The Role of Carbon in the Soil with Rattan Lal

Hi friends, this is John and this is the Regenerative Agriculture podcast. Thank you for dialing back in today. I'm delighted to have with us Dr. Ratan Lal from Ohio State University who is renowned around the world for his work on carbon sequestration. He's earned many more accolades than I can even describe. Dr. Lal, we're very pleased and very happy to have you here with us and you've had a very rich journey doing work in many different areas. Can you tell us a bit about your pathway and your work in agriculture and carbon sequestration so far?

Yes, thank you for having me on this program. I came to Ohio State from India as a graduate student in 1965. I finished here in 1968 and went to Australia. I was working at the University of Sydney, New South Wales for about two years less than that. And then from there I took up a position with the International Institute of Tropical Agriculture in Africa, specifically in Nigeria. And I was based in Nigeria for about 18 years. And about 20 years after I left Ohio State, I came back as a faculty member. So I've been here as a professor of International Soil Science and director of the Carbon Management sequestration center since 87. I have international programs through visiting scholars from around the world. And we had about 180 of them. They come somewhere between three months to one year, some of them for two years, and they conduct their research here with us and then they go back to their own country and continue the research on soil carbon sequestration. I was also privileged to have about 112 graduate students who did their master's and PhD with me and about 55 or 56 postdoctoral researchers and another 10 or 12 research scientists. So I had about 350 to 400 professionals who conducted their research and graduate thesis with me. And they have been the best, among the best of the world. So they have made a lot of contribution to solve carbon sequestration and its potential to mitigate and adapt climate change and advance food security.

With all of this research that you've had the opportunity to observe and look at, what are some of the significant findings that you've observed that have not been widely appreciated or adopted in agricultural space?

Well, in Africa, where I was based in Nigeria, but I was working in a lot of countries in West Africa, for example Sierra Leone, Ivory Coast, Ghana, Cameroon, Nigeria, Zaire, Rwanda, Burundi, Kenya, Tanzania. Many of those countries I did the so called conservation agriculture, no till mulch farming. I was probably one of the first one to do that kind of research in Africa. And yet Africa is the continent where it is least adopted. So that's a little bit disappointment. We have a much better appreciation and adoption through many of the graduate students and visiting scholars from South America, Brazil, Argentina, Chile. The adoption rate of this technology much greater. Recently I had as many as 15, maybe more, 20 visiting scholars from China. And many of them have done a remarkable job of implementing this technology in China. So there have been successes and there have been challenges to get it adopted. But on the whole it is a good progress.

One of the pieces that has always surprised me when we when growers and agronomists think about growing plants and the importance of supplying nutrition, the conversation is often framed around Liebig's law of the minimum. Yes, the nutrient the least supply is going to be limiting plant growth and yield. And we often see presentations with the illustration of the barrel with the broken off staves. You know, I've never seen a barrel that had carbon as one of the missing staves. And yet it's critical nutrient for achieving plant yields. What are your thoughts on carbon as a nutrient?

I think that's a good point. Carbon is not a nutrient. Npk, sulfur, zinc, molybdenum, copper, they are plant nutrients. Carbon, however, is absolutely essential for the nutrients which are available in soil and those that are applied, their effective utilization efficiency. So I always think that rather than using the slogan let's apply npk, we must think of applying cnpk and C must come before npk. And the reason for that is because soil organic matter, for which carbon is about 50% of that is the essence of all life in the soil. And the life in soil is much more diverse. In a healthy soil, you may have in a spoonful of a healthy soil, millions of organisms more diverse than the entire Amazon forest. And it is the biotic activity of those organisms that really governs, is a strong determinant of what we call soil health. Because this organic carbon, organic matter is the food for those organisms. Without this food, they cannot survive. That is why if we do not return the crop residue frequently and in an adequate amount, then those organisms will storm. Soil can eventually die. And by dying I mean the soil does not have a living organism enough to carry on the biogeochemical and biogeophysical processes. So organic carbon concentration in soil should be about 2% in the root zone. Top plows air like 20 to 30 centimeter 8 to 12 inches. And if I translate that information to organic matter, that should be about double so 4% organic matter in the root zone. 2% organic carbon in the root zone is essential for water retention, for recycling of nutrients, for improving soil structure, for transformation of organic matter into available nutrients, for increasing the use efficiency of water and nutrients for controlling erosion of soil, for many things. So CNPK should be the slogan for application of elements that includes nutrients and carbon rather than NPK when we consider.

Increasing our soil's carbon levels. This is a goal that many growers and agronomists strive for through the use of COVID crops and no till agriculture. Managing soils a bit differently there's still often a question of how can we do this more efficiently, more effectively, and particularly in the context of managing other nutrient cycles with the carbon cycle as well as, yes, how can we do this better?

Right? Let me first indicate that soil organic matter content, its management is like managing a bank account. In a bank account, you want to increase your money, your portfolio, your stock, and therefore what you deposit into the bank must always be more than what you withdraw from the bank. And you know how much you are withdrawing and for what, for example, mortgage payment, utilities, purchasing groceries, paying tuition, fee of the family, and so forth. And what if you want your stock in the bank to increase the total balance? What you withdraw must be less than what you deposit. Soil is exactly the same way. If we want the organic matter to increase in the soil, what we put in as a biomass carbon should be more than what is taken out of the soil. Now, similar to what I said, bank account we take out for market or grocery or utilities and so forth, we lose carbon from soil for four reasons. Erosion, serious problem, water and winter ocean decomposition. That's what I was talking about. Microbes, food. They need to eat and they need to respire. This is their source of energy. That is what we call decomposition, mineralization, leaching of this and volatilization. Sometime organic compounds can be volatile. So as long as we know how much losses are happening from our soil for the specific land use that we have, then the amount of biomass carbon we put into the soil must be more than that. Now let's deviate a little bit. The carbon that we add into the soil, let's say at the end of the harvest in Ohio, October, November, end of October, early November, by the time next year comes, October, November, next crop. What remains in this soil at the end of one year is hardly 15 to 20% of what was put in. The remaining has decomposed. So the efficiency of humification is about 15 to 20%. How can we improve that efficiency? Make sure erosion is less we do not plow and disturb the soil. And the CN ratio, carbon in biomass has a very wide CN ratio. In corn residue or in wheat straw residue or barley, the ratio may be 80 to 100. The ratio of carbon to nitrogen in humus is 12 to 15. That means the humus is more enriched in nitrogen, phosphorus and sulfur. Therefore, to make better, efficient use of the biomass that's added, we want to make sure that farmers realize microbes are also going to need nitrogen, phosphorus and sulfur and other element to transform the residue carbon into humus carbon, which is what we need. So that understanding is absolutely necessary. I have an experiment here at Columbus Campus on our research farm and I put in crop residue, 4 tons, 8 tonnes, 12 tons, 16 tons of biomass per hectare. And then I have split those plot into two. I add extra nitrogen and no nitrogen. So the amount of humification, conversion of the residue into humus that stays at the end of the year is much more when there is extra nitrogen, phosphorus and other nutrients than there are none. So this chemistry has also to be understood. Then we want to make sure that the soil biota like earthworms, centipedes, millipedes and microbes, they are also abundant. And one way to check that is we call it microbial biomass carbon. We can determine that from certain test. So if farmers have that understanding how much losses are happening, how much you are adding, whether there's a good balance of nutrients, carbon, nitrogen, phosphorus, sulfur, in some kind of ratio proportion, they are meant the efficiency of humification will be better.

You described a bit of managing nitrogen better. So if I'm understanding correctly, what you're describing is that when the crop biomass or crop residue doesn't contain adequate nitrogen, then the additional carbon is simply lost to the atmosphere.

That's very correct and therefore. Well, one way to understand what I just explained. If sometime you apply crop residue and do not put in extra fertilizer, chemical or manure, you will notice plants are corotic. They look yellow because there is not enough nitrogen. Because the microbes are competing with plants, they tie up the nitrogen to convert organic matter into humus and plant roots cannot get it. So making sure that the plants and microbes both get their needs met, we must apply enough nitrogen for both purposes. And that brings to one more very important question. We are asking farmers to provide a service to the global community. And the survey says sequestering carbon in soil to mitigate climate change. As we sequester carbon in soil, you also improve water quality and renewability. We have a serious problem in Ohio river of the algal bloom a serious problem. Lake Erie. We had a city of Toledo not having water four or five years back. You remember that in summer, four days, no water, water was clean. That's right. So we are now asking farmers make sure water pass through the soil before it goes into the river and lake, rather than running, carrying surface runoff, carrying the nutrients and manure with it at this time of the year, through the snow melt or when it's. So we are asking farmers to do several things for which they are not the only beneficiary. The entire global communities they are creating ecosystem services. Therefore, for them to have incentive to do what we are asking them to do, society must be willing to compensate them for creating those services. I have calculated the cost of how much keeping the residue back in, rather than selling it as a hay or for other purposes in the market. Adding extra nitrogen, phosphorus, sulfur, so that that residue can become humus. Other opportunity causes. It comes to about at the rate at which carbon is sequestered in Midwest, especially in Ohio, $16 per acre per year. In terms of ton of carbon, it is $125 per ton of carbon sequestered in soil as organic matter. If farmers are to be incentivized and they need to know that society appreciates what they are doing, the payment for ecosystem services is about $16 per acre per year. I want to immediately mention that it's not a subsidy. Many people say we are already giving farmers several subsidies. This, what I'm talking about is not a subsidy. It is for asking them to do something which is beyond the call of duty. And it is for the entire global community. Society must be able to pay.

I think there are many things that we are asking of farmers and should be asking of farmers. The ecosystem services that you just mentioned. With carbon sequestration, but then also with quality of food consumption. I think the objective should be to produce higher quality food and then also to be compensated for that.

Very much so. And I think what you just said. I want to repeat a statement that I normally talk at levels at the International. Last week the same question came out the National Academy meeting. I was there Wednesday, Thursday and Friday. And that is the health of soil, plants, animal, people and the environment is one and indivisible. Therefore, if the health of soil goes down because the organic matter content is not enough, the health of everything else goes down with it, including that of people. And when I talk about people, we want to make sure that our agriculture is nutrition sensitive. The food produced is not only enough in Calories, but also in micronutrients and protein. With the global warming, with the increase in carbon dioxide concentration, which is right now about 415 parts per million, it was only 300 parts per million when I was studying in high school and primary school. It has really gone up that much over the last 70, 75 years. That also dilutes the concentration of micronutrients in food. There are 17 of them. So our soils must be healthy enough to produce healthy food. That means the plant and animal that are also we are using as food products are also healthy. But more importantly, that the environment, water and air is also healthy. So that link, soil, plant, animal, people and environment are interconnected is one which is very important. The other part, which I think is important for our farmers and the policymaker to understand is the following. In the US epa, we have Healthy Air Act, a Clean Air act, we have a Clean Water Act. I, as a soil scientist, strongly believe that it is not possible to have clean water and clean air without having healthy soil. Therefore, farmers, land managers, people like those involved in the media, like yourself, must urge the policymakers that we need a Healthy Soil Act. The environment has three legs. It's a three legged stool. Air, water and soil. The third leg has to be there for the stool to be stable. We don't have it.

That's an important point, one that I've not heard expressed before.

It is extremely important point. We are trying to clean water. We are trying to make sure there is no algal bloom. It is not possible until we force the water to go through the soil. And soil is healthy enough to absorb all those nutrients so they do not percolate into the stream.

When we think about absorbing nutrients, I want to go back to what you said about the efficiency of carbon sequestration and managing carbon, nitrogen, phosphorus and sulfur ratios. You spoke a little bit about carbon and nitrogen ratios. And there are two questions that come to mind. The first question is what should the ratios be of carbon, nitrogen, phosphorus and sulfur in crop residue for optimal sequestration? And the second question is how does sequestration efficiency change when one of the three is imbalanced?

I will send you. Maybe you can look it up yourself. There was a paper I wrote, somebody asked me that question in 2014 in the Journal of Soil and Water Conservation. 2014. And the title of the paper is Societal Value of Soil Carbon. In there there's a table. It is a table which says what is the ratio of carbon to nitrogen, carbon to phosphorus, carbon to sulfur in the residue and what it should be in a stable humus, and therefore it highlights how much additional is needed to fill in that gap. I think nitrogen I remember is carbon to nitrogen. Residue is about 80 and humus is about 12 to 15. Carbon to phosphorus in the residue might be about 200 and in the humus is about 50. Carbon to sulfur in the residue maybe 500, and in the humus is about 100. Nitrogen, I remember for sure. The other one you have to check just to make sure that those are the correct value I gave you. So this stichometry chemistry has to be observed, otherwise the biomass carbon that you add, it will not become a stable humus. And for this additional, not only farmers are adding the residue, which they could have used for other purposes, but knowingly or unknowingly, they have to also supply additional nutrients. So when I said farmer should be compensated, I had calculated, and this paper will tell you how I did the calculation. The Chicago market price of hay, of nitrogen, of phosphorus and sulfur. I use those values in calculating of the 2015. I don't think they have changed much by now, last five, six years, but they should be updated just in case there's a bigger change in prices. If I were to calculate the same thing for Asia or Australia or Brazil, I want to make sure that the values I use are for that region or country.

One of the questions that arises for me when I think about this is what occurs in the soil with the crop biomass when we supply needed nitrogen and phosphorus to balance with the carbon. But we're missing one. Let's say we don't have adequate sulfur.

Then the efficiency of the conversion of residue into humus will decrease. As you said Liebeck's Law, whatever is missing will not be adequate conversion of the biomass into humans. So that's exactly why I want to say one more thing, so that I won't forget it. And that is just like society is demanding from farmers, if you do this, we will compensate you to payment for ecosystem services. It's not happening yet. But if we had a Soil Health act, that should be part of that. Payment should be part of that. There's one other part. If I were to write that Soil Health act and it is the following. Soil is a living entity. That's what soil health means. Health always refer to something living. If soil was not a living thing, the word health has no meaning. A dead iron or stone or a gravel, which is strictly inorganic material. We don't talk about their health, we talk about health holding of a living entity. So soil is A living entity. That's why we need a Soil Health act to restore and protect it as a living entity, just like any other living entity. Like animals, like bald eagle, like butterfly, like panda or like humans. They all have rights. Rights to be protected, rights to be given certain basic amenities. Right to thrive, right to be restored. Soil must also have rights. Simply because one owns a soil does not necessarily mean they can do with it either way, because it should have a right. So to pollute a soil by dumping unnecessary things on it, to contaminate it, to hurt the organisms in it, so the soil cannot perform its functions in ecosystem services, should have a protection policy. Just like we had that for water and air. And I have written an article on that substance subject also rights of soil. And so Soil Health act, on the one side it compensates the farmers for doing good things, but on the other side, it also says those who do not good things will not be compensated. But those who do good things will be rewarded. So it's a carrot policy, not a stick policy.

This, I think, becomes an important, very important conversation. Many farmers have a desire to leave the soil better for the next generation. They desire to leave a legacy. And yet many growers also feel trapped and stuck in a management system that has them constantly applying fungicides and insecticides and various different toxins onto the soil profile.

This Soil Protection act will get them out of that rut. How do you do that? Through compensation. Those who do certain things, for example, those who have a discriminate rather than an indiscriminate use of chemicals, can be rewarded. Those who have a cover crops can be rewarded. Those who do not necessarily plow when it is not needed because they did a radish cover crop or other protein, they are returning the biomass. They are protecting the soil against erosion. They are not unnecessarily dumping things that will hurt the soil biotic life. They should be rewarded. Their contribution should be recognized.

Considering that we're thinking about and talking about the implications of pesticides in agriculture, what is the relative impact of pesticide applications to carbon sequestration as compared to tillage? I know this is a recurring question.

Tillage has a very drastic impact because tillage disturbs the soil and it changes the temperature and moisture regime. More importantly, it mixes oxygen the soil that increase the decomposition rate. But anything that affects the life of the organisms and it reduces the biodiversity of the organism in the soil. That means we are killing some and others maybe which are not so favorable take over that there's a shift in the Species diversity because of the use of material which are not very healthy from the soil perspective, that will have implication to carbon sequestration and of course to the quality of the water and air that comes in contact with that material. So our environment, three legged stool, the third leg is missing. And as long as the third leg is missing, especially the water cannot be purified.

Given the present political environment that we have and the existing framework of regulations and laws that are influencing the decisions that we make as growers, what would be some advice that you would have for growers? What are the big opportunities in agriculture that they are missing right now?

I think growers, I won't make any political comment. I think you said our growers are very shrewd, they are very knowledgeable, they are very have a stewardship concept. They certainly want to leave soil better than what they took from their forefathers. And I'm very proud of that. I'm very proud of the farming community not only here in Ohio and Midwest, but also globally. They are all. It is only when they are desperate and some of them in developing countries are desperate where they have to do things which are not very good for the soil. And there are 600 million of them who are small landholder, they cultivate 2 acre, 5 acre, maybe 10 acres. They do not have enough resources, they cannot afford to leave the residue, they have to feed the residue to the cattle. And they cannot invest in carbon sequestration, they cannot invest in soil conservation. And I think this compensation becomes even more important for those. And let me explain why I think desperate and the reason is when people are hungry, desperate, miserable, they pass their suffering to the land which they own. And as the land suffers, it degrades, its health is deteriorated, it in turn reciprocates and passes its suffering to the owner. And this vicious cycle never ends. And one example of this vicious cycle that never ends and also creates problem globally is the number of the migrants going into Mediterranean, for example, jumping while very well, knowing that they may never make it. And those who do make it the other side, they probably know they'll be deported back, but they still do it anyway because they're desperate. So this soil health part, not only that, the I mentioned health of soil, plants, animal people, environment is one and visible. But it's also more critical to, to peace and stability, tranquility, harmony in the world. Then we give it a credit more so than the threat of nuclear arms and weapons of mass destruction. 69 million people displaced, going from world place to place, no place to go and that is because the land where they come from, whether it's a drought in Honduras and Belize or whether it's a problem in the Sahel, or whether the land where they come from do not support that's a bigger threat to world peace right now than are the weapons of mass destruction. And yet nobody knows about it. The political map of Europe has changed because of the people jumping into the Mediterranean.

And at the root of all of this mass displacement that you're describing is the lack of adequate soil carbon and soil health.

It's a deterioration of soil health so that the people who lives on a degraded soil, their basic necessities of food, feed, fuel, water, clothes, fiber are not met.

Dr. Lal, thank you very much for sharing your thoughts and your wisdom for our listeners. I will share the papers that were referenced so that all of you can see those as well. Those will be in the show notes. Dr. Lal, are there any final thoughts that you would like to share with our audience?

I think the thought is that we need people like you who bring up these concepts to the attention of general public and the policymakers. And we also want to let farmers know that they are the custodians of the environment. Agriculture, if done properly, has to be a solution to environmental issues. As long as each one of us like to eat three meals a day, agriculture cannot be ignored.

The team at AEA and I are dedicated to bringing this show to you because we believe that knowledge and information is the foundation of successful regenerative systems. At aea, we believe that growing better quality food and making more money from your crops is possible. And since 2006, we've worked with leading professional growers to help them do just that. At aea, we don't guess. We test, we analyze, and we provide recommendations based on scientific data, knowledge and experience. We've developed products that are uniquely positioned to help growers make more money with regenerative agriculture. If you are a professional grower who believes in testing instead of guessing, someone who believes in a better, more regenerative way to grow, visit advancingecoag.com and contact us to see if AEA is right for you. Thank you for listening and we look forward to working with you.