sorghum only seven per cent of its yield.

Why do plants help each other? It’s risk management, said Entz. “It’s a form of insurance. They want carbon to survive, so why not tap into two income streams as opposed to one,” he said.

Plants that are very mycorrhizal are corn, flax, sunflower, pulses, potatoes and all forage legumes. Plants that are mildly mycorrhizal are oats and barley. Canola and all the brassicas are not mycorrhizal. “That doesn’t make them bad, it just makes them different, and you can actually exploit that difference,” said Entz.

Intercrops in practice

How can producers use this knowledge to increase yields, improve soil and make more money?

Producers could use these root dynamics to reduce nitrogen needs. The best data in this area comes from pasture systems, showing plants shifting nutrients back and forth. In grain legumes, the nitrogen transfer from pea to barley is not usually detected in the field, but it happens. Chinese intercropping research has shown that intercropped legumes contribute about 15 per cent of nitrogen to a cereal.

Phosphorus in the soil is in different pools and only about half of it is in a plant-available form. Plant roots put a lot of compounds like enzymes and acids into the soil to solubilise phosphorus and make it available to plants. Canola and other brassicas are particularly good at this. An intercrop with the right choice of plant species can actually tap into different pools of phosphorus in the soil and make better use of it.

“For example, if you had an intercrop with chickpea that could tap into the organic phosphorus and you had another plant that could tap into the inorganic phosphorus, which is either your fertilizer or your phosphorus attached to the calcium, which is bound, then it’s easy to understand why this whole system might over-yield, why you might get an LER greater than one,” said Entz.

Soil health plays a big part, adds Entz. “The microbial biomass carbon is one of the best measures of the health of your soil,” he said. “Communities of bacteria that are involved in mixed species community increase production by 16 per cent versus bacteria from monoculture. If you have a mixture of plants in your system, you’re building up a healthier soil biological community and this is why sometimes weeds are your friend. They are sometimes the diversity in your system.”

The acidity of roots can also reduce disease such as root rots in cereals. For example, fababean produces a lot of acid, soybeans a moderate amount of acid and corn doesn’t produce any acid. So they can be complimentary. “Research in China showed fababean helped increase phosphorus by 12 to 56 per cent in maize when intercropped,” said Entz.

Plant conversations

Intercrops give above-ground benefits too. They’re collecting more energy from the sun as they fill in more spaces in the field. That can produce more plant biomass and yield.

And plants talk to each other. “There are a lot of volatile chemicals that are given off by plants that other plants react to,” said Entz. When German researchers clipped a sage plant it produced a chemical which caused a wild tobacco plant being grown near it to turn on its self-defense mechanisms.

Experiments at Clearwater, Man., in 2004 and 2005 demonstrated that intercrops not only over yield compared to growing just monocrops, but also help to reduce weed pressure, prevent disease and reduce fungicide use.

When wheat was seeded at half rate with other intercrops, weed numbers dropped and leaf disease in the wheat reduced to 30 per cent compared to 70 per cent on a wheat monocrop seeded at full rate. “If we’re going to try and increase our yields just by increasing our seeding rate, increasing the biomass of that one plant in that one field, we’re going to have diseases and we’re never going to get on top of that,” said Entz.

Entz has studied intercropping all over the world and believes that the way to food security is through intercrops and ecological farming systems.

He shared the story of a nitrogen-fixing tree called Faidherbia albida that grows only in certain parts of Africa. “It’s called a reverse phenology tree, so when the rainy season begins and people plant their maize, it’s roots are full of nitrogen,” said Entz. “During the growing season, once the crop is established, it starts to leaf out a bit and then when it’s really hot and dry and you’re trying to mature your crops, it leafs out and reduces the temperature on your field. You can modify the temperature of the field by the density of these trees. With all the technology for climate change, adaptation, here’s a natural solution.”

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That’s what Jack Schutlz, a biologist and zoologist at the University of Missouri, whose business card describes him as a chemical ecologist, tells me anyway. Schultz admits when he gives a talk, he is a bit of a novelty act at farm conference. But who knew there was actually research into if, when and how plants communicate?

But when you consider all the remarkable natural defence mechanisms animals and plants developed through evolution, why not plants in canola, wheat, pea and corn crops communicating with each other?

Since I retired from my active three-day farming career about 50 years ago I can’t claim to have much first hand exposure to this. But I do know if you cut a hay crop there is definitely an aroma. In Jack Schultz’s research that’s plant communication.

“Plants communicate very effectively with each other both above and below ground,” says Schultz. “By understanding these mechanisms it can help farmers understand how crop production practices might affect these natural defence systems.”

How plants communicate

All plants produce odours, says Schultz and when they are attacked or damaged by a pest they produce a specific volatile odour. His research over the years shows that if one plant is attacked by a pest it emits an odour, which will soon trigger a defence mechanism in the plant next to it, even though the next-door plant isn’t being attacked itself. The next-door plant senses the odour change and takes action. And the odour emitted by the attacked plant will vary depending on which pest is attacking — a different volatile odour for each pest.

Wheat, for example, has a natural defence system. The wheat midge begins feeding on wheat, and the plant emits a volatile odour, which in turn can be sensed by parasitic wasps that feed on wheat midge.

“The parasitic wasp can be very effective in controlling wheat midge, but it is very tiny,” says Schultz. “If there is a wheat midge in a field of wheat how does that little wasp find the pest? The wasp senses the odour being produced by the wheat plant and is attracted to the plant and attacks the wheat midge.”

As well as above ground odours, plants also send signals through their roots into the soil, says Schultz. Experiments showed if an attacked plant was covered with a jar so its odour was contained, neighbouring plants with root connections to the covered plant would still respond to the threat. The signal is carried through the intertwined roots, and perhaps even by the bacteria (mycorrhiza) in the soil.

How else do plants communicate and what other defence mechanisms do they have? With brassicae plants such as canola, for example, when plant leaves fall on the ground and decompose they produce a natural fungicide in the soil, which helps control certain fungi.

Humans are very familiar with other chemistry processes plants use as defence mechanisms. Plants such as tobacco, coffee and hot peppers, for example, produce chemicals, which humans have capitalized on for components in food and consumer products. Cigarettes and cigars, a cup of coffee and hot pepper sauce are all consumer products.

“Why would a plant develop nicotine, or caffeine or some other chemistry we sense as burning or hot?” says Schultz. “They don’t do it for humans to enjoy. These are all natural insecticides. Nicotine or caffeine or that hot pepper spice were all developed through evolution by plants to act as a natural defence against some type of pest or threat.” A damaged or attacked plant will produce higher levels of these compounds.

Now that you know most plant communication is limited to detecting odours, that doesn’t mean you can frolic naked in the barley field with total impunity. A neighbour or some passer-by with a cellphone camera will be watching and your romp will be featured on Facebook, YouTube or maybe even the six o’clock news before you get home. Try explaining your way out of that one.

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Tillage causes physical disruption to soil organisms, especially larger ones like earthworms, and those that have large networks like fungi. “Tillage can physically destroy the networks of hyphae (long, thread like filaments) that fungi create, and for the larger bodied organisms like earthworms tillage could cause death due to crushing, removal of their tunnels and burrows, and so on,” says Dr. Mario Tenuta, professor of applied ecology at the University of Manitoba. “The other thing that tillage does is redistribute materials, and that’s one of the reasons why farmers do till, to mix in surface crop residue below the surface. Once residue is in contact with the soil, it’s also in contact with active soil organisms, which can speed up decomposition of the material.”

Disrupting fungal networks limits P

But the most critical issue from a plant productivity and crop production standpoint is the effect of tillage on the networks of mycorrhizae fungi, which relay nutrients and compounds to plants. “Primarily for crop plants, the network transfers phosphorus to plants, which allows them to photosynthesize for better yields and feed the fungi to keep that network surviving and active,” says Tenuta.

“Tillage breaks the network, which has to be completely re-synthesized and that requires a re-deployment of the whole network,” says Tenuta. “The reconstruction process will take energy from the fungus, and that takes energy away from the process of acquiring phosphorus and translocating it to the plant, because the fungi are trying to repair itself instead. It’s a loss of efficiency for the fungus and the plant.”

Because commonly, farmers till in the fall after harvest and/or the spring before the crop is planted, there is a delay in re-establishing the fungal network. “The early season uptake of nutrients for a crop can be compromised because of that,” says Tenuta. “In that period of time where it’s getting rebuilt, it’s not as efficient in transferring the phosphorus and that can be a big thing for a plant or a crop because it’s often the early season uptake of phosphorus that is really critical for plant establishment and growth.”

Farmers can’t compensate by simply putting on more phosphorus fertilizer. “Farmers can do a couple of things, they can increase soil test phosphorus, or the background level of phosphorus that’s available for plants, but researchers have found that even if they do that, some crops highly dependent on mycorrhizal fungi such as flax, are still compromised for early treatment P uptake,” says Tenuta.

“To get over that negative hit on the mycorrhizal fungus, and its inability to help with phosphorus acquisition, it’s necessary to add phosphorus in and/or near the seed row in a band, not just broadcasting it, so that the phosphorus is more available to the emerging seedling in the early spring. It makes things more complicated, and more input intensive and expensive in management of the phosphorus.”

As well, there is a limit to the amount of phosphorus that can safely be placed with the seed in the furrow without causing seedling injury. The safe amount of in-row phosphorus is well documented and available on provincial websites. Safe levels depend on the soil type, the crop, the source of phosphorus and moisture. Tenuta recommends farmers band phosphorus to the side of the seed-row if unsure of safe in-row limits.

Wet soils tempt tillage

The good news is that the fungal networks do rebuild themselves within a year, but not necessarily fast enough to make a different to the new crop. “If a farmer has done a fall and spring tillage, then plants a crop like wheat or corn, if we compared it to a no-till crop, early on in the season there would be more presence of fungi in the roots of the plants in the no-till situation,” says Tenuta.

“If we went back later in the growing season, colonization of the roots by the fungi would be about the same. They will rebuild the network but it’s delayed, and eventually it’ll catch up and establish with the crop. However, it may not be as efficient later in the season. A lot of our crops need phosphorus earlier on in the season so that’s the problem. If it catches up later on it might be too late.”

Rarely do no-till farmers use tillage unless they have a major issue that is hampering their ability to achieve their yield potential. But do the costs in terms of losing the benefits provided by soil organisms outweigh the benefit of a tillage operation in these cases?

“Often there is a problem related to establishing the crop, in getting a stand emergence that’s decent to get good yields, so if there is something that is near catastrophic happening in their situation, that’s compromising their yield, they are playing a balancing act,” says Tenuta. “That balancing act is, they may compromise their early phosphorus acquisition by doing tillage, but they may not get a decent crop unless they do till. They may be able to compensate with good phosphorus management but it becomes a pragmatic decision for the grower in terms of doing tillage.”

If producers really want to try and get moisture levels down in their soil and decide to till, they need to think carefully about their phosphorus needs, says Tenuta, especially in crops that are very sensitive to early-season phosphorus that require mycorrhizae. “If they have a crop like flax, corn or sunflower that requires early-season phos­phorus and are very mycorrhizal dependent, I would really recommend them to think about making sure they have good phosphorus as a band when they plant,” he adds.

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Over the last several years there has been an emerging and energetic movement to better understand soil health. There has been a spike in interest in cover crops and soil microbiology and really understanding what drives the underground biology that makes agricultural systems tick.

In some ways, this move is not too surprising as we look to increase productivity or enhance sustainability. The exciting part to me is the systems-type approach to the issue and looking at biology in addition to physics and chemistry. By this I mean that soil health is more than identifying a substrate and soil type (physics) and a cation/anion reading or fertilizer test (chemistry). It is really about working with physical and chemical tools and optimizing the soil microflora to create a whole that is more than the sum of its parts.

A look at the benefits

Some of the benefits of soil health are fairly straightforward and predictable, including enhanced nutrient availability, increased water infiltration, reduced erosion and improved resiliency. Additionally, in the world of carbon sequestration and taxation, understanding our soil health at a deeper level may provide tools for improved carbon storage and much-needed ammunition to make our case as stewards of the land and of the atmosphere. If you are interested in history at all, you can track the rise and fall of many civilizations and parallel it with the state of their soil health.

As a simple place to start, soil is built from substrate or inorganic particles. Whether these are small clay particles or large grains of sand is a bit beyond our control as farmers and ranchers, but it is the basic structure that we must deal on our own land bases. How we build on this substrate is our role as managers, since we are unlikely to remove our layer of topsoil and truck in a replacement. Everything we do in the top few inches of soil and above ground will eventually be reflected in the soil underground. This gives us both a tremendous power but also a tremendous responsibility as soil managers.

I truly began to appreciate the role of biology beyond the plant component this fall when I took a soils course from Nicole Masters. What I learned in spades is that the underground food chain is both interesting and a bit scary. Perhaps the hardest part to come to grips with in the human mind is the immense power that trillions of microscopic bugs can have per acre. The influence and impact of these soil microbiota is scales of magnitude larger than the impact that several tons of steel can have on that same acre. Think about that for a minute and it is somewhat staggering. Facilitating the function of the microbiology underground, or debilitating the function of that same microbiology will have more impact on our soil health and productivity than a $1 million investment in equipment.

It’s a jungle down there

If we start above ground, plants are largely responsible for sending sunshine underground and feeding the soil biology. Photosynthesis creates soluble sugars which are sent down the plant to the roots. In return for some of the sugar, mycorrhizae fungi help to extract, mobilize and horse-trade various minerals and molecules from the soil that the plant needs to make proteins and other items. The fungi can represent a larger part of the root function for a plant than the actual plant roots do.

Other soil bacteria are also especially adept at extracting nutrients or creating them out of thin air, such as those associated with nodulation of legumes.

However these bacteria are greedy and don’t like to let nutrients go for plants to use. Fortunately, voracious protozoa eat bacteria and free up these nutrients from the bacteria. Add a few worms, some different fungal types and a lot of bacterial diversity and it is a jungle underground. When we consider all of the variety and the actual underground biomass, it is a lot bigger system in a lot of ways than what is actually going on with the crop that we see.

It is complex enough that it would probably take a thousand issues of Grainews filled cover to cover to even begin to understand or explain a percentage of the complexities and interactions. What is important to understand is that as managers we can either shift things toward or away from a healthy system.

Certainly, many of the practices we follow including fertilization, cultivation and weed control have agronomic merit and situations where the benefit outweighs the cost, but all of these practices have an impact on the underground world. A couple of examples include the addition of fertilizers which contain salts. These salts can greatly impact the growth of soil microbiota and affect fungal:bacterial ratios in particular.

Cultivation is another practice that has some merit, but we need to be aware of the effect it has on soil mycorrhizae in particular. Cultivation breaks up these fungal bodies that help to extend the rooting power of our plants. Many of the biological pathways that we exploit for weed control, are also present in our soil life, so sometimes the chemicals that may be applied for weed control can have broad ranging and unintended consequences underground.

Start digging holes

The basic take-home message is that what we do above ground as managers will eventually be reflected in our soils. Building organic matter and taking care of our soil resource has positive results for our farms and ranches, even if we make a few mistakes along the way. Soil can be a highly forgiving ecosystem, and soil microflora have incredible reproductive powers. As managers, this means that there is some resiliency and coverage in the system for all those times we screw up. It also means that impoverished soils can be renewed and regenerated at a rate that is surprisingly fast.

We need to feed our soils, and there are a lot of recent developments on an industry scale, including cover and green manure crops, micronutrient management and tools to increase organic matter. As well, the ability of GPS and other computer technologies to manage on a more site-specific basis are quite exciting.

One of the best things we can probably do, and I myself do not do enough of it, is to start digging holes. Take a shovel and dig down. Some aspects of soil health such as tilth, colour, root and mycorrhizae mass, moisture infiltration and structural integrity are readily apparent if you dig a few holes. Invest some money in both nutrient and biological soil testing.

We will continue to see soils emerging as a field of extreme interest, in part because they offer a large part of the solution to climate change and provide a huge and living carbon-storage facility. If you are truly interested in soils I would also suggest that you read Les Henry’s columns and start building your below-ground level understanding.

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Our planned grazing system, where we look at the health of the grass on an ongoing basis, has responded well over the 25-year journey. I have written other articles about our grazing data collection and observations of pasture health in relationship to the way we graze our paddocks. It has been a rewarding experience.

• Read more: Report From Down Under: Holistic approach is working

It was an extraordinary observation a couple of years ago to have the “ah ha moment” of discovering improving mineral cycling in the soil and the effects of mycorrhizal fungi assisting with the creation of a strong environment for soil micro-organisms. It frees up soil nutrients that wouldn’t be plant available otherwise. It is especially relevant since we don’t use any form of commercial fertilizer. It is good to see plant species composition across all paddocks have steadily increased as a result of our grazing system.

However, the last two years of bizarre weather patterns, extremely low winter precipitation, below-average snow cover, early-season droughts and slow pasture growth in spring really challenged the soil biology processes that had kicked into gear so nicely.

In addition to the poorer pasture performance, accepting more cattle for our grazing operation compounded the issue as we couldn’t leave sufficient litter in the paddocks to feed the soil fungi. We paid for those decisions but things are looking up.

Pastures recovering

In west-central Alberta last season we received an abundance of rain from early July, totalling over 22 inches by October. Although the pastures were extremely slow to get started there was soon some recovery and the second pass in our planned grazing system saw great stands of high-quality feed.

Early in the spring we noticed that the urine and manure spots were showing across the paddocks, where they weren’t seen before, a sign of poor nutrient cycling. In September, to our delight, as the cattle were well into the second rotation, these spots were gone suggesting with the additional soil cover from the forage stand there was renewed activity in the soil — fungal activity was kicking in again. Soil micro-organisms such as bacteria, nematodes, protozoa and amoeba were all busy exchanging favors with the fungal mycelium and plants responding with healthy growth.

With the relatively poor outlook in the spring we had backed off the 2016 stocking rate slightly, with 62 cow-calf pairs and three bulls for the home quarter and 42 cows and calves and two bulls on the east quarter. We had announced a couple of options for the clients we custom graze for — early exit or destocking by late summer.

As a result, the home quarter herd left early and by fall we were down to 32 pairs and one bull on the east quarter, leaving a great scenario of plenty of carry-over that will sustain a healthy soil biology and allow for recovery from the two years of grazing above a level we felt was sustainable.

We keep close tabs on grazing data on an annual basis and with these adjustments we are aiming at a stocking rate of roughly 10,800 Animal Unit Days (grazing days) for the season on the home quarter and 6,100 AUD on the east quarter. This should prevent the setbacks we saw in pasture health the last couple of years. Leaving litter is crucially important to maintain heathy soils and an active soil biology so fundamental to pasture productivity. It takes years to build a healthy soil function and we sadly discovered how quickly it can deteriorate.

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The first part of the planning process is setting goals, says Kevin Elmy, owner of Friendly Acres Seed Farm at Saltcoats, Saskatchewan. Elmy has been growing cover crops for seven years and now grows and sells cover crop mixes.

“With any cover crop, the first goal is to have plants growing in the soil all the time throughout the whole growing season,” says Elmy. “The next goal is to increase plant diversity by having a wider array of plants in the soil, and the third goal is to make the soil better than it is right now.”

Cover crop mixes can also meet other needs. They could increase production by keeping soil cool, retaining moisture, and feeding the microbes and earthworms that make healthy soil.

Including deep-rooted plants in the cover crop mix can help address physical issues such as compaction or erosion, as their roots can break through hardpan layers and improve water infiltration to prevent runoff. Soil chemical issues such as salinity or low nutrient levels can be addressed with plants such as legumes, buckwheat and tuber crops which release potassium and phosphorus.

Cover crop plant groups

There are three main plant groups: grasses, broadleafs and legumes. Cover crop mixes ideally contain all three groups.

Grasses build organic matter and produce lots of biomass, so for green feed or a grazing crop, or to keep soil covered, grasses are ideal. They have fibrous root systems and are a nitrogen (N) sink. Grasses also support mycorrhizae in the soil (the relationship between fungus and plant roots).

Broadleafs are great nutrient scavengers that will help improve soil quality and build soil bacteria.

Legumes are nitrogen fixers. They add protein to the soil to feed soil biology and more legumes in a rotation will build up mycorrhizae populations quickly.

A good cover crop not only includes a grass, a legume and a broadleaf, but also warm and cool season plants of each of these types. The more diversity in the mix, the better.

“In a monoculture the roots are all growing at the same time, at the same depth and are after the same moisture and nutrients so there is lots of competition,” says Elmy. “When you have a cover crop, plants grow at different times and roots are at different depths, so they are not competing in the same soil, at the same time, for the same nutrients. It spreads risk and takes the stress out of the soil.”

Soil biology

Living material in the soil, mainly bacteria, fungi and nematodes, breaks plant organic material into plant-usable nutrients.

Bacteria is the party animal of the group, says Elmy. “When you plough down green material the bacteria population goes crazy because that’s providing carbon and protein for them and they will recycle nutrients fairly fast.”

Fungi grow slowly and like to eat more straw and humus in the soil. Fungi are the preferred food source for every other microbe that lives in the soil. “Their fine filaments — hyphae — can get into places the plant roots can’t get into, and by doing that they can reach more micronutrients, such as stable carbohydrates, which is what other soil critters want to take in,” says Elmy.

Both legumes and grasses are dependent on mycorrhizae, their relationship with fungi, to absorb nitrogen from the soil. In exchange, the fungi get sugars from both plants.

Earthworms are indicators of healthy soil. They prefer to eat fungi, and they burrow and eat soil, producing castings that are rich in carbohydrates and protein, which attracts bacteria and fungi to keep the nutrient cycle going.

Earthworm populations will be reduced through tillage and growing too many brassicas, such as canola, which reduces mycorrhizae. Repeat applications of fungicides deplete earthworms’ food source by killing the fungi they feed on.

Creating blends

The first question Elmy asks when he helps a farmer develop a cover crop blend is, “What’s your goal?”

“If you tell me you are going to grow a cover crop and you don’t have goals I can’t give you the proper information for the best species,” says Elmy. “If the goal is to deal with high salinity, sugar beets, safflower, some sunflower, and some fall rye, seeded early in the season will help. If a producer wants high biomass and to build organic matter, lots of grasses and some legumes are best. To scavenge nutrients, grasses, legumes and broadleafs will absorb nitrogen. For weed suppression, use broadleafs and grasses.”

As a base for the blend, know what grows in the area and start with those plants. Then add diversity based on what the goals are, but be sure to think about plant growth above and below ground.

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The relationship between fungi in your soil and plant roots has a big impact on your crop health. This relationship can cause flax to be stunted when it’s grown in rotation after canola. Corn and sunflowers can also suffer when they’re planted on canola stubble.

“Following canola, we often see some interesting, funky growth responses,” said Dr. Mario Tenuta, soil science professor at the University of Manitoba. Tenuta was oan hand to talk about fungi at CanolaPALOOZA, a canola-based learning day hosted by the Manitoba Canola Growers and the Canola Council of Canada at Portage la Prairie, Manitoba, in June.

Arbuscular mycorrhizal fungi

“It’s a story of the soil, and fungi,” Tenuta said.

The word “mycorrhiza” comes from the Greek words for fungus and root. Mycorrhiza is the symbiotic relationship between fungi in healthy soil and the roots of a plant. The fungi help the plants take up minerals and water; the plants provide the fungi with carbohydrates.

“Fungi have these hyphae,” Tenuta said, describing their branching structures. When the fungi are living near a plant, their hyphae penetrate into the plant root structures. The fine surface areas of the hyphae help the plants absorb nutrients.

“What they’re doing,” said Tenuta, “is they’re helping the plant by taking phosphorus from the soil, and transferring it through these hyphae, into the root system. They don’t kill the root. They’re not a parasite, and they’re not a pathogen.”

“Most plants, most of our crops will have this relationship with this fungi, and they will take phosphorus from the fungus,” Tenuta said. “But there are some crops, canola being one of them, which do not do this.” Canola doesn’t have this ability to colonize with the fungi, and gets its phosphorus in different ways.

Because they are not fed by a growing canola crop, the arbuscular mycorrhizal fungi (AMF) in the soil are starved for the season when canola dominates in the field. The following spring, the AMF population are reduced, so the next crop will not have as many fungi to work with in gathering phosphorus.

In early season growth crops, phosphorus is very important. Corn is highly dependent on phosphorus, so when corn follows canola in a rotation, yields can suffer. Wheat has a slightly lower dependency on phosphorus in the early season, but, the impact of following canola with wheat can still be seen in lab tests, and there may be a difference in yield.

“What we want growers to understand is this effect that, when they have canola in the rotation, following the canola some plants may be struggling to get phosphorus,” said Tenuta.

What can be done?

No-till farming practices can help to nurture the AMF in the soil. When there is tillage, the fungi can be damaged, and forced to re-grow again. “If you chop them up, and then you plant canola there, they’ll really get hammered,” Tenuta said.

Also, you can add phosphorus to the soil, to compensate for the lack of AMF.

Growing canola is hard on AMF populations, but thoughtful rotations can help them re-build. After canola, Tenuta suggested, grow something that’s not so dependent on phosphorus, something like rye, or buckwheat. “Buckwheat is fantastic,” he says. “Buckwheat doesn’t really need the mycorrhiza.”

Then, Tenuta said, “work your way up” in the rotation, giving the AMF time to recover before you seed flax.

In his extensive work involving soil and agriculture, Tenuta often finds canola standing out from the crowd. “Whenever we do studies with canola in rotations, and look at almost anything, we find that canola behaves differently.”

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After researching chemical control of water hemlock, cultivation seemed the better option. The regrowth expectations after chemical application were high, and the requirements for summerfallowing and potentially respraying several times were also very high. Spending thousands of dollars on chemicals and then not being able to use the land anyway for several seasons due to weed regrowth, clinched the decision to experiment with these 10 acres using more organic methods. The basic premise is that if we improve the soil the water hemlock will not grow. But there are other benefits of increasing soil health.

Studying “When Weeds Talk” by McCaman, J. L. revealed that not only is this land suffering from having had too much moisture, the weeds that are growing there indicate a low soil calcium issue. It is fascinating that nature can show us just through plants what is happening in the soil — largely as a consequence of farming practices over the years.

Dr. Arden Andersen, of Kansas, a respected teacher, consultant, physician and farmer has studied the correlation between soil health and feed nutrition. His research has shown that the nutrient content of foods today ranges from 15 to 75 per cent less compared to half a century ago. According to him we have to look at the soil to decipher why the nutrition isn’t at the proper levels. For a livestock producer this means if we want our input costs to go down we need to be raising our feed and livestock on rich soil that is teaming with life.

Measuring quality

Feed testing can be a daunting task so we are very interested in using Brix. The Brix reading isn’t just about sugar content in a plant, it actually refers to the total amount of soluble solids, that is, sugars along with plant proteins, vitamins, and minerals. A Brix reading lower than 10 tells the farmer that the plant lacks nutrients. The desirable reading is 13, which indicates a robust and nutrient-rich plant.

To measure the Brix a refractometer is necessary as well as a method of extracting the juice from the plant. An optical refractometer uses daylight passed through a glass prism to measure Brix. The reading is read through an eyepiece, and the user measures the refracted light angle on an optical scale. To obtain juice/sap samples some people use garlic presses, but a juicer is better. We have used an optical refractometer, that costs about $100, available online at amazon.ca. There are digital models available as well. A great visual explanation of these machines is found at crossroads.ws/brixbook/BBook.htm.

Watch the animals

Watching the performance of young livestock is the greatest measure of how well the ration is supplying the needs of mature ruminants. Young stock depend on their dams’ milk for growth. Ruminant animals are relativity inefficient at converting grass proteins to milk proteins, only achieving approximately 20 to 25 per cent conversion efficiency. On top of this, some proteins are not well utilized by the animal. Either improving this conversion efficiency or increasing the total grass can increase the total milk output of a cow.

Research proves there is some correlation between this conversion efficiency and high sugar (Brix) content on a farm. IGER Innovations produced research in 2001 suggesting high-sugar grasses have a positive effect on the efficiency of milk production in an animal.

Grass is broken down in the rumen, producing amino acids to grow and produce more protein, which is later used for milk production by the cow. When the diet lacks readily available energy such as sugars, rumen microbes either cannot grow or instead use amino acids to provide energy, meaning less milk production. Feeding energy-rich foods in a concentrate feed is one way to increase the efficiency of the rumen, however the cheaper way is to use the sugars which naturally occur in forages, (Moorby, 2001). This concept is extremely important to grass-based livestock operations that do not depend on adding carbohydrates such as barley to ruminant diets to make up for what our grass is lacking.

Feeding the soil

How do we improve our soil to improve our Brix reading? One idea is utilizing a mycorrhizal inoculant at seeding. Mycorrhizal refers to a class of natural beneficial micro-organisms that live in the soil where grasses grow and enhance the plants ability to utilize the macronutrients that are in the soil. Mycorrhizal fungi are present in most undisturbed soils, such as in forests. They live symbiotically with innumerable amounts of beneficial bacteria, protozoa, actinomycetes, worms, insects, and other organisms. Unfortunately, populations are particularly low in agricultural soils that have been exposed to pesticides, chemical fertilizers, tillage, compaction, organic matter loss, erosion, and other practices that won’t feed them. It is very hard to naturally replace the mycorrhizal fungi because they form their spores under ground and are not easily moved in the air.

Use of mycorrhizal inoculation at seeding can also reduce the need for applying phosphorus because mycorrhizal fungi such as Glomus mosseae, Glomus intraradices and Glomus etunicatum species produce a high level of phosphotase enzymes that specifically extract tightly bound phosphorus from clay particles and make P immediately available to the plant. Since high rates of P application can kill mycorrhizal this needs to be considered when using it.

In my reading I tripped across this quote that reinforced our thinking that we were on the right track: “Can you believe that you can take pretty much identical-looking hay from neighbouring fields, feed 50 pounds a day from one field to a cow and have her drop in milk production and get sick, and feed half as much from the other field and have the cow rise in production and be healthy? What is the difference between the two samples of hay? QUALITY! — Dr. Harold Willis, “How To Grow Great Alfalfa.”Our hay field has needed attention for many years and we’re hopeful the repayment will be seen in many ways.

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We have a really good relationship with the two cattle owners we work with who bring us cattle each year. On the grass-management side, we have reserved the right to decide which paddock the cattle graze in and for how long, and that hasn’t been an issue for the cattle owners. Quite the contrary perhaps as one of the herds is typically made up of first- and second-calvers enjoying some compensatory gain after a hard winter.

I have written before on the positive transformation of our pastures through planned grazing over 22 years and increased species diversity, nutrient cycling and carrying capacity. While I have been inspired by many good graziers over the years — some have become great friends — the grain farming part of my brain had a hard time accepting it was possible to harvest X-pounds of beef per acre without commercial inputs.

I needed some answers as to why we experienced the pasture improvements on 4-Clover Ranch as a natural succession only brought on by a change in management.

Learning about the process

It seems the main key in the transformation of what we were seeing above the ground is really a result of what took place below the surface. It has been said if there is an abundance of plant species above ground there is an equal diverse abundance of microorganisms in the soil below.

I recently watched a YouTube video of American mycologist Paul Stamets on mycelium, the vegetative part of the fungus. It helped immensely in understanding the processes. I found the video captivating as it so plainly highlighted the role of mycelium in building soil carbon, humus and holding the soil together. I also didn’t know fungi arrived 1,300 million years ago or 600 million years before plants, giving plenty of time to create the environment suitable for plant growth.

Mycelium or hyphae are really fungi “roots” and these microscopic hairs are extensive — one cubic inch of soil reaching up to eight miles in length — creating a network of pockets that can capture water and create a microclimate for other microorganisms, protozoa, amoeba, bacteria and enzymes. Mycelia produce oxalic acid, which is key in breaking down rock and freeing up nutrients that would otherwise be unavailable to plants. It took place over millions of years and became the process of the soil building and foundation for plant growth.

Hearing about Paul Stamets’s work gave me a much better understanding of why we had seen increased forage production without commercial fertilizer. We had noticed that the manure and urine spots in pastures were gradually disappearing and suspected it was due to improved nutrient cycling in the soil. Now I had an answer, the effects of soil mycorrhizal fungi and their symbiotic relationship with plant roots.

While I was excited I might have mycorrhizal fungi in our pastures I was looking for ways to know for sure. The answer came from the work of soil scientist Dr. Sarah Wright with the USDA. In 1996 she discovered a soil protein called Glomalin associated with mycorrhizal fungi. The sticky glomalin attaches to the hyphae and tiny roots of plants and holds water, sand, silt and clay and the dissolved minerals like phosphorous and calcium.

Slow process

It takes time for the mycorrhizal fungi to build. Tillage as well as leaving land idle destroys the fungi. Iron and aluminium often binds soil nutrients such as phosphorous and another USDA soil scientist Dr. Kristine Nichols found that the glomalin can bind these metals freeing up the P for the plants. As well glomalin slows down the carbon decomposition and stabilizes the organic matter.

Understanding the role of mycorrhizal fungi and glomalin and their ability to free up calcium and phosphorous and other macronutrients didn’t explain where the plants’ nitrogen requirement would come from.

A pasture full of legumes would have a fair bit of nitrogen coming from the rhizobia bacteria but soil biology researcher Dr. Elaine Ingham’s work at Oregon State University has broadened the scope. Understanding the role of soil protozoa, amoeba, soil bacteria and soil nematodes gives an explanation. Not only does the mycelium allow for housing these organisms but their lifecycle is very short. Simply speaking, the bacteria gets eaten by the protozoa, the protozoa get devoured by the nematode and the whole process releases massive amounts of ammonium.

Bacteria is microscopic, protozoa a smidgen larger and some of the larger nematodes can be seen with the naked eye. While we shouldn’t be confused with the larger undesirable nematodes that can cause crop damage, the good ones are too small to see with the naked eye. Just one teaspoon of soil can house 500 of the “good” nematodes. Their activity in the soil helps explain the mystery of why manure and urine spots were disappearing in our pastures.

Well-managed pastures ability to produce with lower inputs contribute to the bottom line, which is always good. Understanding these pastures’ ability to store enormous amounts of carbon and thereby contributing to a reduction in atmospheric CO2 emissions is an added benefit that society is awakening to and ranchers ought to celebrate.

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