Can Your Garden Benefit From Increasing Atmospheric CO2?

garden.jpgYES! Here’s How (And Why):

Although “Global Warming” is to some people a controversial subject, the one thing that’s not controversial is that the level of atmospheric CO2 has significantly increased in the past 100 years and will likely continue to increase – at least until humans stop burning fossil fuels.

OK, so atmospheric CO2 is at historically very high levels and is going even higher in the decades to come. How will this likely affect plants?

Since green plants use CO2 as the carbon source in photosynthesis, they will probably do more photosynthesis, i.e., produce more biomass.

But as is often the case with things biological, it’s not quite as simple as that.

Fertilize More, Water Less

For your garden plants to take full advantage of this high CO2 world, you will probably need to add more nitrogen fertilizer, but you may have to water less often. Here’s why.

For optimal plant growth, plants need sufficient amounts of carbon and nitrogen and water.

In a high CO2 world, plants will have a sufficient carbon source. But if the availability of nitrogen is limited, then plant growth will be limited. Therefore, to fully take advantage of a high CO2 world, your garden plants will need to have sufficient amounts of nitrogen (N). In most cases, nitrogen is available to plants in the form of nitrate (NO3) in the soil. So to ensure your plants thrive in a high CO2 world, add plenty of compost or nitrogen-containing fertilizer.

Plants in a high CO2 world will also use water more efficiently. This is because the stomates in the leaves need to open less to obtain sufficient amounts of CO2. This is good, because then the plant transpires less water. The result, in general, is that plants will use less water for a given amount of biomass production in a high CO2 world.

corn.jpgDon’t Plant Corn

Not all plants will benefit from a high CO2 world.

So-called C-4 plants already use CO2 very efficiently. Consequently, their photosynthesis will not be significantly improved with increased amounts of atmospheric CO2.

Corn or maize is a classic C-4 plant.

Other C-4 plants include sugarcane, sorghum, and so-called ”warm season” grasses.

Other cereals such as wheat, barley and oats are not C-4 plants — they are so-called C-3 plants — and should benefit from a high CO2 world.

Bottom line: People on this planet show no signs of throttling back their use of fossil fuels. On the contrary, the production of CO2 from the burning of fossil fuels, especially coal, will likely increase in the coming years.

So, it makes sense to prepare for a high CO2 (and probably warmer) world by learning more about how plants will likely respond to such changes in their environment.

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