Managing Spatial and Temporal Variability in Irrigated Agriculture Through Adaptive Control

Abstract

Spatial variability in crop production occurs as a result of spatial and temporal variations in soil structure and fertility; soil physical, chemical and hydraulic properties; irrigation applications; pests and diseases; and plant genetics. It is argued that this variability can be managed and the efficiency of irrigation water use increased by spatially variable application of irrigation water to meet the specific needs of individual management zones (areas of crop whose properties are relatively homogenous). The prospects for spatially varied irrigation applications and the need for adaptive control of irrigation application systems are identified. Current work at USQ directed toward adaptive control of furrow irrigation and centre pivot and lateral move machines is described. KEYWORDSReal-time control, furrow irrigation, centre pivot machines, lateral move machines INTRODUCTIONPractitioners of dry-land agriculture have embraced the concept and potential benefits of precision farming and substantial research has been undertaken on the yield mapping and variable rate technology that underlies the practice. Irrigation aspires to be a precision activity but one in which the traditional intention has been to deliver precisely the same quantity of water to each plant. The cost of any non-uniformity in irrigation applications is assumed to be reduced yield and lower efficiencies. However, this assumes that the requirements of each plant are exactly the same and ignores differences in crop water requirements due to spatial differences in soil hydraulic properties, fertility and other inputs. To counter the effects of this non-uniformity, irrigators are tempted apply larger water applications with a resultant reduction in volumetric and water use efficiencies.

Optimizing accuracy of measurement protocols for nitrogen application in dilute dairy manure

“…The results of this study show substantial accuracy advantages of continuous monitoring systems for PWW application. Automated irrigation systems are in development for surface gravity irrigation systems and have the potential to address water use efficiency and uniformity challenges in addition to fertigation management (Bali et al., 2018; Koech et al., 2010; Smith et al., 2009). Electrical conductivity proxy is one of several instantaneous N content measurements.…”

Integrated Decision Support, Sensor Networks, and Adaptive Control for Wireless Site-Specific Sprinkler Irrigation

“…On the other hand, closed-loop control systems measure the output of a process (feedback, measured response) resulting in periodic adjustments to the controlled parameters during the process in order to minimize the differences between a measured response and the desired response. These types of systems are often referred to as closed-loop or adaptive control systems and have the flexibility to change control parameters to adjust for changing conditions in space and time depending on the feedback mechanisms and limitations (Smith et al, 2009). Closed-loop adaptive control systems are not used with any precision agriculture technology other than site-specific sprinkler irrigation.…”

Precision Irrigation Scheduling Based on Wireless Soil Moisture Sensors to Improve Water Use Efficiency and Yield for Winter Wheat in Sub-Saharan Africa

“…For instance, a study of Mutorahuku irrigation scheme showed that approximately 8m /hr of water was lost due to damaged canals [6]. is is further exacerbated by the observation that irrigators assume that the water requirement of each plant across a eld is the same and ignore di erences in crop water requirements due to spatial factors, which include plant genetics, soil type, and topography [7][8][9], resulting in a blanket application of water. Such anecdotes give credence to the need to improve water use efficiency in smallholder irrigation systems [10,11].…”