**4.2 1980–1990**

PA farming practices were largely believed to originate in the early 1980s [43, 58] linked with the advent of the GIS and later GPS into the agricultural sector [59, 60]. The vision began to materialize for what a personal computer coupled with a GIS and a GPS could mean for agriculture [11]. In the late 1980s, research activities in PA continued with the development of yield monitors, grid soil sampling, soil sensors, GNSS receivers and differential correction capabilities, and VRT, more so in the United States and Europe than in other countries [58]. Both academic (university) and industries were dedicated to improving practical and cost-effective implementation of these systems. The main thrust was to adapt IT software and hardware along with appropriate communications technologies to agricultural settings. The value of the geographically positioning capabilities supported the collection of field data and observations and later produced different derivative products such as yield and VRT maps. However, the main obstacles during this time included lack of understanding, lack of support, evolving equipment, lack of standardization, inefficiencies of design, and many more [57, 60].

### **4.3 1990–2000**

PA has been practiced in the mid-1990's [43]. Equipment manufacturers introduced more accurate GNSS receivers, yield monitors, and software packages. By the early 1990s, yield monitors and VRT controllers became commercially available [58]. A significant step in making the PA possible was the invention of the on-the-go crop yield monitor in 1993 [61]. John Deere developed their first GPS receiver integrating satellite control into their product line in 1996 [62]. The evolving GNSS assisted farmers in tracking the coordinates of material applications or harvested biomass across a field. Popular laptop computers and handheld devices such as personal digital assistants (PDAs) with appropriate software contributed to significant advances in PA. These systems allowed PA to within-field locations, trace field boundaries, and record crop health observations. However, companies utilized numerous proprietary wiring, devices, and file formats for recording and transferring data. Hardware and software incompatibilities along with steep learning curves presented major hurdles for early adopters during this decade [11]. Many companies emerged with solutions for productive agriculture. In fact, industry, agribusiness managers, and farmers have played a significant role in the development of PA [63]. The agricultural community witnessed rapid growth and progress of PA technologies since the mid-1990s with the advances in GNSS, GIS, sensors, and remote sensing technologies [58]. Some equipment companies worked with growers, while others worked with retailers, distributors, crop consultants, and university extension personnel to engage growers. Several international conferences have been held, such as the 1992 First International Precision Agriculture

Conference in Minnesota and Biannual European and Asian conferences in 1997 and 2005, respectively [58], and so on. "Precision Agriculture," a new journal launched in 1999, and PA research have become a popular topic in this and other academic journals on a global scale.
