Considerable variations in soil texture, type and major factors within and between production fields affect agricultural production and have a significant impact on management strategies. Therefore, a uniform rate of input applications across the field can be costly and not maximize benefits. Sensor-based, variable rate input applications, known as site-specific management, can improve farm profits, soil health and environmental quality.
Precision farming tools can respond to variations in the production system to improve plant growth and crop yield. In an ideal precision farming practice, applications would accurately use the quantity, timing and manner of inputs based on variability (single plant management). Soil properties, such as structure, texture, organic matter and electrical conductivity (EC), can determine the type / amount of inputs (fertilizer requirement, irrigation schedule, seeding rate, depth of seedlings, etc.). Variable Rate Application (VRA) and Site Specific Management (SSM) are the methods that adjust input applications for changes in the soil.
Full field management versus zone management
So what’s the difference between whole field management and zone management? Whole field management treats the field as a unit with flat rates of inputs, while area management allows variable rate application of inputs to optimize the use of inputs based on needs. As a result, precision farming tools can help increase production, energy efficiency, and improve environmental quality and profits. The first step in implementing zone management is to find and detect the variations that control yield and create different zones. The next step is to treat each area individually. The precise application or treatment would be based on the information associated with each area individually. In a map-based variable rate application system, the Global Positioning System (GPS) demarcates management areas and computer interfaces with variability maps, and the VR applicator uses the appropriate recommendations.
The creation of zones is based on the study of static, non-random and stationary parameters (such as variation in soil texture: clay, silt, sand, etc.). However, the recorded response of plants to soil variability, such as yield data, can be interpreted and become a reliable factor in creating zones. Each zone should be large enough so that the applicator can technically and quickly respond to rate changes. Usually, it is sufficient to create three to five zones. However, this number may change depending on the variability and size of the field. There are several ways to create the zones in a field, as shown below.
Creating zones in a control
Electrical conductivity of soil (CE)
Soil EC describes the ability of a soil to transmit an electric current and is expressed in milliSiemens per meter (mS / m). An electrical soil conductivity meter sends a known electrical current through the soil and measures the ability of soil particles to transmit that current, marked with GPS coordination for a given field. The measurement of soil electrical conductivity can be used successfully to quantify variations in soil texture and yield potential of production. Measuring soil EC, as one of the decision-making tools in precision agriculture, can help growers decide on their nutrient management, seeding rate, seeding depth, and of their irrigation schedule. Measuring soil EC is one of the fastest and cheapest methods to provide information on soil texture, cation exchange capacity (CEC), drainage conditions, organic matter level and salinity.
Yield mapping is an agricultural technique for analyzing variables, such as crop yield and moisture content. A real-time yield monitoring system on a combine records georeferenced information about mass flow or crop volume, humidity and area covered. This information will then be used to create yield maps.
Aerial imagery or bare ground image
By using airplanes or drones to create high resolution images and by image analysis techniques, zones are created.
Soil data is a key factor in fertilizer recommendations which are usually derived from analyzes of soil samples collected in the field. Two common methods of collecting soil samples based on smaller management areas are grid sampling and area sampling. In grid sampling, a field is divided into equal square areas from which soil samples are taken. Smaller grid sizes provide a better representation of field variability. However, a higher sampling cost is associated with small grid sizes due to the number of samples. The second sampling method is area sampling. In this method, zones are created to determine areas with similar soil properties before soil sampling (i.e. soil texture, soil organic matter, soil electrical conductivity). Depending on the method used to create zones and their size, zones can vary depending on how well they capture variability in the field.
Web ground survey
The Web Soil Survey is a detailed report of the soils of an area provided by the US Department of Agriculture Natural Resources Conservation Service (USDA NRCS). The Soil Survey has maps with soil boundaries and photos, descriptions, soil properties, and characteristic tables.
Any combination of the methods mentioned above.
Zone management allows the application to optimize the use of inputs and has the potential to reduce the overall use of chemicals, seeds, water and other inputs. Through site-specific management, inputs are managed on a smaller scale, allowing producers to accurately respond to variations in a field.