nanning,
by the look of it, this seems pretty poor soil (but I might be wrong)...you will probably need to find some compost, manure, hay, or something to make it darker, stronger, more alive. And use cover crops, especially nitrogen-fixers, eg. (my favourite) planting crimson clover in September (which lives thru the winter and starts growing again next spring), and will have amazing, beautiful flowers in May (pic shown). Then you can just cut it at the end of May when they have flowered. They will not come back, and you can transplant things into this mulch. Just an idea. It helps the soil, it is beautiful, it keeps back weeds and helps water retention as mulch. What's not to like? (the only drawback is that with this you can start planting only at the end, or middel of May, but that is OK, if you do warm loving crops, like tomatoes, basil, peppers, melons, squash, okra, etc)