Deployment Timeline • 1/22: Arrived in the evening • 1/23: Calibrated Sensors at BUET • 1/24: ~9-4PM: Deployed 1st pylon Mote 1 (full ISE suite), Mote 4 (1 moisture sensor) 4:50PM: First data points • 1/25: ~9-5PM: Deployed 2nd Pylon: Mote 11,21 (Each full ISE suite) 5:10PM: First data points • 1/26-1/27: Calibrate sensors for Pylon 3 • 1/28: Construct Pylon 3 • 1/29: Dig Holes for Pylon 3 • 1/30: ~10AM: Deploy pylon 3. Mote 3,22,23 (Full ISE), Mote 24 (2 Temp,Moisture). 4:45PM First data points • 1/31: ? • 2/1: ~9-10AM: Sarah pulled out pylon 2 (motes 11/21). And calibrated sensors? NR took day off 12-2PM: Irrigation happened • 2/2 – Relaxed day, data analysis, checked on pylons • 2/3: Relaxed day. Helped Becca in the field • 2/4: 9:05-10AM: Took out pylon 3; Cleaned sensors for ~2 hours 2-~3PM: Took out pylon 1; Cleaned sensors for ~2 hours • 2/5 – Packing/BUET
Pylon • Sensors were mostly vertical • ISE need to be vertical for reference gel, though concern was that a direct channel is created by keeping them totally vertical • Moisture can be oriented either way • Two types of motes: one has temperature/moisture, and one has ISE sensors attached (to avoid excitation voltage required for moisture/temp impacting ISE sensor readings) • 3-4 ISE sensors per hole, 1-2 temp/moisture per hole • 1 hole per depth • Pylon base buried 2 feet in the ground, sufficient for stability Motes Ground 2 feet ISE Sensors; 2 holes required for full suite of ISEs (3 + 4) Moisture/temp sensors Deployed > 1 foot from ISE
Deployment Layout ~30 feet ~20 feet 3 full ISE suites Mote 22 – 1 foot Mote 3 – 3 feet Mote 23 – 5 feet 1 Full ISE suite Mote 1 - 2 feet 2 Full ISE suites Mote 11,21 – 1 foot Mote 24: Temp1 – 1 foot Temp3 – 3 feet Moisture? – 1 foot Moisture? – 3 feet 1 Moisture 1 foot; (mote 4) Pylon 2 Holes to left: 16”,50” Holes to right: 19”, 55” Pylon 3 Pylon 1
Pylon Layout • Several sensors would go in each hole • Each hole was for a certain depth • Pylon 3 had 6 holes: • mote 22 orp, mote 23 orp, ph and co3 • mote 23 ca, nh4, no3, cl • mote 22 cl, co3, and ph • mote 22 ca, no3, nh4 • mote 3 ca, no3, nh4, and cl • mote 3 ph orp co3
Pre-Deployment ISE Sanity Check • Dip sensors in the water that will be filling hole, and take a reading. Then once you bury the sensors, take another reading to compare (to determine if anything got dislodged in deployment process) Readings are in the format: Before (Dipped in surface water) / After (once buried)
Post Deployment ISE Sanity Check • Very useful for ISE to get an indication if a sensor is capable of giving readings (many of our sensors gave “0” as a reading, but once they were taken out of the soil and tested again, gave readings > 0 • Most sensors gave very stable readings! Format: Values immediately before taking sensors out of the ground / Values when sensors are just sitting in the air * variation with 10 mv in the average
Ammonium Mote 1 pre post avg slope 54.2 54.5 54.3 intercept 420.6 418.3 419.4 r2 0.987 0.983 0.995 range: 0.7 ppb - 3570 ppb With lines every 24 hours (5pm-5pm) Irrigation happens around here ppb
Raw Ammonium mV Mote 22 (1? foot) Calibration curve limits Mote 3 (3 feet) Mote 23 (5? feet) mV Mote 1 (2 feet) Pylon 3 NOTE: After 216 hours: the milli Volts come back up – but concentration is So small that we don’t see any difference – what should we do???
Calcium Mote 1 pre slope 22.7 intercept 367.5 r2 0.980 range: 0.25 ppb - 1250 ppb lost sensor, cannot re-calibrate! ppb
Raw Calcium mV Values Mote 1 (2 feet) mV
Chloride- Mote 1 • pre post avg • slope 55.2599543 55.7213269 56.64715811 • intercept 400.3106253 409.598652 409.5207085 • r2 0.971658264 0.984658396 0.986062158 • Range: 0.00028 mg/L - 2.8 mg/L All values > 2.8 mg/L With lines every 24 hours (5pm-5pm) Mg/L
Raw Chloride mV Values Mote 3 (3 feet) Mote 1 (2 feet) mV
Carbonate: Mote 1 Pre Post Avg Slope -44.57 -32.31 -38.31 Intercept: -31.69 -31.47 -33.42 R2 0.99 0.96 1.00 Range: 0.03 uM - 158 uM With lines every 24 hours (5pm-5pm) uM
Raw Carbonate mV Values Mote 22 (1? foot) Mote 3 (3 feet) Mote 23 (5? feet) Mote 1 (2 feet)
Nitrate: Mote 1 pre post avg:NG slope -50.9 -59.2 -52.4 intercept 77.7 -100.8 -12.7 r2 0.914 0.997 0.711 Range: 0.08 ppb - 16 ppb All values out of range ppb ppb
Raw Nitrate mV Values Mote 22 (1? foot) Mote 23 (5? feet) Mote 1 (2 feet) Mote 3 (3 feet) Sensor comes back to life? Sluggish sensor?
pH: Mote 1 Corresponds to 0s pre post avg Slope -57.6 -56.6 -57.1 Intercept 430.3 439.3 434.8 r2 0.993 0.992 0.994 Range: ph 4 -7 (extrapolate to 7.6) pH
Raw pH mV Values Mote 1 (2 feet) Mote 3 (3 feet) Mote 22 (1? foot) Mote 23 (5? feet) But wired to expect negative values, so We expect 0s
ORP: Mote 1 Pre: ORP test: 172.5 Post: ORP test: 169 Note: expecting negative values in the soil, but this mote wired for positive values mV
Pre and Post Deployment Temp/Moisture Sanity Check • Pre and Post deployment we dipped put temperature and moisture sensor readings in direct sun and water • Less meaningful for temp – groundtruth temp would have been nice, but still useful to show offset differences between sensors
Temperature/Moisture Sensors • Before and after the deployment, we dipped the tested the sensors by taking a measurement in the sun, and then in water. • Uncontrolled temperature, so temp comparisons before/after are meaningless • Did not control time duration before taking a reading, so this could account for differences in temperature readings • Before (1/30) / After (2/4)
Data Problems • We don’t have temperature data for the first two pylons • For pylon 3, we have temp at 1 and 3 feet – can we extrapolate? • Pylon 2 – duplicate sensors were put into the same hole, but rarely got matching data • What do we do with data that doesn’t fall within the experimental detectable range but still shows signs of trends???
Connector became disconnected From sensor
Sensor Faults • Sensor gets disconnected • Sluggish response (See Nitrate sensor) • Bad response after being in solution for extended periods of time (see drift data) • Broken sensor with leaking reference voltage (chloride sensor) • Low battery (see nitrate graph) • Ground wire not connected • Sensor is shaken (gives noisy results, see pH sensor) • Not calibrated with motes • Sudden drops in values (see data after irrigation) • 0 from sensor (could be negative value) • Possibly failed and then “comes back” (see nitrate?) • Duplicate sensors in the same hole provide different data points • Small values (see ammonium data for mote 1) • Despite seeing diurnal trends, may be sensor fault (if below detection level)
Sensor Board Negative Values • THIS IS A MAJOR PROBLEM! • Often we didn’t know if the sensor was faulty, or if the readings were negative • Repeatedly tried swapping polarity on redox sensors and never got a reading
Pylon Construction • Need desiccant in the enclosures to minimize observed daily condensation • Wider poles for the pylon would be nice to enhance mobility of wires (we designed pylon pole to perfectly fit around all sensor cables, but this may have contributed to pressure on sensor wires) • Minimize environmental footprint (need to dig sensor pylon into ground? Maybe use BG setup?) • Mote battery connectors – KEEP BREAKING!! Need more robust than solder joints
Where should extra Sensor cables go?? Note concrete ring in top right corner Need a better method of attaching a wire to the sensors that attach to the pylon (to have alternate way of locating/pulling sensors up). We tried fishing wire but that was a DISASTER
Digging Holes / Placing Sensors • We didn’t even worry about “channels”! Mud all went into one bucket Surface was all clay!
Digging holes when water fills them is difficult, and they would collapse • (our 6 foot hole was no greater than 5 feet)
Long sensor cable is better than doing extensions because connectors are exposed to mud/water Note taped up connectors. NOT GOOD
In rice field, holes filled up with water, so sensors do not easily fall to the bottom. • For shallower holes (~2 feet), we put our hands down the hole to manually place sensors – deeper holes? Mudded sensors to simulate Weight. Mud dissolved
We tried bentonite, but was hard to mix With the clay and keep it dry. Also, as a result, never recreated the plough pan! Holes became a little “undug” several days after deployment (possibly after irrigation?)
Cement Ring Keeps Partially Dry Becca added poles, and cement to keep Sensors in place and protected
Calibrating sensors in the field! • But, temperature was relatively different for pre/post calibration (Nernst?)
Big and little pylons have similar issues Managing cables is HARD!