Field Notes

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Other sites visited today: Hill Slough | Bouldin Corn | West Pond
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Bouldin Alfalfa: 2021-08-25 12:35:00 (DOY 237)
Author: Daphne Szutu
Others: Joe

Summary: Installed soil moisture profile probes, added fan to ATMOS14, sensors dirty from birds, cut alfalfa under structures

2021-08-25
Bouldin Alfalfa

Joe and I arrived at 12:35 PDT. It was warm and sunny with a bit of a breeze. Today was a maintenance trip to install the new soil moisture profile probes from Arable and to aspirate the ATMOS14.

The alfalfa field was mowed last week but not raked or baled yet. Joe and I trimmed the alfalfa around our 3 structures: the bouncer tower, the main tower, and the PL Arable post.
I downloaded the bouncer data and the met, cam, and USB GHG data at the main tower. I skipped downloading the IRT and FD data since weâ€™ll get those next week with the regular data collection visit.

We topped off the wash reservoir and cleaned flux and rad sensors. The bottom mirror of the 7700 and the SWin, LWin, and PARin sensors were all dirty with bird poop or feet marks. Looking at the phenocam photos back in the lab, there was a large group of starlings hanging out all over the tower (even inside the sonic transducers) for a few days.

We installed 2 Sentek Drill & Drop soil profile probes that are on loan from Arable. The probes measured soil moisture, salinity, and soil temperature every 10cm. We used a large cordless electric drill and long, tapered drill bits to drill holes into the ground. The taper of the drill bit was supposed to match the (slight) taper of the probes.

The first probe was 120cm and installed in the ground under the scaffolding near the SW corner of the tower. The cable number was DD35315 and the cable was connected to the Arable Bridge box that also connects the cup anemometer to the Arable. The top of this probe was about 10cm above the surface because we werenâ€™t able to install it as deep as we wanted. The hole was deep enough but the taper of the drill bit was not wide enough.

The second probe was 60cm and installed in the ground under the scaffolding near the NW corner of the tower. The cable number was DD033055 and we wired this SDI-12 probe to C5 on our datalogger. Joe added a screw terminal to make more space on C5 for all the SDI-12 sensors there. I sent a new program to the datalogger that measures the Sentek probe every 10 minutes (like our other soil moisture sensors). This adds 18 new data columnsâ€”6 soil moisture, 6 soil temp, and 6 salinity measurements. The top of the probe was a few cm above the soil surface, but we mounded and packed more soil around the sensor so that the top was about level with the ground surface.

Joe added a 24V fan to the top level of the ATMOS14 solar radiation shield so that this RH/Temp sensor is aspirated. He cut 2 sections of 6-32 all-thread to replace the factory bolts and used small pieces of tubing as spacers to make enough space for the fan. The fan is powered through the 24V (orange) power strip in the datalogger enclosure.

LI-7500 readings:
CO2 399ppm
H2O 613ppm
T 29.2C
P 101.3kPa
SS 98--> 101 after cleaning
LI7700 readings:
CH4 1.97
RSSI 51--> 93 after cleaning

I washed the solar panels. On our way out we stopped at the bouncer tower to chase wasps out of the box and to seal the holes with duct putty. We also cleaned the small solar panel there.

We left at 15:30 PDT.

Next Mowing: 2021-10-13

2 photos found

bouldinalfalfa_2021_08_24_054506.jpg ( 2021-08-24 05:47:52 ) Full size: 1296x960
Starlings everywhere