5 ms·

That's interesting, but a slight oversimplication since nitrogen isn't coming from the minerals. As long as nitrogen fixation can still occur (via decomposition

That's interesting, but a slight oversimplication since nitrogen isn't coming from the minerals. As long as nitrogen fixation can still occur (via decomposition of something organic, etc), I think the general principle seems reasonable, though not an expert.

giantg2 5y ago
Or from crop rotations of legumes with nitrogen fixing microbes. But that too would require a move away from intensive industrialized agricultural practices.
- mcguire 5y ago
  "Fifty-six percent of all land used for corn, soybeans, wheat, and cotton was on farms that used no-till/strip-till on at least part of their cropland in 2010-11: 23 percent of land was on farms that used no-till/strip-till on all land in these crops while 33 percent was on farms that used a mix of no-till, strip-till, and other tillage practices." (From the report summary.) https://www.ers.usda.gov/publications/pub-details/?pubid=44030 https://www.ers.usda.gov/publications/pub-details/?pubid=440... Industrialized farming practices are capable of changing.
- hinkley 5y ago
  Toby Hemenway forwarded a notion that water cycles are sufficient to transport nitrogen from nitrogen-rich plants to their neighbors as a continuous basis instead of on an annual one. The model he builds from research he had read goes something like this: After a rain, as the soil goes from waterlogged to dry, there are phases that are hostile to root hairs and ones that are conducive. So the plant roots pulse with these cycles, advancing and retreating, sometimes arriving at places vacated by other plants. By this mechanism, any plant can scavenge some of the nitrogen left in the decaying root hairs of their neighbors. I would also warn that thinking nitrogen=legume is a potentially limiting strategic error. While something like 7% of all plants fall into the Fabaceae (legume) family, some other pockets of the Fabales order also have root nodules, in particular, alder, and up into the Rosids clade (buckthorn, ceanothus), and then a few odd stragglers like borage, which makes me wonder if it's a taxonomic problem, parallel evolution, or what. And then there's mondo grass (asparagaceae), which nobody expects to have root nodules. I knew about that plant for about two decades before someone pointed out it's nitrogen fixing, and that's not even in the wikipedia article. And in fact I'm having a dickens of a time finding a citation for that.
- tagami 5y ago
  Yes. Nitrogen fixing bacteria (i.e. R. leguminasarum, s. meliloti) love the sugar exchange legumes offer. Cover cropping and inter cropping have potential to rethink the 113-year old haber-bosch solution.
  - mcguire 5y ago
    "Cover crops were in use on less than 2 percent of total cropland (for all crops) during 2010-11 (6.8 million acres), with adoption rates higher in some regions (e.g., the Southern Seaboard and the Mississippi Portal). Although the benefits of cover crops and no-till/strip-till are enhanced when these practices are used on the same fields, the low cover crop adoption rate suggests that these benefits are realized on few acres." (From the report summary.) https://www.ers.usda.gov/publications/pub-details/?pubid=44030 https://www.ers.usda.gov/publications/pub-details/?pubid=440...
    - bluGill 5y ago
      Cover crops have come into style though since then. They are a lot more common. Not nearly as common as they should be, but they still a lot more than 10 years ago.
  - hinkley 5y ago
    I don't know if this is my theory or just heavily implied but rarely stated in the literature: chemical fertilizers are giving plants something for 'free' that they used to pay for, and the reason the crops get bigger is not strictly because of the fertilizers, but because they get to spend those calories on more fruit. There have even been a few studies that warn that some strains of conventional crops are losing the ability to make this exchange. When we hit peak phosphorous and start taxing anhydrous ammonia production, these strains are at risk of going extinct (hopefully not enough of any crop to take us with them). The wrong question is, "how many calories of <X> can I get out of this field in a year?" The right question is "how many calories can I get total out of this field in a year" and there are a number of people out there demonstrating that they can get about 50% of the conventional yield from an acre, but for 4 different crops, and a few other things thrown in to get over 2x the total yield. The "problem", in scare quotes, is that these solutions take more thinking and knowing than scourging your fields every year. But since running a farm practically takes a bachelor's degree these days, that's not really a problem of lack of resource in that area. It's more a problem of perspective and focus.
hinkley 5y ago
I'm not the one oversimplifying, it's 'modern' agronomists that are oversimplifying. Nitrogen is 70% of our atmosphere. When you remove all other plant life in order to get the last 20% of theoretical yield from your land, you end up having to manually provide all of the services that were provided by the plants you killed. The Green Revolution is a petrochemical revolution. Cooking allows us to use lignin calories to recover more calories from our existing food supply. Livestock do the same, either by converting grasses (ungulates) or recycling unpalatable foods (pigs). When the petrochemicals become expensive we will have to go forward and/or backward to some other solution (most likely old solutions with new twists). The sibling comment with the huge bibliography points to some of the more coherent voices in the world of polyculture agriculture, although Gabe Brown exists in a sort of grey area between aggressive crop rotation and polyculture.

giantg2 5y ago

Or from crop rotations of legumes with nitrogen fixing microbes. But that too would require a move away from intensive industrialized agricultural practices.

mcguire 5y ago
"Fifty-six percent of all land used for corn, soybeans, wheat, and cotton was on farms that used no-till/strip-till on at least part of their cropland in 2010-11: 23 percent of land was on farms that used no-till/strip-till on all land in these crops while 33 percent was on farms that used a mix of no-till, strip-till, and other tillage practices." (From the report summary.) https://www.ers.usda.gov/publications/pub-details/?pubid=44030 https://www.ers.usda.gov/publications/pub-details/?pubid=440... Industrialized farming practices are capable of changing.
hinkley 5y ago
Toby Hemenway forwarded a notion that water cycles are sufficient to transport nitrogen from nitrogen-rich plants to their neighbors as a continuous basis instead of on an annual one. The model he builds from research he had read goes something like this: After a rain, as the soil goes from waterlogged to dry, there are phases that are hostile to root hairs and ones that are conducive. So the plant roots pulse with these cycles, advancing and retreating, sometimes arriving at places vacated by other plants. By this mechanism, any plant can scavenge some of the nitrogen left in the decaying root hairs of their neighbors. I would also warn that thinking nitrogen=legume is a potentially limiting strategic error. While something like 7% of all plants fall into the Fabaceae (legume) family, some other pockets of the Fabales order also have root nodules, in particular, alder, and up into the Rosids clade (buckthorn, ceanothus), and then a few odd stragglers like borage, which makes me wonder if it's a taxonomic problem, parallel evolution, or what. And then there's mondo grass (asparagaceae), which nobody expects to have root nodules. I knew about that plant for about two decades before someone pointed out it's nitrogen fixing, and that's not even in the wikipedia article. And in fact I'm having a dickens of a time finding a citation for that.
tagami 5y ago
Yes. Nitrogen fixing bacteria (i.e. R. leguminasarum, s. meliloti) love the sugar exchange legumes offer. Cover cropping and inter cropping have potential to rethink the 113-year old haber-bosch solution.
- mcguire 5y ago
  "Cover crops were in use on less than 2 percent of total cropland (for all crops) during 2010-11 (6.8 million acres), with adoption rates higher in some regions (e.g., the Southern Seaboard and the Mississippi Portal). Although the benefits of cover crops and no-till/strip-till are enhanced when these practices are used on the same fields, the low cover crop adoption rate suggests that these benefits are realized on few acres." (From the report summary.) https://www.ers.usda.gov/publications/pub-details/?pubid=44030 https://www.ers.usda.gov/publications/pub-details/?pubid=440...
  - bluGill 5y ago
    Cover crops have come into style though since then. They are a lot more common. Not nearly as common as they should be, but they still a lot more than 10 years ago.
- hinkley 5y ago
  I don't know if this is my theory or just heavily implied but rarely stated in the literature: chemical fertilizers are giving plants something for 'free' that they used to pay for, and the reason the crops get bigger is not strictly because of the fertilizers, but because they get to spend those calories on more fruit. There have even been a few studies that warn that some strains of conventional crops are losing the ability to make this exchange. When we hit peak phosphorous and start taxing anhydrous ammonia production, these strains are at risk of going extinct (hopefully not enough of any crop to take us with them). The wrong question is, "how many calories of <X> can I get out of this field in a year?" The right question is "how many calories can I get total out of this field in a year" and there are a number of people out there demonstrating that they can get about 50% of the conventional yield from an acre, but for 4 different crops, and a few other things thrown in to get over 2x the total yield. The "problem", in scare quotes, is that these solutions take more thinking and knowing than scourging your fields every year. But since running a farm practically takes a bachelor's degree these days, that's not really a problem of lack of resource in that area. It's more a problem of perspective and focus.

hinkley 5y ago

I'm not the one oversimplifying, it's 'modern' agronomists that are oversimplifying. Nitrogen is 70% of our atmosphere. When you remove all other plant life in order to get the last 20% of theoretical yield from your land, you end up having to manually provide all of the services that were provided by the plants you killed. The Green Revolution is a petrochemical revolution. Cooking allows us to use lignin calories to recover more calories from our existing food supply. Livestock do the same, either by converting grasses (ungulates) or recycling unpalatable foods (pigs). When the petrochemicals become expensive we will have to go forward and/or backward to some other solution (most likely old solutions with new twists). The sibling comment with the huge bibliography points to some of the more coherent voices in the world of polyculture agriculture, although Gabe Brown exists in a sort of grey area between aggressive crop rotation and polyculture.