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Who *doesn’t* love nutrient cycling? A SUSTAG 509 reflection

May 6, 2015 12:00 AM

509 at Field of DreamsFor those of you not lucky enough to be a graduate student in Sustainable Agriculture at Iowa State, you should know that one of the major strengths of the program is the class SUSAG 509: Agroecosystems Analysis, or simply “509.”  After being admitted to the program last spring, I was thrilled to find out that I would get to spend a week in August driving around Iowa for credit: “You mean I get to meet Iowa farmers, talk cover crops, soil quality, and corn production?” Maybe that isn’t everybody’s idea of a dream vacation, but as a newcomer to the Midwest and long-standing ag nerd, I was definitely pumped. Since not everyone is lucky enough to be in my program or to have taken this class, I thought I’d share some of the major insights I gained. Spread over two posts, I’ll first discuss nutrient cycling and its role in agroecology, and then examine a couple of the sites on our field trip from the lens of ecological economics.

If you’ve taken an ecology class or pay attention to ecological issues in agriculture, you’re probably familiar with nutrient cycling. Nutrients are the abiotic building blocks of all the living creatures. As such, the management of their movement in agriculture has profound implications for soils, crops, waterways, and the broader landscape. But even on the micro-level, there are many complexities to them. The term “nutrients” represents over a dozen different elements each with a variety of chemical forms. Nutrients can be either available or unavailable for plant uptake, depending on both their chemical form and physical circumstances.

In studying nutrient dynamics within soils, one thing quickly becomes clear: soil organic matter plays an important role. Soil organic matter consists of, essentially, bits of dead things – plants, mostly, but also all other manner of soil biota and their products. While that dead material exists in various stages of decomposition, the early stages of these serve as a food source for a myriad of soil organisms. These soil organisms play a direct and diverse role in the chemical and biological paths that nutrients follow while in the soil (Magdoff, Lanyon, and Liebhardt 1997). Nutrients can become available through such pathways as mineralization of soil organic matter by a variety of organisms, enhancement of plant nutrient uptake directly by mycorrhizal fungi, and nitrogen fixation by bacteria that can be both free-living and symbiotic with plants.

In natural ecosystems, nutrients follow a tight cycle of nutrients, from soil to plant to soil. However, agriculture, by its very nature, has always required the “export” of nutrients (Magdoff et al. 1997). Grain, vegetables, meat, fiber, hay: when they leave the farm, they also remove the nutrients inside them. Long before soil scientists uncovered the chemical pathways of soil nutrients, farmers understood that certain types and frequencies of crops could deplete the nutrients in the soil. For a long time, farmers used biological materials and processes to replenish these nutrients that had been removed from the soil, through such practices as rotating crops and applying manure.

With the advent of chemical fertilizers, this began to change. Farmers were able to stop using biological processes to replace exported nutrients. Anderson (2009)describes how chemical fertilizers became cheap and commonly used after World War II. New crop varieties could be grown closer together but also required higher levels of nutrients, and farmers became more and more dependent on chemical fertilizers. Farmers were no longer dependent on the limits of biological cycles for replenishing nutrients (there’s a maximum level for the amount of manure that livestock produce or the amount of biomass that cover crops create). Instead, the limits to nutrient application were in the supply and price of chemical fertilizer. Fertilizer could easily be applied in excess.

Tim Smith Farm The use of chemical fertilizers as a source of crop nutrients has impacted the Iowa landscape in three ways. First, as we learned on our field trip, chemical fertilizers are at the root of significant water quality issues in Iowa, stemming from the ability to import more nutrients than are needed and used. While concern about nutrient runoff began in the 1960’s in Iowa (Anderson 2009), it still persists today. We met with several folks who work to stem the escape of excess imported nutrients. One of the farmers we met, Tim Smith, discussed the complexities of planting cover crops. Among other benefits, cover crops can curtail the loss of nitrogen by holding it over the winter and then releasing it when tilled just in time for a spring crop to take it up. We also spoke with Chad Ingels of ISU Extension and Outreach, who gave thorough accounts of how denitrifying bioreactors capture nitrate from field runoff (some of Chad’s video footage of bioreactors is herehereherehere, and here). We also visited one of the prairie STRIPS trial sites, and learned how prairie plantings can capture sediment and nutrients in field runoff. Finally, at the Des Moines Water Works, we saw some of the downstream consequences of nutrient runoff: the facility has an expensive backup capability to remove nitrate from river water when nitrate levels are too high (recent news coverage of the related lawsuit can be found here and here).

Second, the use of chemical fertilizers has also impacted livestock management. Magdoff et al. (1997) describe how older agricultural systems cycled nutrients from soil to crop to livestock to people and back within a relatively small geographic space. Crops and livestock depended on each other for nutrition: crops fed livestock, and livestock manure was returned to the soil as a source of crop fertility. Keeping livestock geographically close to crops made sense. We saw modern examples of this on Gibralter Farms in Iowa Falls, which endeavors to produce as much feed on farm as possible. They have economic reasons for doing so – feed is a cost – but another advantage is that the feed and the manure are both geographically proximate. But in Iowa, the crops and the livestock are often quite separate on the landscape: grain is shipped to where livestock live. Livestock manure is often treated as a waste rather than a resource for nutrients, and that concentration of nutrients ultimately causes significant environmental problems with pollution of air and water (Osterberg & Wallinga, 2004). We saw some evidence of these manure issues on our trip: at Couser Cattle Company we learned about how their constructed wetlands are there to catch and filter manure overflows.

Finally, the use of chemical fertilizers can degrade soil health. Healthy soil ecology can benefit crops through improving nutrient availability. But in providing the nutrients via chemical fertilizers, farmers can essentially ignore whether soil organisms are healthy or even present. We learned about this during our trip to the Doolittle Prairie. While corn and soy fields stretch off in every direction, this prairie fragment has never cultivated. Doolittle Prairie was possibly my favorite stop during our whole trip: I got to check “hold prairie soil in my hand” off my bucket list.

Iowa Prairie Soil When we took a detour to a soybean field just next to the Doolittle Prairie, we saw stark differences in soil structure and general tilth resulting from differences in management. The prairie offered a glimpse of the historically rich prairie soil that Mutel (2008) describes, while the soil in the soybean field barely thirty feet away had similarly high organic matter but very poor soil structure and no visible soil organisms. We guessed that that soybean field must be chemically fertilized and regularly tilled to yield such a combination of blocky soil but vibrantly green soybean plants.

Ultimately, managing agricultural systems can be done in accordance with ecological principles. While many farmers currently rely on chemical fertilizer inputs, the cycle in nutrient cycling needs to be re-established. Currently, it is more of a chain: nutrients enter the agricultural system at one end as fertilizer and end up in manure lagoons or in downstream bodies of water. A couple of our class readings examined of how this cycle could be re-established through altering crop and livestock systems. They examine individual and regional (re)integration of livestock and crop systems, and emphasize the importance of meeting farmers’ management goals as well as they would be met in the original system (see Russelle, Entz, and Franzluebbers 2007 for more detail). Another envisioning of an integrated landscape was evaluated in Santelmann et al (2004). Different land management scenarios were evaluated for two regions in Iowa, including one scenario that integrated livestock and crops. They projected that this latter scenario would result in improvements in most ecological, economic, and social factors.

So those are the first round of my takeaways from 509, which combine insights from the field trip with those from in-class discussions that lasted throughout the semester where we learned the theory behind the practices we’d seen firsthand. In interest of full disclosure, you should know that Dr. Schulte Moore was one of the professors. Check back soon for another favorite topic in round two: ecological economics.

Anna Johnson is pursuing a Master’s in Sustainable Agriculture under the direction of Drs. J. Arbuckle and Lois Wright Morton. Prior to enrolling at Iowa State, she worked for several years at the U.S. Department of Agriculture in Washington, D.C.


Anderson, J. L. 2009. “Fertilizer Gives the Land a Kick.” Pp. 51–90 in Industrializing the Corn Belt: Agriculture, Technology and Environment 1945-19722. DeKalb, Illinois: Northern Illinois University Press.

Magdoff, Fred, Les Lanyon, and Bill Liebhardt. 1997. “Nutrient Cycling, Transformations, and Flows: Implications for Amore Sustainable Agriculture.” Advances in Agronomy 60.

Mutel, C.F. 2008. Setting the stage. Pages 1-34 in: the Emerald Horizon: the History of Nature in Iowa. University of Iowa Pres: Iowa City, IA.

Osterberg, D. and D. Wallinga. 2004. Addressing externalities from swine production to reduce public health and environmental impacts. American Journal of Public health 94: 1703-1708.

Russelle, Michael P., Martin H. Entz, and Alan J. Franzluebbers. 2007. “Reconsidering Integrated Crop–Livestock Systems in North America.” Agronomy Journal 99(2):325. Retrieved October 24, 2014 (

Santelmann, M. V. et al. 2004. “Assessing Alternative Futures for Agriculture in Iowa, U.S.A.” Landscape Ecology 19(4):357–74. Retrieved (


The journals my mother gave me

May 23, 2014 12:00 AM

Journal I took a trip this last weekend up to Superior National Forest in northeastern Minnesota with two of my girlfriends. The winter in Iowa was long and cold, and the pressures of completing my thesis this last spring had forced me to spend most my days deep in the depths of my cinder-walled basement office. Almost all I experienced these last six months were the bone-chilling darkness of the morning and night when I came and left my office, and the flickering of fluorescent above my desk. I was craving the woods. As I left my house, I quickly grabbed one of many journals sitting on my bookshelf.

We set off on our journey to the northwoods and stayed at my friend’s cabin on a beautiful private lake. On Sunday, while my friends were canoeing, I was feeling particularly reflective and decided I would write in my journal. The sheer number of journals I have collected over the years can be attributed to one person, my mother, whom at every birthday and Christmas would gift me with one. I would hold the crisply wrapped present in my hand, knowing in my head that alas, my mother had given me another journal. I grew quite tired of this gift and feigned appreciation and surprise.

As I grew older I learned that I actually received great satisfaction in recording my thoughts. I would write poems, make sketches, record my dreams and goals, lessons learned, love interests, and adventures to exotic places. Journaling helped me to remember what I would otherwise forget, and created more significance around my daily life. One of my favorite things to do on a lazy afternoon is sit down and read old entries. Doing so brings me right back to that place and time in my head, and I can remember and feel an experience as if it was yesterday.

Inside journal - sketch I couldn’t help it this day to also read and reflect on a letter in my journal that I had written to my family but never sent. The letter was dated June 5, 2007, almost seven years ago. The letter describes the first time I had gone out looking for Northern spotted owls in Shasta-Trinity National Forest, California. I was hired as a field technician to locate, monitor behavior, and collect the scat from these federally threatened birds as part of a research team with the University of Washington to assess the effect of off-highway vehicle (OHV) use on stress hormone levels. Every detail in this letter takes me back and allows me to experience those first feelings of finally finding my calling in this world. That job was so monumental in navigating my course in life.

As I read and think back to the time in my life when this conservation-focused world was so new to me, I most fondly remember the feeling of finally belonging to something I had long been searching for- feelings of excitement, mystery, magic, curiosity, adventure, and purpose. When I first entered the woods, my legs were like a fawn, shaky and new. It was difficult to maneuver up the steep, uneven slopes with the loose soil bringing me three steps back with every step forward and winded within moments. By the end of that summer I ran through the woods with ease and joy, lungs full of air. I felt almost native, like the woods had accepted me into their world. I enjoyed the back-and-forth game of Marco Polo that I would play with the owls every day. Being a territorial type, the owls would respond to my hoots and then I would run into the forest and try to find them. This was my job! I fully appreciated things more—food with friends over a campfire, cool dips in the river, a National Geographic article—everything made me feel alive.

Inside journal - writing I didn’t want that summer to end, and when it did I reentered a civilization that seemed foreign to me. I experienced culture shock by my own culture. I held on to that summer, hoping that I could summon it when I was feeling disconnected from my work. And I still can summon it, through the words in my journal. There in the northwoods of Minnesota I was transformed to the northwoods of California. I closed my eyes and could acutely hear the electric chime of the cicadas all around me, the agitated squawking of the Steller’s jay, and the soft, distant 4-note of the spotted owl.

It is these memories that help me remember my purpose, and it is my journal that helps me recall these memories. Thanks mom. What helps you stay connected to your passion?


Comment 1 

Great Reflection! 
Submitted by Monika on Fri, 05/23/2014 - 14:40

Thanks Rayma! Now I'm inspired to get back into journaling. 

I totally know the horrors of spending the day in a basement office or in front of a screen. I stay connected to my passion--and the "real" world around me--by taking daily walks (and a long hike every once in while is FANTASTIC).

Comment 2 

Monika, that is wonderful 
Submitted by Rayma Cooley on Fri, 05/23/2014 - 14:47

Monika, that is wonderful. The weather if finally nice here, and I'm getting outside again into the Iowa woods as well. Feels SO good!

Comment 3 

hoot hoot 
Submitted by Jennifer on Fri, 05/23/2014 - 17:15

Rayma, beautifully written. I was taken back to that summer reading this. Such incredible memories. I've never felt as alive as I have when I've done spotted owl surveys. They are such an amazing animal. The northwoods of MN sound beautiful... I've always wanted to explore them. Maybe you'll take me with you someday?!

Comment 4 

Absolutely Jennifer! I hope 
Submitted by Rayma on Sat, 05/24/2014 - 15:26

Absolutely Jennifer! I hope we can go owling again too :) And maybe a owler reunion?!

Comment 5 

Vet Research 
Submitted by Rachel on Sat, 09/12/2015 - 03:55

Hello there. I am Rachel, and I'm a vet registered nurse for Currently I am looking up veterinarian practice and pharmaceutical subject matters for a vital project associated with medication procedures our team are carrying out at the center. I sourced various appealing and important info checking out this site and just intended to say thanks. Continue the great work!

Comment 6

So happy you recorded your experinece! 
Submitted by Lisa Hayward on Fri, 05/23/2014 - 22:24

You're a great writer Rayma, and it sounds like you may have your mom partly to thank for that too. : ) Thanks for sharing your thoughts. I feel so lucky to have gotten to have some of those magical experiences in the woods with you. I'll treasure the memories always!

Comment 7 

Me too Lisa! I'm so glad I 
Submitted by Rayma on Sat, 05/24/2014 - 15:27

Me too Lisa! I'm so glad I met you and was a part of your project :)


The simple life isn't an easy one

February 12, 2014 12:00 AM

Simple life 1 - cabin After parking our car where the Forest Service road is no longer plowed, I step outside to be greeted by the howling of a nearby wolf pack. We load up our gear, put on our skis, and glide into the woods under the illumination of the Milky Way. An hour later the moon is peaking over the pines, outshining the stars and pouring light into the Northwoods, which I have grown to love. Approaching the glowing cabin window in the distance I am greeted by my friend Thistle, a massive polar husky retired sled dog. I open the cabin door, wipe the fog off my glasses, and warm up next to the wood burning stove. It’s good to be back.

Last summer I worked as a field technician for Rayma Cooley studying the Pagami Creek fire in Northeast Minnesota. I thank her for introducing me to two of the most inspirational people I have ever met: Bert and Johnnie Hyde. This couple lives completely off the grid deep in Superior National Forest just south of the Boundary Waters Canoe Area Wilderness. Their lifestyle is unconventional, but it along with their vast knowledge of the land in which they live is truly humbling and something we could all learn a great deal from. Here are some of the lessons I have learned.

The simple life is not an easy one. Bert built their cabin and sauna with the red pine and white cedar he cut himself from their land in the 1980’s. They have propane gas for lamps and cooking, but there is no electricity. Heat comes from the firewood you split for the winter, and bathroom trips often mean braving -30 degree temperatures in the latrine. Your weekly shower can be accomplished by rinsing off in the lake (weather permitting) or sitting in the sauna. If you want drinking water for the next day, you have to boil some lake water before you go to bed. The year’s refrigeration comes from ice blocks cut from the lake during winter, which is what brought us to the Northwoods in late January.

Simple life 2- iceRayma, I, and two friends traveled north to help Bert and Johnnie with their annual ice harvest. We cut long slabs out of the lake, chopped them into manageable chunks, shuttled them to the icehouse via snowmobile, stacked them up, and tucked them in with sawdust and snow for insulation. The following day we split firewood to insure there would be enough fuel to last the winter. During breaks we warmed up inside the cabin watching gray jays, hairy woodpeckers, goldfinches, pine and evening grosbeaks through the kitchen window (a fine replacement for television). When we ran out of daylight we soothed our sore muscles in the comfort of the cedar sauna. At the end of the weekend and after a good night’s rest, we pack our bags, said our goodbyes, and skied out; stopping along the way to marvel at the massive wolf tracks imprinted in fresh snow.

Returning home on I-35, the pines and birch eventually turned back into barren corn fields. I romanticized about someday having my own cabin in the woods, living a simple life. Is it that farfetched I wonder? I turned my phone back on and got bombarded with messages and notifications which made me about my own resource use…

It’s amazing how the majority of the world looks up to the American economic growth model. America, the ‘land of opportunity’, but the American dream is an unsatisfying journey. We excel at production, consumption, and wastefulness at the expense of our natural resources. People working jobs they don’t like for years and years in order to earn money they can spend on material things they don’t need under the impression that they will be happy because of it, or to fill a void. We, as a nation, have lost our connection to the land we are a part of. No wonder so many people want to get their hands in the soil and start a farm.

Simple life 3 - Uganda While an undergraduate I was fortunate to participate in two international service learning trips, one in Uganda and one in Ecuador. These were invaluable experiences. Seeing people’s resilience to what most would regard as poor quality of life makes real the principal that quality of life is measured by things within, not by possessions or monetary wealth. Despite extreme poverty, malnutrition, disease, and government corruption the people of Uganda have a genuine happiness about daily life unmatched anywhere else I have visited. In Ecuador, I was amazed by the deep connection that the local people have with their land. Ecuadorian farmers recognize the important role forested land plays in the water cycle. They may not understand the biophysical processes, but they realize the importance of conserving their forest resources to store and deliver water consistently throughout the year. On service learning trips like these we are often considered “experts” since we have college educations, but in fact we often learn much more from the local communities we visit from the way they have been living for generations.

The transition back to my home is always a difficult one. I remember staring at my faucet feeling guilty I could access clean drinking water with the turn of a knob. In Uganda getting water means walking miles to a well and hauling heavy jugs back to your home every day. After returning from Ecuador I was in disbelief you can buy bananas at Kwik Star for 39 cents a pound.  It is at the expense of local Ecuadorian workers enduring long hours, poor wages, lack of unions, and heavy chemical exposure that we have the ability to access these tropical fruits at our convenience. It’s easy to take things for granted when you don’t see how the majority of the world lives or the repercussions of your choices.

Simple life 4- Bert Bert and Johnnie offer a similar learning opportunity to the service learning trips I participated in, but closer to home. They display the satisfaction of simple living. It may not be feasible for everyone to live off the land like they do, but what a difference it would make if we all sacrificed a few daily luxuries for minor inconveniences. Whether deciding what business to support or opting to bike to the grocery store instead of driving, the decisions we make every day have a real impact regardless of whether we see the results first hand.

Simple life 5 - Johnnie Bert and Johnnie remind me to live an examined life and aim for simplicity. Do what you love, start a garden, ride your bike, eat produce in season, learn an instrument, support local agriculture and businesses, get outside. The simple life is not an easy one, its hard work; that’s the point.


Louis Hilgemann completed his undergraduate degree in Forestry at Iowa State University last spring. After an informative field season last summer, he began pursuing his master's degree in Forestry with Dr. Peter Wolter. For his project, he is working with The Nature Conservancy to develop strategies for using remote sensing data for adaptive management and landscape monitoring in the North Shore Highlands of Minnesota.


The differences I found between Ames, Iowa and Fuzhou, Fujian

November 12, 2013 12:00 AM

Can and LisaAs a Chinese person who came to USA the first time, I am impressed by so many differences between the two cultures and environments. Here are a few of them:

1 - People are so sweet. Almost every person I meet in the lanes in downtown Ames or the campus will say "Hello, how are you doing?" to me with big smiles. I am flattered, but am not used to it because I do not get the sweet greetings from people walking in my hometown. This is maybe because there are so many people you can meet in streets that it is impossible for us to greet each other in China. However, the kind atmosphere really makes me feel warm in my heart, especially after I just arrived.

I realize that greeting to a stranger, even a foreigner, is a culture and politeness. If it is a few people or social elites, it is not strange. But it is a common phenomenon that shows high moral quality and well education of the people in the state. It should be learned by all the countries in the world; not only the politeness but also the kindness and peace.

2 – It is so quiet on weekends. Unlike noisy weekends on the streets of China, it is so quiet at Ames. There are hardly people walking except some runners and dog-walkers on sidewalks. People share their weekends with their family members. Weekends are rest time for most people but not working time. Even most stores are not open or open only for short time during weekends. In China weekends are the busiest time for stores because they can earn much money from so many crowds of people flocking to the stores for shopping. However, I like the quiet and the peaceful sceneries on a beautiful weekend. Not only can I take a rest but also can find peace in the heart by myself.

3 - There is no break at noon. The work time usually lasts from 8am to 4pm or 5:30pm, and there is no break at noon. In China, we often take one or two hours to break or have lunch during the mid-working time so that some workers could take a small nap or obtain some services, especially from the government. Here obtaining services is not a problem. I think it is the customs differ between countries, although the total working hours they spend are the same.

4 - Food is cheap. The food is cheap, especially in the super market. People can get a lot food with very little money in comparison with their income. People don't worry about the cost of food. Iowa is a state famous for agriculture. One day when I visited a farm I found that a farmer could feed 800 cattle by only himself, and also raised corn and soybean. I was really shocked and I know why the food is so inexpensive. In fact, food is the basic of people's life. Safe and enough food provided for the people, with a rational price, shows the greatness of a country. In this respect, it is certain that America is a great country.

5 - The sky is so beautiful. The first surprise Ames gave to me, indeed, is the amazing sky with no or little clouds floating there leisurely. I grew up in a city where it is a basin and often rains, and the environment is not as well as in Ames. So I have never seen so clean a sky before. The pure, blue, big and deep sky of course is part of the result of the big flat land of Iowa. But the good and not polluted environment is the key reason.

6 - The air is so clean and the water could be drunk directly from a fountain or tap. Like the clean sky, the air is so clean that I don't need to polish my leather shoes every day as often; which is what I usually do in China for there is dust everywhere. The clean air combined with clean drinking water is a benefit for people's health. There are also so many public drinking fountains, which is really convenient. One thing I am not used to is that all the default water is so cold, because I’m used to drinking warm water for many years in China.

7 - The winter is really cold outside but warm inside. Winter in Ames was a little hard for me at the beginning because I come from a subtropical city, where it almost never snows. Here it is cold outside and the winter lasts too long for me. However, it is really warm inside because there are heaters everywhere. In fact, the winter impressed me very much once I got used to the cold and the big differences of temperatures between inside and outside. After adapting to the temperature, I found that winter may be a good season for thinking.

8 - The management of a lab. Here the management of a lab is usually specialized and effective. Special people are responsible for their own things and all things run on their own ways. All the managements are worth learning by other countries. I am very lucky to have an opportunity to attend the weekly meetings of the LESEM Lab. I really appreciate Lisa and other lab member’s help. I will bring some of what I learned about lab management to China, such as implementing more meetings almost every week to discuss more with co-workers and students and so on.

A new environment is often full of curiosities and differences for a newcomer. However I don't know if I’ve gotten so used to my new environment in Ames that when I go back to China I will need to re-adapt. Ha ha!

Dr. Can Chen was a visiting scholar in the Department Natural Resource Ecology and Management at Iowa State University between November 2012 and 2013.  He is a lecturer in Forestry at Fujian A&F University in China. He focuses on urban green-belt landscapes and coastal protection through forests in Fujian province in China.

Comment 1 

Great article Can Chen! 
Submitted by Maeraj on Wed, 11/13/2013 - 23:11

Your observations reminded me of all the small things I developed an appreciation for when I first moved to Pakistan. Every place in the world is uniquely beautiful.

Isn't it amazing that there are so many little things we fail to notice in surroundings familiar to us--until we get the opportunity to experience life in a new place?

Comment 2 

Can, I love your writing 
Submitted by Rayma on Thu, 11/14/2013 - 09:22

Can, I love your writing. You really bring to life your experiences. You made me feel as if I was the one visiting from another country, looking through your eyes! We all miss you, but are happy you are home with your family.