Select a date range and analysis, then click 'Get Data'. It may take some time (20 seconds or more) to load. The calculations behind these graphs are complex, and carried out at the time the data is requested to ensure they are up-to-date.
The nutrient concentration data behind these graphs has been derived either from actual chemical analysis, or estimated from electrical conductivity where an analysis is not available. Check the 'Measured / Estimated' checkbox to distinguish between measured and estimated data. Estimated data will be marked with '+' symbols, making the line look fuzzier and less certain, to give a clear visual distinction between measured and estimated data.
Each autosampler includes a basic rain gauge, mounted on the autosampler box. This is included as an added bonus, to help with irrigation management and general farm records. However, it does not measure rainfall to the level of accuracy that drainage is measured to, and it is not appropriate to directly compare the rainfall volume measured with this gauge to the drainage volume.
Above-ground rain gauges are inherently inaccurate, because due to wind effects they do not capture all rainfall. A rain gauge mounted on a post or pole will frequently capture 10% less rainfall than actually hits the ground, but the level of undercatch depends on many factors including the wind pattern, and in some circumstances pole mounted raingauges may catch only half the true rainfall.
Rain gauges are particularly inaccurate during snowfall, as less snow settles on the gauge than lands on the ground, and as it melts a large proportion of the water may run down the outside of the gauge, not through the sensor. Expect less than half of true precipitation from snowfall to be captured by the rain gauge.
The lysimeter, on the other hand, is affected by every drop of rainfall and snowmelt that reaches the ground. This means that the lysimeter may in some circumstances actually drain more water than was recorded by this rain gauge, or by any other rain gauge on the property. This is normal and to be expected, because all such rain gauges are inherently inaccurate.
These concerns apply to all above-ground rain gauges, they are not just a problem with this particular device but will apply to any such rain gauges on the farm. If you wish to compare drainage volumes to rainfall data, compare the drainage to the nearest high-quality professional weather station. However, some cautions still apply. Many professional weather stations use rain gauges that sit on the surface of the ground, with the opening of the gauge still at least a foot above ground level. These still miss some rainfall (though less than if they were mounted on a pole), and will seriously undermeasure snowfall. The highest quality weather stations use rain gauges installed in pits, so the rim of the rain gauge is at the ground level, and covered by a metal grid to minimise wind effects. Such a rain gauge should give data that is fairly comparable to the drainage from the lysimeter, though still somewhat questionable during snowfall.
In summary, the rain gauge provided is accurate enough to assist with irrigation decisions over the summer months, because snow is not a factor. It will also give an indication of precipitation in winter, but not accurately enough to directly compare with drainage.
Three measures of electrical conductivity are given: Bulk, Pore and Paste. Bulk is the actual EC measured by the sensor, the electrical conductivity of the entire soil in-situ. Pore is the estimated electrical conductivity of the pore water alone, which should relate to the concentration of salts & nutrients in soil water. This is estimated from EC, water content and temperature. Paste is the estimated electrical conductivity that would be obtained in a standard saturated-paste laboratory test for EC.
The data table may take some time to load (e.g. 20 seconds or more). The calculations behind this table are complex, and carried out at the time the data is requested to ensure they are up-to-date.
Total drainage and N loss is listed for each installation, in each year. The measures given are:
Drainage (mm): Total depth of drainage.
Total N (kg/ha): The total N loss, including all forms of N. This is the figure most relevant to annual N loss calculations for regional council compliance
% measured: The GroundTruth system measures total N in two ways. N loss is estimated in real-time based on the electrical conductivity (EC) of drainage water and the relationship between past EC measurements and analysed total N. Then, once water has been chemically analysed, the estimated N loss value is replaced with an actual value. The '% measured' column shows the proportion of the 'Total N' value that has been derived from actual chemical analysis, as opposed to being estimated. In the current year, this will be less than 100%, as recent drainage will not yet have been analysed. For past years it should be 100%, unless some individual samples were never analysed, in which case a small proportion of the N loss may still be estimated.
Every time the sample collection switch is used, the system assumes a sample has been collected, and records this as a sampling event in the above table. The sample time is the time this signal reached the server - in sites with poor radio reception, the recorded sample time may be later than expected. Each new sampling event must be selected using the below dropdown menu, and classified as follows.
No sample: The table is wrong, there was no sample collected (e.g. the switch was turned on momentarily simply to test whether the pump was working, or by accident). The sample will be deleted from the above table.
Sample will not be analysed: If a sample was collected, but will not be analysed (e.g. the sample was lost, deliberately discarded, or has been archived and there are no plans to analyse it in the forseeable future). The sample will remain in the above table, but the sample will no longer be listed as awaiting sample analysis results. DO NOT use this if you are simply waiting for analysis results, only use this for samples that will not be analysed. This option will remove your ability to enter analysis data for that sample.
Analysis available: The sample has been analysed and the results are available for entry into the database.
Select the appropriate option from the dropdown menu. If 'analysis available', also add TN and/or TON analyses in the below fields.
Occasionally a sampling event will not be automatically recorded, and will not appear in the above table. If this occurs, add it manually below. Enter the date, site and installation, and click "Submit". The sample time will by default be assumed to be 12 noon
Add a new type of analysis that can be recorded in the database, if it does not already appear in the above list.
Code: A short code that can be used in column headings, and internally in the database, as a common reference for this measurement. Must be unique. Example: "TN"
Title: A clear, readable title for the measurement. For example, "Total Nitrogen"
Units: The units the measurement is in. For example, "mg/L"
The device status is as of the time of the last transmission. This may be slightly different to the actual status right now.
Idle: No drainage is occurring.
Pumping: Drainage has occurred, autosampler is pumping and collecting samples.
Frost: Temperature inside the box is approaching zero. Pumps are switched off to avoid frost damage. Any drainage that occurs during this time will accumulate in the lysimeter and be sampled once the day warms up.
Low Voltage: Voltage has dropped below 11.8V (precise threshold may vary between devices). If the actual voltage is higher than 11.8, the voltage is dropping below 11.8 when the pumps are turned on. Pumping has been halted, and will resume when the sun comes out.
Sample pump running: The sample pump is running. If you are not currently collecting a sample, you probably left the sample collection pump switch on. Please go and turn it off!
Error: This could have several causes, but generally means a pumping problem - water is present in the lysimeter, but when the device attempts to pump it out, no water comes. If the error persists the main pump may need replacing. This is very simple to do.
Water in lysimeter column: If 'TRUE', there is water in the lysimeter awaiting pumping.
Select the checkbox below to display the last 7 days of voltage, status, and radio signal quality data. On the 'Status' pane of the graph, 1 = Idle, 2 = Pumping, 3 = Frost, 4 = Low Voltage, 5 = Sample pump running, 6 = Error. 'RSSI' and 'SNR' are different measures of radio signal quality. In both cases, higher values are better (with -90 being higher than -110).
Select date range, and click button to download a spreadsheet of drainage, rainfall or soil sensor data
Four tables of drainage data may be downloaded.
Drainage: Raw drainage volume and EC, as measured in real-time.
Data columns: 'time' = time this data was recorded; 'mm' = depth of drainage water; 'ec' = electrical conductivity of drainage water;
Samples: Samples collected, including drainage mm and EC preceding this sample.
Data columns: Time = sample collection time; 'Drainage mm' = mm drainage preceding that sample; 'EC' = volume-weighted mean EC of all drainage increments contributing to this sample; 'Nutrient' = nutrient analysed; 'Concentration' = nutrient concentration
Analysis: Nutrient analysis results, for all samples that have been analysed.
Data columns:'Nutrient' = nutrient analysed; 'Concentration' = nutrient concentration
Drainage + Nutrient Estimates: Combination of Drainage and Samples, extrapolating nutrient concentrations from Samples across drainage increments, using EC. This is the raw data behind the graphs on the 'Drainage' tab. This is for indicative purposes only, as the algorithm behind it is proprietary. For publication, a regression of EC against nutrient concentration on the Samples table should be used, and these nutrient concentrations recalculated.
Data columns: 'analysed' = whether this drainage increment formed part of an analysed sample (1), or not (0); 'sample_id' = nearest sample that was analysed for this specific nutrient; 'measurement' = nutrient analysed; 'increment_conc' = estimated concentration of this nutrient in this increment; 'kgha' = estimated kg/ha loss of this nutrient loss in this increment (will be accurate only for nutrients that are measured in mg/L).
Each sample is bulked from many drainage increments. Where that drainage increment formed part of an analysed sample, 'analysed' = 1 and the sample_id identifies the relevant sample. Where the sample that this drainage increment formed a part of was not analysed for this specific nutrient, 'analysed' = 0 and the sample_id identifies a different sample that was collected near in time to this drainage increment and was analysed for the nutrient in question.
Data columns: 'time' = time this data was recorded, 'rainmm' = mm of rainfall.
Data columns: 'time' = time this data was recorded; 'vwc' = volumetric water content; 'temp' = temperature in degrees celcius; 'ec' = bulk soil electrical conductivity (as measured by the sensor); 'ecpore' = estimated electrical conductivity of pore water; 'ecpaste' = estimated electrical conductivity that would be measured in a saturated paste laboratory test; 'position' = whether this device is installed in the Lysimeter itself, or elsewhere in the Paddock; 'depth' = sensor depth in cm; 'rep' = if there are multiple sensors installed at the same 'position' and 'depth', each sensor is given a different 'rep' number.
The values of 'ecpore' and 'ecpaste' are estimated using standard equations from the electrical conductivity, water content and temperature measured by the sensor, and an assumed soil bulk density.