Field Notes

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Other sites visited today: East End | Twitchell Rice | West Pond | Mayberry
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Twitchell Alfalfa: 2015-06-09 09:00:00 (DOY 160)
Author: Joe Verfaillie
Others: Patty, Dennis, Miguel

Summary: Windy, Field half baled, swapped out soil CO2 system, repaired theta cables cut last time, took soil cores, soil respiration, camera did not take photos

Alfalfa
2015-06-09

I arrived about 9am with Dennis, Patty and Miguel. It was mild and overcast with a strong wind from the west. The part of the field to the west that had been mowed last time was baled and the bales were being picked up by tractor. The part of the field near the tower had been mowed and raked, but not baled yet. There was still some alfalfa with lots of purple flowers standing around the edges of our field sensors. Dennis cut this and added the cuttings to the drying rows.

Miguel dug a pit and took soil cores for bulk density and diffusion measurements. Three reps of soil cores were taken at 0-5cm, 5-10cm, 10-15cm and 15-20cm. He also did the 6400 soil chamber measurements â€“ readings varied maybe due to the wind.

I spliced the three theta probe cables we cut last time then worked on replacing the box with the soil CO2 equipment. I built a complete new box in the lab with CR1000 (sn 4190), AM16/32 (sn 1164) and eight new GMM Vaisala boards. Eight new Vaisala probes went in as well. The existing theta probes, thermocouples, Forerunner probes and power lines were piped into the new box. All cables on the ground are now enclosed in aluminum flexible conduit. The new GMM Vaisala boards are using 24VDC because the site was already setup that way. The system seemed to run, but when I tried to put it into test mode the data logger restarted. The Forerunner probes were on the relay and seemed to pull too much power on start up. Even though the system seemed to work when not connected to the netbook, I disconnected the Forerunner probes and test mode worked. I maybe need a bigger 24-to-12VDC converter, or a capacitor to support the startup draw.

New probes are
sn K1340005 replaced by sn L2058002 set A -2cm
sn K1340007 replaced by sn L2058003 set A -8cm
sn G0150037 replaced by sn L2058006 set A -16cm
sn Y2009100 replaced by sn L2058005 set B -2cm
sn F4960018 replaced by sn L2058007 set B -8cm
sn Y0710013 replaced by sn L2058001 set B -16cm
sn Z2720011 replaced by sn L2030063 forced diffusion ambient
sn H1630066 replaced by sn L2030064 forced diffusion soil

The 7500 read: 398.8ppm, 539.7mmol/m3, 81.25SS, 27.2C, 100.7kPa
The door to the 7550 box was unlatched.

The camera only had a day of images on it. I thought it might have been the updated CHDK software so we reloaded the old software. But I changed the software two visits ago. The new software ran for two weeks with no problem.

1 photos found

TA_autocam_20150609_1115.jpg ( 2015-06-09 11:15:01 ) Full size: 1920x1440
Joe on site and gathering bales