When you eat fruits and vegetables, do you ever pause to consider where their life-sustaining nutrients came from?

Each week I receive a bag of fresh, locally grown organic vegetables from Skokomish Valley Farms. Opening the bag on Saturday mornings and seeing what I'll be cooking with that week has become something I look really look forward to.

But in a world where veggies typically come from the veggie aisle, and meat from the meat aisle, it can be easy to forget that all food - and life - is born out of a web of intricate interdependencies formed over many millions of years.

A few weeks back I received a farm update email from Skokomish Valley Farms that explained how they’re adding over 200,000 lbs of fertility inputs (primarily fish compost and feed for their chickens) into their soils each year in order to produce around 10,000 lbs of produce, while continuing to build soil organic matter and nutrient levels (they expect the amount of required inputs to decrease over time.) 

This inspired me to send some follow-up questions, and Farmer Paul Miller of graciously agreed to an interview. The following back and forth ensued. I learned a lot, and I hope you will as well!

(And if you care about the nutrient content of your produce and excellent land stewardship, be sure to check out Skokomish Valley Farms!)

Grant Jones: You write, "Farming, by nature, means we are extracting nutrients from the land that need to be replaced." What would happen on your farm if you stopped bringing in farm inputs? 

Paul Miller: The productivity would decrease dramatically. Within the first season, plants would not grow as quickly, nor be as large. They would be less healthy and unable to successfully defend against disease and pests. We would not be able to make it financially viable. The only way that we may be able to continue, would be to focus on certain crops that have very low fertility requirements, that tolerate very acidic soils, and rotate them every season around the farm, grown in small enough quantities that their usage of nutrients could be replaced annually by the nutrients that wash down the river from the mountains.

It sounds like inputs are critical to preserving soil fertility, and soil fertility is critical for producing abundant yields of nutritious foods. With a smaller and smaller percentage of the human population engaged in the daily work of preserving soil fertility, do you ever worry about the quality of earth's soils in the coming decades?

Definitely! We used to ask if we could truly feed the population of the planet using organic methods - now I ask if it would be possible, in the long run, using conventional methods. One reason we grow the way we do is so that the soil gets better and better every year, rather than being used up.

"One reason we grow the way we do is so that the soil gets better and better every year, rather than being used up."

You mentioned that most plants grown for human consumption are heavy feeders, meaning they require a lot of soil fertility to grow properly. Do you find there's a correlation between the nutrient requirements of the plants, and nutritional value of the food produced?

It seems logical to me that if the plant is pulling up large amounts of nutrients, then those nutrients are likely to be passed on to us as nutrient dense foods when we eat them. Regenerative Agriculture is a concept gaining a lot of traction these days, as means to get back to the founding principles of organic agriculture. Many of the discussions around Regenerative Agriculture also revolve around the nutrient density of food and how important that should be to consumers.

Every time I receive a bag of sugar snap peas in my weekly CSA delivery, I devour it immediately. Does this mean I'm deficient in some vitamin or mineral? 

They're just delicious! But really, that would seem to be a possibility. I don't have the science to back this up, but most cultures (including traditional American culture from before mass transport of frozen and refrigerated supermarket food) have a diet that varies with the seasons. It seems plausible that we tend to crave what is in season - peas are in season now. I'm not sure how much of it is that something about our metabolism or nutrient usage during different seasons matches what foods are in season - seems like a stretch. 

More likely, the reason we enjoy foods in their season, is that they are more nutrient dense at those times. To get a plant to grow out of its season, we have to force it one way or another which would reduce it's nutrient density (grow far away - pick unripe - transport for many days, grow under artificial light / heat - likely without natural living soil because that would be out of season too, store for a long time while nutrients reduce over time.)

"To get a plant to grow out of its season, we have to force it one way or another which would reduce it's nutrient density..."

I've read that many organic veggie farmers, such as the author of The Market Gardener, Jean-Martin Fortier, have a preference for composted chicken manure. You also utilize chickens as a source of fertility on your farm. What's so great about chicken poop?

It is in a molecular form that the plants can put to use quickly. While dumping bags of fresh chicken manure can be too "hot", and not provide balanced fertility, by having chickens free range over the beds before planting, the birds distribute the poop evenly, and scratching mixes it into the soil. Additionally, with the high cost of organic chicken feed, I figure that about half of the nutrients go through the bird and are put on the soil in the form of poop - the cost of that half bag of feed is comparable to the same amount of nutrients in a bag of fertilizer.

So plants are able to put the nutrients in chicken poop to immediate use. But isn't that also the case with conventional fertilizers? Why not just use those?

It depends on what kinds of fertilizer you choose. Some are quick release, others slow. I haven't really looked into how chicken manure in a bag from the store compares to other fertilizer inputs from bags at the store - the main reason I like it is that the birds serve multiple purposes, INCLUDING improving fertility of the soil - plus they spread it around for me. Without being able to fully justify it, I also get the sense that it feels better than dumping bags of bought stuff on the beds to improve fertility. 

Is it the case that conventional fertilizers can adversely affect the long-term health of the soil in a way that manure does not?

Conventional fertilizers are very concentrated, so while a farmer may choose to apply them at a lower rate to prevent "burning" the plants, it seems to me that, at the microscopic level, the biome near each granule of intense fertilizer is still negatively impacted by the artificial intensity of the fertilizer. Therefore, the living component of the soil may be injured. Also, if the chemical fertilizer is quick release (as most are), then the microbes are put through a roller coaster ride of a spike in fertilizer, then a slump as it quickly is dispersed. Manure however, even chicken manure which is considered "hot", is less concentrated, and releases the fertility over a longer period of time, which is more conducive to the biome of the soil.

With organic, slow release fertility inputs, like manures, the plants rely heavily on the living soil microbes to process the nutrients to present them in a form that the plant can use. To balance that relationship, plants exude sugars and other things they can feed to the soil biome so that it can provide the nutrients back to the plant.  Some studies have shown that up to 40% of the production of the plant can be released through its roots as exudates to feed the soil around it.  

Another problem with application of high amounts of water soluble fertilizer is that it can disrupt this relationship between the plant and the microbes in the soil.  When the plant can get so much of its nutrients directly through its roots from the fertilizer, it has little incentive to feed exudates to the soil. As a result, it may not feed the soil so there are not as many living microbes close by to feed the plant when it comes on hard times.  Eventually, that water soluble fertilizer has washed away and the plant really needs that living soil to transform nutrients in the soil into something it can use. However, since it had been neglecting the biome, there is no relationship established, and the plant suffers.

Besides chicken feed / manure, what other farm inputs do you use and why? 

Lime and fish compost - our soil is naturally very acidic. The lime raises the pH to bring it into the range that most vegetables need in order to thrive. Annual winter rains drive the pH back down, acidic, so reapplication of lime is required regularly. We purchase some compost made with fish scraps and wood chips as its base, made from locally sourced materials; plus we make about as much of our own, using fish scraps, hay, mushroom substrate, coffee grounds, and kelp. The compost allows us to target fertility applications, and keeps the soil in good tilth to prevent compaction and make it easier to keep weeds under control. The complex organic materials in compost allow for slower release of nutrients - to balance with the immediately available chicken manure, As the compost continues to break down in the soil over the next many years, it continues to release nutrients. About half the nutrients can be used the first year, but the rest are more slowly made available over the next 5 years or so. 

What do you think it is about animals - whether flesh, in the case of fish, or manure, in the case of chickens - that makes them such valuable sources of soil fertility?

Many of our grasses co-evolved with pasture animals. They form a symbiotic relationship that cannot be easily replicated by human deposited fertilizer. I've read about this, but do not have as much first-hand experience - yet. Regarding fish, they have been the natural way that many nutrients have been restored to the land as salmon swim upstream to spawn, die, and are reincorporated into the soils. As peak predators in the ocean food chain, they are able to concentrate many of the nutrients (especially micronutrients) that have been washed out of the soil into the ocean - so, by using fish as part of the fertility inputs, we are closing the loop, rather than simply robbing from Peter to pay Paul. Also, the multiple purposes of chickens (pests, fertility, eggs, meat...) make them a more valuable part of our operation than only assessing one part of their value, such as egg sales.

"Regarding fish, they have been the natural way that many nutrients have been restored to the land as salmon swim upstream to spawn, die, and are reincorporated into the soils."

So animals concentrate nutrients, spread fertility around with their manure, and, in the end, their carcasses become food for other animals, ultimately returning to the soil. Nutrients naturally settle in low places, such as bottom land and oceans, and animals - including human animals - help to move them uphill and spread them around. How does it feel to be participating in this natural process of fertility redistribution that's been occurring for thousands of years? 

I love it. While I applaud and assist the restoration of salmon habitat to ensure that this natural process continues, I also think its really cool to be able to help the parts of the salmon that humans would otherwise waste (leftovers from gutting/cleaning freshly caught fish) make their way back into the food cycle, rather than just go to the landfill. Since we're asking the land to grow food for us at a more intense rate, it makes sense that we're returning much of the nutrients in a targeted manner to match that withdrawal from the soil bank.

Have you found other benefits - besides improved soil fertility - to keeping animals around?

Pest control. By having chickens on the beds before the crops, the pest pressure is practically non-existent for the first succession of crops, and greatly reduced for the entire season. The birds have eaten pests, and larvae, or eggs, or at least scratched up the eggs to expose them so they are no longer viable. Having chickens near the crops (separated by poultry netting to keep them from eating the veggies), also seems to reduce the pest presence; especially if the birds are on the upwind side. Finally, even though they are sometimes annoying when you have to catch them and return them to their pen, the birds provide entertainment as they are funny, and interesting creatures.

You seem to be developing a nuanced symbiotic relationship with your chicken flock, as they assist with fertility and pest control while you provide them with food, shelter, and protection from predators. But couldn't you spray insecticide on your crops to achieve the same result without needing to maintain the chicken flock?

One of the problems with spraying insecticides is that you also kill the beneficial insects/microbes, that are so important to the health of the soil. The living aspect of the soil is so complex that we have only begun to scratch the surface (literally and figuratively) to understanding it - and I can't see how we could ever hope to directly replicate that complex arrangement in any practical manner with artificial human inputs. Let's find a way to let biology work for us, rather than fighting it all the way. Rather than spending most of my time killing things, I'd like to focus on getting things to grow well. It is true that chickens would also eat up beneficial insects; however, those predator insects are often much more mobile than the detrimental bugs, and therefore would presumably survive in a higher ratio. The chickens also seem to be less destructive to the sub-soil microbes than insecticides would be.

One study in the Midwest sampled all the varieties of insects they could discover on hundreds of farms.  Among questions they asked the farmers was how they would rate their pest level. The study found the highest correlation between a wide diversity of insects and LOW pest pressure.  It therefore seems reasonable that while spraying insecticide may solve  pest problem in the short term, it is likely to induce a long term pest problem that is much worse.

The way you talk about soil is as if its an entire complex ecosystem of its own that we should pay attention to, care about, respect and nourish. 

We're also finding out more and more about the complex universe within our own bodies: how there are many more cells that make up our internal biome than there are human cells in our body. Everyone has something that they are passionate about - and as they get to know more about it, the more they realize there is that they do not know about it - how much more complicated the complete system is. Well, farming is the same - there's always more to learn, and the soil is a great example of a complex system that we are only beginning to understand. It's kind of like watching a documentary about the vast expanses of the ocean that we have not explored and all the creatures that we have yet to discover there - the microscopic world of the living soil is also a frontier that has many worlds waiting to be discovered. It's like going to an alien planet in a spaceship.

"...the soil is a great example of a complex system that we are only beginning to understand."

You mentioned the coevolution of plants and animals. These are deep relationships between species formed over millions of years. In your work farming organic fruits and veggies, have you happened upon any other interesting examples coevolution?

Recent research is finding more and more cases where microbes in the soil are symbiotic with plants growing in the soil. A classic example are legumes with the nitrogen fixing bacteria that live in nodules on their roots. They are bacteria, not animals though, but same concept. Fruiting plants are classic plant/animal symbiotic relationship:

1. Plant makes a flower to attract pollinators for better sexual reproduction advantage. Pollinator insects get a tasty meal from the nectar (and pollen). Many pollinator insects also eat other insects, but rely on nectar as a main part of their diet - couldn't survive most of the time without the plants.

2. Plant encases its seed in a tasty package (fruit) to encourage animals to eat it, and by carrying away the fruit, disperse the seed. Many animals rely on seasonal fruit to survive.

3. As a final bonus, in many cases, the seed goes through the digestive tract of the animal and is deposited right in a nice pile of manure, high in fertility, to get a good start growing.

On your farm you're leveraging the natural predatory instincts of one animal species - chickens - to eat many other animals like insects, arachnids, and gastropods. 

Yes, we also have dabbled in bringing beneficial insects like ladybugs into our operation as well. While I cheated and bought some this year, I'd really like to do more than simply plant a few flowers in the coming years to encourage even more native beneficial insects to help us control pests. I love seeing all the garter snakes around the farm. I’m even happy when I find frogs/toads (so long as they are not the invasive species) as they are voracious eaters of pest as well. 

So can we produce organic veggies without animals?

Not as well. I know many organic farmers do not directly integrate animals, and use green manures (cover crops). However, even if they are not using domesticated animals (livestock), they are still using animals - insects, worms, etc. to do very important work on their farm. I think if we were to survey all organic farmers, we would find that most all are at least using animal inputs (manure), if not directly using animals - and most of them would say they would love to find a way to better integrate animals into their operations.

What can non-farmers do to support this important work?

Well, many of the suggestions of the environmental conservation movement are good - but beware of greenwash; there are many things touted as green that have marginal benefit at best, and sometimes they only hide the damage that is done behind that process/product. If it sounds too good to be true - do your research into it, but watch out for self-fulfilling bias which would lead to you to only do internet searches to confirm what you already want to believe. Try to find something that argues against what you already think.

"The closer you can get to your food source, the more likely you'll be able to know if that food is being produced responsibly."

At the bottom line: know more about where your food comes from. The closer you can get to your food source, the more likely you'll be able to know if that food is being produced responsibly. Then you can make an informed choice in what food systems to support with your purchases.

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Grant Jones

About the author

Grant Jones grew up on the Olympic Peninsula and studied English Literature & Philosophy at the University of Washington. After living in Seattle for 12 years, he left the city in search of a better tree to people ratio, and found it on the family farm in Shelton. Today, Grant farms full-time and envisions a Western Washington region where humans forge positive and sustainable relationships with our region's unique environment, preserving and enhancing it for future generations.