Hiring a content writer for my blog when I have no capital

I have a science and tech blog that needs a ton of work as I try to monetize it.

I want to get a content writer, so I can concentrate on fixing the blog, optimizing adsense, SEOing it, etc.

But, I don't necessarily want to pay up front per blog entry.

How can I hire someone?

I thought about a % of adsense revenue (I already have about 50 blog entries). Would 25% or 50% be good, or that a bad idea? Is there some way to make the adsense revenue dependent on the traffic generated by the specific blog entries the content write creates?

If I do end up paying up front by blog entry, how much is one entry worth? (maybe 1 hours work = $20-$30??????).

These are short entries (several hundred words, if), preferably current developments, with many links.

Here is the blog so far -- (so you can get an idea of the length and scope of each entry if you want):
http://www.scitechy.com