Yes it certainly could be that. The margins for sheep & beef farmers especially are quite thin so they are essentially surviving year to year and wouldn't want to risk even a short-term impacts.

Although I would argue that some of it is common sense which is eschewed because of the thin margins. In NZ, farmers will annually replace phosphate, nitrogen, and potassium because they know it is lost to produce/erosion/environmental factors. But the same isn't true of 20+ other nutrients that make a healthy soil. Soil is like the human body which has an amazing ability to survive on just bread and water, but that doesn't necessarily mean that's all you should feed it