The researchers wanted to see how much nitrogen from chopped green manure helps barley grow the next year. They chopped the green manure and left it on the field or removed it. On one type of soil, leaving the chopped green manure increased barley yield by 10%. But on another type of soil, it didn't make a difference. The extra nitrogen from the chopped green manure only accounted for 3% of the total nitrogen in the plants. This shows that nitrogen loss from chopped green manure can be significant, and we need to find better ways to use it.