I came across a study that poinked my interest immediately. Who studies this?
A chemical analysis of 100 municipal leaf samples collected from across New Jersey shows that leaves are a valuable source of all crop nutrients. Although nutrient concentration values vary considerably, the application of 20 ton/acre of leaves would add on average 400 pounds of nitrogen, 40 pounds of phosphorus, and 152 pounds of potassium.
So I thought it would be fun to ballpark what that translated to in my 750 sq. ft. of planted space (which excludes paths).
An acre is 43560 sq. ft. Divide that by my 750 sq. ft. and you get 58.2. So the actual planted area of my garden is about 1/58th of an acre (yikes, so tiny!)
The amount of leaves I’d need to put onto my garden to replicate the 20 tons/acre cited in the example would be about 700 lbs.
I don’t weigh the leaves I collect. Absolute negligence.
But 700 lbs. doesn’t seem out of the realm of possibility at all. Those tarp-loads are heavy, and I couldn’t even begin to guess how many loads I collected, let alone their weight.
I believe it was many more than 700 pounds, but let’s use 700 for convenience. That would translate to almost 7 lbs. of nitrogen, 2/3 lb. of phosphorus and 2 1/2 lbs. of potassium. Nice.
But (isn’t there always a but?) all that goodness isn’t like plopping down a bucketload of nitrogen or potassium:
The abundant carbon content of leaves leads to extensive development of fungi and bacteria in the soil which uses up the supply of available nitrogen for the production of microbial cell tissue. As decay proceeds, the carbon-nitrogen ratio decreases and some of the nitrogen becomes available to plants. Because of the high carbon content of raw leaves relative to their nitrogen content, there will likely be very little of the organic nitrogen in leaves available to crops for a period of time after application. Observations of crops (including legumes) planted on soil to which leaves have been applied indicate that plants suffer from a temporary N deficiency unless additional N fertilizer is added.
In human talk, you can’t just dump leaves and get a poof of nitrogen immediately useful for your plants. It takes time.
What does this mean to me? Uhhhh…
Quantifying gardening is like stapling jello. Mostly stupid, but fun. I think it means that leaves on the garden are good.
Let’s go with that.