ways to reduce agricultural greenhouse gases

[screener]

I take it that you would leave your straw and stover on the field, not sell it for feed/bedding if you were farming? That would help the soil for sure. I guess the problem that i was trying to point out was that commercial fertilizer is expensive in a couple of ways. It utilizes a large amount of fossil fuels to produce it, transport it, and apply it. Then a good percentage of it is wasted by the crop.

As you said, farmers can't afford to lose soil moisture to less valuable crops, and I was saying that perhaps we aren't placing the right value on such crops as clovers, alfalfa, etc. It's my experience that land that has had legumes for a couple or three years retains moisture better than land that hasn't. The nutrients and soil fibre put in the soil by those crops doesn't have to be expensively produced.

[UrbanFarmboy]

Ther is not much demand for bedding in my area as most use synthetic bedding which is easier to maintain and reduces bacterial growth.

Dry stover has a very low nutritional content and we grow enough silage that there is no need to go to the trouble of making bales out of it.

Silage creates its own problems as it does not put much back into the land as almost the entire plant is chopped and bagged. Corn silage is particularly hard on the ground.

When it comes to valuing legumes, your really asking people to place value in something they will never realize.

The only way anything like that would make sense in our area is if carbon credits were traded taking into consideration the reduction of CO2 from fertilizer production. Though it would have to bring huge returns, more that I would wager the market is willing to pay, for commodity farmers to utilize them. However that begs the question what has a bigger impact.

The use of legumes for 3 years would reduce fuel and input costs, but the application of manure, which is again very prevelant in our area, reduces methane emissions greatly as the manue does not pool in lagoons.

Manure is really the best of both worlds for us, though we do not derive all or even most of our nitrogen from it. We use manure as a soil conditioner and to replenish phosphorous, but we do use urea or liquid nitrogen fertilizer annually.

The thing about synthetic fertilizer being expensive is really a non issue. Farmers will use it as long as its viable and once it reaces a price where it no longer makes sense, we will have to change. We also try not to waste any fertilizer since it costs around $120 bux an acre.

That being said, if renewable energy ever becomes economic, you may ver well see wind powered fertilizer plants which would completely negate the fossil fuel cost for the production of nitrogen.

[Robert Northup]

If you can get hold of it, there is an EXCELLENT review article about everything that is known (as of 2006) about how agricultural management influences release of nitrous oxide from soil, and proven as well as experimental strategies to minimize it, primarily by minimizing nitrification, which can ultimately lead to denitrification, and both processes emit nitrous oxide as a by product.


G.V. Subbarao, et al. “Scope and Strategies for Regulation of Nitrification in Agricultural Systems – Challenges and Opportunities”. Critical Reviews in Plant Sciences, 25:4, 303-335, 2006.

[Robert Northup]

I completely agree with Urbanfarmboy on many good points. Tons of CO2 emitted just to MAKE the nitrogen fertilizer. But the price of fertilizer has, historically, been so low that it was a good investment to over fertilize. There is almost always spatial variability of fertility within a field. A rule of thumb is that the least fertile soil within a given parcel requires about three times as much fertilizer to get maximum yield, compared to the most fertile soil there. Applying at a uniform rate, the only way to ensure maximum yield in every part of the parcel is to use the high rate. This means that large areas of the field receive a lot more than they need. So long as fertilizer was cheap enough, combined with severe economic pressures to use any means necessary to get absolute maximum possible yield, it was foolish NOT to over apply, despite the environmental damage associated with all that excess fertilizer.

Technology now offers a practical way to minimize this problem, while still getting maximum yield. Variable rate application can selectively provide the high rate to the limited areas of the parcel that need it, and use much lower rates in those areas that don't need it. The bugs have been pretty well worked, and there are a broad range of sensors, mapping technology, satellite guidance, etc. commercially available to accomplish this.

Tragic chapter of my life story. About ten years ago, one of the world's largest producers of farm machinery was ready to cough up millions to develop a near infrared sensor for nearly instantaneous assay of soil organic matter content, and available nitrogen, phosphorus, and potassium. The bench top version wowed them, as it gave accurate readings for the unknown soil samples they brought in to test it. It was going to be a win-win for everyone, allowing farmers to save money on fertilizer and reducing the adverse environmental impact of our agricultural nitrogen. Two things killed it. First, farmers were losing their shirts at the time, and sales of new tractors, etc., were way down. They were losing money, and they just couldn't spare any millions for R & D at that point. Second, until the technology was truly perfected, there was the risk that some infertile microsite within the parcel would receive the lower application rate, reducing the yield. Fertilizer was still cheap enough that the trade-off was a bad risk. Farmers were on the edge of bankruptcy, and the banks were often dictating the crop and management practices to protect their investment. The market just wasn't ready for such a thing. Sigh...

[Robert Northup]

Variable-rate technology, also known as "precision agriculture" or "farming by the foot", is based on the idea of matching the spatial variability in soil or crop requirements to application rates of agricultural chemicals.

It has come a LONG way since I first got involved in it. For example, the ability to precisely regulate nitrogen fertilizer application rates, and the technology to precisely match that to the spatial variability in soil nitrogen requirements is commercially available, in multiple versions, and from multiple sources. Some variations produce an extremely detailed map of soil spatial variability, and use that for satellite guidance of variable rate application. Other variations have sensors on board a moving vehicle, with application rates being adjusted "on-the-go" as the sensors respond to the spatial variability.

On-the-go sensors for variable rate technology include the infamous "weed zapper" that uses machine vision to distinguish weed from crop, and a targeting system to aim herbicide spray very precisely on the weed. Could anyone of any persuasion about the morality of pesticides disagree that it makes good sense to apply them as selectively as possible, and that this is a vast improvement over blanketing the field with the stuff?

Another application we were working on to sell to the unnamed tractor company that nothing runs like was use of hyperspectral imaging on the crops. In a greenhouse I grew a bunch of corn, with multiple replicates at different degrees of stress for nitrogen, phosphorus, and potassium, as well as excess N, P, and K, and, of course, controls.
Hyperspectral imaging was capable of clearly distinguishing different shades of corn green, and the idea was to create a catalog and calibration set for in-season correction fertilization. The idea was for an on-the-go sensor that would "read" the crop in the field to see how much additional fertilizer it may need, to regulate variable rate application. I believe that these, too, are now commercially available, but I haven't kept up lately. I had the good fortune of working with some exceptionally competent aerospace engineers in those days, and we had high hopes for our soil and crop sensors...

[UrbanFarmboy]

Robert,

You stated:

"A rule of thumb is that the least fertile soil within a given parcel requires about three times as much fertilizer to get maximum yield, compared to the most fertile soil there. Applying at a uniform rate, the only way to ensure maximum yield in every part of the parcel is to use the high rate. This means that large areas of the field receive a lot more than they need. So long as fertilizer was cheap enough, combined with severe economic pressures to use any means necessary to get absolute maximum possible yield, it was foolish NOT to over apply, despite the environmental damage associated with all that excess fertilizer."

As a farmer, I apply fertilizer based on a mix of things. With the cost of comercial fertilizer, we it simply doesnt make sense to use the high end threshold to fertilize an entire field. Our agronomist will recomend a level and highlight spots that may be dificient. We will apply fertilizer based on a cost benefit ration. Over application when only a portion of your land is extremely deficient doesnt make sense, at least for our operation.

I remember hearing about the technology you speak about, but when it comes down to it, it is still cheaper to apply with an over the top spreader. It may not be as efficient, but with weather veribility, we may be granted only a short window in which to use nitrogen and the system was simply too slow and too expensive to make sense.

I would love to have only the optimal amount of nitrogen per acre, but it would mean more time, effort and fuel to use the machine you speak about.

The weed zapper is of interest to us as glyphosate and other herbicides are getting expensive.

[Robert Northup]

As fertilizer becomes more expensive, people are getting a lot smarter about how they use it. I don't mean to imply you or any other farmer in particular, suggesting that you deliberately over apply, but the global average is that less than one third of the applied nitrogen actually gets into the crop, and the other two thirds, well some of goes where we really don't want it to go, and does things we really don't want it to do.

Ten years ago, it would have taken a rather bold pioneer to risk investing in the new technology, although many were certainly willing to give it a try. It was very expensive and a lot of bugs hadn't been worked out yet. It is rapidly becoming less and less expensive, and as the price of agricultural chemicals increases, it is becoming a more attractive investment, even for smaller operations.

One low-budget option is just to briefly rent a yield monitor for the harvester, with a GPS system. You get a very detailed map of productivity at all points in the field. That alone can guide a lot of management decisions.

Fertilizer isn't as cheap as it used to be, but it may still not present the most compelling argument for precision agriculture, from a farmer's economic perspective. Other agricultural chemicals may offer greater savings. The herbicide neutralizing capacity of soil is often directly proportional to its organic matter content. A map or a sensor that knows the spatial variability of the organic matter content can guide variable rate application. Besides saving money on expensive herbicide, you have other reasons to want as little of it in the soil as you can get away with. Machine vision can recognize weeds or pest infested crops, applying the potentially hazardous chemicals required very selectively.

Trust me. Before long, they will be offering a package you can't resist at a price you can't refuse.

[screener]

Originally Posted by UrbanFarmboy

Ther is not much demand for bedding in my area as most use synthetic bedding which is easier to maintain and reduces bacterial growth.

Dry stover has a very low nutritional content and we grow enough silage that there is no need to go to the trouble of making bales out of it.

Silage creates its own problems as it does not put much back into the land as almost the entire plant is chopped and bagged. Corn silage is particularly hard on the ground.

When it comes to valuing legumes, your really asking people to place value in something they will never realize.

The only way anything like that would make sense in our area is if carbon credits were traded taking into consideration the reduction of CO2 from fertilizer production. Though it would have to bring huge returns, more that I would wager the market is willing to pay, for commodity farmers to utilize them. However that begs the question what has a bigger impact.

The use of legumes for 3 years would reduce fuel and input costs, but the application of manure, which is again very prevelant in our area, reduces methane emissions greatly as the manue does not pool in lagoons.

Manure is really the best of both worlds for us, though we do not derive all or even most of our nitrogen from it. We use manure as a soil conditioner and to replenish phosphorous, but we do use urea or liquid nitrogen fertilizer annually.

The thing about synthetic fertilizer being expensive is really a non issue. Farmers will use it as long as its viable and once it reaces a price where it no longer makes sense, we will have to change. We also try not to waste any fertilizer since it costs around $120 bux an acre.

That being said, if renewable energy ever becomes economic, you may ver well see wind powered fertilizer plants which would completely negate the fossil fuel cost for the production of nitrogen.

I would argue that renewable energies have become economic. The use of fossil fuels isn't costed properly to account for environmental degradation or reduced resource stocks, which makes the alternatives look more expensive.

No farmers are wasting anything that we understand. I'm glad to see that farmers in your part of the world are using their manure to repenish the soil. However our use of such huge amounts of Natural Gas to produce fertilizer is more of a system inertia problem than a matter of bottom line decision making. I think it's safe to say that alternative energy proponents aren't going to voluntarily take less than the gas sector demands for its product.

The below mentioned article discusses some of these issues, and in relation to them and the option of having a more viable agriculture it's time that farmers and governments lean away from unsustainable practices



Implications of Fossil Fuel Dependence for the Food System | Energy Bulletin

For most of human existence N fixation (the splitting of N2 to form Ammonia) was limited to bacteria (primarily Rhizobium). With the invention of the Haber-Bosch process in 1913 humans began domination of the N cycle (Smil 1991). This process is extremely energy intensive requiring the reaction of 1 mole of nitrogen gas with 3 moles of hydrogen gas under temperatures of approximately 400°C and pressures of approximately 200 atmospheres (Marx 1974). This accounts for 30% of the energy expenditures in agriculture. The hydrogen gas for this process comes almost exclusively from natural gas which is considered as a feedstock and not factored in as part of the energy expenditure (Hendrickson 1996). It is also possible to get the required hydrogen by the electrolysis of water but this requires more energy, making it an unfavorable alternative at this time (Gilland 1983). Natural gas currently accounts for 90% of the monetary cost of N fertilizer (Wenzel 2004).

[screener]

Thanks Robert Northrup, I'll try to get ahold of the regulation of nitrification in agricultural systems paper you mentioned.

[Robert Northup]

As we find more and more practical ways to reduce fertilizer use, one place to start is to improve the efficiency of crop uptake. At present, the global average is that only about 30% of applied nitrogen fertilizer actually gets into the crop. The other two thirds is causing a lot of trouble.

Many fertilizing saving technologies are already in hand, and others are on the horizon. Here are some thoughts about where it might go:

To obtain sufficient nutrition from unfertilized soils in natural ecosystems, most plants have one or more species of symbiotic microorganism in mutualist association with their roots. Nitrogen-fixing bacteria permit many plants to use nitrogen acquired from the atmosphere rather than “mined” from the soil, and mycorrhizal fungi can be crucial for enhancing root capacity to take up soil nitrogen, phosphorus, and other nutrients. Although these benefits are acquired by plants at a substantial “cost” of photosynthate allocated below ground, they permit sustained productivity without fertilizers. Most nutrient cycles in natural ecosystems are regulated by the chemical composition of decaying organic matter in such a manner that potential nutrient availability is synchronized with root uptake capacity. During snow melt in northern forests, for example, nutrients are preserved in insoluble form, preventing their leaching loss during the period when roots are still too cold to take advantage of them. As we shift away from using crops that are dependent on being supplied with chemical fertilizers, nutrient cycling dynamics of these natural ecosystems can serve as models for selection of appropriate agroecosystems.

Since most plants in natural ecosystems enhance the nutrient uptake capacity of their root system through association with mycorrhizal fungi, this is a natural place to start in the search for ways to enhance crop nutrient uptake in minimally-fertilized fields. Selective breeding and genetic engineering could lead to cultivation of crop-mycorrhizal associations that permit highly-efficient use of native soil fertility or applied chemical fertilizer, thereby minimizing leaching loss or denitrification. The benefits of using nitrogen-fixing symbionts in agriculture were discovered many centuries ago, and are now being rediscovered as an alternative to excessive use of nitrogen fertilizer. The tradeoff with either mycorrhizal fungi or nitrogen-fixing bacteria is that more of the crop’s photosynthate must be allocated below ground. However, this is compatible with an overall strategy to reduce excessive fertilizer use and counteract global warming through the build up of soil organic matter, enhancing fertility and protecting long-term sustainable productivity.

A variety of fertilizer application technologies exist to increase the fertilizer use efficiency of crops. Variable-rate application of fertilizer in accordance with spatial variation of soil fertility (“precision agriculture”) can dramatically reduce fertilizer loss due to excess application. Slow-release varieties of fertilizers can avoid provoking a sudden, ephemeral “spike” of high nutrient availability followed by a rapid fall back to pre-fertilization levels. “Fertigation”, the use of a dilute nutrient solution for carefully-regulated irrigation, can be employed for even greater fertilizer use efficiency, especially if it is integrated with variable-rate technology. Chemical mechanisms can be employed to prevent or delay transformation of fertilizer nutrients into forms that can be lost. Whereas ammonium can be adsorbed to cation exchange sites, nitrate is easily leached from soil or lost to denitrification. To minimize transformation of ammonium to nitrate, commercially-available nitrification inhibitors are applied. Whereas ammonium can be taken up by a wide variety of soil organisms, including weeds, and can be readily transformed to nitrate by nitrifying bacteria, organic forms of nitrogen tend to be much less bioavailable, mobile, or likely to be transformed to a form that could be lost from the (agro)ecosystem. Supplied with plant photosynthate as substrate, mycorrhizal fungi have an advantage over other decomposers for being able to produce the kind of enzymes required to solubilize nitrogen from recalcitrant organic forms such as protein-tannin complexes. “Smart” fertilizers could be used that can only be solubilized “on demand” by crop-specific mycorrhizal enzymes, synchronizing nutrient availability with crop needs and uptake capacity, minimizing potential nutrient loss from the soil, and minimizing fertilizer nutrient availability to weeds or other competing soil organisms.