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Computers and Satellites: New tools help with crop and soil management.

Crop and soil management have evolved into a technical, finely tuned system for many of today's farmers and their advisers.

New technology development and implementation in these areas has recently advanced as other industries create tools for agriculture. Farmers can survive without these new tools, but to compete with neighbors in the United States and abroad producers must keep their farming systems up-to-date.

What some consider one of the most exciting and challenging innovations in recent years is site-specific management. This type of system has only recently become practical on a large scale due to space industry technologies developed and adapted for the farm. Computers and satellites are becoming common tools of the farmer's trade.

A site-specific soybean/com management system project is being coordinated by the Foundation for Agronomic Research and sponsored in part by the United Soybean Board. The project involves about 60 cooperators in nine states and includes farmers, researchers and agribusinesses. It covers all aspects and elements of the site-specific management system.

Soil survey

Site-specific management requires accurate soil characterization. Natural Resource Conservation Service (NRCS) staff cooperating on the soybean/corn project have developed a protocol for Order 1 Soil Surveys designed for site-specific management systems.

Most major crop areas in the United States have had NRCS soil surveys. Prepared by professional scientists, these surveys provide basic comparison information on soil characteristics. They rate the soil resources of an area for crop productivity, tillage system suitability, herbicide use, water management, nutrient management and other purposes.

Soil sampling and analysis have for the past 50-plus years been a primary means of estimating a soil's ability to meet crop nutrient needs and response to nutrient applications. Soil sampling today is aided by global positioning system (GPS) satellites and geographic information system (GIS) software. These approaches determine nutrient variability in the field. They also provide data for formulating recommendations for variable-rate nutrient application to match the needs of specific parts of a field.

Taking detailed soil samples on 2.5 acres (1 hectare) per sample or less can be a sizeable investment. But the cost is necessary to provide data for site-specific nutrient management. Sensor systems under development offer opportunities for more efficient, automated and timely nutrient management.

Electrical conductivity

Several methods are being studied to use electrical conductivity as a decision-making tool. Conductivity is effective for estimating topsoil depth, variations in organic matter, salinity and other parameters. Knowing the potential sources of change in conductivity is helpful for interpreting data. It may also aid in detailed soil type mapping. Popular versions of technology related to this area include the EM-38, being tested by the University of Missouri, and the Veris system.

Remote sensing

Measuring spectral variability in light reflectance offers a new means of soil characterization. Whether satellite-, airplane- or ground-based, spectral scanners can collect large amounts of data in a short time. If necessary, the method could be conducted continually to measure and monitor characteristics such as soil type differences, soil moisture and organic matter content.

Research by NASA and USDA in cooperation with various university, industry and farm organizations will evaluate remote sensing for management. Similar tools are being evaluated as part of the management systems project. Linking remote sensing imagery with other GPS-registered data in a GIS system shows potential for decision making.

Field preparation

Once a field is characterized, variability can be managed to provide the best environment to support a crop. Fertilizer application and tillage are the main concerns related to this area for most farmers.

Variable-rate fertilizer, liming materials and livestock manure application can supply a crop's nutrient needs without posing environmental problems or wasting economic resources. GPS, GIS and computerized rate controllers make variable-rate application practical for field use. In the future, on-the-go sensors may improve these systems.

Sensors and computer controls help make on-the-go adjustments in depth, ground speed and other components based on variable field characteristics. Sensors will be used with GPS to document variability in soil parameters affecting tillage, water movement, root growth and nutrient availability to the next crop.

Many modern seeding systems offer on-the-go seeding rate, depth and other input adjustment. Equipment technology is ahead of the agronomic knowledge base to determine the proper rate for different areas.

Conventional recommendations are based on the assumption of field-average management. There is no guarantee that the same relationships between input and response will hold true for smaller areas within a field.

Herbicide application

Various sensors are being evaluated to help identify weeds in a field. The goal is to detect weeds within a crop stand and use a controlled spraying system to remove them.

Other sensors estimate variability in organic matter and adjust herbicide application rates as affected by the matter.

A promising application for remote sensing in crop production is identifying weed patches in fields. Field scouting and spot spraying can be targeted to areas identified as potential weed problems.

New electronic tools are being used by field scouts in research and commercial fields. Some are too expensive and specialized for general commodity grain production. But they may play a role in fields of specialty crops, seed crops or high-value varieties. Following are some examples:

* Chlorophyll meter - Researchers have studied using a sensor called a SPAD meter to estimate chlorophyll content. The meter can detect areas of a field lacking in nitrogen in time to reduce yield loss. The SPAD meter can detect changes before they are visible to a a field scout.

* LAI meter - Estimates leaf area and measures it in the field to indicate crop vigor variability. This meter also does ground referencing in remote sensing operations.

* Cardy meter - A hand-held electronic tool about the size of a credit card that can estimate nutrient status in the field and do quick soil nutrient tests. Research shows that this tool can estimate laboratory test results. Several models are available with ion-specific sensors.

* VideoMapper - Used to videotape crop conditions, pests and other field scouting observations. Along with an image, voice and sounds are recorded and the GPS coordinates of the site are attached on the sound track. Geo-referenced images are indexed and linked to a GIS mapping package. The taped image, sounds and GPS location can be reviewed by displaying the map and clicking the cursor on-screen to retrieve the video clip for the area of interest.

Other new sensors and modeling tools help track development of moisture stress and guide irrigation applications.

In-field weather stations are becoming more common on the farm. Some offer telemetry transmitting data by radio signal to a central site to be stored on computer for either dial-up access or use with software that predicts crop response.

Yields for small plots and strip tests can be measured more accurately in the field at harvest. On-the-go yield monitors for crops develop continuous tracking of yield variability. Coupled with GPS/GIS tools, they can produce a data set of yield variability within a field for making management decisions and documenting production factor effects. Sensors that monitor moisture and quality components such as protein and oil are also being implemented. They may eventually be used to subdivide a crop into holding bins during harvest.

Computer communication

Video-conferencing helps diagnose field problems. A video or photo of problems can be sent to consultants or diagnostic clinics. Industry and extension field staff are equipped with cameras and cellular phones to implement the system.

Commercial data warehousing systems are being developed to help farmers store, manage and utilize information. Some of these systems also collect large amounts of data that can be summarized by input suppliers, farm managers, consultants and extension specialists. The systems can identify trends and problems and improve services.

Farmers are using e-mail to communicate with suppliers, landlords, markets and other sources. E-commerce allows them to shop for supplies and services without leaving the office.

Harold Reetz Jr. is midwest director, Potash & Phosphate Institute, vice president, Foundation for Agronomic Research, 111 E. Washington St., Monticello, IL 61856-1640, USA; 217-762-2074,
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Author:Reetz, Harold Jr.
Publication:Resource: Engineering & Technology for a Sustainable World
Geographic Code:1USA
Date:Oct 1, 1999
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