The city gardener: Making your own natural fertilisers

Delores Johnson / The National

When I first began composting, I found it to be a somewhat odious business. The idea had immense appeal and bringing home a shiny new Bokashi bin was fun. The bin went under the kitchen sink, where it received all kinds of food waste – almost everything except meat and dairy. Layer by layer, we ­sprinkled these leftovers with the microbe-laced Bokashi bran, which activates the waste and starts it on its composting journey. Filling up the bin was hugely satisfying. What came after was a little trickier.

Since all my gardening exploits happen on my terrace, I emptied the first Bokashi lot into a large plastic bucket, sandwiching it between two layers of sweet sand. If you have a proper garden, you can bury the waste in a hole in the ground and forget about it until it finishes composting. For us, a couple of weeks into the process, the area around the compost pot presented a stomach-turning sight: a ring of brownish compost juice and fat white worms slithering up and down and all around the pot.

I scooped the worms back into the pot, not sure what else to do with them. The task was disagreeable – but what more than made up for it was the richness of the compost, which was immediately obvious. After almost a month, the kitchen waste had turned into soft and fragrant organic matter, rich in microbial life and alive with wriggling red and brown worms that were less offensive than their cousins.

Worms aren’t called ecosystem engineers for nothing. They help decompose dead organic matter, allowing bacteria and fungi to feed on it and release nutrients. Worms are also experts at burrowing, helping to loosen and aerate soil. Worm casts in these tunnels are ­nutrient-dense, creating a great environment for root growth.

We have also ventured into making our own fish fertiliser. Some gardeners skip the step of actually decomposing the fish before using it to improve growth. They bury fish heads and bones and a variety of other growth boosters into the planting hole before they transplant their seedlings. We weren’t that brave, mainly worried about the putrefying smell of rotting fish on our small terrace. But we did use one of the many online recipes for making fish fertiliser that called for quite an eclectic assortment of ingredients – fish bones, blackstrap molasses, sawdust, powdered seaweed and Epsom salts (although the last two are optional).

After mixing together the ingredients for the fish fertiliser, all you have to do is stir the mix every couple of days and keep the flies away to stop your fishy bucket from becoming a maggot haven. After a month, the fish fertiliser was ready. Since we already made compost to improve the soil, we strained our fish fertiliser to make an emulsion. Adding one to two tablespoons of fish emulsion per gallon of water makes an excellent foliar feed thanks to its speedily available high nitrogen content.

Using homemade fertilisers may not provide the knowledge that comes from a boxed product that lists exactly how much nitrogen, phosphorous and potassium it provides. However, there’s more to natural fertilisers than meets the eye. Take seaweed and kelp, for example. The real benefit of seaweed lies not in its nitrogen, phosphorus and potassium levels, but in the mix of trace elements, biological stimulants and disease prevention properties it provides to a growth environment. Mix seaweed with compost or fish meal, and you have a complete and excellent natural fertiliser.

Shumaila Ahmed is a ­Dubai-based gardener, teacher, ­researcher and writer.

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