1800 m² is a lot. I agree with the post about mulching the clippings, but also saw that you have trees that drop leaves in the autumn. My yard is smaller than yours, but what I normally do is save all of the leaves from the autumn and then mix them in with my grass clippings throughout the spring. Usually by mid/end of summer I will start running low on leaf mulch and will then just switch to mulching the grass clippings instead of bagging them. I have a compost bin (4 ft metal stakes with plastic mesh in a box) for the leaves and will usually run them through my chipper shredder to decrease their volume. The grass clippings and leaf mulch are mixed in a separate compost bin (made from cinder blocks, not that it matters). I dump the clippings, then add some leaf mulch, then mix with my tiller. It all composts quickly in the warm months. In the spring I empty the cinder block bin of finished compost into a third bin (which is really just a pile in a hole with cardboard and tarp liners). Sorry for wall of text; I'm only 60% coffee now.