Hi Marco,
There is quite bit of research regarding your first two research requests but regarding ‘nothing but coffee grounds’ generally research has focussed on coffee as an amendment rather than on its own for reasons I describe below. I’ve given some examples of each if you want more copy and paste my search terms into google. Hope that helps.
>>Compost teas just used for watering plants :
Example
(google search : 'compost teas' and 'on plants' and university)
>>Growing strictly in compost :
They do a lot of that kind of thing when someone has made some compost and they want to test for toxicity : eg, (google search : germination index and compost , or 'planted in compost' and toxicity tests) :
Example
>>Growing on Coffee grounds. An analysis of essential and beneficial elements in coffee grounds would give a good indication of what to expect related to growing.
It’s is
high in N but low in P and K, which makes me think it is better as an amendment or mixed with something else to balance it. (I always get the feeling that the closer to the patterns and products of nature you can get with your activities the better or you stack up problems for later. There seems to be inherent checks and balances. I did find the story of how hydroponics came about very interesting, which made me reflect on what is the boundary between anthropogenic activities and nature or if there was any boundary at all.) Getting back to matters more central to this post.
Growing on coffee grounds :
Overview
Example 1 This was up to 30% SFG (Spent Coffee Grounds) and compared composted and uncomposted grounds. ( google search 'coffee grounds' uncomposted journal university )
Example 2 Getting past the effects of chlorogenic acid present in coffee which restricts plant growth.
(google search : 'growing on coffee grounds' and studies and university)
There was one study at Haifa university that used
100% coffee grounds that was not well reported.
1
