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

1. Cover Crop Effects on Corn Plant Sap
Flow Rates and Soil Water Dynamics
Lalith M. Rankoth, Ranjith P. Udawatta, Clark J. Gantzer*,
Shibu Jose, Kelly A. Nelson
School of Natural Resources
University of Missouri, Columbia, MO

2. • Cover crops (CC) are used for soil conservation and
soil quality improvement. But, their effects on soil
water are less well known.
• Does use of cover crops change water relations for
corn?
Rationale

3. • To quantify plant sap flow dynamics in corn (Zea mays L.),
soil water dynamics, and corn yields in response to CC and
no cover crop (NCC) management.
Objective
• University of Missouri
Bradford Research Center
Columbia, MO
Experimental Site

4. Experimental Management

5. Experimental Management

6. • Mexico silt loam (fine, smectitic,
mesic Aeric Vertic Epiaqualf) or
claypan
• Annual precipitation: 1083mm
• Mean annual temperature:
18.2°C
• Mean monthly high
31.1°C, July
Soil, Precipitation, and Temperature

7. • Plant sap flow measurement techniques are useful
to characterize plant-water relations, water stress,
plant transpiration, and plant water consumption
(Backes and Blanke, 2007, Acta Hortic. 732:573-
578.; Fu et al., 2016, Agric. Water Mgt. 177:172–
180).
Dynamax Sapflow Measurement

8. • Measure whole plant transpiration
• Using a constant power heat balance gauge
• Allow for stem flow measurements
• Xylem mass flow rate is calculated from a balance of heat
into and out of a stem
Dynamax Sapflow Measurement
(Dugas, 1990, Theor. Appl. Climatol.
42:215–221.)

9. • Campbell
CR1000 data
logger
• Eight SGB19-WS sensors installed on 4
corn plants (NCC) & 4 corn plants (CC)
• Dynamax Flow32-1K sap flow
measurement system

10. Volumetric Soil Water Content
Campbell CS-616 (Campbell Scientific Inc,
Logan, UT) Time Domain sensors installed at
10-, 20-, and 30-cm soil depths (Campbell
Scientific Inc, Logan, UT)

11. Results Corn sap flow rate

15. Volumetric Soil Water

16. (A) June-December 2018
(B) Planting to harvesting
(C) Harvesting to December 2018

17. 0
5
10
15
2017 2018
Yield(Mgha-1)
Year
b aa b
20
30
40
50
2017 2018
100seedweight(g)
Year
CC-100 SW NCC-100 SW
CC-Yield NCC-Yield
Corn yield

18. • CC soil held 14% more soil water at 10 cm and provided
water to corn plants for a longer period during June-
December 2018.
• Sap flow rate was greater in NCC corn plants during
vegetative period.
• CC treatment increased sap flow rates after the 100 DAP
stage.
Conclusions

19. • Reduced sap flow during the vegetative period may
reduce corn yield. Yield in 2017 was greater in NCC
treatment (8.1 Mg ha-1) compared to CC (9.4 Mg ha-1). No
yield difference was observed in 2018.
• Sap flow rate was 1.2 times greater in NCC corn plants
during from 30 – 90 days after planting in 2017.
• Sap flow rate was 1.3 times greater in CC corn plants
during from 100 days after planting in 2017.
Conclusions

20. • Soils with the CC treatment can hold more soil water and
provide it to corn plants for a longer period compared to
NCC.
• The ability of CC soil to hold more water and provide
them to plants may benefit farmers especially in drought
years.
Conclusions

21. Thank you - Questions