Orchard Compaction: A Pressing Problem

A compacted “plow pan” layer often forms about 8 to 10 inches below the surface in both mowed and tilled orchards. This is a widespread problem in orchards regardless of soil type. Growers are often unaware of its presence and impact. In some cases, no-till orchards haven’t been ripped for decades.

Just ask Mark Schmidt, who grows almonds and walnuts in Waterford, CA, located in the northern San Joaquin Valley. He has one block of 20-plus-year-old walnuts that has sandy top soil, but just about 8 inches down a hard pan, or plow pan, has formed. “Just doing normal work on the ground over the years compacted it down,” he says.

Last spring, Schmidt deep-ripped the orchard, and the results were dramatic. “In one year, the growth was just unbelievable, from 1 foot a year, to 3 to 4 feet this past year,” he says. “It was all because of the compaction; the hard pan was cutting off the roots. The roots were just getting by.”

Schmidt, who’s also known in the ag community as a beekeeper, certainly learned a lesson he won’t forget. “This year I ripped that ground both ways; last year I ripped it just one way,” he says. “I did a real massive break-up job this time.”

 

Let Roots “Breathe”

A greater understanding of soils and the effect of compaction on tree growth and yield will help in developing approaches to minimize the problem and increase productivity. Soils are complex mixtures of mineral particles that vary in both size (sand, silt, clay) and arrangement. Soil texture refers to the proportion of sand, silt, and clay in a soil. Soil structure means how the particles are arranged; it largely determines the amount of pore space, the spaces between the particles, in the soil.

Pores are an important part of healthy soils for several reasons. They affect water intake and movement through the profile, the amount of water soil can hold for use by the tree, and drainage below the root zone. Soil water content increases above compacted layers and may create conditions that encourage root and crown diseases. Compacted soils are more subject to runoff and erosion.

We have seen a number of orchards where the ground was wet in the top few inches but water never reached the roots.

Compaction also affects air exchange between the soil and the atmosphere. Did you know that roots need to “breathe?” Roots and the beneficial microorganisms that live in the soil need to take in oxygen and release carbon dioxide.

Microorganisms fix nitrogen from the air and help break down organic matter which releases nutrients to the tree. These are important points to keep in mind because cultural practices have a direct impact on soil quality and sustaining tree health.

 

Lighten Up

As Schmidt learned, soil becomes compacted primarily because of the pressure applied by the weight of orchard equipment. It compresses the soil particles together, causing the soil to be denser with less pore space. It is more difficult for roots to push through dense soil and so root growth can be reduced. The best strategy to minimize compaction is to prevent it from occurring in the first place. The risk for compaction is greatest when soils are wet. Driving on wet soils is the single biggest cause of compaction.

A dry soil is much more resistant to compaction than a moist or wet soil. Sandy soils are particularly susceptible to compaction as the weight of equipment can cause the sand grains to interlock. Soils with high organic matter are also less susceptible to compaction. Test for compaction by probing the soil with a pointed metal rod, bucket auger, soil tube, or shovel. It is more easily done on a somewhat moist soil.

Apply even pressure and push the probe into the soil. Compaction is the resistance found about 8 to 10 inches below the soil. Alleviate compacted layers by ripping or chiseling when the soil is dry. A shank depth capability below the compacted area is necessary. Curved shanks require less draft than straight shanks to loosen the same amount of soil. Space the shanks no further apart than the depth of ripping and cover the width of the middle to within a few feet of the trunks to avoid injury to larger roots. A single shank down the middle is of limited value. Do not worry about injuring smaller roots; root pruning actually stimulates root growth in much the same way that heading cuts in the canopy promote new shoot development.

For nine ways to minimize compaction, go to the next page.

Topics:

Leave a Reply

Nuts Stories
(Photo credit: USDA NCRS)
Nuts
November 23, 2016
Nation’s Largest Nut Grower Wins Prestigious Corporate Citizenship Award
The Wonderful Company is honored with the 2016 Corporate Citizenship Award, in the category of Best Community Improvement Program. Read More
Spring Valley Farms in Umatilla, FL, from a drone
Citrus
November 22, 2016
Arysta Partners With Beem Biologics To License New Technology
Agreement to expand Arysta’s portfolio with new biocontrol releases. Read More
Scanning electron micrograph of fresh pollen removed from wax storage cells of honey bee colonies. In choice tests, bees strongly preferred freshly collected pollen over aged pollen. Photo credit: USDA-ARS
Citrus
November 21, 2016
Bacterial Imbalances Can Be Troublesome For Honeybees
A recent study reports that bees given fresh pollen or fresh supplements fared better than bees given pollen or supplements that had first been aged for 21 days. Read More
Port Tampa Bay shipping channel
Citrus
November 19, 2016
USDA Gives $200 Million To Expand Ag Exports
USDA Secretary Tom Vilsack has announced the USDA’s Foreign Agricultural Service (FAS) is awarding $200 million to more than 70 Read More
Almonds growing in a tree. (Photo credit: University of California Division of Agriculture and Natural Resources)
GenNext Growers
November 17, 2016
Deadline Nearing For 2017 Almond Leadership Program Applications
Program dedicated to preparing next generation of industry leaders. Read More
U.S. map of significant climate events that occurred in October 2016
(Image credit: NOAA NCEI)
Citrus
November 9, 2016
U.S. Sweats Out Third-Warmest October On Record
So far, 2016 is the second-warmest year-to-date in 122 years. Read More
2016 Donald Trump in Iowa (Photo Credit: Trump for President Campaign)
Citrus
November 9, 2016
It’s Time To Turn The Page On Election 2016 [Opinion]
Mr. Trump has the White House and Republicans have the Congress. They are in a position to lead, and they must. Read More
The Latest
Fruits
December 2, 2016
The Burchell Nursery 2017 Variety Showca…
The Burchell Nursery, Inc., in Oakdale, CA, offers a new self-fertile almond, an early-season nectarine, and a late-season peach. Read More
Fruits
November 29, 2016
Orchard Spray Oil Now OMRI Listed
Orchex 796 Orchard Spray Oil can be used on number of tree and nut crops. Read More
Citrus
November 29, 2016
Review Shows Low Risk To Aquatic Inverte…
Peer-reviewed evaluation of more than 100 studies finds uses of imidacloprid are unlikely to harm aquatic invertebrate communities, or the birds and fish that rely on them. Read More
Nuts
November 23, 2016
Nation’s Largest Nut Grower Wins Prestig…
The Wonderful Company is honored with the 2016 Corporate Citizenship Award, in the category of Best Community Improvement Program. Read More
Citrus
November 22, 2016
Arysta Partners With Beem Biologics To L…
Agreement to expand Arysta’s portfolio with new biocontrol releases. Read More
Citrus
November 21, 2016
Bacterial Imbalances Can Be Troublesome …
A recent study reports that bees given fresh pollen or fresh supplements fared better than bees given pollen or supplements that had first been aged for 21 days. Read More
Citrus
November 19, 2016
USDA Gives $200 Million To Expand Ag Exp…
USDA Secretary Tom Vilsack has announced the USDA’s Foreign Agricultural Service (FAS) is awarding $200 million to more than 70 Read More
GenNext Growers
November 17, 2016
Deadline Nearing For 2017 Almond Leaders…
Program dedicated to preparing next generation of industry leaders. Read More
Citrus
November 9, 2016
U.S. Sweats Out Third-Warmest October On…
So far, 2016 is the second-warmest year-to-date in 122 years. Read More
Citrus
November 9, 2016
It’s Time To Turn The Page On Elec…
Mr. Trump has the White House and Republicans have the Congress. They are in a position to lead, and they must. Read More
Citrus
November 8, 2016
National Farmers Union Seeks Amendment T…
Comments sent to IRS say change in provisions makes it difficult for farmers to accurately valuate assets. Read More
Citrus
November 2, 2016
FDA Releases Preventative Controls Guida…
Compliance information available for small and very small businesses. Read More
Nuts
November 1, 2016
High Density: The Future Of Almonds?
The early returns on this trial block — planted with dwarfing rootstock — are impressive, but time will tell. Read More
Nuts
October 30, 2016
Pistachio Crop Smashes Record
This isn’t just an “on” year for the biennial bearing crop, it’s a limb-buster. Read More
Nuts
October 27, 2016
You May Be Blowing Off Almond Spray
Air blast sprayers can lay leaves flat, allowing for little chemical contact. Read More
Nuts
October 25, 2016
Pecan Growers Still Assessing Damage Fro…
Growers are hoping for federal assistance as cleanup from the storm continues. Read More
Citrus
October 24, 2016
$62.5M In Specialty Crop Grants Awarded
More than 690 specialty crop production projects funded to strengthen the future American agriculture. Read More
Citrus
October 23, 2016
Take Precaution, Free Trade Could Be Cos…
With more imports, we have to redouble our efforts to protect ourselves from foreign pest invaders. Read More