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Soil health vital to this potato operation

Soil health is part of virtually every farming decision, from land and equipment to fertilizer and crop protection.


November 15, 2007
By Helen McMenamin

Topics

6aHarvesting a good crop of high quality potatoes is only a part of the challenge
Harold Perry sees in growing potatoes near Coaldale, just east of Lethbridge,
Alberta. He and his father Gerald and brother Chris view maintaining and improving
the soil as vital to every part of their operation.

"Soil health is key to healthy plants," he says. "And, healthy
plants mean more nutrients in the food we produce as well as crops that have
some ability to fight off diseases without the need for costly crop protection.

"I want my children and their children to have the option of farming this
land with soil and natural resources in as good or better shape than they're
in now. Future generations deserve that from us."

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Wind erosion has always been a major issue for all farmers in southern Alberta,
especially in winter and spring. Strong chinook winds that can blow for days
evaporate snow cover and carry off soil. The lack of crop residue puts potato
fields at particular risk in the fall and spring before the crop and after harvest.

To prevent loss of topsoil, Perry seeds a cover crop of barley as soon as the
potatoes are off. When harvest is relatively early, the soil is still warm and
the barley sprouts and grows quickly with a little irrigation. If harvest is
too late for a barley cover crop to hold the land, Perry ridges it.

Like a growing group of producers in southern Alberta, Perry grows only potatoes
and rents land or trades it so the land is in other crops for non-potato years
of his four year rotation. Whether the arrangement is a land swap or a rental,
it includes working together to ensure both parties know how the land has been
treated while it is outside their control.

"We talk every year to make sure everything is fair, both in financial
terms and in agronomics," he says. "A land swap or rental has to work
for both parties. It helps us all to know what the others are doing. We work
together and they commit to growing a cereal the year before we take it over.
We like to know things like whether they use Cruiser on the cereals – that
helps us with our wireworm control.

"Two of our partners have livestock operations, so they put manure on
the land, but they do it the first or second year they have the land. Then,
when we have the land in the fourth year of the rotation, there's a good balance
of nutrients in the soil. It also makes the soil easier for us to manage for
the processing potatoes we grow."

Perry does all his pre-plant work in the fall, starting with shredding and
heavy harrowing the straw. He broadcasts a fertilizer blend of 50-50-0-42 along
with coral calcium and four tonnes an acre of compost as soil conditioners.
"I know we have a lot of calcium in our soil," he says. "But,
some of our land has only 25 percent sand. The calcium improves soil tilth so
we have a little more flexibility in timing operations on those heavier soils.
It helps low areas drain better and limits erosion."

Fall para-tilling helps water penetrate the soil without ponding or leaching
N. Last year, para-tilled land absorbed all of a six inch (150mm) rain. Unfortunately,
a second storm brought another three inches (75cm) a few days later and overwhelmed
soil moisture-holding capacity.

Perry is a fan of the Phoenix rotary harrow. He uses it to spread crop residue
and behind the para-tiller. "It levels nicely," he says. "It
mellows the soil well and sticks the straw into the soil to help anchor it over
the winter. It helps seal moisture into the soil after the deep tillage pass,
too."

After a light cultivator pass, the land is fall-bedded and dammer-diked with
GPS guidance to prepare for the auto-steered planting operation. The ridges
run north-south, across the prevailing winds.

The volume of straw in the ridged soil holds it through the winter as well
as helping with clod management. Any small clods in the ridges break up with
freeze-thaw cycles. The dammer-diker scoops out dikes between the rows to hold
over-winter moisture and provide more erosion protection.

In spring, Perry plants directly into the hills, with fertilizer placed two
inches (5cm) to the side and above the seed pieces. The minimal tillage operations
and incorporating crop residues maintain or increase soil organic matter to
help cut down clods.

Most of the fertilizer nitrogen the crop needs goes on through the pivot. "That
way, we can apply exactly what we think the crop needs," says Perry. "Our
total use of commercial fertilizer is usually about 200 pounds of N, 80 pounds
P and 100 pounds of S. The sulphur works as a buffer for the nitrogen and it's
good for the soil."

On his own land, Perry has just installed new half-mile-long low-pressure pivots.
"We lose a little land compared to a quarter section pivot with corner-arms,"
he says. "But, these have a much better water pattern. Every acre they
water is a good acre. And, with a half-section under one pivot, we can improve
our turning efficiency.

"The low pressure application means less surface sealing from compaction
by water droplets. We get fewer, but bigger droplets, so there's less evaporation
than from a finer spray. The application is much more efficient. On a windy
summer day, a lot of water from a high-pressure sprinkler is lost to evaporation."

The sprinkler heads on the new pivots are about 60 inches (1.6m) above the
ground to minimize evaporation, but still clear a cereal crop – they are
also a convenient height for changing or cleaning. The drops are attached on
alternate sides of the pivot and fastened to the support beams to widen the
water application pattern.

"Costs are lower with longer pivots," says Perry. "We replaced
four 75hp motors with one 130hp and saved on pumps and filters, too. And, we
have fewer pivots to manage and maintain."

After potato harvest, Perry seeds a cover crop of barley and irrigates it to
protect the soil until the following crop is seeded.

All the soil that is cleaned off the harvested potatoes is trucked back to
the fields. At one time, Perry used to dump the soil in low spots, but now his
thinking has changed. "You'll never fill up a low spot with a few truckloads
of soil," he says. "And, those areas already have a lot of nutrients
and organic matter. Now, we're putting soil on the sandy hilltops that don't
produce as well as the rest of the field. We can improve those."

Perry is testing some natural products. One is a foliar nutrient spray that
includes kelp and fish emulsion. He is not sure yet whether it improves his
crop, but on some fields where he used it last year, he was able to lower his
use of fungicides despite the cool, wet summer.

"We hope these products build healthier soils to allow us to cut down
our fertilizer use and have healthier plants that need less crop protection,
and maybe more nutritious potatoes. I hope we can learn to coexist with the
microbial community in the soil, working with it in a symbiotic relationship
to improve nutrient availability and uptake."

Perry is constantly looking for new, better ways to manage his land and crops
as well as those that might benefit his fellow growers. He chairs the research
committee of the Potato Growers of Alberta. An electricity- generating compost
operation, fuelled with cull potatoes is 'next on the radar'. -30-