Global warming and its effects on agriculture

In wikipedia I came across this rather substantial piece on the impact of global warming on agriculture. Their perspective appears to be ambiguous with perhaps a lean toward the negative. The lower latitudes would be hurt the most and the upper latitudes would perhaps benefit on balance. When estimating what happens beyond a 3 deg. C temperature rise they become definitively negative.

https://en.wikipedia.org/wiki/Climate_change_and_agriculture

Being from California I see it as a big negative. One because of the loss of snow and ice in the Sierra Nevada mountains resulting in the loss of a year round water source and two due to the increase in wildfires. Increases in weeds, diseases and insect pests are another concern.

 

<sigh> Look up the average per-area agricultural productivity of tropical and temperate countries. And then compare that with productivity in greenhouses, where temperatures and CO2 are even higher.

 

Yep, compare to greenhouses where plants truly thrive.

 

And where plants are really expensive. Also...one mistake and the greenhouse plants are dead. Why...because a greenhouse is a controlled environment.

 

Things in greenhouses receive artificial watering.

Areas of the world that are depending on water from rivers from glacier melt could be in big trouble if the glaciers disappear altogether. IMO China's interest in Tibet is partially for that reason...I believe several of their major rivers originate there.

And there is conflict in other areas already regarding which country is taking more than its "fair share" of water from rivers going through more than one country. Our own Rio Grande was little more than a little rivulet along the Mexican border when I saw it, and that was years ago.

 

This excerpt should give one a sense of the uncertainty and incompleteness of the studies.

 

Greenhouses need a lot more water per plant. You not only have to consider watering the plants themselves but the evaporation cooling systems greenhouses require. On sunny days the temperature rises quickly and the humidity drops to near zero. So then you must raise the humidity to lower temperature. A swamp cooler uses a water mat and a fan to evaporate water and cool the air. Greenhouses use a lot of water.

 

And warmer climate accelerates they hydrological cycle, increasing rainfall.

A glacier is just a natural reservoir. We can build reservoirs, and get more control than glaciers give us.

That's the Three Gorges project.

Yes, so we should welcome the accelerated hydrological cycle and increased rainfall that global warming implies.

 

It is not how much rainfall a plant receives it is how much water percalates into the soil. Or....how much water the plant can use. Temperature affects the hydrology of the soil. At a soil temperature of 100 degrees f. only 15% of water is used for plant growth. The rest is lost through evaporation. At 140 degrees soil biology for plant growth ceases.

 

That depends on the soil. Soils can be improved to reduce evaporation, and drip irrigation can direct water directly to plants.

Yes, well, that kind of temperature is almost impossible to reach when soil is well watered or protected from the sun by decaying plant matter. You don't seem to understand that given water, people can figure out how to use warmth and CO2 to grow food.

 

I have been studying plants and soil my whole life. I will admit I am insanely obsessed with the subject. It is true that no till and proper land management will increase productivity and profitability. And organic mulches and drip irrigation work within reason. But when considering conventional agriculture these systems fall short. Irrigation on a large scale empties wells and depletes aquifers. A better way is to increase the water holding capacity of the soil. This is done by keeping a living root in the soil as long as possible , using as little mechanical disturbance as possible, using biodiverse cover crops , and eliminating the use of chemical fertilizers. A conventional tilled soil can reach a 140 to150 degrees on a hot day with ease. You should U Tube Gabe brown and watch his video on farming in nature's image.

 

Unless the water is taken from rivers that would otherwise just run into the sea.

Again, it depends on the soil. Many soils are deficient in certain micronutrients -- boron, iodine, etc. -- and chemical fertilization is by far the best way to make up their lack. Other soils have been compacted, and mechanical tillage is the best way to aerate them. There is no one-size-fits-all solution.

Conventional agriculture can be described as a quick and dirty solution: crude but effective. There are better ways now.

 

You have to have access to rivers in order to pump water from them and most chemical fertilizers on sale consists of NPK only. The trace elements are missing. Tilling soil goes against nature and if soil is compacted how is running heavy equipment over it going to help? Most compaction is under the surface of the soil where the plow doesn't reach. Getting plant roots deep in the soil will help reduce compaction. I will agree that there is no one size fits all solution but consider this.....if a farmer would set aside a small plot....enough he can sleep at night and try regenerative farming practices for five years. I would let the results speak for themselves.

 

Improvement in soil is the key. Farmers have learned to accept a degraded resource. A tilled soil is hungry, thirsty, and running a fever. Tilled soil is also erosion waiting to happen. How can running heavy equipment over fields decrease compaction? Most fertilizers on sale consists of NPK and no trace elements. Cover crops reduce erosion and reduces compaction. They also put organic matter in the soil. When you have decaying roots from cover crops and earthworms in the soil where are your roots going to go? They are going to follow those pathways down into the earth. The water will do the same and the soil will store the water. Plants on the surface will shade the soil and reduce evaporation. This is how nature works. If a farmer would try this on a small experimental plot of land for five years I am willing to let the results speak for themselves.

 

And hydrological projects can give farmers access to rivers.

Because that's what is most depleted in most places. How is that relevant to the use of trace element fertilizers where trace elements are depleted?

How on earth do you imagine an observation about most chemical fertilizers could be relevant to facts about how SPECIALIZED chemical fertilizers are useful in treating trace element deficiencies? You could with equal "logic" observe, in response to facts about raising mammalian livestock, that most mammals are rodents.

So does agriculture. Hello?

By digging it up. Are you perhaps unaware that the heavy equipment pulls the plow, so the soil compacted by the heavy equipment is immediately dug up?

There you go again: "most." Irrelevant to the specific cases.

But not in a matter of minutes, as plowing does.

Regenerative farming based on SCIENCE is fine. But not based on superstitious gaia worship or Luddite opposition to chemicals and machinery.

 

Research Dr Laura Ingham. Gabe Brown. Most farmers that produce real profit must be just as stupid as I am. When a farm gets 50 inches of rain and has to irrigate another 50 inches the resource is degraded and the land is no longer soil it is dirt. Thomas Jefferson wrote George Washington about this very problem. Mankind depends on six inches of topsoil and the fact it rains. You can get as snippy as you want but that is a fact. Most land is depleted because of tillage and erosion.

 

All of what I have said is based on real science. No till agriculture leaves the residue on the ground reducing erosion and returning organic matter in the soil. Cover crops are used before, after, or during the growing of the cash crop. Farming should be done with as little mechanical disturbance as possible. This is how nature works. Armor on the soil. To protect it from erosion and to manufacturer organic matter through decaying roots to add humus to the soil. Debris on the field also conserves water. The more organic matter in the soil the less need for chemical inputs. It is about signing the back of the check and not the front.

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Would you like to discuss mob grazing?

 

Everything about the AGW hypothesis is uncertain and incomplete, why should this be any different

 

I agree with everything you say on this subject but it can only work on the small plots you suggest farmers experiment with. Mas food production at affordable prices can only be done like we currently do it, sad but true

 

I used to think the same way. But modern agriculture can adopt new farming systems. No till has caught on. Cover crops are also catching on. Planting legumes for nitrogen fixing is also finding a place. My pastures are dry. We are in a drought. It is now considered severe. So now I am trying to figure out how to get my pasture grass to root as deep as nature will allow. All my grazing animals are on a small pasture eating hay. I have seen it get so bad people have fed shredded paper just to keep their cattle alive. The local pasture that has had chicken manure spred on it is in much better shape. Our state produces 1 million tons a year. It is a very rich fertilizer. And a good use of an otherwise source of pollution. You should check out the You Tube videos by Gabe Brown. Especially the one called farming in natures Image. He uses no commercial fertilizer, no pesticides, and herbicides once every two years. He farms 5,000 acres. Also check out the soil food web.

 

Where I disagree is in the use of heavy equipment and mass production. We can't efficiently log with horses and cross cut saws and axes anymore and we can't efficiently farm without huge combines anymore either

 

The equipment is the same except the plow is replaced with a seed drill. A tall cover crop is planted in the fall and grows during the cool season. When the cover crop (usually ryegrass) reaches the seed pollination stage a roller crimper knocks the rye down and crimps it. This kills the cover( without herbicides). Then the seed is planted using the seed drill. This provides mulch for the cash crop. The mulch reduces weeds, adds organic matter , and slows the evaporation of water. The cover crop can be knocked down with the roller placed on the front of the tractor and planted with a seed drill placed on the back of the tractor. So the field can be mulched and planted in one pass. The crimper roller runs about 2,000 us dollars. The harvesting is done with the usual methods. It is not going back to horse driven farming and besides....a tractor doesn't eat when it isn't working.

 

The fourth is outdated by the fifth assessment. How do they define confidence ?? The answer will/should surprise you. And in the fifth assessment the lower range of climate sensitivity to CO2 is 1.5 deg C which matches historical data. The ranges listed in the quote are from models which cannot match (over predict) historical data.

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And yet yield per acre keeps going up and the number of acres used for farming keeps going down.

 

And the cost per acre keeps going up. If your yield cost 4.00 a bushel for corn and my cost per bushel is 2.00 who is going to see the most profit? I will have a better bottom line even if my yeild per acre is less. Profit is what farming is about.

 

Source ?? Corrected for inflation ?? Everything is a balance - yields are increasing on existing lands implying that whatever costs are being incurred justify whatever added expense is being applied to increase the yield. If not yields would remain stagnant.