Earlier, we posted about kickstarting the rooftop farm at Spectra Secondary School by growing green manure. You can read about that here. We are happy to report that the legumes have been growing very happily and rapidly. We have been intentionally lazy and have not watered or done anything. There is a time for us humans to work hard and there is also a time to sit back and watch nature do her magic. As expected, the monsoon rain really sped up the growth of our green manure.

Week 3

The legumes have sprouted and grown through the thin layer of mulch. You can literally see it growing by the day!

Day 17

Day 17

Day 19

Day 20

Day 20

Week 4

Day 23

Day 23

Week 5

Many of them have started to flower and a minority have become pods. Some say that this is the best time to dig the green manure into the soil. At this growth stage, the plants have not directed the nitrogen and other nutrients into the seed yet. If you dig it into the soil now the nutrients are all in the plant. Another benefit is that the seeds have not developed and the legumes will not grow again to compete with the next batch of crops. However we decided to leave them to grow a while longer to accumulate more organic mass.

Day 29. Flowers and pods.

Day 29

Day 29

Day 29

Week 6

By this point they have grown to be so lush and thick. Many of the pods have matured and turned into bean seeds. There is a lot of biodiversity up on the roof with dragonflies, hoverflies, bees, wasps, and more. Compared to what it was when we first stepped up to the rooftop, it has been a drastic transformation!

Day 40

Day 40

Day 40. Maturing pods.

Day 40. A busy bee with the flowers.

Day 40

Next Step: Chop and Drop

The green manure has done a great job as a pioneer species and it is time to move on. Other than rhyming nicely, “chop and drop” is a very useful technique. It simply means chopping the plant and letting it drop on the spot. The fallen plant will act as mulch and slowly release nutrients as it decomposes. If you remember, we mentioned that these legumes are great nitrogen-fixers and have accumulated lots of nitrogen in the plant body.

There is no uprooting required because we prefer not to disrupt the soil structure. The roots will rot inside the soil and as they do that they will feed the earthworms and microorganisms before creating air pockets for a loose and crumbly soil. There is no need to remove and chuck the chopped down plant matter as well. Less is sometimes more.

Before we started with the chop-and-drop, we were asked if it is wasteful killing the plants when they are thriving. We said that we didn’t think so because the dead plants will feed the soil. The fallen plants might not be food for us but they will be food for many insects and micro-organisms. After the soil is nourished then will we be fed. In nature, there is no waste or pollution.

The day of reckoning has come! Thank you green manure for your hard work. Time for you to return to the soil.

The extremely hardy legumes can survive even in the drain, albeit growing at a slower pace.

The nodules (little balls) contain nitrogen-fixing bacteria. If you squeeze them they burst open with an orange-red fluid.

We ended up pulling up the green manure by hand because it was easier than cutting or chopping.

We have a few beans already seeding, while some are still in the pod stage.

After the massacre…

Fallen warriors for a good cause!

We tried mulching the fallen plants to speed up decomposition.

A/B testing, pretty scientific hey!

For now, we will leave the fallen green manure warriors to rest. The plan is to let them rot for a while and settle into the soil. We will then return to plant…

Read other posts about Project Spectra here.