Spent SubstratesWe use peanut hulls and wheat bran to make our mushroom substrates. The spent mushroom substrate makes a great compost/fertilizer for farming and gardening. We put our spent substrates into bulk bags that weigh over 1000lbs and four bags can cover an acre of farmland. We are offering our substrate at $20 a bag if you pick up.Or $100 a bag for delivery, minimum order of 4 bags for delivery to help cover delivery costs. There is no minimum if you pick up and we can load the bags onto your trailer or truck. Scheduling a pick up time is required.You may contact us anytime if you have any questions.over Order compost