Rick. Search "Dynamic Accumulators" and you will find.
Here is one article on nutrients accumulated by weeds.
http://permaculturesource.wiki...
Dave: I meant to say also that you don't have to be a brawny guy to handle a shovel. Now I am not so sure about a steel handled shovel, or the most recent fiberglas handled shovels, but the traditional Ash handled Razorback shovels, still made to day, are perfectly balanced, and its the balance of a long handled tool that gives the momentum to slice into dirt, either skimming or digging. I am 5 ft 6in, 130 lbs, and Ive moved literally tons of dirt with an Ash handled Razorback. I must say at the end of season you have more muscles than earlier in the year! Shoveling as explained to me (by a master shoveler) gets its momentum to cut from the bending the legs. It is a whole body movement, not just using the biceps and forearms. {He also said that the key to shoveling for 4 hours or more on a hot day, was chewing tobacco--and learning how to spit correctly without hitting the toes of your Swartzkoff boots.) At 75, I am still a pretty good shoveler, but I never did get the tobacco spitting part.
