Farmers Like to Try Growing New Crops

I recently ordered a drink at my local smoothie place and it had hemp seed protein powder in it. That made me curious about the agricultural crop of hemp. I was confused and thought others might misunderstand it as well. Here’s what I learned.

Isn’t it just marijuana?

No, hemp is most notably grown for use as a fiber crop. The long stalks have stringy interiors that can be processed into things like cloth and rope. Most natural fibers that we use for things like clothing come from cotton (a plant) or wool from sheep (an animal). Bamboo has become a popular alternative fiber crop. But cotton and bamboo can’t be grown in the Iowa climate. Sheep are raised in Iowa and while wool has a lot of advantages as a fiber, wool and sheep aren’t as popular as their plant alternatives. Corn and soybeans can also be used to make fibers and cloth, but they take more processing and therefore can be more expensive. Hemp can be grow in the Iowa climate and offers an interesting option for Iowa farmers to get into the fiber industry. But hemp offers a lot of other options too and can be raised as feed ingredient for livestock or for other purposes.

When you hear the word “hemp,” I know for many marijuana is the first thing that crosses your mind. Hemp and marijuana do come from the same cannabis genus. However, hemp has a Delta-9 THC of less than 0.3%, and marijuana has a THC level of more than 0.3%. Tetrahydrocannabinol, or THC, is the psychoactive compound in cannabis that creates euphoric effects when consumed. The 0.3% of THC in hemp is so low that it would take 2,500 lbs. of the commodity to equal the same amount of THC in one joint typically used recreationally. So there is no chance anyone will be able to use hemp as a recreational drug.

Photo by Kindel Media on Pexels.com

Is it legal?

In 2014, the Farm Bill passed, allowing pilot programs and research to start on the hemp commodity. This farm bill started the discussion on whether hemp farming would continue in the United States and if it was beneficial to everyone.

Four years later, the Hemp Act of 2018 passed. This act moved hemp, with a THC concentration of less than 0.3%, from a controlled substance category to an agricultural commodity. In addition to how hemp was categorized, the act also introduced that hemp producers could receive federal crop insurance. Each state would oversee its laws regarding the production of hemp.

Specifically, the Iowa law allows the production, processing and marketing of hemp products. It does not include using marijuana recreationally, smoking hemp and using or selling hemp for animals.

To farm hemp in Iowa, farmers must first obtain a hemp license. The licensing requires applicants to submit official fingerprints, pass a background check, and have no drug-related felony for the previous ten years. Once the farmer is adequately licensed, they must grow 40 acres or less of hemp and record all farmed hemp. Iowa State University Extension and Outreach offers a number of different resources for farmers interested in trying to grow this fiber crop.

Farming hemp is not for everyone. Seeds are germinated in a greenhouse and the seedlings have to be transplanted into fields – either by hand or with small scale equipment. Some farmers are refurbishing old machinery previously used to plant things like strawberries to plant the seedlings. Hemp allows for interested farmers to start small and scale up as they become familiar with the agronomics of unfamiliar crop.

Why farm hemp?

Washington Post

Food, building supplies, textiles and oils are just a few of the thousands of different uses from hemp. Hemp is a versatile commodity; the plant’s seeds, stalks, roots, leaves and plant can all be used in one way or another. I personally have tried hemp seed protein in my smoothies. It was a plant-based alternative to my typical whey protein that I purchased because it was cheaper. New products like this are now on the market because of the growing industry. With these new products coming on the market, hemp farming is a place for farmers to invest their money and a portion of their land.

This up-and-coming specialty crop can be grown as either a fiber, grain or for CBD. Out of these niches, CBD or cannabidiol has the most profit potential. CBD is a non-intoxicating phytochemical that has potential health benefits for things like pain, nausea, addiction, and depression. Farmers can usually profit around $1,000 per acre of corn. In contrast, hemp farmers can gain up to $40,000 per acre when their hemp is grown specifically for CBD.

Hemp can be grown in many different regions and climates, making it very easy to grow. However, hemp does prefer certain soils over others. Aerated and loose loam soil can best produce hemp. This kind of soil has mainly sand and silt with a little bit of clay and has enough room for oxygen to flow through the soil. Iowa offers ideal soils.

Hemp also has a short growing season. This fast-growing season means that farmers who live in cooler climates (like Iowa) can fit hemp into their season when they might not be able to with other crops. Farmers with warmer climates may have multiple harvests in one year.

Because hemp only became legal to grow in 2014 and 2018, everyone is still learning how to farm it. There are always opportunities and challenges in growing new crops and some Iowa farmers are embracing this new crop.

~Madison

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

Farmers Can Save the World!

Or maybe they can at least help prevent climate change?

How many bacteria are there in a teaspoon of soil? Over one million bacteria are present in every single teaspoon of soil! Up to 400,000 different species of bacteria can be found living in that teaspoon of soil.

Soil is the earth’s fragile skin that anchors all life on Earth. It is comprised of countless species that create a dynamic and complex ecosystem and is among the most precious resources to humans. The Earth’s soils contain about 2,500 gigatons of carbon—that’s more than three times the amount of carbon in the atmosphere and four times the amount stored in all living plants and animals. Currently, soils remove about 25% of the world’s fossil fuel emissions each year. A 2017 study estimated that with better management, global croplands have the potential to store an additional 1.85 gigatons carbon each year—as much as the global transportation sector emits annually.

Improving soil biology is key to this carbon sequestration. This is where farmers come in and can save the day! By planting cover crops, practicing no-till, and otherwise helping promote microbial activity farmers can increase the fertility of their soil AND sequester more carbon. These practices have lots of benefits. Having living roots in the soil throughout winter preserves soil structure and sustains the microorganisms that are so vital to healthy plants. Complex soil structure also makes soil act like a sponge. With lots of tiny holes and tubules created by the roots and worms, it retains water and doesn’t disintegrate.

But planting cover crops adds expense to the farming operation. And doing no-till may require different equipment and machinery – again an added expense. While yields may increase in the long run earning the farmer more money, in the short term those expenses are not immediately recouped. How is a farmer to pay for it? To encourage more farmers to plant cover crops and help combat climate change (by sequestering more carbon in the soil) some companies and organizations are looking at paying farmers to bury carbon emissions by using regenerative growing practices.

Some farmers have already started these practices to improve soil health and sequester carbon. But by incentivizing more farmers to adopt the practices, the idea could advance more quickly. It is a win-win. Farmers get more fertile soil that is more productive and can earn them more money. And they are a part of the solution to solve climate change!

Now consider one acre of soil (approximately the size of a football field). How many pounds of biomass is below the ground (in the form of worms, fungi, protozoa, and bacteria)? That one acre of soil may hold 10,000-30,000 pounds of biomass! How many cows would it take to equal 10-30,000 pounds? Approximately 20-30 full grown cows! One pound of roots is worth 1.5 pounds of above ground plant material when trying to build soil organic matter. The lesson may be to never underestimate what you can’t see.

-Will

Science 101: Roots

Roots. They are the hidden heroes of plants. We rarely see them, but they provide the foundation from which all plants grow. Without them, we would not have fruits, vegetables, grains, wood products or beautiful flowers to enjoy.

Roots have two primary functions. They collect water and nutrients, and they provide anchorage and support for the plant. Both of these functions are essential. Plants cannot grow and produce flowers and fruit without water and nutrients, and plants would blow away without being anchored in the ground by roots.

The shape, size, and structure of roots vary greatly from species to species, but they are generally categorized into two main types – fibrous and taproot. Most dicots, or broad-leaf plants have a taproot system, and most monocots, like corn, wheat, asparagus, and rice have a fibrous root system.

Credit: United Soybean Board

Plants with taproots have a thick, main root that grows deep into the soil and smaller lateral roots growing from it. Some plants, like radish, have relatively shallow taproots with very small lateral roots. Others have a very deep primary root and an extensive system of lateral roots growing from it. The taproot system of soybeans, for example, can reach 6 feet deep with lateral roots that spread 1-2 feet wide in favorable conditions.

Some plants, like carrots, parsnips, and beets, have an extra thick taproot that hold large quantities of nutrients. These enlarged roots store extra sugars and other carbohydrates for the plant and provide a valuable food crop for us!

In contrast, a fibrous root system is usually formed by a network of thin, branching roots of about equal diameter. Plants with fibrous root systems often form a mat of roots underground. While they do not have a large taproot as an anchor, their many small roots firmly secure them in the ground.

Plants with shallow fibrous roots, like grasses, are also great at stabilizing the soil and preventing erosion. This makes them a good choice for cover crops, terraces, buffer strips, and other conservation practices.

Not all fibrous root systems are shallow. Corn roots, for example, often grow three to five feet deep. Some have even been found extending more than 10 feet!

Roots grow from their tips and are thin at first. New and rapidly growing portions of a root system are the most permeable and have the greatest ability to absorb water and nutrients. These thin roots are often covered with even smaller roots called root hairs. They may be small, but root hairs are numerous and mighty! Their large surface area to volume ratio makes them very efficient in absorbing minerals and water.

A common feature of almost all root systems is mycorrhizae, a symbiotic relationship that forms between fungi and plants. Plant roots secrete compounds that interact with microorganisms in the soil. In exchange for a bit of sugar, the fungus helps the roots pull in more nutrients and water than the plant could on its own. Mycorrhizal fungi occur naturally in soil and can be added as a seed treatment before planting.

Roots are influenced by the soil in which they live and are good indicators of soil health If the soil is compact, is low in nutrients or water, includes high populations of root pathogens, or has other problems, plants will not develop a healthy root system. On the other hand, roots also benefit the soil in which they grow. Roots help keep soil in place, add organic matter, and feed beneficial bacteria and fungi.

Healthy plants are essential for good crop yields…and healthy plants have healthy roots.

– Cindy

Why Soils are Important

942783176_083c95a60c_b.jpgIt is easy to understate the importance of soil. It seems benign. It seems inert. But the ground beneath our feet is literally teaming with life – most of it too small for us to see or register as important. But all of it IS important and vital to our human life systems. Soil provides the anchor to plant roots. It holds water and nutrients. It is home to micro-organisms and so much more.

When we think of soil, we often think of the physical properties of the soil. How big are the particle sizes? Sand is the biggest, silt is a medium size, and clay is the smallest. We think about the water holding capacity. Clay soils have a lot more surface area of the individual particles and so therefore can hold a lot more water than sandy soils. We think of availability of nutrients and soil structure as indicators of healthy soil. But it is these last two that offer a huge level of complexity that we rarely think about.

Nutrient availability

Whenever a soil is lacking in available nutrient for the given crop it is easy to consider adding an amendment. If the soil is low in nitrogen, then just add some ammonium nitrate and you are good to go. While this method offers a quick (and needed) solution to the immediate nutrient deficiency, it doesn’t take into consideration the complex biology of bacteria, nematodes, fungi and other microbes in the soil that play a role in nutrient cycling. In theory, with enough organic matter present in the soil and the right microbes in the soil, nutrients like nitrogen should be readily available for whatever crop or plants are currently growing.

38362547684_a5e3746e8a_b.jpgSoil structure

Soil structure shows up when soil clumps together and creates peds. These peds allow for cracks and spaces in the soil for water to permeate down and more easily get absorbed. Soil structure can take years and years to form and can easily be destroyed through mechanical cultivation. What causes soils to form these peds? It is largely due to the network of BIOLOGY in the soil. Plant roots send off tiny root hairs that can hold some of the bigger pieces of soil together. Fungi and their mycelium can act as little webs and nets that bind to the plant root hairs and bind to smaller pieces of soil. And proteins excreted from things like protists and other micro-organisms can act like glue that binds individual soil particles together. This inter-connectivity of many different organisms to create soil structure shows the need to pay attention to biology.

Functions of soil

  1. 6230526315_bc10fdf6da_b.jpgWe consider soil to have six major functions. First and foremost, soil is used for food and biomass production. Eleven percent of the globe’s land surface is used in annual crop production with up to 36% of land suitable for some kind of agriculture (livestock or crop). This land grows our food crops, it raises livestock, and it produces biomass like lumber for houses and paper, cotton for clothes, and biomass for fuel like ethanol. The soil is the anchor for the plant roots.
    • Consider that U.S. agriculture produces about 500 million tons of crop residue annually, most of which contributes to maintaining soil organic matter. Plans to use crop residues for bioenergy production could deprive agroecosystems of important inputs for future soil productivity, potentially upsetting existing agroecosystem balances.
  2. An essential function of soil is the storage, filtering and transformation services that it provides. Soil filters water removing harmful micro-organisms, chemicals, and other pollutants to make for clean and safe drinking water. We have created some artificial processes to clean water for drinking, but soil is still the most important filter for us. Soil can also store our garbage (landfills), it can store excess water (think of heavy rains and the soil absorbing that liquid), it can store carbon (living and nonliving matter in the soil store carbon that would otherwise be released in the air). Removing fossil fuels from the soil and burning them and releasing them into the air has shifted the balance and been a primary cause of global climate change. Soils can also facilitate environmental interactions to transform things. For example, bacteria that live in the soil transform atmospheric nitrogen into plant available nitrogen.
    • Wetlands and the soil in the wetlands deliver a wide range of ecosystem services that contribute to human well-being, such as fish and fiber, water supply, water purification, climate regulation, flood regulation, coastal protection, recreational opportunities, and, increasingly, tourism. Despite these important benefits, the degradation and loss of wetlands is more rapid than that of other ecosystems.
    • Consider that through natural processes, such as soil adsorption, chemical filtration and nutrient cycling, the Catskill Watershed provides New York City with clean water at a cost of $1-1.5 billion, much less than the $6-8 billion one-time cost of constructing a water filtration plant plus the $300 million estimated annual operations and maintenance cost.
    • Covering just 6% of Earth’s land surface, wetlands (including marshes, peat bogs, swamps, river deltas, mangroves, tundra, lagoons and river floodplains) currently store up to 20% (850 billion tons) of terrestrial carbon, a CO2 equivalent comparable to the carbon content of today’s atmosphere.
  3. 303107524_94683698cf_b.jpgAnother function of soil is as a biological habitat and gene pool. Soil provides the habitat for seeds to germinate and grow. It provides everything they needs like water, warmth, nutrients, etc. Soil provides habitat for a myriad of animals like worms, moles and insects, but also bacteria, protists, and fungi as well. All of these creatures come into contact with each other and can interact. The insects can mate and produce offspring. The bacteria can divide and reproduce. And sometimes when they do, they evolve and two species can share a little bit of DNA. One success story of this is when a sweet potato absorbed some DNA from a bacteria. This horizontal gene transfer can make the plant resistant to diseases.Consider that there are more living individual organisms in a tablespoon of soil than there are people on the earth.
    • Almost all of the antibiotics we take to help us fight infections were obtained from soil microorganisms.
  4. Functionally, soils are also a source of raw materials. For much of modern human history, ceramic dishes made from clay were the primary tableware. Only in very recent years have we started using more glass, plastic, and one-time-use dishes (styrofoam). Soil can also be the source of countless minerals through mining processes. Soil can also be used for bricks and other materials in building houses.
  5. 5186540530_98ebc01950_b.jpgSoils can also play a functional role in our physical and cultural heritage. Around the world soils have  been shaped for things like effigy mounds potentially for religious ceremonies, burial ceremonies, or other purposes. Soils also protect our cultural past. Artifacts that get covered up by soils can be protected from the elements creating a bookmark and window into our past and heritage.
  6. Finally, soils can serve as a functional platform for us to build our structures on. Whether it is houses, highways, skyscrapers, or football fields, we need a base of soil to provide the stability to build on. Even things like bridges over water, still go down to the soil at the bottom of the river or lake to rest on.

So, could we live without soil?

Sure, we could produce food through things like hydroponics and aeroponics. But without soil we couldn’t produce the amount of food that we need to sustain human life for all seven-plus billion of us. Sure, we have figured out other ways to filter water and store garbage. But our water filter systems haven’t been scaled up to do what soil does naturally. And garbage management systems like burning garbage has other negative environmental repercussions. Without soil countless organisms like moles, worms, bacteria, and fungi would be without a home. Most of those creatures are uniquely adapted to live in soil. Without soil we wouldn’t have the raw materials we need or the base to build our structures. In short, the answer is no. We couldn’t live without soil.

Soil is easy to overlook and some may even call it dirt. But soils are important for many reasons and as farmers and agriculturalists we can protect and improve soils for the betterment of all.

-Will

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.

Mg deficiency.jpg

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

Soil – it’s not just dirt!

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Pedology – this is a crucial field of science when it comes to growing plants on the land, but what does it actually mean? A popular guess would be that the root ‘ped’ is derived from the Latin word for foot, such as pedestrian, biped, or pedestal. On the other hand, the ‘science of feet’ makes absolutely no sense when talking about agriculture! According to the dictionary, pedology is soil science. In this case, ‘ped’ comes from the Greek (not Latin) pedon meaning ground or earth. To expand upon that a bit, pedology is the study of soil’s physical properties, chemical properties, texture, contributions to an ecosystem, and how it moves. It’s impossible to photo 12imagine a society where there was no soil, no ground, no basis for life. I hope that after reading this blog you give a little more thought to what it is we walk and live on every day.

Physical properties

Did you know the ideal soil for farming is only composed of about 50% solids? This percent can be further broken down into about 5% organic matter, with the remaining 45% being mineral content. But now this begs the question – what is the other 50% of soil made of? The remaining space is split equally between available water, unavailable water, and pore space. Simply put, pore space is the tiny pockets of air that microorganisms live in and plant roots use for gas exchange. Available water is soil water that is held a pressure that is easily taken up by plant roots. Using common sense this means that unavailable water is held at too high of a pressure for plant roots to take up, basically stuck to the soil particles and probably won’t move anytime soon.chart (1)

 

Chemical properties

Believe it or not, soil has chemistry too! Lots of farmers complete soil tests on their land, which will measure many varying characteristics within the soil. To start off with, soil pH is very important when considering nutrient uptake availability! Even if a nutrient is abundant within the upper portion of a soil profile, a plant cannot use it unless the soil’s pH is ideal for that specific element. The most common way of raising the pH of soil is by adding agricultural lime, also known as calcium carbonate. Another important quality of soil is its cation exchange capacity, also called CEC. Although it may sound complicated, CEC refers to the ability of the soil to hold and exchange positive charges. Some common cations are calcium, magnesium, potassium, sodium, and hydrogen. Farmers and researchers alike are able to calculate their soil’s CEC, which then translates to how many nutrients the soil can hold at a given time.

Texture

Soil is composed of three main types of particles: sand, silt, and clay. Each differs from the next in terms of shape, size, and chemical properties.

  • Sand is the largest particle with a size from 0.05 mm – 2.0 mm. Fields with high quantities of sand have good aeration but poor water holding capacity.
  • Silt is unique with it being smaller than sand but larger than clay. Its size ranges from 0.002 mm – 0.05 mm, and it comes with a high available water holding capacity.
  • The final size is clay, which is 0.002 mm or smaller. This is obviously the smallest soil particle, has a high water holding capacity, and exhibits very poor aeration.

When defining a soil texture, a loam is a mixture of all three textures and is ideal for growing crops in the Midwest!

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This is a texture triangle, useful when determining your soil’s texture! Photo from FAO

 

Role in the ecosystem

Soil is found everywhere around the world, from agricultural fields, to big cities, to forests, and everything in-between! Generally speaking, the ground in metropolitan areas will be very compacted and likely not supporting any biota beneath the surface. In contrast, once outside of urban areas the biota dependent upon the soil vastly changes. Some soil microorganisms include bacteria, fungi, nematodes, algae, and many more! Did you know that a fungi called mycorrhiza has a symbiotic relationship with plant roots?

Where will it go next?

You might think it’s uncommon to hear about soil moving, but it has two main mechanisms for relocating to other regions. Erosion can be caused by wind and water, both having potentially detrimental effects on the soil. Water erosion occurs in three steps: 1) sheet erosion, 2) rill erosion, and 3) gully erosion. Sheet erosion is the film of soil moving from the impact of a rain drop or in a film of water. This is the most difficult to spot and occurs over almost all bare soil during a rain storm. Rill erosion occurs once small channels are formed from the movement of water. If the situation becomes too dire, then gullies will form. This is when the big channels are too deep for field equipment to cross. Wind erosion also occurs in three main steps. The first step is called saltation, and this occurs when fine sand particles are bouncing across a landscape. If the wind picks up, the following step is when particles are becoming suspended in the air. The final step of wind erosion is called creep, which is the rolling and sliding of particles that are too big for the air column.

So the next time you’re out driving along a road, walking through a park, or tending to your garden, I hope you’re thinking about more than solely what’s on the top of the soil!

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-Rosie

P.S. Yes I am a new name to these blogs, and I’m here to stay for a while! I recently started as the new intern with Iowa Agriculture Literacy Foundation and I’m thrilled for what this year has in store. So a little bit about me – I’m currently a student at Iowa State University double majoring in Agronomy and Agriculture Communications. I love growing plants of all types, and that might show a little in future blogs! I look forward to creating some more intriguing and informative posts that you all can enjoy!

Science 101: Germination

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Seeds are amazing. Although they might appear to be tiny lifeless objects, seeds are powerful living things just waiting for the right conditions to do their thing! Each seed contains exactly what it needs and is designed specifically for the job it must do. All seeds have the same mission. To germinate and grow into a plant that will produce more seeds.

It is important for farmers, and gardeners, to understand the science of seed germination so they can maximize yields while efficiently using resources.

So, what exactly is germination? And how does it work? Let’s explore these questions and others.

What is germination?

In simple terms, it is the process of a seed developing into a plant. Germination occurs below ground, before the stem and leaves appear above the soil.

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How does germination work?

To understand the process, you’ll need know the main parts of a seed and their function.

All fully developed seeds contain three basic parts, the embryo, endosperm and seed coat. The embryo is the part of the seed that develops into a plant. It contains the embryonic root (radical), embryonic stem (epicotyl and hypocotyl), and one or two seed leaves (cotyledons).

structure and fuction of dicot and monocot seeds - lumenlearning.com

Structure of Seeds (Source: Lumen Learning)

The endosperm contains the starch or stored energy for the developing embryo. The endosperm is the largest part of the seed and packed around the embryo. The seed coat is the outer layer that protects the seed’s internal structures.

The first stage of germination, called imbibition, occurs when the seed is exposed to water. The seed absorbs water though its seed coat. As this happens, the seed coat softens.

Next, water triggers the seed to begin converting starch to sugar. This provides energy for the embryo during germination.

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More water is then absorbed and the seed’s cells start to elongate and divide. The radicle, or primary root, is usually the first part of embryo to break through the seed coat. It grows downwards to anchor the seed in place and absorb water and nutrients from the soil.

Next, the shoot and seed leaves emerge from the seed coat. The process and order depends on type of seed. Monocot and dicot seeds are structurally different, which affects how they germinate.

Soon the shoot will emerge from the soil. The seed tissue will diminish as the plant’s roots, stems, and leaves develop.

What do seeds need to germinate?

All seeds need water, oxygen, and the proper temperature to germinate.

The soil temperature must be warm enough so seeds can germinate, but not so hot as to damage the seed. Cold soil temperatures can cause seeds to remain dormant, increasing their vulnerability to diseases and insect damage. Temperature requirements vary between species. Soybeans, for example, need a minimum soil temperature of 50 °F for germination, but 77°F is optimum.

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Water triggers germination to start and is needed throughout the germination process. Soil should be moist, but not saturated with water. Some seeds require more water than others. The critical soil moisture level for corn is 30%, while soybeans need soil that it at least 50% moist in order for germination to occur. That’s because beans absorb more water. Beans take in two to five times their weight in water, while corn only absorbs about 1.5 times its weight.

Oxygen is found in the air we breathe, and in soil too! Oxygen is usually on the list of things plants need to grow. However, it’s not always included when discussing germination.

When a seed is exposed to the proper conditions, water and oxygen are absorbed through the seed coat and cause the embryo cells to enlarge. If there is not enough oxygen present, germination may not occur. The most common reason for a lack of oxygen is too much water in the soil due to over-watering or flooding.

Do seeds need light to germinate?

Sometimes, not usually. Most seeds do not require light for germination and germinate best in dark conditions. However, some seeds like carrots & some lettuce varities need light to germinate. The stimulus of light causes them to break dormancy and start germination once exposed to water and proper warmth. These seeds germinate best when planted on the soil surface or just barely covered with soil.

soybeans in field

Why does planting depth matter?

Although it may be tempting to plant seeds shallow so they emerge sooner, it is important to follow the recommended planting depth. Planting too shallow can result in insufficient soil moisture for germination or a weak root system. Planting seeds too deeply causes them to use all of their stored energy before reaching the soil surface. Like temperature and moisture, ideal planting depth varies by plant species. As a general rule of thumb, larger seeds can be planted deeper because they contain more stored energy to reach the soil surface than smaller seeds. Farmers consider other factors like soil type, planting time, and temperature when deciding how deep to plant.

Nearly everything we eat and most of what we use would not be possible without germination. Vegetables, grains and fiber crops are grown from seed. Meat, eggs, and dairy products come from animals that were fed seeds or plants that grew from seeds.

As you drive past fields of emerging crops this spring, think about the amazing science phenomenon happening before you.

– Cindy

Why do they do that? – Liming Fields

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In late fall and early winter, you might see farmers applying a fine white dust to their fields. So, what is it? And why do it?

That white dust is agricultural lime, sometimes called aglime. It is a soil conditioner made from crushed limestone. Once the lime dissolves, it releases a base that lowers the acidity of the soil. Farmers apply lime to increase yields. Homeowners and landscapers use it to improve the appearance of lawns that have acidic soils.

Making sure soil does not become too acidic is critical to good plant health. Soils that are too acidic can stunt root growth, limit nutrient availability, and reduce the effectiveness of fertilizer and herbicides. Most soils have a tendency to become more acidic over time for variety of reasons such as erosion, leaching, decomposition of organic matter, and fertilizer application.

Resized952017121895140443Limestone is a sedimentary rock composed mostly of calcium carbonate. It is mined and mechanically crushed into varying degrees of fineness depending on its intended use. Limestone’s versatility, durability, and affordability make it a useful for many construction, industrial, home-improvement, and agricultural applications. Coarsely crushed limestone can be used to rock driveways, support railroad tracks, and prevent erosion on slopes and shores. Lime used as a soil amendment is ground into a very fine power so it easily dissolves in the soil. Soil amendments are organic or inorganic materials added to change the physical or chemical properties of soil and improve plant health.

 

Lime is a good soil amendment for acidic soils because it contains a high amount of calcium, which works to neutralize the soil’s pH level. Soil pH indicates the acidity or alkalinity of the soil. It is measured on a 14 point scale. A pH of 7 is neutral. Values below 7.0 indicate acidic soil, and values above 7 indicate alkaline, or basic, soil.  A soil test is used to determine the pH of a soil. Farmers who practice precision agriculture often use grid sampling to determine where and how much lime to apply in specific parts of a field.

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This field map displayed on a monitor in the tractor cab indicates where higher and lower amounts of lime should be applied.

Lime can be applied any time after the previous crop is harvested. Lime is not lost by leaching, so farmers can apply it whenever practical. Agronomists recommend putting down lime several months before planting, so the lime has enough time to neutralize acidity.

It is common for farmers to hire a contractor to apply lime using a large truck-mounted spreader. It can also be applied with a smaller spreader pulled with a tractor. Lime can be incorporated into the soil or spread on top and left to dissolve and leach into the soil by rain and snowfall.

Resized952017121895140456Iowa farmers do not lime fields every year. They only apply it when soil tests indicate the soil pH is too low. For corn and soybeans, Iowa State University Extension and Outreach recommends a soil pH of 6 or 6.5 to be sufficient, depending on the subsoil pH of the area. A higher pH is recommended for alfalfa and other acid-sensitive crops.

Now you may be asking, should I apply lime to my lawn or garden? You should only apply lime when recommended by a soil test. The optimal pH range for most turf grasses, flowers and vegetables grown in Iowa is 6.0 to 7.0, and most lawn and garden soils fall within that range. However, some plants like blueberries and azaleas prefer more acidic soils and others like lilac, peony, and salvia prefer more alkaline soils. If you are curious to know the soil PH of your soil, consider sending a soil sample to a soil testing lab on the Iowa Department of Agriculture and Land Stewardship list of certified labs.

-Cindy