Open-Format Prescription Maps for Variable Rate Spraying in Orchard Farming

Abstract

Highlights Straightforward procedure to code prescription maps independent of manufacturers. Methodology suitable for orchard crops and vineyards including pressures up to 10 bar and flowrates up to 100 L/min. Algorithm validated for both trellis-based continuous rows and traditional orchard rows of discrete trees. Method scalable to other agricultural operations, such as fertilizing or data registration for auditing purposes. Abstract. The implementation of crop protection solutions contributing to significant reductions in the use and risk of chemical pesticides has motivated the interest of site-specific systems, such as variable rate technologies based on user-set prescriptions. However, the practical implementation of variable rates has been dissuasive for many growers who are not familiar with digital solutions, as proprietary firmware is often difficult to grasp. This paper presents a method for formatting prescription maps that is independent of manufacturers, can be easily and freely implemented by industry and can be adopted by growers not familiar with advanced software tools. The methodology was successfully demonstrated for perennial specialty crops, in particular for trellised vineyards in vertical shoot position and for traditional olive groves. Results showed that the variations within user prescription maps were translated to the fields, but flow errors appeared due to the challenge of measuring flow and pressure in the highly pulsating actuation of pulse-width-modulated (PWM) valves. Such errors diminished with the use of low-volume rates and the optimal selection of the nozzles when adjusted to the real pressure measured in the field. The use cases validated in the field showed the consistency of the method for highly populated prescription maps of 1,221 points/ha accessible to advanced farmers, as well as for modest maps of 80 points/ha within reach of the majority of growers. Keywords: Automated map building, Local tangent plane coordinates, Orchard crop operations, Precision farming, Prescription maps, User-centered approach, Variable rate spraying.