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How to add soils to blocks

Helpdesk
  • Updated

Advice

In terms of where soil information should be derived from - there is a preferential hierachy

  1. Farm specific soil mapping by a qualified professional (trained soil pedologist) is best. This can be done by first selecting the appropriate Soil order and then adding further definition within the Soil profile and properties section.  
  2. Where available, use S-map in association with a physical understanding of the farm to assign soils
  3. Using soil order sourced from a national scale soil map(Fundamental Soil Layer)
  4. Using soil group with unknown soil order.

  • Soil profile/properties should only be changed based on expert observation where S-map is not available

  • Number of soils in a block is limited to 3, so roll up “like” soils into most dominant and enter soils where they have sufficiently different properties

Adding S-map soils

Adding soils by soil order/group

Soil profile and property defaults

Adjusting soil percentages

Using existing farm soils

Adding S-map soils

OverseerFM now auto assigns soils to a block using the S-map information available. Up to three soils can be added to a block. Each soil is defined as representing a percentage of the block area.

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These auto-assigned soils can be edited by selecting the block name, which will bring up the Edit Block Soils screen. 

The S-map soils (where available) that intersect the block are shown on the map. The soil areas drawn on the map are called polygons. Each polygon may contain one or more soil siblings as defined by Manaaki Whenua Landcare Research. Where there is more than one soil sibling within a polygon, each soil sibling is given a proportion (percentage of the polygon that is likely to be that sibling). 

Each polygon defines a percentage of the block that it intersects. The total percentage is determined by multiplying the proportion of the polygon by the percentage that polygon intersects the block.

Currently OverseerFM does not return polygons that are less than 5% of the block. Therefore, the total intersecting percentage may not add to 100.

The soils (siblings) are listed in a box at the top right of the map. You can switch between viewing by sibling reference or viewing by polygon (soil outline):

             

Select ‘+’ for the soils that you wish to add to the block. It is important to apply a physical understanding of the land to what S-map provides. For example if it is known that there are two distinct soils on the block but the change in soils is further north then is shown in S-map, you might lower the contribution % of the second polygon. Only add dominant soils, such that any single soil is not too small in area. Picking dominant soils for the block involves a combination of physical understanding of soils and boundaries, matching this with the information provided by S-map and estimating a percentage of up to three of the dominant siblings. Where siblings have very similar characteristics, these could be rolled into one soil. Where they are significantly different it is important that this is recognised in the setup of the block. A sibling may be repeated  in more than one polygon and so this should be considered when looking at dominant soils.

It is important to note that S-map does not claim to be accurate at farm scale and so should be used in conjunction with a physical understanding of where soils change on farm to setup the soils on each block. The percentage of each soil can be adjusted in OverseerFM in order to reflect this better information.

Adding soils by soil order/group

Where S-Map soils are not available auto suggestion of a blocks (soil group and order) will occur based on the block’s location if it is drawn, or the farm location if not drawn. To automatically select soil order, click 'Select this link to assign soils'

Then click '+Automatically select soil order'.

You will know soil order has been automatically selected if you get the warning message below. Alternatively soil group and order can be added manually by editing the soil order and soil group drop down menus

Alternatively you can manually select the Soil order and/or group; there are then two different areas in which you can enter data (Soil Profile and Soil Properties).

Soil Profile and Property defaults

Soil profile/properties should only be changed based on expert observation.

If using an S-map sibling these values are set and so there is no reason to change them unless you have your own soil data that overrides these values.

If using soil order only, it is recommended that these profile values are set based on expert observation of the soil in the block

If overriding system defaults, use the following hierarchy for 'Drainage class', 'Topsoil Texture', 'Max rooting depth' and 'Impeded layer depth', and 'Non-standard layer':

1.  Use farm-specific soil map, produced by a trained soil pedologist to determine profile drainage class.

2.  Obtain this information from S-map Online.

3.  Obtain from the Fundamental Soil Layers.

4.  Obtain from farmer knowledge.

5.  Overseer default (this will be determined from soil information).

For 'Is stony':

1.  Use farm-specific soil map, produced by a trained soil pedologist to determine if top soil is stony (if the stone content in 0–10cm layer is >35% stones).

2.  Obtain this information from S-map Online.

3.  Obtain from legacy maps and accompanying bulletins.

4.  Obtain from the Fundamental Soil Layers.

User discretion is required because even 35% stones will affect PAW. 35% stones aligns with soils identified as very stony soils on soil maps.

For Lower profile properties (10–60 cm pasture and cropping):

Choices will critically affect PAW and therefore drainage, and hence nutrient losses

1.  Use farm-specific soil map, produced by a trained soil pedologist to determine soil texture group of the lower profile.

2.  Obtain from legacy maps and accompanying bulletins.

3.  Obtain from farmer knowledge.

Adjusting soil percentages

Adding soils will populate the block soils section (shown below). You can adjust the percentages of each soil by selecting and dragging the blue circles on the slider. No single soil can be under 10% and the total of all soils must equal 100%.

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Using existing farm soils

If you have altered the soil properties, there is the option to continue using that soils for other blocks so you don't have to re-enter the data- select Existing farm soil when adding a new soil to a block. Soils that have already been used on the farm are also displayed in a table on the map. These can also be selected for the block from here.

 

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