Between Carbon Sequestration, Nitrogen Loss, and Yields - Gardening Beyond Basics 60

Welcome to Gardening Beyond Basics. I'm your host Diego, D-I-E-G-O, bringing you podcast

since 2013. If you're new here, welcome. Gardening Beyond Basics is a deep dive into the

topics that you thought were simple when it comes to gardening. From vegetable varieties

to soil to pests to seeds, we'll talk to knowledge experts to go way beyond the basics

and dive deep into the nitty-gritty about subjects that you thought were simple, but in reality

are much more complex than you can even imagine. In every episode, we'll dive deep into

one specific topic to make you a better grower. I hope you enjoy it. It's Gardening Beyond

Basics. Let's say we know a lot of cultivated soils are degenerative, and they're low on

that carbon saturation point. Are there specific plants or crops that are net carbon sequesterers,

like they are going to end up putting more in than they take out at the end of the day?

Okay. That question, like the complexity behind it, depends on if you isolate a plant by itself

without management. As you see it with it, it's one story. If you manage, so the example

that obviously comes natural would be a corn plant, right? A corn versus a native, a

sweet grass or a mix of native vegetation. Corn, if it is managed properly, can reach a

significant amount of biomass that is accumulated, and it's still one of the kind of crops.

It sequesteres more carbon that are forest at saturation because you will own a saturation

meaning that has already growth. But even nearly when you accumulate the woods, what is the

forest brings in terms of sequesting the leaves, then the leaves can't. So that's to put it in

numbers. It forest sequests about eight tons, and a corn crop on average will be at least 20 tons.

But is it a net? No, because corn uses fertilizer, and that goes down the drain already. The

emissions and all the life cycle analysis, and we can go there. The perennials we have, for example,

one crop, miscanthus gigantus. I don't know if you've heard, it's one of the bio-new bioenergy

cellulosic crop. The yield is 50 tons, okay? Not so big. So no fertilizer. It takes this somehow,

it just does anything. So in the amount of roots and rhizobium that accumulates, it's massive.

So that will go the problem with miscanthus is that can be an invasive species.

And so DOE, the department of energy that has funded the bioenergy centers across the

nations, has almost allocated the University of Illinois looking at miscanthus, missing a state

and University of Wisconsin. I'm looking at switchgrass that has much more of a broad range of

possibility of growing, but switchgrass on average would accumulate about eight tons of biomass.

So those are the natural behavior to answer your question. Yeah, big differences in plant,

wheat is by tons, maximum, and half of that could be grains. And so I'm talking about in general

average total the primary productivity of their particular crop. But I want to spend a minute

on saying that people may not realize that nowadays the level of photosynthesis done through

two things, improved genetics and management basically spoon feeding a crop. We have reached

the level of yield of corn of 600 bushels. So the average national is 170 bushels and world record

for the last four or five years has been in the range of close to 580, 50, and 600, the last one,

actually, which when you convert into total biomass, we're talking about now 50 tons per hectare.

But the amount of that's very positive a meter because of the amount of, it doesn't accumulate

carbon per state because of the balances through the amount of inputs that they're used as.

I initially said they go with agriculture being an anthropogenic component to the climate

is through fertilizer addition. We lose 50% of the greenhouse gas emissions coming from agriculture

come from main to all emissions. Okay, and so that's another balance because even the potential of

total accumulation of carbon is still requires nitrogen to go with it. There is a CN ratio. So

you will always be depleted by nitrogen unless you have fertilizer. So if you want to feel all

the soils with 5% in the globe, it will be equivalent to have 75% of the fertilizer production that

we currently have in the world, which is really heavy sorts of emissions. Now that doesn't mean that

fertilizer has to come from synthetic fertilizer. There are legumes that they can be. So if we want to

come back to the species, yes, different species have different capacitors, different photosynthetic

capacity and rates of accumulating carbon per unit area. The amount of this carbon remember there

is a component above the plant, but there is also roots. So there is this root shoot composition

that actually in situation where war is not available, roots become deeper. And so they basically

the plants provide this feedback mechanisms of saying, okay, the root says there is actually a

simple way to think and if plants is exposed to a stress and the stress comes from above,

what would be a stress coming from above? Reduced light, shading from then all the

things and the assimilates will go to the top and the plants will try and go faster, rather than

to elevate. If the stress comes from the soil gets the priority, the part of the plants in the soil.

So if there is a water stress, plants doesn't grow higher, actually says, okay, no problem, I'm going

to invert and shuts down. In some of the assimilates go down to the roots because remember it's not

photosynthesizing, but the roots are growing because they are desperately in search of water. And so

you get more roots that way. So this mechanism changes by species. But to again, to your question,

yes, different species, different capacity. And I mean, separation in the beginning depends

how they manage. So if corn is managed, we know fertilizer and it lets grow for so many years,

it would be far from where it is, you barely get 100, 100 bushels at the end because you run out

of corn is a very highly consumptive crop because of the sizes and it doesn't fix nitrogen on

its own like scams. So I actually switch glass glass pretty well without fertilizer. So there is

that mechanism that complicates even things. On fertilizer emissions, being a big source of

greenhouse gases are all fertilizers critical. So if we had chemical fertilizers and organic

fertilizers, manuars or, you know, byproducts from the animal processing industry, do those

contribute to greenhouse gases equally? No, they don't. So synthetic fertilizer

are immediate emission. You put them and you have these big flushes of, again, the color biological

station, we have a series of long-term data, the long-term ecological research site led by

Phil Robertson for so many years now, Nikadad. They've been measuring end to just basically

continuously, right, on automatic chambers. And so it's very de-eurnal depends on the amount of

water that after the rain there is. So synthetic fertilizer immediately and you may be aware of this

is basically about roughly 1% of the fertilizer there is added. This is a very simple concept. It's

called the mission factor that the intergovernmental panel on climate change has done a very

comprehensive review of looking at fertilizer rates comparison and emission. And so there was a

consistent number. You put 100 times, you lose one pound. And the problem is that one kilogram

of N2L is 300 kilograms of CO2. It's 300 times more powerful in the global warming potential,

like much rougher in the atmosphere. It traps a lot more 300 times more powerful.

And so manure, it's an organic form, okay, does not have plans to do not use nitrogen in the organic

form. And you have to be mineralized. So mineralized first in form of N2L from N2 to N03. And then it

can be used or nitrification to NH4 ammonia. So this takes time. So the release is the decomposition

it takes time. It doesn't immediately make nitrogen available from an organic compound available

to the plains. So there is not an immediate loss. And that percentage is lower because it builds

carbony, retains carbony, nitrogen is trapped more. The problem with the amendments of organic

amendments is you also may have CH4, methane and emission associated to that application,

which is about 25 times more powerful than CO2. But overall, no, synthetic fertilizer

are the ones that they used the most, obviously, and they are the greatest. But there is a new

approach to slow release fertilizer. So basically, they have shown to, they're still synthetic,

the cost is still very high, but it does reduce N2O emissions because it slowly releases the amount

of mineral nitrogen that could be volatilized. And the other aspect of N2O emissions and fertilizer

is that has to be in a conditions that creates D-nitrification. So back to N2 in the form. And that

occurs when there is a flooding conditions, right? When there is lack of oxygen. And normally,

when you add organic compounds, that doesn't happen. You are back on the healthy side of having

greater porosity, better conditions in general. So synthetic fertilizer are certainly the ones

that you think the most. But it's not even a natural, a cover crop will have emissions, not

SI, obviously, as a fertilizer, but it's a natural process.

Where would a crop be in terms of net nitrogen loss? If I planted corn year after year in the

same place, and I wasn't doing tillage, and let's say I had really good soils, would I,

would I need to add nitrogen? Or could I get that system to function without nitrogen addition?

If I left all that biomass. Very good question. It goes back on the temporal time. It's on the

first year. So I, you may have seen in some of my research by scaling and understanding this

spatial variation, as I identify that each field as like a farmer will know, but don't all the

farmers know that, and then come and scale that there are parts of the field that they're much better

because they have deeper soil, like deeper volume. And so those, they, it becomes back to the

virtuous cycle where you have greater biomass, greater roots, greater decompositions, and you do

accumulate that. The mineralization, so an organic, fully, let's say, in this way, would be an

organic source of management. If it's managed correctly, it could compensate, but you may not have

the same level of yields. The yield could have a penalty in the beginning. In the first years,

it may not be sufficiently to compensate what you were used to. So we also seen

at this long-term study that organic systems, and in our case, it was only cover crop and no

tillage. It could come close to the yields of the mineralization just because it isn't just about

all nitrogen. They have more water. And the conventional tillage ran out of water much quicker.

So it's really a system. So to answer your question, immediately, no, long-term certainly can.

But the yields are not obviously the 600 bushels, but they can easily get to the level of

average yields, which will bring the benefits of trade-off analysis of the cost of doing things.

Farmers need to understand that, and they do process it for sure, and not necessarily all of them,

but profit is also obtained by spending less. Investing. So it's now, unfortunately, nitrogen is

a cheap and economic source of insurance as a thing. It costs the significantly lower to put an extra

pound compared to its basically 50 cents versus $4 a bushels that you could get from the addition.

And that's again, back onto the trade-offs. Are we serious about accumulating carbon and using

it carbon to store and offset emissions and so on versus the profit? I'm always of the idea that

we need to be able to reward farmers for what they do in long-term sustainability, basically

and keep carbon there and using more sustainable management, which is to reduce among the fertilizer.

To reduce the amount of fertilizer, it's very interesting back to the space of variation.

There are parts of the fields shouldn't even be cultivated with the same crop, but they are even

cultivated with the same management. So a corn crop that yields 100 bushels on either on the edge

of the field, on some poor conditions, that receives 200 pounds per acre of on average,

on depending on, let's say, typical. And that's unacceptable because you're really

omitting much more. So converting those areas into more perennial in legumes,

then you will build the soil and the system to be able to mineralize that.

Given some of the work you do with SIBO and just some of the academic work you've done,

it seems like a lot of the focus is on carbon emissions, but if you have nitrous oxide,

which is worse at the end of the day, shouldn't there also be some concern about

containing nitrogen within the system? And is nitrogen the same as carbon? If you reach

that carbon saturation point in the soil, where it's at equilibrium, could nitrogen be the same

in a cis-natural system where everything that's being used is being stored in the soil,

either in the biomass or in the living microbial biomass in the soil?

Yes, very good. The first question, Diego, that's not necessarily, when we say carbon emissions,

everything is converted into SIBO to equilibrium. So everybody knows that the greatest emissions

come from into all. And we reduce angle, we aim to use angle emissions, but there are

address lots of SIBO to equilibrium. So I am working on a way to basically create carbon credits

by reducing, but better managed in fertilizer, it comes as a benefit to the atmosphere because

you reduce the SIBO to equivalent from nitrogen. Nitrogen is critical also because people

have talked enough, but it's lost now in terms of benefit from water quality as a critical

aspect of nitrogen, where the system by definition is a liquid system. So nitrates, because of them,

the way the molecule has these negative charts, they are basically very mobile. So the point of

saturation is really hard to get, because you get a flush and it very goes down to the next layer

and so on. So the nitrogen in general, it's never on a fully positive accumulation, because it's

used by the wind, is the de-volatized. The most of it is basically lost as nitrate leaching.

And in addition, some will be surface runoff, so that soil is taken with that. But a third or more,

so back to the spatial variation, in the areas of low nitrogen use efficiency, these areas will take

only 40 to 50% at the most of what it was applied. So I bring this example often when I talk to

growers, it's imagine you buy this pound, a hundred pound bag, and you've done the first 15,

the parking lot, and then you go back to your field and you apply. Why did you apply for so much

more on these areas? It's just an example. They don't necessarily know. But now technology

with eventually, possibly in the end of the talk, we could go on the future of how data and digital

technologies could help. But we have a very good knowledge of where these low areas in a field are,

and so you could now have 100% efficiency by putting 50% of the amount, because the yield is basically

that plain small and only requires half for what it was humanity initially. So again, the point

is saturation. It's impossible because of an open container. It doesn't have a bucket at the end.

Carbon doesn't move as tight, and it reaches, if you can only put so much around it,

then we nitrates because of the nature in the leaky system. They're lost as nitrate leaching.

And so that's very difficult to manage just because of that.

You know, this time you may notice that there's still a tendency for various reasons. I'm not here

to judge, but the majority of the application of fertilizer, it's done at the end of the season,

without even knowing what you're going to basically get in the year. And so obviously for

reason of logistics, reason of possible lower prices, and in the middle of the summer, you may very

well be sure, but they don't necessarily go back. And so what did they do? They compensate with

a larger amount in the beginning. That's changing, and they're doing all the way to now

variable rates of application where one area gets one amount and another gets a different amount.

So there's quite a bit of improvements, both in science of understanding the dynamics,

detecting this deficiency, but there's a combination of a culture of managing maybe more

traditionally, but that's very split. There are lots of progressive farmers. And so as a

suggestion in general, imagine not going to be like your food. You don't just stand up and cook

and use your mouth. You will be eating it through time. You won't be eating it all at once.

So what's the point of cooking 10 states when you can only eat one, then the rest is thrown away,

because it will be spoiled. That's equivalent of the leech. And so if you apply the nitrogen,

when it's needed, which is difficult because synchronizing supply and demand is as a conflict,

sometimes you cannot go back in the field, but there are times when you can, and there is a

limit when you can. There are alternatives with high boys and I'm more describing, obviously,

a mid-west phase. In vegetables, it's very important to feed with more of the spoon type of

the fruits and having all the ones because a fraction of that will be lost through water.

Yeah. So even in the healthiest or best managed system, you're going to be needing to add some,

because it just is leaky. There are pores. There are micro pores and water comes down. It takes you

don't lose it just to give you an idea is how long will it take for me to lose what I put in.

It's usually nitrates are never lost in the season. They're always lost when the plants are not

there to be taken up. So what's good about, you know, growing vegetables, you do have

nitrogen that, if you have another crop coming in, very sleptovers that can be used.

The difficult thing is remember because of the nature of leaching,

some of these nitrates are not in the surface. They're now a little bit deeper,

quite a bit deeper, and now they are on the second foot of sorts. So you could prevent some of it

when you know deeper roots back. So again, the leaching could be up to 50%, but you know,

you'll be dropped to be as low as between.

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