From pretty pictures to decision making - how to make use of your yield maps

Take home messages

• Data correction
• Analyse
• Investigate/interrogate

Introduction

Most modern harvesters as part of their standard, come with yield mapping capabilities. A yield map can be a very valuable layer of information when it comes to assessing crop performance and paddock variability.

To enable a yield map to be used as an accurate layer of information, the raw data needs to be assessed and all data points which have inconsistencies need to be removed.

The processing of a yield map involves identifying and removing all data points which are not consistent with the area that they are in. These inconsistent data points are a result of normal harvest operations where the normal throughput of grain in the harvest operation is impeded, for example; head land turns, edge effects when opening paddocks up, partial header front passes, etc.

Once inconsistencies have been removed, the yield map is a reliable layer of information of what was recorded in the paddock at harvest and the yield map can then be calibrated to actual yield.

Most precision ag software programs will allow post calibration using actual tonnage, and therefore, production of an accurate yield map.

Yield maps are best viewed as raw data points when analysing to pick up subtle differences from pass to pass.

A contour map can be produced at the end of the process for easier viewing.

From this point a legend can be manipulated and produced to define an accurate map of information.

Most programs produce a legend as a standard spread in yield increments and this can show a large range of variance within the yield map. Manipulation of a legend can assist in identifying finer variability of a focused area, i.e. making the map tell a story.

Identifying and ground truthing the points of variation is the key to understanding the factors behind the variabilities and whether actions are then required.

Variabilities can come in several different forms; some that can be acted on (nutrition, pest control, irrigation, wild life, soil type, previous rotations, etc) and some that are climatic (frost, hail, heat stress, drought water logging, wind, etc).

A corrected yield map can then be used as a base to produce the following maps:

• Nutrient removal map
• Gross margin map
• Water use efficiency map
• Assist in the creation of a variable rate map
• Can also be used to verify applied nitrogen efficiency.

Contact details

Ian Delmenico
Crop-Rite P/L
2/270 Campbell Street, Swan Hill, Victoria 3585
0429 330856 
deli@croprite.com.au
Twitter: @croprite