Precision Agriculture Series: Volume 1: Utilizing EM38 Surveying and Soil Coring for a Variable Rate Gypsum Program
Introduction: The Journey to Precision
Welcome to the first edition of a quarterly series on Precision Agriculture (PA). This journey is designed for farmers eager to move from scepticism to strategy, transforming colourful, unused maps into valuable, actionable insights. As the agricultural industry evolves, so does the need for more precise, data-driven farming practices. This series will walk you through a demonstration farm's year, showing how on-farm data collection and analysis can lead to the successful implementation of precision agriculture practices on your farm.
The Promise of Precision: Beyond the Scepticism
Many growers have been stung by high-cost, low-value PA solutions—colorful maps and complex data that end up forgotten in a drawer, creating no real value. The true potential of Precision Agriculture lies not in the accumulation of data but in its analysis and application. By tailoring PA techniques to your farm's specific environment and management systems, you can derive actionable outcomes that deliver real value.
Implementing a Variable Rate Gypsum Program: A Step-by-Step Guide
In this instalment, we focus on optimizing soil health and productivity through a Variable Rate (VR) Gypsum Program, leveraging EM38 surveying and soil coring. Here's how:
1. Understanding Your Soil: The EM38 Survey
- What It Does: The EM38 survey provides a detailed view of your soil's conductivity, helping to identify variation in soil properties across different zones of your farm. For example, clay is more conductive than sand and hence will return a high EM38 reading. This is visualised in figure 1, with the red indicating a quite sandy soil type. As the map colour becomes darker (green/blue) this indicates higher conductivity, usually associated with clay content and other mineralogy. This relationship is not absolute however, it requires soil coring to define if other mineralogy or factors are at play, soil coring to ground truth is essential.
- The Outcome: By understanding these variations, you can tailor your gypsum application rates to different areas, ensuring each zone receives the optimal amount for its specific needs. This can result in maximising your return on investment for applied gypsum.
Figure 1. EM38 maps from Mallee district, higher mS/m indicates higher conductivity. Soil core ESP (0-10,10-40,40-80cm) also shown. Note low conductivity (red area) is a sandy-acidic area, with high radish population
2. Digging Deeper: Soil Coring
- What It Does: Soil coring gives a more in-depth analysis of your soil's physical and chemical properties, including nutrient levels and soil structure. Soil surveys such as EM38 can help locate cores to reflect the dominant soil types. Soil coring provides a ground truthing layer to define exchangeable sodium percentage (ESP), a key determinant of dispersion, these levels can then be modelled against the EM38 results to predict sodium levels across whole paddocks. In the core samples, the presence of other minerals, including significant amounts of different salts like magnesium and chloride, can help rule out soil types where these elements primarily contribute to high conductivity readings from EM38 measurements, indicating that such soils may not respond to gypsum treatments.
- The Outcome: This data, combined with the EM38 survey, refines your understanding of each zone's requirements, enabling more precise gypsum application.
3. Implementing the Variable Rate Gypsum Program
- Planning: Use the data from your EM38 survey and soil cores to create a map of your farm's management zones. Once the data has been interrogated for anomalies, platforms such PCT allow regression analysis to be performed. Simply put, a regression analysis uses the real EM38 readings and soil cores to predict at a particular EM38 (e.g. 200 ms/m) what the ESP level could be (10% ESP). This theoretically “cores” at a high resolution across the farm, this layer can then be utilized to create a variable rate gypsum application map, targeting rates to where return on investment is most likely.
- Execution: Many modern machines are equipped with active telemetry, such as GS4 and AFS Pro screens, allowing network connectivity for seamless transfer of VR maps directly from platforms like MyJohnDeere or AFS Connect. This eliminates the need for physical USB transfers, which remain necessary for older models. The process for uploading VR maps, regardless of the method, has been significantly streamlined, enabling easy selection of the appropriate map for each paddock. This allows for efficient, zone-guided operations with minimal manual intervention.
- Monitoring: Continuously monitor soil and crop responses to the gypsum application, adjusting your strategy as needed. The beauty of improved data flows through platforms like MyJohnDeere and PCT is that trial strips can be easily implemented and analysed year on year.
Figure 2. VR gypsum map created utilizing processes detailed above. Allowing high rates to be targeted, maintaining an average application rate (2.5t/ha) which is economically viable.
The Role of Technology: Harnessing Data for Success
Incorporating technology, such as the PCT Agcloud platform, can significantly enhance your precision agriculture practices. By integrating data from various sources like EM38 surveys, soil tests, and yield data, you gain a comprehensive view of your farm's performance. This holistic approach allows for more accurate decision-making and easier implementation of trials, like the Variable Rate Gypsum Program.
