You're going to want to be careful starting young plants in a heavily manure based mix.
Like Tex says, good leaf compost is the best substitute for 'composted humus', and it's a great source of organic material.
Make sure you have PLENTY of perlite and good drain holes!
That other stuff is 'mushroom compost', whcih is used media from commercial mushroom farming, and is nice for our plants. Liek all composts, it needs drain material added. Perlite is best, but outdoors, sand is fine, as long as it is free of salts.