Sorry to disagree Ken. I don't know anyone who puts up fresh cut chopped grass or legumes as silage. Dosen't mean it won't work or doesn't happen, and I'd be interested to read any info you had on the topic. Haylage is ensiled forage of any type stored in any method at 35% moisture, and it is because of the lower moisture that it must be kept air tight. Corn silage can be ensiled on the ground uncovered if well compressed because of it's higher moisture. The top spoils but due to the weight, holds in place and acts as the air tight seal for the rest of the stack. Forages would dry on the top and blow off exposing the feed under to spoilage. If high moisture grass or legumes were sealed the moisture seepage would be enormous, breaking the seal. All silage should be harvested at 35-40% moisture so there is some aair in the pile/stack/bale/silo. This air allows aroebic digestion to start, (spoilage) which changes the PH of the crop using the byproduced, butric acid. Once the air is used up the PH will be correct for anaroebic bacteria (the inoculent if used) to start working producing lactic acid, preserving the feed. If air gets in the dormant butric acid producing bacteria can grow again spoiling the feed. There is a hay harvesting system which is mostly grass hay dried with the same bacterial inolculant used to make livestock feed silage. A few use propeonic acid too. This stuff is ending up as stored feed running 16-18% moisture although it is harvested at 20-25%. That stuff does not need to be stored air tight.