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Improving Farm Production Through Grid Soil Sampling

Variable rate (VR) application of lime, gypsum and phosphorus is used to correct soil issues in paddocks with high soil variability. VR applications are generated from grid soil sampling which is showing us that not all paddocks are consistent throughout.

Identifying soil variability within paddocks, enables soil types to be managed appropriately, intern spending money where it is needed. It assists decisions on fertiliser quantities and where applications are required to better match soil and crop requirements.


Grower Experiences

The soil in the Bordertown/Kaniva areas can differ greatly within a paddock. 3 years ago after encouragement from his Western AG agronomist a client within the area tested what he perceived as his most variable paddock based on crop yields. The variability within the soil was more than we expected. It showed we needed to VR Lime, Gypsum & P.

Since then, regular Precision AG mapping is in the budget for this grower and he is now successfully growing beans on soil he never imagined he would be able to. By identifying chronically underperforming areas of the paddock we have been able to significantly increase production through variable rate application.


A comment I recently had from a client using grid mapping; ‘This is the most exciting thing in farming I’ve been involved with, being able to identify why my poor areas are poor and fixing them is instantly lifting my paddock average yields and improving my bottom line’.


Included below (Figure 1) is the VR mapped paddock in which there is very large variability in pH. The maps clearly show the significant differences in soil pH across different zones. Once the target pH has been set the prescription is created and the file can be transferred to the spreader for variable rate lime application.


Figure 1. Soil pH map (L) and the prescription file with lime rates (R) for target pH 5.5 CaCl2

In summary, VR Mapping has changed soil testing for the good. The amount of data points we are generating from grid mapping soil allows for far greater management of our soils. In most cases the farmer can tell us where the paddock is under-performing, and we can relate that to one of the parameters tested in the grid mapping service. It is not always pH, as shown in Figure 2 sodium (Na) and Colwell Phosphorus levels can also be soil constraints. Prescription files for VR Phosphorus at sowing and VR gypsum can also be generated to improve soil fertility and production levels.


Figure 2. Exchangeable Na (L) and Colwell P (R) field variability shown from grid soil mapping

There has been a significant undertaking of grid soil sampling in the Bordertown area due to our soil’s variability. If you are reading this and have the same variability within your paddocks, I strongly suggest you test a paddock and see for yourself. Please contact your Western AG agronomist today to discuss grid soil sampling in your fields.

Article produced by - Kate Pfitzner, Western AG Bordertown

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