Mulch and compost, you have to look at where the stuff comes from, and what it's made of. A lot of places around here, or bagged products will mention "locally sourced products". This is a catch all BS statement. In our area this means poultry bedding - this bedding is usually made of or consists of rice hulls. What do you know about rice hulls. In the last 20 or so years plant breeders have increased the amount of silica in the plant. This means a stronger stem that will prevent lodging of the rice head as the plant matures in standing water. Silica doesn't break down very easy, and rice hulls are cheap organic matter/bulk. It is like filler. Now if you live in a dry arid area, like Nev, Az, Cent Calif. Organic matter is very important, but the high temps, along with other biologic activity will eat this up very quickly. Secondly, in order to facilitate the decomposition of organic matter, you need lots of (N) Nitrogen. The bioflora and fauna of soil microbes is fueled by N. In order to get rid of salt and alkali you need to use; Yes, organic matter, AND a good soil amendment. Forest mulch is good in the compost (if particulate size is small). Now let's talk "s***".
Manure is good, but where does it come from. Steer Manure is from feed lot cattle and this is where you can pick up weed seed, based on what is feed to the cattle. Dairy manure, this is where the questions come up. Most all dairies have a manure separator. Liquid from solids. Yes salts can be elevated, but only if you are getting it from "The source", composted should be fine. I have had numerous growers compost dairy manure with (cotton) gin trash. The left overs from processing, cleaning, and seeding the lint after harvest. Additionally, a word of caution about dairy manure is the high amounts of ammonia from the urine, but this will break down to NO3, or was it NO4, ammonic nitrogen.
Test question: a source of N to assist in breaking down organic matter, which was combined with gyp in your application.
It is important to maintain a balance in your soil of organic matter, nutrients, and amendments. One source I've dealt with was a solution of bovine and poultry manures that was enhanced with lab grown beneficial soil microbes, and a sea weed extract. (Cytokines) from the sea weed (prob kelp) are a growth hormone. A lot of my old customers thought I was trying to get them to use a Snake Oil.
Long story short, keep your soil healthy, feed your plants, AND feed your soil. FEED IT, LADDY.
I let it grow, around here it likes the stuff I like to weedwack.