{"id":16127,"date":"2016-08-01T10:05:18","date_gmt":"2016-08-01T14:05:18","guid":{"rendered":"https:\/\/extension.umaine.edu\/publications\/?page_id=16127"},"modified":"2024-05-22T10:26:05","modified_gmt":"2024-05-22T14:26:05","slug":"1080e","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/publications\/1080e\/","title":{"rendered":"Bulletin #1080, An Introduction to Using Site-Specific Farming to Manage Field Variability"},"content":{"rendered":"\n

Assistant Professor of Sustainable Agriculture Lakesh K. Sharma, Crops Specialist James Dwyer, and Associate Extension Professor Andrew Plant, University of Maine Cooperative Extension, and Dave Franzen, Extension Soil Specialist, North Dakota State University
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For information about UMaine Extension programs and resources, visit extension.umaine.edu<\/a>.<\/strong>
Find more of our publications and books at extension.umaine.edu\/publications\/<\/a>.<\/strong><\/p>\n\n\n\n

Conventional farming practices overlook spatial and temporal variability within the farm. Treating a whole farm as a single unit can result in over-fertilization and under-fertilization of areas with differing residual nutrient levels, as well as unnecessary insecticide\/herbicide applications in areas where no insect\/weed problem exists. Satellite imagery and small flying units (drones and raptors) have shown promising results to detect the difference between nutrient deficiencies and insect\/weed problems. Site-specific farming has the potential to increase farm income and resolve environmental issues, thus easing farm management decisions.<\/p>\n\n\n

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\"Satellite
Credit: NASA<\/figcaption><\/figure><\/div>\n\n\n

Whether you are farming conventionally or organically, sustainability can be achieved through precision agriculture, with its site-specific approach. By guiding growers to apply inputs based on the problems and yield potential of a specific area within a field, efficiency is increased through reduction of application rates, time, energy, and costs.<\/p>\n\n\n\n

Site-specific thought is soils-oriented. It takes into account the differing soil properties caused by human and natural activities \u2014 including past agronomical practices \u2014 within each field. Such differing soil properties are unavoidable and cause crop production fluctuations within the field. Consider the ease with which a farmer can detect differences in soil color by simply standing in a field. Site-specific management is used to identify specific soil differences, collect information about them, and then change management practices, such as input requirements, in response.<\/p>\n\n\n\n

Adopting the Site-Specific Approach<\/strong><\/h3>\n\n\n\n

Many farmers think that site-specific farming tools are highly expensive and difficult to use, making them impractical in dryland agriculture systems. However, studies at various land grant institutions, including North Dakota State University (Franzen et al, 2015, Sharma et al, 2015, Sharma et al, 2014), Oklahoma State University (Raun et al, 2005), and the University of Nebraska\u2013Lincoln (Schepers et al, 1992), have proved that the high level of precision enabled by site-specific tools results in lower costs, better yields, and more net income. For example, ground-based active optical sensors (GBAOS) have been successfully calibrated in North Dakota, Oklahoma, Nebraska, and Missouri for side-dress nitrogen application in corn. (Note that these states have adopted zone and grid soil-sampling techniques that help farmers identify low and high fertility areas for variable-rate fertilizer applications before or at planting.)<\/p>\n\n\n\n

Site-specific farming requires farmers to think ahead and think differently than conventional farm practices do. It involves some important steps that must be followed properly:<\/p>\n\n\n\n

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  1. \"Illustration<\/a>Finding your location<\/strong> through the use of Global Positioning System (GPS) receivers, Global Information System (GIS) mapping, ground-based sensors, and\/or satellite imagery<\/li>\n\n\n\n
  2. Evaluating your location<\/strong> by gathering information<\/li>\n\n\n\n
  3. Applying variable-rate inputs<\/strong><\/li>\n<\/ol>\n\n\n\n

    Finding Your Location and Mapping It<\/strong><\/h3>\n\n\n\n

    Global Positioning System (GPS)<\/h4>\n\n\n
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    \"Illustration<\/a>
    GPS Satellite Network. Credit: NOAA.<\/figcaption><\/figure><\/div>\n\n\n

    GPS technology is in use throughout the world. It functions through a system of satellites — developed by the U.S. Department of Defense — that transmit signals to any receiver on earth. By measuring the amount of time it takes for signals from multiple satellites to reach a GPS receiver, the receiver can calculate its location in three-dimensional position (latitude, longitude, and altitude).<\/p>\n\n\n\n

    Depending upon the capabilities of the receiver, a GPS can determine location with a precision of a few inches to a few feet. Small errors in exact coordinates can occur, but readings can be improved using \u201cdifferential GPS\u201d (DGPS). In northeastern Maine, real-time kinematic (RTK) GPS systems are available that improve the precision of GPS data and are ideal for horizontal and vertical applications such as water drainage, auto steering, strip tilling, and mapping. RTK systems need either a base station or a subscription to a company (such as Verizon), that provides base-tower signals for GPS receivers.<\/p>\n\n\n\n

    Advantages of GPS<\/h4>\n\n\n\n