Trying to prepare my plot for root vegetable seed planting. It is quite claggy/clay type soil, i have managed to break it down to smaller pieces - about golf ball size, maybe a bit smaller, - I then plan to do small trench with compost and plant seed in that. Problem is I haven't time to do that yet as away for a couple of weeks, should I just cover the prepared ground with black plastic until my return, or leave it open to the elements, in the hope it will slightly improve the soil structure. I have scattered chicken manure pellets on there as well. Any advice/suggestions? Thanks.