Not being traditional by nature, and being interested in new technology and methodology, site-specific farming was naturally attractive to me. Especially when combined with the potential benefits in the areas of economics, agronomy, and the environment.
       Site-specific applications in the geographic region known as the Palliser triangle are particularly challenging due to a semi-arid climate. Referred to as short grass country—my experiences in livestock taught me these areas are sometimes "damn short of grass," probably explaining why the buffalo had to roam in this area.
        Total precipitation is approximately 9"-13". In recent years, precipitation in the area has been unpredictably sporadic, but pattern specific. It is not unusual to have seasonal precipitation differences of as much as 4 1/2" within 4 miles. This introduces another challenging variable into delineating realistic target yields when writing prescriptions for different fields within this zone.
        The list of viable crops grown in this region range from low value oats at (CAN)$1.60-$2.00 per bushel, to higher value canola at $8-$10 per bushel. In semi-arid regions, the timeliness of precipitation is very often more critical than seasonal totals in determining yield. For example, 1" of precipitation at 3 week intervals totaling 4" can produce higher yields than a total of 6" which falls at a rate of 2" prior to planting, and 4" between 20 June and 8 July.

         In 1994, a stand-alone yield monitor was used to confirm what was already known-that certain areas within a field produced significantly different yields. However, the yield monitor provided actual numbers, making the differences measurable.
        Yield monitor accuracy of .1% of the total harvested volumes are common, and published reports of .003% are not unrealistic. My concern is not in total volumes but in differences; measuring response to trials in varieties, plant population, micro or macro nutrient application amounts, pesticide treatments and rates, as well as other management decisions. A desensitized yield monitor makes measuring trials more difficult, requiring longer comparison strips of 100'-200' over the same topography and soil types in order to acquire a valid response result.
        

A Flexi-Coil 50 Series air cart and 6000 no till seeding system provide the cornerstone to Rick Hobbs' site-specific dryland farming practices.

With continuous cropping and some drier than normal years, yields were becoming more uniform but uniformly poor, more so than could be attributed to the low levels of precipitation. Soil tests had been regularly taken and nutrient applied at recommended levels.
        At this time, I was fortunate to connect with Dr. Dan Pennock and the Soil Science Department at the University of Saskatchewan. Using Provincial Surveyaerial photographs and a GIS spectrographic software program, maps depicting management zones were generated according to soil color. The process seems relatively simple, however, these photographs were taken in 1981 when most land was farmed half crop and half summer fallow. Depending on when the photos were taken, half of each land parcel would depict vegetative growth and half would depict bare soil. This requires that the individual fields be processed separately and then seamed together. Initially, four accurate management zones were created. Except in cases of salinity or unusual soil type changes, these maps overlay directly with topographic maps. The lightest shades designate hilltops and mid-slopes, the two darker shades indicate toe areas and bottom land, the darkest areas are where water relocates and puddles. Further data was collected using soil sampling techniques in which 10-15 individual samples were taken from each zone.

Yield maps, when overlaid with prescription maps, provide varifiable measurement of the positive, negative, or immeasurable responseds from variable rate practices.

Results of the zone testing showed Nitrogen available on hills and mid-slopes to be 75 pounds and 85 lbs. respectively. Toes and bottoms had no Nitrogen available. There were up to 20 lbs. differences of Nitrogen available within zones. In keeping with uniformity, all samples were taken between rows of the last crop. These results possibly explain some of the yield questions. With 75-80 lbs. being available on hills and mid-slopes, an extra 50-60 lbs. of Nitrogen applied during a dry year could create conditions leading to plant burn. Conversely, an application of 60 lbs. in a low lying area combined with a low factor may only allow a 40 bushel crop to be grown in an area that had the potential for 60-80 bushels (Bu.) per acre.
        Planting operations were performed using a Flexi-Coil 6000 no-till air drill equipped with Barton II Double Shoot disk openers in combination with 50 series variable rate air cart, FlexControl multi-function console and a task controller. This unit was connected to a Trimble Ag 132 GPS and band differential correction with parallel swathing option light bar.
        The Flexi-Coil 6000 can be configured with 7 1/2" or 10" row spacing and is available in 30' or 40' widths. I found it to be precise and very adjustable as to depth-of-nutrient, depth-of-seed, and the separation between each. The design of the angle discs eliminates the problems of penetration and hairpinning. The unit was also very versatile and, with minor adjustments, performed equally well over a wide range of conditions including pre-tilled loose soil, hard packed soil, wet and dry, as well as heavy and light textured soils.
        The Flexi-Coil 50 series air cart, equipped with variable rate drive technology (which is available for all their air cart sizes), combines low uses of electrical and hydraulic energy in a simple, reliable, wide-rate range, yet highly accurate metering system. Meter rollers are available from extra fine to extra coarse to provide tailored, precise metering of products from fine granular pesticides to coarse seeds such as peas or beans.
        The multi-purpose console from Flexi-Coil is used to monitor and control air carts, an as-applied seed treater, or a Flexi-Coil sprayer. When connected to Flexi-Coil's task controller and a GPS, a PCMCIA card can be inserted to control functions and events at specific sites. The console is completely programmable as related to antenna offsets, as well as distances to tillage tool, air cart, and preset delays.
        Speed-of-rate change and amount-of-rate change can be configured for each tank or controlled product. Rates can be regulated according to a minimum, maximum, or average variation across the width of the seeding tool. Cell size for this application is 5 meters (m) or 16'4". Flexi-Coil uses the emerging ISO 11783 CAN Bus system to transfer information. This would appear to be the future industry standard for North American device connections.
        The Trimble AG 132 with light bar has a guidance system that hooks directly to Flexi-Coil's electronic system. The dual port feature of the 132 lets the operator hook more than one peripheral device to the receiver. The receiver can be mounted so as to be an auxiliary display screen. The sub-meter and 2 sigma accuracy of this unit provide accurate and precise guidance towards the elimination of misses and overlaps. It is well supported and user friendly.
        The AGRIS AG LINK GIS software program was used to create prescription maps. Although I did not create the maps, this software will be used for future prescriptions. It provides an affordable program that can be used by a producer or commercial professional. The economic functions of the program combine costing and billing in conjunction with other entries. The program provides profitability pictures using different application and cost factors prior to prescription decisions, and keeps an actual cost record of each parcel.
        Another economic benefit realized as a result of site-specific technology was in the area of Phosphorus application. Three years of application trials at increments of two-times the recommended rate, the recommended rate, and a zero application zone on several fields resulted in no measurable response difference. Among the calculated variables were date of maturity, yield, and protein. Continued analyses will be made on an ongoing basis to monitor for a response to and/or a depletion of Phosphorus. But until such time as the results from these test warrant, Phosphorus will not be included as a necessary prescription input, providing a savings of $1,100-1,300 per 160 acres.
        For every answer sought through all of the testing and data acquisition, ten more questions have surfaced. This is not surprising when considering the complexities of soil biology, plant biology, and the interrelationship that occurs. The technology that makes site-specific farming possible was simply adopted into agriculture as it was created, outpacing research which is normally conducted in concert with technology development.
        Testing and trials will continue with varieties, macro and micro nutrients, inoculates, and pesticides. Flexi-Coil's variable rate technology, which incorporates as-applied logging functions when combined with GPS, will be used to generate maps of planting and treatment applications. These maps, when overlaid with yield maps, are necessary for measuring positive, negative, or immeasurable responses to be used in management decisions. As the information database increases, management strategies that can be used to further maximize economic returns will increase as well.

Back