Each packet contains a mix of field peas, oats, and tillage radish!
The peas are legumes; they form a symbiotic relationship with a type of bacteria that has the power to fix nitrogen gas (N2) from the air and transform it into plant available nitrogen in the soil! The pea plant attracts and feeds these rhizobium (rhizo meaning root-zone) bacteria with sugars that it produces through photosynthesis (Water plus carbon dioxide transformed into carbon chains – aka sugars – and oxygen). The bacteria feed on the plant’s sugars and their population expands rapidly! Their fast growth causes the plant’s root hair – where the bacteria have taken up residence – to swell, forming nodules on the pea plant’s roots.
The oats are fast growing and they give the peas something to climb up. They provide lots of organic biomass to feed back to the soil and have long roots to hold the soil in place while providing exudates (sugars and other foods) to diverse soil microorganisms.
Tillage radish is amazing for breaking up compacted soils and reducing the need for mechanical cultivation. Leave the radish to decompose in the ground to create wonderful air and water channels.
These seeds are best planted in the fall and will be killed by a cold winter, leaving a nice blanket on the soil and living roots in the ground until the coldest days. The above ground plant material and the below ground roots will slowly decompose as microbes eat the debris and are in turn eaten by larger organisms. Cover crops are sometimes called “Green Manure” for this reason – they nourish the next set of plants that will be planted in the same spot!
Image courtesy of: http://www.trawinseeds.ca/cover-crops/