Introduction

Cibo Labs have developed and deployed a PUBLIC survey form for the visual calibration or field collection of pasture biomass information. This form is:

• Pasture Biomass Image Library - Visual Calibration

• Pasture Biomass Collector - for initial data collection by users to create a one-pager of reference images (low, mod and high biomass) for different types of pasture. AND for quadrat data collection along transects

The survey form is a mobile data collection app for undertaking rapid pasture assessments in the paddock, and have been designed to stream line data collection in the field.

This collected data can be used as information for direct input to forage budgets, or for calibration of satellite imagery. The survey allows the user to undertake visual quadrat assessments along transects; take photos and record information on pasture types and condition. The survey form works offline with both Android and IOS devices using the ESRI Survey123 mobile application (https://esriaustralia.com.au/survey123-for-arcgis).

The survey form is designed to be used initially, as the collection of pasture data with:

Collecting and Submitting Records

Accessing data collected on the App

Once the data has been sent or saved for editing later, you can edit these created or sent transect records by clicking on the other menu items ‘Sent’ or ‘Outbox’. This will display all survey records ever sent by this device.

Visual Calibration with the Pasture Biomass Library Reference

The App has been developed specifically for estimation of pasture biomass based on visual quadrat estimates along a transect with known GPS coordinates. We must assume that users have undertaken practice in pasture biomass estimation, however, some tips are also included here.

There are numerous resources available to assist with making visual estimates of pasture biomass (https://www.feedonofferlibrary.com/, https://futurebeef.com.au/knowledge-centre/pasture-photo-standards/. However, we highly recommend that in order to get “your eye in”, prior to field sampling, you undertake your own cuts; complete some oven drying to estimate pasture dry matter (DM), and take some photos to create your own reference library over time.

You will need the following: 0.25sqm quadrat for most northern pastures and a 0.1sqm quadrat for most southern improved pastures; plastic bags for doing “wet weights”; paper bag for oven drying sub-samples of pasture; electric clippers or hand shears.

1. Start with ‘Collect’, then enter your email address, property, paddock

2. For a given pasture type, select a low, medium and high biomass location.

3. Place the quadrat on the pasture and take a vertical reference photo

4. Cut and bag the pasture as close to ground level as possible.

5. Weigh the samples in the paddock as soon as possible after you have cut them to avoid them drying out. Don’t forget to “zero” the scales with the bag to remover the bag weight.

• Weigh and record the quadrat samples.

• 0.25sqm quadrat - grams x 40 = kg/ha

• 0.1sqm quadrat - grams x 100 = kg/ha

• Remember these are “wet weights” and must be adjusted for the moisture content to derive dry matter (DM%)

1. Dry matter samples (DM%) - Take a representative sample of pasture next to the quadrat and place in a paper bag for oven drying. A handful is enough.

2. Weigh the dry matter samples as soon as possible and record the weight on the bag. Place in an oven at 80degC for minimum of 12 hours. Weigh again and place back in the oven for another 2hrs and weigh again. You can also use a microwave (see ‘Silage Note No. 7’).

3. If the weight hasn’t changed it is ready to calculate DM content

• DM% = dry weight / wet weight

• Hay would normally have a DM% of ~85%

• Actively growing cereal crops are likely to be ~30-40% DM%

• Partially cured perennial pastures might be 50-70% DM%.

• The message here is that DM% varies substantially and has a huge effect on estimates.

For most properties you should be able to collate enough cuts and photos across your major pasture types and biomass levels in a morning. Complete the oven drying overnight, compile your photos against the DM weights into a document, and you have your own library to refer to, and to provide staff with a local reference.

Doing Visual field estimates using the Pasture Biomass Collector

Once you are confident in your ability to make visual estimates based on using existing photo standards, or creating your own library, you are ready to use the Biomass Collector App.

1. Open the App from your home screen, and enter your email address, property, paddock

2. Ensure that you are at least 100m away from roads, or abrupt changes in biomass.

3. Locate the start of the transect and place your quadrat on the ground with the bottom left corner next to your toe.

Doing Pasture Cuts for Wet Weights

Collecting Pasture Cuts – to create calibration equations.

• The objective is to collect pasture cuts across the range of biomass levels for a given pasture type that you have just collected EC20 transects across.

• You should be able to do this within walking distance of your vehicle so you don’t have to carry your gear too far.

• Create a [Paddock/Site] in the EC20 App called <Cal><time>. e.g. Cal1145.

• Knowing the range of heights you have just traversed – select a number of low, medium and high locations – usually within a few paces.

• Drop the EC20 on the selected locations to get a height reading – then place the Quadrat down on that location. Make sure you have sampled down to at least 50mm and up to the tallest plants. Please ignore rank pastures.

• Label the bags with the time, pasture type and EC20 height.

• Dry Matter % cuts see section 6 below.

• Repeat until you think you’ve sampled across the range of height/biomass levels – Generally 9-12 quadrat cuts should be enough for the initial calibrations for a pasture type. We need several cuts for each of your low, medium and high categories.

• Weigh the WET Quadrat cuts as soon possible within a couple of hours of collection and keep them out of the sun. Don’t forget to zero the scale with the bag. You can throw these cuts away. Don’t throw the DM% samples away just yet:

1. Dry matter samples (DM%) - Take a representative sample of pasture next to each quadrat and place in a paper bag for oven drying. 1-2 handfuls are enough.

2. Write the date, time, species on the bag for later weighing.

3. Weigh the dry matter samples as soon as possible and record the weight on the bag (within 2hrs). Keep them out of the sun, and do not put the paper bags in another plastic bag where they might create condensation.

4. Place in an oven at 80degC for minimum of 12 hours. Weigh again and place back in the oven for another 2hrs and weigh again.

5. If the weight hasn’t changed it is ready to calculate DM content

6. DM% = dry weight / wet weight

• You can also use a microwave (see ‘Silage Note No. 7’) but an oven is faster for a large number of samples.

• Hay would normally have a DM% of ~85%

• Actively growing cereal crops are likely to be ~30-40% DM%

• Partially cured perennial pastures might be 50-70% DM%.

Using an EC20 Plate Meter with Pasture Biomass Collector

The EC20 Plate meter provides a rapid means of collecting reliable estimates of compressed pasture height that can be related to pasture biomass at specific locations which we then use for calibrating remotely sensed imagery. However, different pasture types and growth stages will have different relationships that need to be quantified before reliable field estimates of biomass can be made. This guide provides quick explanation of how Cibo Labs carries out the calibration and field survey process where calibrations are not currently available for specific pasture types.

1. Follow the EC20 User guide to set up your device and get the plate meter “talking” to your device.

2. You will need the following equipment:

   1. EC20 Plate meter

   2. Electric clippers (recommend Stihl). Having a sharp knife is also handy for long tropical pastures.

   3. 3 x 0.1sqm Quadrats made from PVC. These can be a round quadrat with a diameter of 35.7cm or square quadrat inside width of 31.6cm

   4. Large plastic freezer bags (~33cm) or paper bags for collecting wet weight cuts

   5. Smaller paper bags for collecting samples for oven drying to calculate moisture content and Dry Matter %.

   6. Bulldog clips and thick felt marker pen.

3. Selecting Sampling Sites - Remember the process we are undertaking here is not for completing a paddock survey using the EC20, but rather to rapidly collect field biomass data at specific GPS locations for calibration of remote sensing.

   1. Identify your primary pasture types across the property.

   2. Identify several paddocks that are representative of the important pasture types and grazing regimes. This includes “mixed” pastures.

   3. Identify some low, medium and high biomass areas in those paddocks using the Cibo imagery. See the image below. Remember you can save the Cibo Web Map to the home screen of your phone and click the location buttom on the top left. Select sites that are easily accessed by a vehicle. Sites must also be at least 50-100m away from roads or other significant boundaries.

   4. Avoid rank pastures that won’t compress and recently grazed paddocks.

1. Completing the EC20 transects – Once you have identified the pasture types for which calibrations on sites are going to be undertaken, we’re ready to complete the EC20 transects.

   1. Open the EC20 App

   2. Select [SETTINGS]->[EQUATIONS]->”pick equation”. Remember for the first survey this “default equation” is unlikely to provide accurate estimates.

   3. Select [WALK]->[Add or select farm]

• Use the following naming convention: <WINDY><date> .e.g Windy20200227

• This is important because it will allow you to export data for a specific date later

• Enter [Residual]=0.

Select [Paddock]

• We are using this to identify a “site” rather than a paddock and we simply want the time and pasture type recorded against the name. We need the pasture type to apply the appropriate equation later. Use the following naming convention: <time><pasture_type> e.g 1124mitchell.

• Enter [Ha]=1

1. You are ready to start a transect. The idea is to traverse around the “low”, “medium” and “high” sites previously identified in the imagery.

1. Pick a target and walk in that direction as straight as possible, taking EC20 readings (plonks) at each step. When the EC20 gets to 30 readings – STOP and save the transect. Each transect should be around 25m long.

2. Walk ahead until you see a change in the pasture biomass and then enter a new [paddock/site] name. 1129mitchell, and so on

3. Repeat the above with the objective of sampling across range of biomass levels for that pasture type.

4. Keep an eye on the range of height readings as you do the transects. Remember, the biomass reading you are getting from the default equation is NOT the true biomass.

5. Calculate the DM yield (kgDM/ha) - by multiplying your Wet Weights by DM%.

   1. e.g Wet Weight = 1500kg/ha x 0.7 (DM%) = 1050 kgDM/ha.

   2. Enter the DM weights back into the Quadrat pasture cuts spreadsheet.

6. Export and send the transects from the EC20

7. Select [Reports]->[<Farm>date>] e.g Windy20200227.

8. Select All ->select the share icon on the top right of the screen and email that to yourself and info@cibolabs.com.au

9. Email the Cuts and DM% spreadsheet to info@cibolabs.com.au

10. Cibo Labs will generate the EC20 equations from the height, cuts and DM% estimates for each pasture type and then apply to each transect to generate an estimate of TSDM/ha for each transect.

11. Equations will be created for the EC20 App for future field surveys and the transect data will be used to develop the prediction model from remote sensing.

These equations will then be loaded into your EC20 for future assessments, noting that we also expect to need a few calibration cuts at different points in the growing season to ensure field data is accurate.