Mulches with a hard cellulose structure such as sawdust, wood chips,I'm having a hard time figuring out a mechanism for nitrogen to be drawn up more than a couple of millimeters, then across an interface, and into a fresh mulch layer. Rain and gravity will carry N downward. Volatilization might cause nitrogenous gases to rise, but mulch won't have any effect on that. If anything, a mulch layer would slow that down by keeping the soil cool. Movement of N upward seems to require an organism that gets its N in the soil, takes it upward into the mulch, and then eats the mulch carbon to balance the nitrogen, or vice versa. What would move more than a couple of mm? Bacteria won't move that far. Fungal hyphae can transport nutrients, but it would be unusual to have a fungus with intact mycelial strands that cross the interface, from nicely decomposed earth into rough woody mulch. Insects or worms? Maybe, but it seems weird. If someone knows of a mechanism, I stand eager to be enlightened.
eucalyptus leaves and pine needles have high N demands to break down. Some N
will be drawn from air but can also use up N from the top soil layer.
Archive powered by MHonArc 2.6.24.