root development in soils
DESCRIPTION
Root Development in Soils. Root Growth Hypothesis—Minimum Effort. Root Growth Hypothesis—Profile Rebuilding. Measure depth and root length density in situ Frequent measurement can reveal root birth and death patterns (root turnover) Soil genesis. Undisturbed. Four Treatments. - PowerPoint PPT PresentationTRANSCRIPT
Root Development in Soils
Root Growth Hypothesis—Minimum Effort
Root Growth Hypothesis—Profile Rebuilding
• Measure depth and root length density in situ• Frequent measurement can reveal root birth and
death patterns (root turnover)• Soil genesis
Four TreatmentsUndisturbed
Minimum Effort (a.k.a. Builder’s
Special)
Enhanced Topsoil
Profile Rebuilding
4 in (10 cm) topsoil
4 in (10 cm) topsoil, interface scuffed by tilling
Includes compost, subsoiling, and topsoil
Characterizing undisturbed soil
• Shottower Silt Loam
Applying Compost: Profile Rebuilding
Preparing the plots: Pre TreatmentVegetation and topsoil scraped and stockpiled
8 passes with a compactor at
optimal moisture for compaction.
Bulk density = 2.0 g/cm3
Tilling: “Enhanced Topsoil” and “Profile Rebuilding”For the ET and PR treatments, the topsoil was rototilled to a depth of 8 inches (20 cm).
ET: to disrupt interface
PR: to prepare planting surface (eliminate clods)
• Similar to technique suggested by Kaj Rolf, Swedish researcher
• Can be used in confined spaces (median strips, parking lot islands)
• Addresses subsoil compaction
Subsoiling Technique Step 1: Apply 4 inches leaf litter compost
Step 2: Use backhoe to go down 2 feet, scoop, and allow to fall down to break up clods. Large clods may require a prod with the backhoe. Creates veins of compost deep in profile.
Step 3: Apply 4 inches reserved topsoil
Step 4: Rototill to 8 inch depth
Soil Preparation Affects Growth in First Year
Burr Oak Elm First Lady Flowering
Cherry
Red Maple Swamp White Oak
0
100
200
300
400
500
600
700
Enhanced Topsoil
Minimum Effort
Profile Rebuilding
Undisturbed -Check
Aver
age
cros
s-se
ction
al tr
unk
area
incr
ease
dur
ing
year
on
e m
m2
Bur Oak and Elm Canopy after 3 yrs
Soil TreatmentPR UN ME ET
Can
opy
m2
0
5
10
15
20
25
Profile Rebuilding
• Short termAids in establishment
• We will be able to quantify how much canopy you get for your investment
• To be determined in the long term– Soil biogenesis– Carbon storage– Root production and depth– Soil water capture
Questions to Pose
• Can we improve soil function for stormwater throughout a city?
• Can trees roots improve drainage from bioretention areas and make underdrainage unnecessary?
Partial support provided by the Tree Research & Education Fund