after the first year: it can be used as a replacement map to replace the nutrients that have been removed to grow the crop. This method won’t account for any in-soil nutritional requirements, it will just replace what has been taken out of the soil to grow the crop. An interesting comparison to make against these yield zones is the positioning of historical fence lines or field boundaries. In many instances the historical fence line will be the old-fashioned way of splitting up a field. With the old fence lines removed,


Data management is currently low down on the list of priorities for farmers, with many handing the task to their agronomist


be no consistency in the data being viewed. Therefore, a grower should ensure the scaling or bandings for winter wheat, for example, are the same across winter wheat in all fields and across years. Otherwise the data starts to become misleading. Is there any point in comparing canola yields with wheat yields using the same scale? Not really. However, comparing average yield trends


for canola and wheat against barley in the same field over a number of years is vital to the performance toolkit available to farmers and agronomists. Does the same part of the field always yield highly? And by how much compared with the low yielding parts of the field, regardless of the crop type. This is good, solid performance-related information. The natural step is then to ask why there


is a consistent yield difference. Once the cause has been identified, a variable rate map can be created to manage the consistent variability in the field.


How many zones? To start with, my preferred approach is to work on the basis that less is more. The


fewer zones you have the more manageable they are. So a field with three clearly defined yield zones will be easier to manage than a field with eight or nine zones where the difference is less defined. We also have to take in to account the


accuracy, or otherwise, of the yield monitor. The yield can vary across the width of a header by a significant amount and all the data is effectively an average from across the swath width. Focusing on the last few kilogrammes of yield is not going to affect the final analysis in terms of understanding general trends. In many instances, it is easier to understand and manage three or four zones compared with eight or nine, but over time the resolution can be increased if needed. Equally, resolution can be determined by the width of the seed drill, sprayer or fertiliser spreader. The wider the machine or the fewer controllable sections it has, the less resolution you require.


Multi-year use I get asked a lot if a yield map can be used after one year. As long as the data has been collected accurately, it can definitely be used


technology is putting digital fence lines back in to allow farmers to utilise the larger, more efficient equipment. The principles, though, are very similar. The old-fashioned boundary approach can be carried forward to soil texture zones as well. In many cases the zones are the same, which helps a grower decide if conductivity scanning is required or not. Looking at yield maps and old farm and field maps will help produce a soil management strategy. There’s a great amount of work that can be done before money is spent on scanning to understand what type of sensing technique should be used.


Look for trends, not the detail The advantages of using software analysis tools is the ability to look at a field in many different ways. It allows a farmer and agronomist to understand what was done in the past and whether the same or a new approach is needed to help grow crops successfully in the future. It brings together a range of information such as nutritional data, yield data, soil conductivity data and weather data, among others. The challenge is not to look at the detail in the information, but the trends. It’s the trends in the data over time that bring the most valuable information. One wet or dry year doesn’t or shouldn’t stimulate a sudden change in agronomic strategy. Continual poor zones in fields should


encourage farmers and growers to identify why the variation is there and understand how to manage it.


▶ FUTURE FARMING | 09 November 2017 39


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