17 November 2021
What’s happening in the First Creek Wetland’s ‘settlement’ pond?An alga has been growing there that hasn’t been recorded in Adelaide for many years.
Date posted: 18 September 2015
Welcome to the first City Crop blog of 2015! This is a place where you can not only keep up-to-date with news and events from the City Crop, but also find out why this fascinating plant is so important.
First up – and we know you’re probably wondering – why Lucerne (Medicago sativa)? We’ve already mentioned, via this page, that Lucerne is a perennial (it lives for more than two years) flowering plant in the legume family, and it’s an important plant in Australia for grazing and/or hay production (it feeds cows, which produce the dairy products many consume each day). We also mentioned that you might be more familiar with Lucerne in another form – in your sandwiches and salads as alfalfa sprouts!
But did you know Lucerne has another really important function?
One of the reasons Lucerne was chosen for the City Crop this year was the plant’s ability to “fix” nitrogen in soil.
Our previous crops of corn, barley and wheat were a lot of fun, but testing at the City Crop afterwards revealed the soil was lacking in nitrogen, which is a major element that plants need so they can grow.
Legumes like Lucerne (or peas, beans and clover) are incredible plants because unlike most plants they’re able to get nitrogen from air in the soil.
They do this by forming a symbiotic relationship (living with one another) with a type of bacteria called rhizobium, which live in little things called nodules on the plant’s roots. This bacteria can take the nitrogen from the air and feed it to the legumes, and the process is called nitrogen fixation.
The great news for City Crop’s soil is that when the Lucerne dies or is mown, the plants’ remaining nitrogen is released back into the soil, which becomes available to other plants – serving as a fertiliser for future crops!
We first tested City Crop’s soil in August, and the results indicated that nitrogen levels were low. We’ll be testing the soil throughout the Crop’s journey, so stay tuned to the blog and sign up for the City Crop e-newsletters to keep up-to-date with the soil’s progress!