Clover & Agriculture

Every year many people around the world celebrate St. Patrick’s Day on March 17th. When thinking about St. Patrick’s Day, images of leprechauns, pots of gold, green, or Ireland might swarm your head. Did agriculture come to mind? One of the symbols of St. Patrick’s Day, the clover, is a valuable plant to farmers.

I’m not sure about you guys, but I spent a good chunk of my childhood outside intensely staring at the grass, searching for the lucky four-leaf clover. Sadly, after spending hours on the lookout, I never found one on my own.

Photo by Sudipta Mondal on Pexels.com

Clover or Shamrock?

It turns out I wasn’t even looking for a shamrock since a four-leaf clover is just a genetic mutation.

Shamrocks fall under the broad term of clover. Clover is the common name for the species in the Trifolium family, which translates to “having three leaves.” It’s kind of like how dogs, foxes, and wolves all fall under the canine family.

If you ask a botanist or the Irish what kind of Trifolium a shamrock is, most likely, you are going to get at least two different answers. Most botanists believe that the white clover is the same thing as a shamrock. In contrast, those staying true to the Irish tradition believe that the three leaves symbolize the Father, Son, and the Holy Spirit as taught by St. Patrick.

So, how do farmers use it?

While many probably recognize clover growing in their lawns, some farmers will grow it in their fields as a cover crop. Cover crops are planted to reduce erosion between growing seasons and add organic matter to the soil. To learn more about cover crops, check out the blog post “Cover Cropping. Why Do They Do That?”

According to Practical Farmers of Iowa, it is one of the best possible cover crop options. They describe it as the “Cadillac of cover crops.” Clover has many, many benefits as a cover crop. As a legume, it helps contribute nitrogen to the soil, it reduces soil erosion, and it helps limit the number of weeds in the field. Clover also helps a lot with the soil’s moisture hold capacity and water retention, which is great for those dry summers like we had last year.

Photo by Zhanna Fort on Pexels.com

Clover and livestock

Not only do farmers use clover as cover crops, but some feed their livestock with it as well. Integrating clover in pastures through a process called overseeding has its benefits: increase of yield, improve animal performance, Nitrogen fixation and grazing season extension, to name a few. Adding clover to a pasture will help the soil, the livestock and other grasses, but it does come with a warning.

Farmers need to be careful because too much clover could cause bloating. An abundance of clover consumption may cause cattle or other livestock species to have a gas buildup and can be very dangerous if this leads to pressure on the internal organs.

There are ways to prevent this bloating. Farmers can mix the clover with other grass species in the pasture, wait to feed livestock clover until it is drier or rotate their grazing.

Despite these risks, few farmers cut out clover feeding entirely due to its significant protein and fiber amount.

4-H

Other than the shamrock around St. Patrick’s Day, another famous clover is the clover emblem of 4-H. 4-H is a youth development organization for 4th-12th graders where members can create projects in health, science, or agriculture fields. The four-leaf clover emblem representing the 4-H organization has an “H” on each leaf, meaning head, heart, hands and health.

As you are celebrating St. Patrick’s Day this year, don’t just think about all of the green you’re going to wear, but think about how much agriculture is tied into this holiday!

~Madison

Why the Peanut? A Look at George Washington Carver’s Research

As many Iowa students and you may already know, George Washington Carver invented over 300 uses for the peanut. But what you may not know is — why the peanut?

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As some background, George Washington Carver was born into slavery in Missouri sometime in the 1860s. When slavery was abolished, Moses and Susan Carver took George and his brother James in, raised, and educated them. George went on to study art and piano at Simpson College in Indianola, Iowa, before realizing his passion for botany and science and enrolling at Iowa State Agricultural College in Ames, Iowa.

Though Carver gained an education in Iowa, his work with the peanut was not in this state. After he obtained his bachelor’s and master’s degrees from Iowa State, he spent 47 years teaching and doing research at the Tuskegee Institute. As Tuskegee is in Alabama, his research there focused on areas like crop rotation and diversification to help cotton farmers protect their fields and crops from pest pressures, nutrient loss, and soil degradation.

This is why the peanut became important. Peanuts are a special crop, because they are not a classic nut that grows on a tree. Instead, they are a legume, like alfalfa or soybeans. Legumes are an interesting group of plants because each specie develops a symbiotic relationship with a different strain of bacteria that forms nodules on the roots of the plant, and fixes atmospheric nitrogen into a plant-available form of nitrogen. This means that legumes need less nitrogen fertilizer, and leave a nitrogen “credit” in the soil for the next crop. This works really well alongside more intensive crops, like cotton or corn, that need more nutrients and don’t have the handy nodules available.

The problem George Washington Carver ran into, though, was that even when you find a scientific solution to a problem, you have to convince people to use it. This caused Carver to set off to find uses for the peanut to create a market for it. If you create a market for a product, that product will gain value, and it will be more feasible and more exciting to get into that market. In short, he was trying to incentivize growing a crop that would help protect soils.

Though this is some of his most famous work, his botany career was not solely dedicated to peanuts. He also worked with sweet potatoes, plant diseases, and even worked with Henry Ford to develop plant-based products to be used in cars. He was known for being frugal and helpful, as well. He could have filed for multiple patents, but chose not to in order for other people to be able to use his findings without restraint.

For good reason, George Washington Carver remains one of our most famous Iowans even now, close to 80 years after his death. For teachers that are interested in using Carver’s story and work in their classroom, check out IALF’s Lending Library to find books and other resources about him.

Geo.Wash

-Chrissy

Nutrient Cycling in the Environment

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“The nation that destroys its soil destroys itself.” This quote by Franklin D. Roosevelt simply explains the importance of managing soil quality. This becomes extremely applicable to farmers who are trying to maximize crop production, which can be achieved by maximizing the productivity of their ground. Fields contain much more than just dirt. They’re a complex ecosystem that contains a large amount of diversity when it comes to chemical and biological composition. One major factor in soil’s productivity when related to crop production is the nutrients found in soil. Some nutrients come from organic materials that are naturally occurring, while others are added to the soils because they are deficient. This process becomes a bit complicated when talking about specific nutrient cycling. This post will showcase how nutrients move throughout the environment while shining a light on the importance of managing soil nutrients. 

How do nutrients cycle in the soil?

Nitrogen (N)

Nitrogen is a macronutrient required by all plants, and is especially correlated with high yields in corn and soybean production. But first here’s a little bit about the basics of nitrogen in a cropping system! 

  1. Nitrogen gas (N2) is abundant in the air, however it cannot be taken up by plants. The plant available forms of nitrogen is nitrate (NO3) and ammonium (NH4+). 
  2. Nitrate is mobile in the soil profile. Due to this molecule’s negative charge, it repels from negatively charged soil particles and is easily lost to leaching and soil runoff. 
  3. Plants use nitrogen to synthesize amino acids, proteins, and chlorophyll. Ammonium is the easier form of nitrogen to use because it requires less energy in the reduction process. 

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This diagram helps to visualize each process in the nitrogen cycle. Photo from wikiwand.

Now that we understand the importance of nitrogen in crop fields, here’s how it cycles and moves around in the environment! Nin the atmosphere goes through ammonification to become NH4+, which occurs due to nitrogen-fixing bacteria found in the soil. Legume roots have a symbiotic relationship with these bacteria, which adds plant available N to a field. Once in the ammonium molecule, nitrifying bacteria changes NH4to nitrites (NO2) and then nitrates (NO3). From this point, the molecules can either be taken up by plants, processed back to N2 through denitrifying bacteria, or leached with water. If the soil’s natural amounts of nitrogen is insufficient for a specific crop, the producer can apply fertilizers to a field.  It’s important to remember that these processes are constantly changing the chemical makeup of a soil, and that severe weather events could deplete the soil of many plant-available forms of nitrogen. 

Phosphorus (P)

Phosphorus is another essential macronutrient that’s found in phospholipids, lipids, and the backbone of DNA.

  1. Crop grain contains a large amount of phytic acid, which is primarily comprised of phosphorus molecules. 
  2. Phosphate is the plant available for of phosphorus, and the two most common forms of P are HPO4-2 and H2PO4

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This diagram helps to depict and simplify the chemical changes that occur in the phosphorus cycle. Photo from soilmanagementindia.

Unlike nitrogen, phosphorus’s most abundant form is a solid found in the ground. Organic P is created over an extremely long period of time with plant residue, hummus, and microbial biomass. Organic P is turned into a plant usable form through mineralization, and the reverse reaction is called immobilization. Once phosphorus is available and held in solution it can become unavailable by reacting with clay and various mineral surfaces or by binding with cations such as calcium, iron, and aluminum. Phosphorus held in solution is susceptible to leaching, much like nitrogen is. It’s important to know that the main P inputs into ecosystems are derived from fertilizers and plant residue. 

Potassium (K)

Potassium is a macronutrient that’s required for protein and starch synthesis, acid neutralization, enzyme activation, as well as water regulation in plants. 

  1. Plant available potassium is K+. Some soils can contain a lot of potassium, but not in the cation form. 
  2. If a plant is deficient in potassium, it can exhibit stunting, necrosis, lodging, and an overall reduction in yield. 

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This photo showcases the major steps and processes in the potassium cycle. Photo from nutrien-eKonomics.


Potassium starts as a primary mineral such as mica. After years and years of weathering, it changes into a nonexchangeable form. K cations change between nonexchangeable and exchangeable molecules through release and fixation. Once K is in an exchangeable form, it changes into a plant available form through desorption. K in solution is able to be leached, but is much less susceptible than nitrates. In terms of mobility within the soil profile, potassium is immobile. This is because a large percentage of soil K is nonexchangeable, due to its location and attraction to soil minerals. The main inputs of potassium into systems is through fertilizer and plant residues. 

How are these cycles manageable? 

Since these cycles are constant and on-going, it’s crucial for producers to maintain a knowledge of the nutrient levels within their fields and which areas are the most susceptible to losing nutrients faster than others. One way to measure nutrients is to test the plant’s vegetative matter for chemical composition. While these results are helpful and accurate, it doesn’t necessarily provide information for the available forms within the soil. This is where soil testing comes into play! Soil tests can be used to qualitatively measure nutrient levels precisely, which helps to give producers recommendations on management practices in the future years. 

Hopefully this opened your eyes a little to the vast possibilities within soil science, as well as provided a better understanding of some prominent nutrients that cycle through ecosystems!

~Rosie

Soil and Water Conservation Practices – What are They Doing?

Agricultural run-off has been a big talking point in recent years. Many people know bits and pieces of the conversation, but the scope of the issue can be a bit complicated. There are many factors and smaller issues that need attention. So, what is the deal with run-off?

As you may know, Iowa is under national pressure to reduce the amount of nutrients washing off of our land and into the rivers, and ultimately into the Gulf of Mexico. The main issue at the Gulf is hypoxia, which basically means there are too many of specific kinds of nutrients, which promotes algae growth, which in turn chokes out other organisms like fish. Clearly this is not ideal.

The main nutrient that gets the press is nitrogen. Nitrates in the water has been one of the bigger issues people talk about. The main concerns are removing nitrates from drinking water (primarily because of the blue baby syndrome that was a larger problem in the 1950s), issues of environmental stability, and even cost of wasted nutrients on the farm associated with nutrient loss from the field.

The other nutrient we are now paying attention to is phosphorus. This one isn’t quite as popular to talk about in the public space, but it impacts aquatic ecosystems similarly to nitrogen. They both support the growth of algae, sometimes to the point of using up all of the oxygen in the water and killing off native fish.

Nitrogen and phosphorus (along with potassium) are two of the three main macronutrients that plants need to grow. Nitrogen tends to be the nutrient that is applied most to Iowa farm fields, because of how important it is to crop growth. These are naturally occurring elements in the soil and play a vital role in life on Earth.

However, we’ve come to this issue. Aquatic ecosystems are being negatively impacted by these nutrients. Farmers pay to apply these nutrients to their crops and don’t want to lose their investment. How can we reduce those nutrient loads in our waterways and keep nutrients and soil where they belong?

The good news is those questions are being asked, and many programs are underway. The more difficult news is that there is not a one-size-fits-all answer either for fields or for the nutrients themselves.

Let’s back up a little bit and talk about how these nutrients interact with the soil and water. Soil particles are made up of sheets of molecules that when bonded together create an overall negative charge. This works out pretty well because most nutrients have a positive charge in their plant-available form. This means that most nutrients bond with the soil and stay available to the plants living in that soil. Phosphorus is one of these nutrients.

But then we get to nitrogen. It sometimes is in a form with a positive charge (NH4+), but it doesn’t really like to stay like that forever. It gets broken down or may volatilize into a different form. It could be lost into the atmosphere, or it could become NO3-, which is nitrate. When nitrogen changes into its nitrate form, it is no longer attracted to the negatively charged soil and ends up leaching its way through the soil profile along with ground water.

Since nitrogen moves with ground water, the primary way it gets around is through tile lines. Field tile is commonly used in Iowa to help keep excess water from the field. If soil is too waterlogged, the crops may struggle. Thus, Iowa farmers have been tiling their fields for decades to give the water a quick and easy way to escape the field.

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Iowa Learning Farms display highlighting differences between nitrogen and phosphorus loss from a field and how tile lines play a part.

Both of these nutrients cost money to apply. They are important for crop growth. The soil that can hold them is also valuable. Farmers don’t want them to leave their field partially because they don’t want to lose that value, and also because of the negative impacts too much of them can have on other ecosystems. But because these two things come into the waterways in different ways – phosphorus comes into the water with soil that has eroded, and nitrogen through the water itself – they have to be managed in different ways.

So what are some ideas?

There are some practices that can be built or installed to help modify the landscape or the way the elements interact with it. These can cost real money, but in some cases, government programs or even corporate incentive programs can help fund their start up. These can be largely grouped as permanent structures

One cool new idea is saturated buffers. This system uses both buffer strips and tile lines. Buffer strips are areas of natural plants parallel to ditches and waterways left fallow to help filter runoff. Conventional tile systems are installed 3-4 feet deep to catch and take extra water from the field and into a near ditch or waterway. The outlets of these tile lines have conventionally been placed directly into a ditch or waterway uninhibited. However, the idea with a saturated buffer is that if you place the tile line parallel to the ditch or waterway, the soil and plant growth in the buffer strip will filter the soil particles and nutrients in the water before it reaches the waterway. The Agricultural Research Service claims this system filters an average of 42% of the nitrate load from the water.

The saturated buffer idea is similar to the idea of bioreactors. Bioreactors also help filter nutrients from tile line outlets, but with artificially created biological processes. Essentially a pit is filled with organic, carbon-rich materials, like woodchips, where microscopic life can flourish. These microorganisms help break down and filter nitrates from the water introduced to the system. This is a slightly older technology than saturated buffers, but is costlier to implement and will need redone roughly every 15 years.

Buffer strips and bioreactors are considered “edge of field” practices. This means that they don’t need to take up area in a field, but instead use the less productive or less safe land to farm near a water boundary. Though it still may be a hard sell to pull that land out of production, it is argued that those areas likely aren’t making the farmer much money, and proper water management may help make other areas better. Since these practices help filter ground water before it reaches the stream, they are some promising pieces in removing excess nitrates.

Terraces are another way farmers can make changes to the land to slow water runoff. You may have seen pictures of farms in other parts of the world where terraces are cut like stairsteps into a large hill so that the crops can be grown on flat land. Here in Iowa, we use a different kind of terrace that essentially builds up a smaller hill on a broad hill to slow water running off the slope. When the water runoff is slowed, soil particles and nutrients can have more time to settle out in the grassed front and back-slopes of the terrace. For more info on terraces, check out our previous blog post here, Clean Water Iowa, or the Natural Resource Conservation Service.

Avoca Terraces

Terraces placed on the slope protect the soil from erosion in Avoca, Iowa.

Grassed drainageways or grassed waterways are a common sight to see around the hills of Iowa. These are natural waterways that farmers leave in native grasses to slow water flow, intercept soil runoff (to decrease P loss), and hopefully the plant life will also absorb excess nutrients in the water (to decrease N loss). If not left in a grassed waterway, these areas of the field would be susceptible to rill and gully erosion.

There are also cropping practices that can impact soil and water conservation. These can be opted into or out of any given season.

Another very cool idea is cover crops. We’ve written previous blogs about cover crops, but in a nutshell, cover crops are plants grown in a farmer’s field during the off-season (fall to spring) to keep the soil covered and protected during a time it would usually be left bare. Cover crops protect the soil surface from wind and rain, the roots help improve soil structure, they add organic material that makes soil healthier, hold nutrients near the soil surface, help suppress weed growth, and do lots of other cool things. Because cover crops help use nutrients and protect the soil, they can help with both nitrogen and phosphorus loss.

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Soybeans sprouting through a terminated rye cover crop on a strip-tilled farm near Algona, IA.

Our grandfathers and great-grandfathers broke the land using moldboard plows year after year. Eventually we realized that even though tillage can help prevent soil compaction and help with weed control, it has a negative impact on soil structure and makes soil more susceptible to erosion. Because of this, some farmers swung the pendulum to the opposite side of the spectrum and went no-till. This means they never till the soil on their fields. Instead, they are more dependent on herbicide weed control, and use crop rotations and cover crops to help mitigate soil compaction. When the soil is not tilled, the structure becomes stronger, and previous years’ crop roots and stems help protect the soil. This helps prevent soil from washing off the field, thus preventing phosphorus loss.

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This is a field that has been strip-tilled. Strip tillage is a form of conservation tillage where only part of the field is tilled.

If we think of no-till and moldboard plowing as the two far swings of the pendulum in terms of tillage, likely the middle of the road or slightly more toward no-till would be conservation tillage. This is the idea that a field can benefit from tillage for compaction or weed control issues, but can also benefit from increased soil structure and added organic material from less tillage. These practices vary greatly, but likely include less of the topsoil being broken up.

Contour farming is a way to plant a field so that the rows follow around the hills. This means that when the water runs down the hill, it would run perpendicular into the rows instead of parallel between the rows. This should slow the flow of water, giving soil time to settle out of the water before it continues down the hill.

There are many options available for farmers and landowners in the area of soil and water conservation. More research is being done every day for the best and newest ways to decrease risk, decrease cost, and maximize benefit. Because of the nature of these practices (particularly permanent structures and cover crops) is that it costs real money up front to earn intrinsic value later (i.e.: will not earn them a paycheck), it can be difficult to implement new things. However, farmers recognize the good that these things do, and are interested in new cost-share and grant opportunities that can help them do better with what they have.

What do you think the next big idea will be? Maybe you’ll be right!

-Chrissy

Macronutrients in Crop Production

elements in the environment

When growing crops of any type, it’s important to understand the required inputs in order to receive the desired yields. One of these inputs, arguably the most important and critical one, revolves around nutrient management. All plants have these requirements, whether it be crops grown for biofuels, fruit production, or landscape ornamentals. Each plant needs various amounts of nutrients, which can be used to classify them (by quantity) into macro or micro nutrients. It’s important to remember that each one is vital for plant growth, simply required in different doses. As a sidenote – this blog is going to be mainly focused upon corn production, but all of these elements are necessary for any plant you’re trying to grow! First I have a couple questions to spark your curiosity about nutrients in plants…    

  • A plant can be deficient in oxygen, how is that possible?
  • Plants need calcium just like humans do. If it doesn’t go towards bone and teeth strength, then what’s its purpose?

Macronutrients

Let’s start with the big three: carbon, hydrogen, and oxygen. If you’re reading a fertilizer label, they don’t typically advertise for these elements. So, where do plants take them from? Why are they necessary for plant life? Should I be worried that my garden isn’t receiving enough hydrogen? The simple answer is that no one should be concerned about their plants being nutrient deficient in C, H, or O, as long as the plants are surrounded by air!

Carbon (C) – Thanks to many fields of science, we know that carbon is the base for life on Earth! This means that if plants are going to continue to be alive, they must obtain and maintain C. In more direct terms, plants produce and uses chains of carbon with other atoms called carbohydrates, lipids, proteins, and nucleic acids. But what happens if the plant is unable to take in carbon? This would be a very unfavorable scenario for the plant, especially since carbon is essential to photosynthesis. More specifically, without carbon (in the carbon dioxide form) the Calvin cycle wouldn’t occur. This means there’s no G3P, which helps make glucose, and without energy the plant cannot continue to live.

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This depicts the Calvin cycle in photosynthesis. Diagram from Khan Academy

Hydrogen (H) – Whenever I think of elemental hydrogen, I don’t normally think of it as a nutrient. I don’t directly eat anything that is marketed as “high in hydrogen”, so how could a plant use it? To start off with, every living organism on Earth needs water (H₂O) to live. Plants use water to obtain hydrogen atoms when splitting H₂O molecules through the light reaction of photosynthesis. The hydrogen ion is then used to create NADPH, which is a crucial ingredient in the Calvin cycle. If a plant is missing this chemical compound, then photosynthesis would cease and the plant would die.

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This shows the light-dependent reactions in photosynthesis, commonly referred to as the z scheme. Image from LibreTexts

Oxygen (O) – Wait a minute – oxygen is a product of photosynthesis, why would a plant need to take in oxygen too? In order to break down food through aerobic respiration, there must be oxygen present. Yes that’s right, plants respire just like humans do! Cells within leaves and stems obtain oxygen atoms that are a product of photosynthesis. However, cells found in areas that aren’t photosynthetically active must find oxygen elsewhere. To solve this issue, roots are able to take in O₂ from the air between soil particles. If the ground is saturated to capacity, then the roots cannot take up oxygen in the gas state. If the area is flooded for longer than 72 hours, it’s likely the plant will run out of oxygen and not recover.

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The chemical equation for photosynthesis.

Nitrogen (N) – This is a much more commonly discussed nutrient, especially since it has a huge correlation to high yields in corn production. If you were to walk into a farmer’s field, you would be surrounded by nitrogen in many forms! N₂ is a gas found in the air, whereas NO₃⁻, NH₄⁺, and NH₃ are compounds found in the soil. But if nitrogen is found in the air, why can’t corn absorb it like carbon or oxygen? This is because corn can only take up nitrogen when it’s in a nitrate form, which can be found in solutions and attached to soil particles! When taking a closer look at NO₃⁻, it’s more prone to being lost to the environment due to its negative charge. Soil naturally has a negative charge, which means that a nitrate is more likely to move elsewhere in the environment than wait around to be absorbed by a plant. This is why many agriculturists use anhydrous  ammonia as a N fertilizer, because it contains NH₃ and not NO₃⁻. Overtime soil microorganisms will convert ammonia to a plant available nitrate. Why is nitrogen so important in corn physiology? N is essential to grain fill and development. This means that if the plant is deficient in nitrogen, the kernels and ear won’t fill to their genetic potential. A common symptom of N deficiency is a yellowing midrib on a lower leaf.

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Nitrogen deficiency in corn. Photo from SDSU Extension

Phosphorus (P) – This is another very important macronutrient! In a similar respect to nitrogen, plants are unable to absorb and utilize the elemental form of P. This creates a problem in fields, because P is most commonly found in a plant unavailable form! Luckily, roots have a symbiotic relationship with Mycorrhizal fungi which are able to turn P into a more usable form. Corn can easily uptake phosphates, and the most common compounds are H₂PO₄⁻ and HPO₄²⁻. Since phosphates have negative charges, they are more prone to leaving the soil than the elemental form (similar to nitrates). This is why synthetic fertilizers that contain significant amounts of phosphorus are delivered in a P₂O₅ compound. Why is phosphorus so important in corn physiology? P is directly correlated to crop maturity, yields, and overall plant growth. More specifically phosphorus is a huge makeup of sugar phosphates, which directly affects ATP. Energy transfer with ATP is crucial, due to it’s role in both RNA and DNA. A lack in P will affect the overall efficiency of any plant. Phosphorus deficiency in corn appears in older leaves and starts as a purple hue. An increase in severity will turn leaf margins brown.

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Phosphorus deficiency in corn. Image from Channel.

Potassium (K) – When applying synthetic fertilizers, it’s common to see potassium in the K₂O form. However, this form is not immediately available to plants. Plants can only take up K+ when it’s in a solution. This form differs from the available compounds of N and P, since potassium is a cationWhy is potassium so important in corn physiology? A deficiency in K can have a multitude of negative affects upon the plant. This could be seen as an increase in susceptibility to drought, temperature stressors, and pests. Agronomists refer to K as “the quality nutrient”, meaning there’s a direct connection to traits like seed vigor, size, color, and shape. To be more specific, potassium helps build cellulose, increase protein content, maintain turgor, and move sugars and starches throughout the plant’s vascular system. K deficiency symptoms start as a yellowing of leaf margins on older leaves, and an increase in severity turns the pale color to a brown necrosis.

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Potassium deficiency in corn. Photo from Thompsons.

Secondary Macronutrients

There are three elements that fall under this category, as they’re needed in higher quantities than micronutrients but lesser amounts than N, P, and K.

Calcium (Ca) – Calcium deficiencies are most common in sandy and/or acidic soils, since the Ca ions can be leached through the soil profile. Similarly to potassium, Ca²⁺ can only be imbibed by plants when in a soil solution. Why is calcium so important in corn physiology? Ca holds a vital role in the creation of cell walls and membranes. Calcium deficiency symptoms are visible in new growth, so in corn this would be around the growing point. It typically appears as a yellowing color, slowed growth, and leaf tips sticking together.

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Calcium deficiency in corn. Image from Crop Nutrition.

Magnesium (Mg) – Without Mg, a plant would not be able to photosynthesize. This element is a sizable component within chlorophyll molecules, which is 100% necessary for capturing the sunlight’s energy! Additionally, Mg serves as a phosphorus carrier. Simply put –  if there’s not enough Magnesium then the plant would be unable to uptake P, even if it was available in the soil! Mg²⁺ is the plant available form, and can be heavily affected by the pH and sandiness of soils. Mg deficiencies are first seen in older and lower leaves, starting as a purple interveinal discoloration.

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Magnesium deficiency in corn. Photo from The Mosaic Company.

Sulfur (S) – The last, but certainly not least, macronutrient can be absorbed both through the roots and stomata openings. In the environment, sulfur is commonly found in the air as SO₂ and within soil solutions as SO₄²⁻. Unlike the previous secondary macronutrients, this one is taken up as an anion as opposed to a cation. Due to the negative charge on a sulfate molecule, it is mobile in the ground (just like nitrate or phosphate) and can be leached through the soil profile. Why is sulfur so important in corn physiology? Without adequate S, some amino acids and proteins would be unable to synthesize. Sulfur also has a connection to winter hardiness, which is a major trait in certain crops. S deficiency in corn appears as a general yellowing of younger leaves, starting between veins but widening to encompass the entire leaf with increasing severity.

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Sulfur deficiency in corn. Image from Successful Farming.

This is merely a glimpse into some of the chemical factors and management systems that a row crop grower oversees each and every year. If you liked this blog or learned something new from it, let us know! Or maybe if you’d like to see a similar breakdown of micronutrients too? Either way I love writing about agronomic science and can’t wait to share another blog with you all!

-Rosie

 

Why do they do that? Anhydrous

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Early in the spring and late in the fall it is common to see tractors pulling large white tanks across bare farm fields. So, what are these strange white tanks? What’s in them and why is it applied to fields?

They are anhydrous tanks filled with anhydrous ammonia (NH3) – one of the most efficient and widely used sources of nitrogen fertilizer for agricultural crops like as corn and wheat.

Nitrogen is one of the 17 essential elements required for plant growth. Nitrogen is most commonly found in the atmosphere making up approximately 78% of the air that we breathe. But in the air it is in the form of N2 which is not available to plants to use. Nitrogen is part of chlorophyll which makes plants green and allows them to use sunlight to produce sugars (food) from oxygen and carbon dioxide through photosynthesis. Nitrogen supports strong vegetative plant growth, which is vital for good fruit and seed development.

Plants use nitrogen by absorbing either nitrate (NO3) or ammonium (NH4) ions through their roots. Soybeans and other legume plants can convert atmospheric nitrogen into a usable form because of nitrogen fixing bacteria on their root nodules. Other plants, like corn, need to have an ample supply of available nitrogen in the soil. Farmers can add nitrogen to fields in the form of livestock manure, granular urea, liquid nitrogen (UAN solution), and anhydrous ammonia.

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When making environmentally and economically sustainable decisions about fertilizers, farmers consider the 4Rs best management practices. This helps them select the right fertilizer source and apply it at the right rate, right time, and right placement in the soil.

Anhydrous ammonia is often a preferred nitrogen source for many reasons. It is more concentrated than other forms of nitrogen, containing 82% nitrogen. It is readily available, because it is used in the manufacturing process of other nitrogen fertilizers. It can be applied long before the crop is planted. It is usually the most economical option as well.

Farmers store and transport anhydrous ammonia in liquid form in pressurized tanks. Using an anhydrous applicator pulled by a tractor, the high-pressure liquid converts to a liquid-gas mixture as the pressure drops while traveling from the tank to the knife outlet on the applicator. The knife slices the soil and injects the fertilizer 6 to 8 inches into the soil.

Once in the ground, the ammonia (NH3) ions react with moisture in the soil and convert to ammonium (NH4). Ammonium ions are very stable in the soil. They carry a positive charge and are bonded to negatively charged soil particles like clay and organic matter. These ammonium ions can be taken in by plants and used directly in proteins. Over time, the ammonium converts to nitrate (NO3) which is the form of nitrogen most used by plants for growth and development. Nitrate does not bond to soil like ammonium does and could leach out of the soil and into waterways. Nitrogen fertilizer stabilizers are often added to anhydrous ammonia before application to slow the conversion of ammonium to nitrate, thus helping to reduce nitrogen loss from leaching.

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Because of the stability of anhydrous ammonia (and converting to ammonium) it can be applied in the fall with less potential to leach, volatilize, or to be lost in water runoff than other nitrogen fertilizers. Cooler soil temperatures help keep the ammonium ion stable and so farmers try to apply it in the fall after the soil temperature drops below 50°F. If applied in the spring, it is best to apply it at least 3-5 days before planting to avoid damaging seeds and emerging roots.

Good nitrogen management is critical for growing healthy plants, good yields, and a profitable farm business. Farmers consider crop nutrient requirements, results of soil tests, soil conditions, weather, cost, time, and equipment available before choosing a fertilizer program that is the best fit for their operation.

-Cindy

Why do they do that? Floor Slats in Pig Barns

Earlier this fall, I was attending a STEM Festival, where we were presenting our Feed Sacks Pork Lesson. In this activity, students make a snack mix based on the feed rations a pig gets. As part of our set up, we had some photos on the table of modern pig barns, and some real pig feed samples.

At this event, one family came to our booth very curious about what they were seeing. They told me that they had recently moved to Iowa from Alabama, and were not familiar yet with Iowa agriculture.

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Upon seeing one of the pictures, the mom asked why the floors looked the way they did. Since many people don’t get the opportunity to see inside the pig barns they notice from the road, I thought this was a great question. Why do they make pig barn floors the way they do?

The flooring in pig barns is slatted, meaning there are long, narrow holes in the floor. This essentially creates a waste disposal system in the barn, making sure that the pigs don’t have to lay around in messes. This is also a much less labor intensive system than having to scoop or remove the waste regularly.

Slatted floors can look different. In the photo above, the floor is cement. Other flooring systems with the same concept could be plastic, or metal coated with rubber. Different producers or different barns might use different styles of flooring depending on cost, the size of their barn, and how safe the flooring will be for their pigs.

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Source: http://www.prairieswine.com/about/6551-2/

But what happens to the waste that falls through the flooring? Does it just fall to the ground and stay there? Not quite! Underneath pig barns like these, there are manure pits. Other types of barns have systems where the manure is then moved to a pit outside of the barn instead of directly underneath it. All of these pits are monitored carefully for air quality to make sure there are no accidents that can harm either humans or the pigs. Sometimes the gas produced can be collected and made into biogas, which can generate energy for the farm!

So then what happens with the manure? About twice a year, these pits get pumped out into tanker trucks, and the manure is used as a fertilizer for farm fields. Manure can be tested for nutrients (along with the soil from the fields), and this can help make sure the farmer applies just the right amount of the manure to the field. Manure is most rich in nitrogen, but it is also rich in phosphorus, potassium, and other nutrients essential for plant growth.

In modern manure pits, the waste is stored as a slurry, meaning it’s mostly liquid. This makes it easy to move, and easy to apply to the field. Today, many farmers will inject the manure into the ground instead of applying it to the surface. This is beneficial for multiple reasons. First, this means that the manure is less susceptible to the elements and is less likely to be washed away into a nearby stream. Secondly, by injecting the manure into the soil, it also helps to stabilize the nitrogen in the manure for longer. If the nitrogen was applied to the surface, it would be more susceptible to volatilization, meaning it can transform easily into a chemical form of nitrogen that isn’t available to plants.

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Source: https://www.striptillfarmer.com/articles/224-strip-tillers-putting-manure-in-its-place

 

This whole system of dealing with the messy side of livestock is called manure management. It can also include innovative and interesting ways to keep the smell under control, like using windbreaks and even creating air biofilters out of things like woodchips.

Though manure may be smelly, it plays a big role in Iowa agriculture. We grow crops to feed our livestock, and our livestock produce fertilizer for our crops. It’s an elegant system for an un-elegant topic, don’t you think?

What other agriculture questions have you had? Let us know in the comments, and you might see another “Why do they do that?” blog about your question!

-Chrissy

How Many Ears?

How many ears will you find on a stalk of corn?

The question seems simple enough. Often times, cartoon drawings of corn plants show bountiful plants with six or eight or more ears of corn – one with every leaf. But the reality is much different. How many ears of corn on a single stalk? The short answer is….one.

But as Paul Harvey would say…and now, the rest of the story.

How many ears on a single stalk of corn? It depends! Corn or maize is a grass and like other grass species it has the possibility of producing tillers (stems that grow after the initial parent shoot grows from the seed) or branches. In the case of corn, the branch is called the shank which is a small stalk-like structure that grows out from a leaf node. Leaf nodes in the middle of the stalk have the potential of growing these shanks. It is from this shank that an ear of corn will grow.

One factor that will influence ear production is population density. Over the last half century, farmers have been able to plant corn plants closer and closer together. This allows for more total production and more bushels of corn per acre to be harvested. As the plant’s genes interact with its environment the plant will respond. More light, water, and nutrients will produce more branching. In high density populations (like in a typical cornfield) light doesn’t get all the way down and so there is less branching. The plant can dedicate all of its resources to producing one really good ear of corn rather than wasting water and nutrients on producing multiple, less viable ears. The corn plant’s main goal in life is reproduction and it wants to give its seeds the best chance of survival. One ear of corn with 600-800 seeds is better than two ears with only 200-300 seeds.

In modern cornfields in the U.S., farmers may plant 30 inch rows with 30 to 35 thousand seeds per acre resulting in that many individual plants. Some farmers are planting 12 inch rows with as many as 60,000 plants per acre! Soil and available nutrients have to be able to support that many plants, and each farm and each field is different. Corn varieties that farmers use today have been selected and bred for high densities, meaning that they can tolerate high populations and usually only produce one ear per plant.

But in the right conditions things could change. If those high density varieties of corn (or any other cultivar of corn) are spaced out with low competition, plenty of sunlight, water, and nutrients, they could branch more and produce more ears of corn. Often times, farmers will see more ears at the edges of fields because the end rows have more sunlight and more space. But the second ear will not usually be as good of quality. The primary nutrient that is a limiting factor for overall growth and ear development is nitrogen.

Sometimes farmers can increase the population of corn planted and actually decrease the number of ears. Some plants would be barren and not produce an ear. If the farmer is growing the corn as stover (stem and leaf materials) to feed to livestock as chopped silage, there is no need to produce a large ear.

Of course with all of this, we are primarily talking about field corn (also called dent corn). Field corn accounts for 99% of the corn grown in Iowa. Field corn can be used for human food (tortilla chips, cornbread, etc.), animal food (both ground corn and fresh silage), and fuel production (ethanol and corn oil biodiesel).

Sweet corn, the kind that we enjoy fresh off the cob in the summer, is sometimes considered a low-value crop when compared to other vegetables. This is because it takes up valuable room – a lot of room – in a garden and only produces one ear per plant. Sweet corn can take up to 3 square feet of space. If you harvest a cucumber from the garden, more will grow and you can get multiple harvests. But if you pick an ear of corn, the plant is done producing. Sweet corn may produce two or sometimes three ears per plant because there is wider spacing and less competition. Early maturing sweet corn varieties may still only have one ear. Later maturing sweet corn varieties might have multiple ears.

So, don’t believe those cartoon drawings! Corn usually only has one ear per stalk.

And now you know the rest of the story.

-Will

 

6 Reasons Farmers Use Cover Crops

There is a challenge that farmers are faced with every day of their career—how do we protect the land we work on? Farmers work with the land everyday of their lives and work to protect and restore the land for future generations. They understand how the land provides for them—after all, without taking care of the land they work they would not be able to grow a product, such as corn and soybeans, and be able to make a profit for their livelihood. One way farmers work to protect the land is through cover crops.

What is a cover crop? This is a plant that is grown in fields to protect land quality for the future. There are many benefits of implementing the use of cover crops—and here are 6 reasons farmers use cover crops in their operation.sloans-cover-crop-in-corn-stubble

1.)Soil Erosion: One thing I will always remember from my American History lesson of the Dust Bowl is that bare ground is not the answer. Open topsoil is something to avoid in farming practices. Wind and water can carry the soil away through erosion. My dad always said that we can’t rebuild the soil, and he’s right—it takes many years to produce organic matter that makes up Iowa’s rich topsoil. By planting cover crops we help stabilize the soil and protect the topsoil layer by not exposing it to erosion by wind and water.

2.)Nutrient Management: Cover crops are a great way to add valuable nutrients back to the soil. Not only that but cover crops also add back organic matter to the soil as they decompose. In my agronomy class at Iowa State University, I am learning how certain types of legume plants have the ability to ‘fix’ nitrogen in the soil, such as hairy vetch and winter peas. Nitrogen is an essential element in plant growth. By adding in certain cover crops we are also adding in ways to produce nitrogen. Adding in nutrients is not the only benefit, but also balancing nutrients in the soil is a great perk of cover crops too. Adding in certain cover crops, such as non-legumes cover crops (radishes and rye), also have the ability to tie up the nutrients and prevent them from runoff or leaching. Which leads us into our next reason, water quality.

3.)Water Quality: With nitrogen in the soil also comes nitrogen runoff—both which farmers work towards maintaining. Our water streams are easily exposed to nitrogen runoff and other pollution sources. Not only do some cover crops help produce nitrogen, but others like, radishes and rye, also work to lock in nutrients and keep them from producing runoff or leaching. If you think about it, cover crops work as an extra filter system on fields.

4.)Biodiversity: Not only are farmers introducing a new plant onto these fields, they also introduce new interactions of all types of life. Cover crops bring in new habitats, they bring in beneficial or repelling insects, they attract wildlife, and provide protection against wind and water erosion. Creating an area of diverse species only boosts the circle of life and provides new opportunities to grow.

5.)Weed Suppression: Competition is a real thing in the plant world and farmers use cover crops as a way to eliminate weeds from their fields. Roots of cover crops extend deep down into the soil to take up any nutrients or water available. While doing so they also ‘weed’ out other weeds (no pun intended) for those nutrients. Not only do cover crops compete with weeds below the soil surface, but they also compete above the surface for sunlight and space. The competition from cover crops is too stressful for the weeds to handle, making it easy for farmers to have complete weed control.

6.)Green Pasture: Some farmers who also have cattle also have the option of grazing their cattle on the cover crop fields. Its just another way farmers can save feed costs. Cattle love to graze on certain forages, especially crops like clover, radish tops, and rye. Not only can the farmer feed his cattle, but he can also fertilize his fields in the process. The cattle’s manure makes a great source of fertilizer—so basically it’s a two for one deal here.screen-shot-2017-02-07-at-11-47-14-am

There are many reasons why farmers use cover crops—each reason presents an opportunity to improve soil and land quality for the future. Now you may wonder why not all farmers use cover crops. Well even though there are benefits there are also challenges. Cost is a big challenge facing farmers and one of the key reasons that they do not use them. Although cost takes a toll in the present, the benefits can outweigh the costs for the future. For example adding in nutrients and managing weeds work to boost yields, not to mention protecting the topsoil works to help plant growth too. A farmer may be faced with many challenges each day, but they also know how they can work to make the best decision for their operation as well as for the land to be worked on in the future.

-Hannah Pagel

A Global Industry from A New Perspective: Agriculture in New Zealand

Kiwifruit, deer, avocados, dairy goats…..Oh my!

The diversity of agriculture is really amazing when you explore it globally!

Iowa State University has taken me on yet another adventure exploring agriculture. Recently, I was able to study abroad for two weeks with 23 other College of Agriculture and Life Sciences students and faculty to New Zealand, exploring their agriculture. How awesome it was to see their diversity of agriculture through the lens of a producer, by stepping straight onto their farms, learning first hand from them.

Agriculture is important to the United States, there is no doubt about that!  Agriculture continues to play a vital role in our culture and economy. The same statement rings true, loud and clear, in New Zealand. Over 95% of agricultural products they produce are exported to different countries. Visiting New Zealand exposed me to the true global nature of agriculture along with its’ extreme diversity.

IMG_1679.JPGKiwifruit’s ancestor came over to New Zealand from China by a school teacher in 1904. Originally named the monkey fruit in China, the school teacher gave the seeds to an orchard owner, after some selective breeding, the kiwi was cherry sized. After more breeding, a New Zealand native had bred the famous oval shaped kiwifruit by the 1930’s. Did you know kiwifruit vines have male and female flowers on separate vines? Orchards are typically planted with a one male tree to four female vine ratio. In order for any fruit to be produced, bees must come in to pollinate the flowers. Four beehives to the acre is the running recommendation. Once the kiwi is harvested it is exported to mainly China, Europe, and the U.S.

IMG_1857.JPGDeer are an agricultural product in New Zealand. Not what you expected, right? Me either. We stepped foot on a diversified livestock farm that had sheep, beef cattle, and deer. Deer are ruminants, just like sheep and beef! Meaning, they can eat grass (high forage diets) and convert it to energy their bodies use to produce yummy meat called venison. Venison is not the only prized possession of deer farming though. While visiting with the producer, we learned that velvet was another prized product harvested from the deer yearly. The antlers are cut off under veterinary supervision through a sterile and safe process while they still have velvet on them. The antlers are then frozen and shipped to the Asian market, mainly China. The velvet is used for its’ medicinal properties, which may include lowering blood pressure, reducing high cholesterol, and curing migraines.

IMG_1732.JPGGuacamole anyone? Sixty-five percent of avocados from New Zealand are grown in the Bay of Plenty. Did you know they grow on trees kept under 10 meters tall? Avocado fruit is also pollinated by honey bees. Once the fruit is set, it hangs on the tree for 12-18 months, until the desired size is reached, or the market is ready because they won’t ripen until they are picked. Farmers export 75% of their crop, mainly to Australia and Asia.

Dairy goats have grown in popularity in New Zealand because of their niche market to make baby formula, claimed to be more similar to a human’s milk. Yes, you heard me right! Dairy goat baby formula is all the rage in the Asian and European market, selling for around $45. Dairy goats are milked just like dairy cows, the milk is harvested, brought to the Dairy Goat Cooperative where it is processed, and spray dried to make the prized baby formula. All but a few goat producers send their milk to the Dairy Goat Cooperative to be made into infant formula.

The four mentioned above are simply four of the many operations we toured in New Zealand. I could write for days about pastoral based dairy farming, blueberries, sheep, vineyards, nitrogen credits, maize (who knew Pioneer, yes the same company in Johnston, Iowa would have an independent counterpart in New Zealand, named Genetic Technologies), beef farms, soils, forestry, and much, much more!

IMG_2413.JPGThe diversity of agriculture is breathtaking. Global agriculture is astonishing.

I encourage you, if you ever have the opportunity, go! Explore agriculture abroad, you will not regret the amazing experience awaiting you.

-Lizzy Widder is a student at Iowa State University. She had recently been involved in Ag in the Classroom as the county contact for Dallas Co.