There is a good chance you will have a lot of straw left over when you complete your house. Most of it, if you did your estimating right, will be in the form of loose straw. You will be amazed at just how much loose straw is produced on a building site. As I have said earlier, this loose straw is dangerous to the site as it poses the highest fire risk of any building material on site: dry, loose piles of straw! Be sure to move it away from your structure. But what to do with it all?
The best answer is: grow things! Use the straw in your garden as mulch. Use it to plant potatoes. Use it to make compost, especially if you have chickens. In fact, use it as chicken bedding or other animal bedding. There are so many wonderful uses for the “waste straw” that it really isn’t waste at all. There are not too many building materials that can honestly claim that.
If you do not have the space to use all of the straw, I suggest you contact your local farmers. Many, especially those who grow vegetables in small scale farms, will be thrilled to have free mulch. There are also farmers who make organic compost that need straw one of many ingredients in their mixes. They too enjoy free straw. The point is, it is never wasted if you take the time to find a good home for it.
Now what about the left over bales? You might be able to sell them to someone interested in building or in need of bales for something else. If you just have a few, you can use them as planters. It’s actually pretty cool. You carve out holes in the top of the bales and plant directly in the bales. The straw keeps the roots insulated and moist and the slow breakdown of the bales provides food for the plants. In addition, the roots have free run of the place throughout the bale, making a stronger plant. When you are done and are ready to harvest the plant for the last time, you can then thrown the whole planter into the compost and begin the cycle for next year!
Of course, there are plenty of things you can do with bales which I have not discussed. Build the kids a fort. Protect areas from run off. Build a garden wall. Many options are out there. Be creative and have fun.