Figure 1a – Veris Electrical Conductivity Sensor
Figure 1b. Mobile soil mapping platforms.
It has been noted in other sections of this web site that there has been tremendous progress in reducing tillage operations and encouraging organic matter increase in the soil (See the Conservation Tillage section). Other modern technologies are also being used to detect and manage crop nutrient needs, including Global Positioning System (GPS) receivers, multi-spectral images and ground-based sensors to map out soil property variations in the field. The use of these combined technologies is often referred to as "precision" or "site-specific" agricultural management – "precision ag" for short. Today, almost 50% of U.S. cotton producers indicate that they employ some type of precision technology in their management, with most reporting that they use it for the site-specific application of soil nutrients.1
The basic Precision Ag approach uses a ground-based sensor to map the variability present in soil type within the field. This is done by matching the sensor reading to the area data from which data was collected using the GPS signal (see figure 1). The resulting maps are then used to identify areas of the field with different soil types. Soil samples are taken to analyze the nutrient need of each soil type present. Figure 2 shows an example of a high-resolution map of sand content that was created using such a technique. Once the map is created, it is loaded into the controller of the fertilizer applicator and then each soil type receives only the amount of nutrient that is required in that area of the field. This insures over application does not occur, and assures that crop needs are met.
Figure 2 –Example map of variation in soil type in a 40-acre cotton field in Arizona. Each numbered polygon represents a unique soil type that will receive soil-specific inputs.
The latest research effort is focusing on the use of sensors to detect the condition of the crop and vary the amount of nutrient applied in real-time (Figure 3). This eliminates the time spent creating and loading maps, and will provide even greater precision by letting the plant signal its needs.
Figure 3b. Applicator equipped with crop sensing units.
Figure 3a. Example of a sensor mounted on an applicator to control the amount of product that is applied, based on crop need.
