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Lessons in asparagus… and water

When a soil scientist grows vegetables, it soon becomes a lesson in the water table

Western Canadian farmers have two main ways to generate income: growing something that either goes through a grain auger or walks on two or four legs. But there are other things to grow.

In 2002 I planted a small asparagus plot: 1,000 crowns of Jersey Knight male sterile hybrid imported from New Jersey. It is now 14 years old and in its prime. Some say a plantation will last 30 years; it sends down roots to 12 feet and is very salt tolerant. My choice of site was simple — it was a piece of ground that was available. The original idea was a commercial venture but it has become a community resource and I enjoy having friends come to pick and visit.

The asparagus harvest starts in early May and many pickings are taken until sometime in June. It can be picked clean one day and three days later be ready to pick again. The photo at the top of this page shows the harvest stage, but in one row a killdeer set up a nest so we left it alone until the chicks were gone.

After harvest we give it a shot of fertilizer and leave it to put down root reserves for next years crop.

The 11 rows are clearly visible in the photo below, in a recent Google Earth image. The joys of Google Earth — what a grand time we live in!

Asparagus rows visible from space? Google Earth image.

Asparagus rows visible from space? Google Earth image.
photo: Google Earth

Now for the groundwater story

Other than getting the plants started I have done little watering — the asparagus seems to grow well all by itself. I suspected perhaps the deep roots might be accessing a water table, but did not know.

When 2015 came along we had no rain in May and very little in June so I thought it might be time to load the water tank and spill a little on the asparagus. But, several pokes with my trusty Backsaver soil probe showed that the soil moisture was fine. It was time to install a 10-foot observation well and find the water table at less than six feet (1.79 m to be exact) and well within the reach of the asparagus roots.

On July 14, 2016 the asparagus was eight feet tall. The long handle red spade shows the scale.

On July 14, 2016 the asparagus was eight feet tall. The long handle red spade shows the scale.
photo: Les Henry

With no rain in early- and mid-July the water table dropped to over eight feet (2.52 m). July 28 gave our first real rain, 3.6 inches, and with rain more in August the water table rose to six feet. Asparagus grows until freezeup so there were minor fluctuations and it froze up at about 6.5 feet (2 m).

Spring was early in 2016 so after snow melt and 1.9 inches of rain in early- to mid-May the water table was at a very concerning 2.7 feet (0.81 m) on May 23. Asparagus uses very little water when at harvest stage and the interrows (six-foot row spacing) had been clean cultivated. That was changed by planting the interrows to barley just to use up some water. A close look at the photo above shows the barley between the rows. It seems to be helping. As of July 25 water table was at 4.8 feet (1.45 m) despite 10 inches of rain from May 1 to July 25.

So, it turns out my accidental choice of site was a good one and a crop like asparagus does not have to be in an irrigated situation.

I also have two water table wells in the nearby barley crop. They were installed in 2015 and were buried for fall anhydrous and spring seeding. With GPS, a large disk over the pipe and a metal detector I was able to easily find them and re-install the length of pipe that had been removed in fall.

Keep tuned for a more complete water table story after this year’s crop is off and two-year record is available.

About the author

Columnist

J.L.(Les) Henry is a former professor and extension specialist at the University of Saskatchewan. He farms at Dundurn, Sask. He recently finished a second printing of “Henry’s Handbook of Soil and Water,” a book that mixes the basics and practical aspects of soil, fertilizer and farming. Les will cover the shipping and GST for “Grainews” readers. Simply send a cheque for $50 to Henry Perspectives, 143 Tucker Cres., Saskatoon, Sask., S7H 3H7, and he will dispatch a signed book.

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