Thursday, July 26, 2012
Drought…from a plant’s perspective
1st of all... HOORAY FOR THE RAIN!!! We got an inch last night & it was so wonderful to harvest in the wet fields today. I swear I could almost feel the plants waking up & drinking deep. Hopefully this will help rejuvenate the greens, size up the carrots, and germinate the last of the fall crops.
Obviously plants need water to grow, but I wanted to take a few paragraphs to explain how the drought has been affecting agricultural crops both directly and indirectly this year.
Many plants don’t grow above certain temperatures, preferring instead to save their energy and water underground where it doesn’t so easily get lost through transpiration.
Under stress, crops tend to shorten their own lifespan – going to seed more quickly than they would in more favourable growing conditions in order to increase their chances of reproductive survival. Especially with greens, this means the plants remain smaller, go bitter earlier, and have a shorter harvest window.
Yields are also lessened by smaller fruit and root sizes. Water is required for cell growth, so without water, crops produce less. In our fields, we’ve noticed this particularly in the carrots and cucumbers (the latter started so strong, but quickly tapered off their production – not surprising I suppose, given how much water is in a cucumber fruit!) One positive is that, although smaller, some vegetables actually become sweeter in hot, dry weather – the flavour isn’t watered down, and the starches are more effectively transformed into sugars. Carrots and tomatoes are good examples of this.
Finally, hot dry seasons create the perfect condition for many pests. This has been an intense year for beetles, caterpillars, aphids and even earwigs! Pest pressure not only decreases yields, but also affects the aesthetic quality of the crops.
Livestock farms have been severely affected by loss of pasture (imagine trying to feed a cow off your un-watered lawn!), and are concerned about how little hay has been produced – a staple food for overwintering many animals. Corn and grain yields are down – also standard livestock feed.
We’re doing our best to keep the vegetables producing and are lucky to have a deep well to draw from. One additional thing to note is that organic farms often fare better in drought situations due to the higher organic content and microbial activity in the soils (Here's one 30-yr study that demonstrates this). I'm curious if this has been the case in Southern Ontario this season.