Personally, if you want to improve the dirt I would add more texture to it. It's pretty much one solid color right now so it doesn't have much personality to it. And you have a point - the ground will be utterly covered in blood over time...but by that same logic - why put any design into anything? It's like saying "Meh, people won't be in this town forever, no point in taking time in designing it well" Though, I know that's a bit extreme.
However, it's up to you whether you like the clean look of the dirt and grass right now. Personally, I find that it's pretty flat and boring. Adding dark spots, maybe even muddy spots because yknow...pigs <_<...would make it more interesting. The grass could be more interesting by adding more blades of actual grass, which you have spread about, but you could use more.
But even more so than that just grass, dirt, and some trees isn't very interesting. You're a farmer right? Make some hay bales, maybe a farmhouse, picket fence, tractors, etc. These additions would make the environment way more dynamic in the way you have to deal with enemies - such as the possibility of being cornered and will make the player feel like they're in an actually interesting place.
I hope this helps. :S