I believe that the reason why those fields are uniformly yellow is because of desiccation. A terrible process to make crops easily harvestable. They spray glyphosate over the entire crop to kill it evenly.
The problem is that glyphosate kills more than just they crop intended and that long term studies have shown that it is a carcinogen. People that live near an area where they are spraying have a much higher chance of getting cancer.
Studies have also show that higher than allowed amounts
of glyphosate are found in the water supply of nations that allow the use of Round-up.
Its another example of mega corporations (Monsanto/Bayer) in control of any thing is not a good thing for the citizens of any nation.
I could site many articles and many cases of these studies but I will let you decide if you care. If you do you will look into it yourself. Here is a good place to start
There are various things farmers do that can harm us, but these may just be like that due to several weeks with no rain. Wheat has been turning golden for centuries