Precision Nutrient Management – Grid Soil Sampling

Grid soil sampling is a method of collecting multiple soil samples from a paddock in order to give an accurate nutrient map of variations in nutrient levels within that area.

Thanks to GPS technology, the data is accurate and the process repeatable from the same points in the future. Typically soil samples are taken at a grid spacing of one sample per hectare or less, however this can be altered to suit the need of the customer. In all instances, one sample bag is taken with multiple cores per GPS location.

Grid soil sampling enables you to undertake accurate variable rate application of nutrients, which can:

• Reduce fertiliser and lime expenditure
• Reduce soil nutrient variability
• Improve yields and pasture performance where soil nutrients are limiting factors
• Help you manage your fertiliser and lime more sustainably with targeted placement
• Reduce environmental impact by eliminating application in areas where soil nutrients are already high
• It also enables you to return to the exact same GPS coordinates in the future to monitor the effects of rates and management practices. Grid Soil Sampling equips the grower with the tools of accountability and traceability, very important requisites for establishing farming best practice.

The process and results:

• Create grid soil sampling plan (~ 1ha grids)in conjunction with the farmer/manager
• Take the soil samples from each location using the plan loaded into the handheld GPS
• Send the soil samples off to the laboratory for processing
• Create soil nutrient maps for pH, Olsen P, K, Mg, Ca, Na, Sulphate Sulphur, CEC or any other nutrients tested that the farmer is interested in for decision making
• Discuss with the farmer the soil nutrient map results for each map/paddock
• In conjunction with the farmer / fertiliser company / consultant decide on a fertiliser strategy that puts the right fertiliser in the right place and meets the farmer’s goals
• Create zones for variable rate fertiliser applications and assign product rates to each
• The zones are then loaded into the spreader for variable rate application according to the prescription map built
• Variable rate spreading is then carried to optimise nutrient placement

Summary:

• The more information available the more targeted the recommendations and applications can be
• The additional topography related layers, e.g. Landscape Change, Slope & Aspect (available through EM Soil Mapping), can be very useful in determining areas that might need to be managed in a different way rather than only in accordance with soil nutrient levels. This is a useful management tool to combat potential nutrient leaching or to assist with nutrient best practice issues.

To find out more, click here to download the Grid Soil Sampling flyer