Field Notes

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Other sites visited today: Hill Slough | Bouldin Alfalfa | Mayberry
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Bouldin Corn: 2022-02-03 11:00:00 (DOY 34)
Author: Daphne Szutu
Others: Dennis, Carlos, Manuela

Summary: Regular data collection/cleaning, field still flooded and draining slowly, talked with Dave Forkel

2020-02-03
Bouldin Corn

Dennis, Carlos, Manuela and I arrived at 11:00 PST. This was Manuela's first time to the Delta and I think her first time seeing eddy covariance towers. Our field is still flooded and the water is ankle-deep at the tower. The water was still flowing slowly out of the drain on the southeast corner of the field. The field to our south is flooded, the field to our north is mostly dry, and the field to the east has puddles.

I was planning on reinstalling the FD chamber today but I’ll wait until it’s a bit drier. I also need to check if I have the wire hooks we use to attach the chamber to it’s usual green garden stakes.

It was partly sunny with thin high clouds covering 2/3 of the sky and there was a steady breeze.

The 4x4 post holding the power outlet had rotted and the post and enclosure were laying against one of Tyler’s blue boxes. We had brought a steel post today to swap out the 4x4. Dennis pounded the new post in the ground next to where the old post had been. We had planned to use u-bolts to mount the enclosure to the new post, but the enclosure didn’t have appropriately spaced holes on the mounting plate. I didn’t bring a drill today so this will have to wait until next time.

I downloaded met, cam, and USB GHG data. I downloaded the PA data and had to power cycle it twice before the card slot LEDs blink appropriately. I downloaded the IRT data by swapping the microSD card and using CardConvert to convert the fast data to TOB1 and the slow data to TOA5.

Carlos and Manuela cleaned the flux and rad sensors. Dennis topped off the wash reservoir.

Just as we were getting ready to leave, an SUV pulled up with Dave Forkel and Ralph(?) one of his employees. Dave Forkel talked with Dennis and Carlos about using OpenET and had questions about drawing his own polygons and about why the different models had predictions up to 50% different. Carlos recommended using specific models intead of using the ensemble.

Ralph used to be a farmer on Bouldin Island but now works for the Metropolitan Water District managing the 4 reclamation districts owned by the Met. He is usually in the area at least once a week, unless there’s a flood watch or a flood fight, in which case he would be here every day. It sounds like there are always ongoing levee rehabilitation projects to bring the levees up to current standards. Current rehabilitation practice includes adding toe berms to the land side of the levee, which from what I remember helps compact the peat at the base of the levee and therefore stabilize the levee with less settling of material. He said that even though the Met probably has enough “juice” to support levee work independently of the state, the state also contributes a significant portion of the budget. Unfortunately, small farmers just can’t afford this scale of levee rehabilitation. The Met are about to start rehabilitating portions of the levee on the north side of the island.

He also said that the farmers used to flood the fields in the winter for weed control, to keep moisture in the peat soil (hard to work with the peat in the spring when it’s too dry), and if they hunt, for waterfowl. Now, the hunting club pays for the flooding. However, the hunting hasn’t been as good recently because the corn is being harvested for silage instead of for grain, which leaves less food behind in the fields to attract birds.

Ralph also asked us to keep the gates closed as much as possible. He had put in the electronic gates to make it easier to keep them closed. People with the code could open it easily from the digital keypad, and then the gates would close automatically behind them.

We also asked about alfalfa irrigation. Ralph said they should be irrigated after each cutting with a quick fill of the drainage ditch, which then “subs” (i.e., travels by subsurface flow) out to the fields. He said it’s a quick fill and drain, so he’s not surprised we usually see a dry ditch out there.

LI-7500 readings:
CO2 420ppm
H2O 322ppm
T 12.0C
P 102.5kPa
SS 101 --> 103 after cleaning
LI7700 readings:
CH4 2.0ppm
RSSI 34 --> 78 after cleaning

We left at 11:45 PST to head to alfalfa.

1 photos found

20220203BC_FloodedField.jpg ( 2022-02-03 10:50:36 ) Full size: 1920x1440
Flood field that is slowly draining. It's about ankle-deep at the tower but Tyler said it was much deeper in the middle of the field.