Field Notes

Twitchell Alfalfa: 2014-08-27 14:50:00 (DOY 239)
Author: Cove Sturtevant
Others: Sara

Summary: Swapped 7500. Swapped out 3 probes in soil CO2 system. Regular fieldwork.

Twitchell Alfalfa
2014-08-27

We arrived about 14:50 PDT. It was sweltering with no wind. The alfalfa is flowering heavily and wasps were buzzing all over the place. I attended to the tower, swapped the 7500 (removed sn 75H-2180, installed sn 75H-2182) and did maintenance on the soil CO2 system while Sara did spectral, veg height, soil respiration (she labeled the collars as well), LAI 2000, and clip plots. The battery for the 6400 was smelling kind of funky, and there was a small amount of goopy stuff on top, but the voltage was ok and it performed fine.

The forced diffusion probe #1 was reading 0. I swapped the probe (removed sn z2720011, installed sn z2720014) and readings seemed reasonable afterward. Probes 4 & 5 of the soil CO2 profiles (profile B, depths 0 cm and 8 cm) were also reading 0. I swapped the probes (#4: removed sn F4960019, installed sn Y2009100, #5: removed sn F4960018, installed sn K1340006) and readings seemed reasonable afterward. When I was first testing to see which profile was the correct one, I accidentally pulled out the pvc tube for Profile A, 8 cm depth. I replaced it but had to re-dig the hole since it backfilled with dirt.

I collected data from the soil Co2 system.

7500 readings:
CO2 = 383 ppm (same after cleaning, 385 after swap)
H2O = 670 mmol m-3 (same after cleaning, 590 after swap)
signal strength = 94.02% (95.15% after cleaning, 82.91% after swap)
p = 101.46 kPa (102.0 kPa after swap)
t = 33.3 C
sos = 352.7 m s-1

Corrected pressured cal after swap.

Met ok.
Rad ok.
Cleaned rad.

Veg Height (cm): Tape measure from ground to top of plant - Flowering
32, 47, 65, 51, 53, 33, 43, 36, 44, 53, 42, 35, 62, 44, 54, 36, 55, 60, 38, 31, avg = 45.7, stdev = 10.48

3 photos found

TA_autocam_20140828_1915.jpg ( 2014-08-28 19:15:02 ) Full size: 1920x1440
Moon after sunset