Automatic adjustment of harrowing intensity in cereals using digital image analysis

Michael Späth,Markus Sökefeld,Adnan Nabout,Victor Rueda Ayala,Roland Gerhards,Gerassimos G. Peteinatos

doi:10.1111/wre.12458

Michael Späth, Markus Sökefeld + Show 4 more

Open Access

https://doi.org/10.1111/wre.12458

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Abstract

AbstractPrecision farming technologies were implemented into a commercial harrow to increase selectivity of weed harrowing in spring cereals. Digital cameras were mounted before and after the harrow measuring crop cover. Crop soil cover (CSC) was computed out of these two images. Eight field experiments were carried out in spring cereals. Mode of harrowing intensity was changed in four experiments by speed, number of passes and tine angle. Each mode was varied in five intensities. In four experiments, only intensity of harrowing was changed. Weed control efficacy (WCE) and CSC were measured immediately after harrowing. Crop recovery was assessed 14 days after harrowing. Modes of intensity were not significantly different. However, intensity had significant effects on WCE and CSC. Cereals recovered from 10% CSC, and selectivity was in the constant range at 10% CSC. Therefore, 10% CSC was the threshold for the decision algorithm. If the actual CSC was below 10% CSC, intensity was increased. If the actual CSC was higher than 10%, intensity was decreased. Image analysis, decision support system and automatic control of harrowing intensity by hydraulic adjustment of tine angle were installed on a controller mounted on the harrow. The new system was tested in an additional field study. Threshold values for CSC were set at 10%, 30% and 60%. Automatic tine angle adjustment precisely realised the three different CSC values with variations of 1.5% to 3%. This development contributes to selective weed control and supports farmers during harrowing.

Highlights

Chemical weed control still plays a dominant role in weed management strategies, there is a strong need for alternative measures and integrated management
Selectivity curve shows a steep increase in weed control efficacy up to approximately 10% crop soil cover (CSC) (Figure 2)
If the CSC was lower than preset threshold, the tine angle was increased to achieve a higher weed control efficacy (Figure 3)

Summary

| INTRODUCTION

Chemical weed control still plays a dominant role in weed management strategies, there is a strong need for alternative measures and integrated management. Rueda-Ayala et al (2013) mounted an electronic soil density sensor on a harrow tine to measure the draught force of the soil at a depth of 2–5 cm Their decision algorithm decided to harrow more aggressively in areas with dense and heavy soil and with a reduced intensity in field sections with light soil. They applied the highest intensity of harrowing at locations with high weed density and reduced harrowing intensity in areas with medium and low weed infestation Other factors such as the crop coverage remaining immediately after treatment and the soil moisture were not considered in the decision algorithm. A controller was installed on the harrow to analyse the images, compare the actual CSC with a preset threshold value and transfer the decision to the online hydraulic tine angle regulation system for adjusting the harrowing intensity.

| MATERIALS AND METHODS

Findings

| DISCUSSION