1. Presented by Robert Raley

2. Reminder: Impact of different mulch treatments on soil properties.
Preliminary analysis of the variations in soil chemical properties
Environmental monitoring: soil temperature and moisture
Future work

3. pH EC
CEC
Total N
Total C
Soil aggregate stability dropped due to new mesh bag study.

4. Year one method – samples taken from each treatment using hand spades
New method – mesh bags with mulch pieces buried in each plot.
Soil tests to be run on soil from inside of mesh bag.
First mesh bag samples received from TN and TX, part WA

5. TN TX WA
pH Max
7.5
8.1
6.9*
pH Min
6.2
6.8
5.9
pH Median 7
7.8
6.5
EC Max
0.14
0.33*
0.18
EC Min
0.06
0.09
0.08
EC Median
0.13
CEC Max 19
18.2
CEC Min
9.9
14.1
CEC Median
12.8
15.5
Total N Max
0.17
0.2
Total N Min
0.05
0.11
Total N Median
0.1
0.07
0.12*
Total C Max
2.2
2.4
1.7
Total C Min
0.78
0.45
1.3
Total C Median
1.1
0.69
1.4

6. SAS software
ANOVA model
- Allows combination of all sources of variation
Duncan mean separation
Duncan allows us to look at specific source of variation

7. The ANOVA Procedure
Dependent Variable: CEC
Sum of
Source DF Squares Mean Square F Value Pr > F
Model
Error
Corrected Total
R-Square Coeff Var Root MSE CEC Mean
Source DF Anova SS Mean Square F Value Pr > F
mulchtrt
rep
location

8. Means with the same letter are not significantly different.
Duncan Grouping Mean N rep A A
B A
B A
B A B B

9. TN: CEC, Total N, Total C
TX: EC, some variation in pH between rows from Duncan
WA: pH, CEC, Total N

10. Tripathi et al (2006) reported lower microbial activity with increasing salt concentrations in salt affected areas in India.
Several studies have shown the dependence of plastic degradation on pH.
** How do we want to use this data to explain differences in mulch degradation?

11. Base setup for all states:
Hobo U30 (HT FP) – leaf wetness, 6 soil temp, RH& air temp, visible light, wind speed. Manual Soil moisture varies with the number of rows with current crops.
Additional at Tennessee
- Campbell hourly data
- Two rows each with 12 soil moisture 6 sensors at 6” and 6 sensors at 18”
- Six soil temp 6” and 6 surface added later last summer.

13. Advantages
Disadvantages
Less expense
Ease of installation
User friendly
Limited number of sensors
Limited types of sensors

15. Advantages
disadvantages
Nearly unlimited types and numbers
Data management and storage within logger
Program how data is collected time and frequency
Requires knowledge of programming to set up
Cost
Not as user friendly

16. Observations from Campbell
Irrigation water temperature was high.

17. Observations from Campbell
Soil thermal gradients under mulch treatments.
- At 6” depth: Duncan mean for Max, Min and Average shows a 1 – 2 °C gradient between treatments.

18. TX HOBO
TN Campbell NB BB BT SB CC NM NB BB
( CC SB
BT) *<0.4 C NM

19. Duncan Grouping Mean N mulch
A BB
B BT B
B CC (grey)
C NB C
C NM
D SB (white)

20. Duncan Grouping Mean N mulch
A BB A
B A BT B
B CC (grey)
B NB
C NM C
C SB (white)

21. HT Tomato
Field Plot Tomato BB CC SB BT NB NM

23. Jaehoon, on this slide I shortened the x axis but I was afraid if I shortened the y axis additionally then the graph to the left it would underplay the difference in tensions. This looked to be the most extreme case of variation in moisture.

25. Dr Hayes’ study looking at different moisture levels

26. Soil moisture greatly affects heat movement in soil which can also impact mulch degradation.
Very important to understand the processes of coupled heat and water transport.
For example, it has been known for some time that a 1 °C gradient is more than enough to cause water movement in soil (Cassell et al ).
Cassell measured water movement due to a thermal gradient as low as 0.5 °C

27. Additional soil temperature and moisture sensors at different depths.
Looking to track heat and water movement from soil temperature measurement.
The information is important for mulch degradation, crop yield and disease, as well as nutrient movement.

28. Importance of knowing the soil and environmental conditions to help explain any variance in mulch degradation as well as other variation.
Thermal gradient more important for this summer.
Unknown how the change of SB mulch will affect the thermal gradients.