2019 SWCS International Annual Conference July 28-31, 2019 Pittsburgh, Pennsylvania

1. Soil Health Indicators in Semi-Arid
Regions of Texas
Paul DeLaune
Partson Mubvumba
Texas A&M AgriLife Research – Vernon
Katie Lewis
Joseph Burke
Texas A&M AgriLife Research- Lubbock
R. Louis Baumhardt
USDA-ARS– Bushland, TX
74th SWCS Annual Conference
29 July 2019
Pittsburgh, PA

2. Manage more by disturbing soil less
Keep the soil covered as much as possible
Keep a living root growing throughout the year
Diversify soil biota with plant diversity
NRCS Soil Health Management -
Common soil health management practices on the THP -
Reduced or no-tillage Cover crops Crop rotations

3. Project Objective
Overall Objective – assess
the usefulness and
repeatability of proposed
soil health metrics across
regions
Soil health indicators
–Physical:
Single-ring
infiltration
Cornell
infiltration
Dry aggregate
stability
Wet aggregate
stability
Chemical:
Soil organic C (SOC)
Active C (POxC)
Electrical conductivity
pH
Inorganic N
Biological:
Soil respiration (C-min)
β-glucosidase
β-glucosaminidase
Phospholipid fatty acid
(PLFA)

4. Study Locations
Bushland
Lamesa
Bushland
- Pullman Clay Loam
- Wheat-Sorghum-Fallow since
1949
- N0-till and Stubble Mulch
Tillage 1983
- Dryland
Lamesa
- Amarillo Sandy Loam
- Continuous cotton
- Conventional Tillage and No-
till
- NT Rye cover crop since 1998
- NT Mix cover crop since 2014
- Pivot Irrigation

5.  Soil organic carbon (organic matter) has been gold standard
to measure progress of conservation practices.
 Little to no changes in soil organic C
 SOC change limited to upper 15 cm (sandy soils).
 Observed improvements in infiltration and soil strength
Historical Data

6. Lamesa
Resistance (kPa/cm)
0 1000 2000 3000 4000 5000
Depth(cm)
0
5
10
15
20
25
30
Conventional Till
No-Till

7. 0
0.1
0.2
0.3
0.4
0.5
0.6
Time 1 Time 2
Conv
No-Till
Lamesa Infiltration
Infiltration(in/min)

8. USDA-ARS, Bushland

9. 0
0.5
1
1.5
2
2.5
3
Native Exotic NTWheat NTSorghum NTFallow CTWheat CTSoghum CTFallow
Percent
A A
B B BBBB
Soil Organic C - Bushland

10. B
A
A
A
C
AB
A
BC
0
2
4
6
8
CT R-NT M-NT NAT CT R-NT M-NT NAT
0-5 cm 5-10 cm
SoilorganicC(gkg-1)
Management practice
Soil Organic C - Lamesa

11. y = 0.0128x + 0.8997
R² = 0.79955
p < 0.0001
N=60
0
3
6
9
12
0 100 200 300 400 500 600
SoilorganicC(gkg-1)
Permanganate oxidizable C (mg kg-1)
POxC vs SOC

12. Total PLFA -Bushland
0
50000
100000
150000
200000
250000
Native Exotic NT Wheat NT Sorghum NT Fallow CT Wheat CT Soghum CT Fallow
TotalPLFA(pmol/gsoil)

13. Total PLFA-Lamesa
C
B B
A
B
A A
A
0
10000
20000
30000
40000
50000
60000
CT R-NT M-NT NAT CT R-NT M-NT NAT
0-5 cm 5-10 cm
TotalPLFAs(pmolgsoil-1)
Management practice

14. C
A
B AB
B
A
A
AB
0
50
100
150
200
250
CT R-NT M-NT NAT CT R-NT M-NT NAT
0-5 cm 5-10 cm
β-glucosidase(mgPNPkg-1soilhr-1)
Management Practice
β-glucosidase

15. Aggregate Stability-Bushland
StabilityCoefficient
0
2
4
6
8
10
12
14
Native Exotic NT Wheat NT
Sorghum
NT Fallow CT Wheat CT Soghum CT Fallow

16. 0.00
0.30
0.60
0.90
0 3 7 10 13 17 20 23 26 29 32 35 38
fluxdensity(cmmin-1)
Time (min)
r rot it
-0.30
0.00
0.30
0.60
0.90
1.20
0 3 6 9 12 15 18 21 24 27 30 33
fluxdensity(cmmin-1)
Time (min)
r rot it
Infiltration and Runoff
Native
Cropland

17.  In general, soil health indicators for native sites exceeded that
of cropland. Tillage degrades soil resources, difficult to “catch
up”.
 Little differences observed between mulch tillage and no-till,
cover crops seemed to improve soil health in a continuous
cotton cropping systems.
 How do we relate meaningful soil health indicators to farmers;
yield is often benchmark of success. Soil health indicators not
always linked to yield.
 Are more expensive and time-consuming testing procedures
necessary.
Conclusions