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location | Land Surfer,
I agree with all the comments posted and have some observations and twists of my own.
First off yield data is very important but at the same time over rated. Whole bushel values are plenty good as the scale and the agronomy is not that accurate. That said I pay an agronomist and he is very good but not a tenth or a 100th good. Secondly if yield data was that accurate I could buy and sell with the elevator on yield maps alone. If you are comparing say treatment plots WITH THE SAME VARIETY the yield monitor will probably show you relative differences which is what you are looking for. AS for absolute values go ask the elevator man to use your yield data. I don’t think yield monitors work good for variety selection unless the yield difference is blatantly different. I would not analyze a test plot with them but I would possibly cross calibrate and confirmed with a scale for kicks. Post processing of GPS yield data with actual scale data should happen more easily than it does in the industry.
What yield data is good for is finding relative differences in areas of the field which points out opportunities to enhance profits or reduce losses depending on the situation.
The catch to all this is finding what the opportunities really are as opposed to doing subjective delineations of other data sets and then calling them management zones when in fact they may not relate to yield at all. (Yield x Price – Expense = Profit or Loss) You have to start with yield data before you start on other things or you have no way to evaluate any changes you might make to different areas of the field.
Instead of management zones I like to talk about Profit Management Areas or PMA’s because profit is why I do things. While I love the life style it is no fun without profit.
I had the good fortune to work with some Nebraska Academics and their resulting grants from NASA, USDA, etc etc to pound to death with data collection a 160 acre section of ground with a pivot on it. Now the money has since run out and they are on to other grants etc. Some of the hooks with the grants had OF COURSE fertility data of all sorts along with many other things but we never got down to the issues of water, soil, topography, and other related data sets that you can create from some of those. But having the data in my GIS I have found (in this case) that while fertility is certainly important it pales in comparison to topographical related data sets when worked against yield data.
While there was a lot of “data messaging” going on in this project I could still drive around on any yield data set cleaned up or not and find the bad, average, and great parts of the field. After harvest my scout and I could get out of the GPS vehicle and visually verify that in fact the yield monitor took us to those poor spots very nicely (small ears on the ground etc)…and I think we just looked at whole numbers!!…….Now that is just a simple mapping exercise that can lead to poking some holes and asking more questions and thus a great reason to at least have crude mapping software……..BUT you can’t beat a powerful Agricultural GIS to get down to the brass tacks of querying data sets, creating new ones, or what ever it takes to find answers or at the very least new directions to take. I might add that a very small number of one stop shop Ag GIS packages exist out there but as was stated by others you need to work at it by investing money and time to use them. But when you think about it farmers do that all the time when they decide something is worth their time and money.
That then leads to…..you can do it yourself if you are probably staffed and ready for the challenge or you can hire someone to do it for you but most of all are you willing to pay them the true cost of that service or will it be bundle it up with some other product or service to “make it more affordable”?
A comment about using different packages to do different things…..Sometimes that is unavoidable but mainly that is because everyone is trying to make you buy everything from them and fence you in by constantly changing “standards” and muddying up the waters with new data set “standards” when all that is needed is a location on earth and a data value (lat, long, data, data, data, etc.). Remember the small numbers of Ag GIS that exist are still analyzing data but sometimes it has to be converted from the other companies’ packages that are “reinventing the wheel”. And so the saga continues….
To you final point about diminishing returns. In my opinion…..In a nut shell the more stable your yield variability of a field the quicker your diminishing returns happen and the less you can spend on all this fun. The more variable your yield data the more time, money, and energy you need to spend on all this to stop the bleeding. Thus your diminishing returns take longer to happen because you have so much to gain by dealing with the profit variability of your field and related operations.
Sincerely,
Arnie
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How deeply should we be looking at yield data?
