Field Notes

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Bouldin Alfalfa: 2024-10-09 10:15:00 (DOY 283)
Author: Joe Verfaillie
Others: Daphne

Summary: Moved tower to edge of field, both our field and field to the east plowed, remove two sets of ground sensors due to tractor damage. Left scaffolding supplies for future work.

Bouldin Alfalfa
2024-10-09

Daphne and I arrived at about 10:15 PST. It was mild and breezy with some high thin clouds but still very dry and dusty. Tractors were working on our field and the field to our east - the reason for this fieldtrip. The tractor on the field to our east seemed to be dragging some kind of leveler and a couple of rollers. The leveler was a big bin that scooped up dirt from high spots and added dirt to low spots. The plan is to plant winter wheat now followed by corn this coming summer then back to alfalfa the next year. I think a field near the highway has nearly completed this transformation.

Our field looked like it had a single pass of shallow disking and the tractor was working on a second pass of a deeper plowing. The tractor was on the far west side of the field and was working its way east toward our tower. The northwesterly breeze was keeping most of the dust away from us, but we wore face masks.

At the tower the first pass of the tractor had hit the soil sensors to the south and north and just missed the soil sensors to the west. It had nicked the power line in one spot cutting the unused data cable and exposing the copper in the positive and ground but not in the negative wire. I removed the broken data cable, taped up the wires and repaired the aluminum conduit. The under canopy PAR had also been tossed but we were able to recover all the sensors except a couple of the thermocouple rods. We dug everything up and measured locations and depths of sensors. The surface was very hard but softer further down. We turned off the power and disconnected the power line at the tower.

While the tower still had power. Daphne collected the Flux, met and camera data. We will get the FD data in the lab. She cleaned the rain bucket, the radiometers and 7500 - all were dusty.
The 7500 read: 413ppm CO2, 580mmol/m3 H2O, 29.6C, 101.2kPa, 85SS - 98 after cleaning

The tower feet were 2-3cm below the surface - looked like mostly accumulated litter. We bolted 8ft 1x4 boards to the long side feet and hooked up the front to the truck with webbing straps. We were able to drag the entire tower, sensors and all, to the side of the field. We pulled it a little farther north passed the reach of the power line to get to the edge of the field and then had to pull it back south. One skid broke and we had to jimmy it a bit to get it closer to the edge. We had made an earlier stop at Mayberry to pick up two scaffolding frame sets, a couple extra posts and two concrete piers - we didn't know what we might need. We also brought a boardwalk from the lab. One idea was to put to whole tower in the ditch and that would need an extra frame. We might also have to make the tower higher for wheat or corn which will need another frame. But the tower seemed okay at the edge of the field so all the supplies were stacked on the east (ditch) side of the tower. We got it straight and level and the power hooked up about the time the tractor was getting closer and we were getting blasted by dust. So we decided to go to Bouldin Corn while the tractor finished up.

We left at about 13:30 PST and returned at 15:15 PST

When we returned the tractors were parked from the day. Daphne disconnected ground sensors sets #1 and #3 that were damaged. I reinstalled ground sensor set #2 and the Delta-T soil moisture under the tower at the original depths. I put in the fence posts and tie downs on the southeast and northwest corners. I don't remember if the grounding rod got put back in the ground or not. We washed the solar panels. I added some mothballs to the solar controller box. Daphne sealed holes in the met box.

We left at 16:22 PST

To do:
The radiometer boom should probably be moved to the short side of the tower to point to the WSW more into the field instead of along the ditch at the edge of the field. Need to check the sonic heading and height. Repair ground sensor sets. Figure out how to reinstall the Sentek soil moisture rods. Check the grounding rod.

Sensor locations and status
Under Canopy PAR
WAS: 248cm at 210deg from the SW corner of the scaffolding, disturbed by plow
IS: hanging sideways on the tower

Delta-T soil moisture sn M003369
WAS: 242cm at 350deg from NE scaffolding post at -15cm
IS: under the scaffolding at -20cm

Ground sensors set#1
Was: 430cm and 151deg from the SE corner of the scaffolding
IS: removed
Soil moisture sn 17127
SHF sn 10866, 62.90uV/(W/m2)
TCs 1-5 on mux cut and rod lost

Ground sensors set #2
WAS: 240cm at 200deg from NW corner of scaffolding
IS: Reinstalled under the tower at the same depths
Soil moisture sn 17135, z=-5cm
SHF sn 11334, z=-2cm, 61.04 uV/(W/m2)
TCs 6-10 on mux - okay - loose TC retaped to top position

Ground sensors set #3
WAS: 605cm at 335deg from NW corner of scaffolding - disturbed
IS: Removed
Soil moisture sn 17132, tines bent sharply
SHF sn 11332, wire cut, 60.95uV/(W/m2), mux 3H/L
TCs 11-15 on mux, cut, rod lost

Also removed:
FD chamber sn FD20180026
Sentek soil moisture rods

Estimated Next Mowing: 2024-11-02

3 photos found

20241009BA_TowerAreaDisked.jpg ( 2024-10-09 11:14:58 ) Full size: 1920x1440
One tractor pass around the alfalfa tower before we could move it

20241009BA_PlowedTowerMoved.jpg ( 2024-10-09 17:10:15 ) Full size: 1920x1440
New location of the BA tower after the alfalfa fields have been plowed and tilled