Our Green Gurus

Guest bloggers share all you need to know to lead a greener lifestyle.

The low-fertiliser garden

Zucchini

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By guest blogger Christian Monahan from The Produce Garden tells us how he doesn't need to buy fertilisers for his vegie garden.

No fertilisers? But what about trace elements, potash, lime, dolomite, blood and bone, Epsom salts, magnesium, sulphate and everything else that we’ve been told to feed our veg garden beds? I’ve told a few people about my no-fertiliser theory. Most gave me a puzzled look of disbelief. Some laughed. I didn’t tell the laughing ones any more of my theories for fear of further ridicule, but I am absolute in my no-fertiliser policy – my garden must provide for itself.

My initial spark for not buying fertilisers came from a paper I wrote on what I call the 'rainforest theory'. All forests contain fauna which no doubt poops, pees and eventually dies on the forest floor. This, in turn, gives back to the plant/tree system in the form of manure and blood and bone, in their most basic and natural states. Which also brings me to the other natural process involved, that of plants and trees decaying on the forest floor, providing a basic form of compost and mulch. So, instead of pulling up harvested plants and composting them, I simply ripped them up and put them back on top of the beds to break down naturally. At the start I was curious to know whether I would achieve the same result as using fertilisers.

In my first two experimental garden beds, the answer was a resounding yes! Initially the harvested and returned plants didn’t seem to be doing much except sit there, but after 1-2 months they started to break down and not only did my plants suddenly perk up but I also noticed greater life in the soil. I wasn’t sure that what I grew would be enough to totally replenish the soil, so I started using fodder crops – also called green manure crops - to give me more to harvest back in and increase the nutrient return to the soil. I called the process 'self return'.

At first, I planted loads of peas. They were easy to grow, I liked eating them and saving their seed was simple. Plus, they gave a good return in fixed nitrogen on their root systems and in mulch from their vines. They grew fantastically and exploded with produce. I was giving everyone I knew peas and snowpeas by the kilo. Once they started to yellow and I’d saved the seed I wanted, I squashed them down along the beds as a mulch. It worked beautifully.

Other nitrogen fixing plants I use include comfrey, clover, parsley, lupins and various beans. Clover is easy. You just sprinkle seed across the beds. Once it sprouts and the plants are 12-15cm in diameter, I just pull it up and put it under the mulch to break down. Same with the peas, beans and other legumes. Mostly, I just chop them off at ground level, leave the root systems in the ground to break down naturally and throw the rest on top of the bed or tuck it under the mulch layer.

I do use some well broken down manure in the vegetable garden throughout the year, mainly because my sheep and chickens provide it for me. I believe it and the harvested green plants together provide a complete macro/micro nutrient return.

If my calculations are correct, the nutritional value of the harvested plant should be higher than the nutritional value that the plant took out of the soil to begin with. In theory, by putting the harvested plants back, I am always adding more nutrients than were initially taken away.

The idea of just harvesting and throwing the leftovers back on the beds sounds good in theory. It is the most basic form of composting, though I must add that due to their anaerobic form and the fact that they don't generate much heat when they break down, it does take longer and is subject to weather conditions. I should mention that though I still mulch the beds, I don't use as much as I used to – maybe a light scattering of pea straw, lucerne or sugar cane mulch twice a year. I even throw the weeds back on, but not if they’ve formed seed heads or I'd be asking for trouble. I don't put any 'runner' variety grasses on either as they’re extremely resilient and will continue to grow.

Before I started this 'self composting', I would often go out at night to hunt down snails and slugs that were having nightly picnics at my expense, but after a while I stopped seeing those slimy suckers all over the place and instead saw all kinds of tiny and medium-sized frogs: green ones, brown ones, striped ones. They’re such wonderful little creatures. They obviously saw the good times available over yonder from the pond and came across, not only massively reducing my pest problems but giving my nightly jaunts an aspect of awe and wonderment at Mother Nature.

I not only had a whole new crew of friends hopping about above ground, but beneath all the newly layered plant material I was also seeing a change that was nothing short of wonderful. Brushing aside the litter and old foliage to reveal the soil's surface, I found a hive of insect activity. The soil was cool to the hand and remarkably friable even though it hadn’t had seen a shovel, fork or any other gardening implement in 18 months because of my no-till practice.

If you were really keen to 'fertilise' but wanted to follow what I’m doing, you could always make a weed tea. Put the weeds in an old pillowcase or the like (this will catch any seeds and makes the weeds easy to remove) and soak the bag in water for a week. Dilute one part weed tea to five parts water and pour it on your vegetables. Alternatively, you could make a simple manure tea. Add two handfuls of manure (cow poo is good) to a bucket of water, leave it for around five days, then pour it on. Tomatoes love this one!

For me, liquid feeds like this are OK. It’s the bought fertilisers that I don’t use – the petrochemical ones that really don’t need to be used at all. We have all the natural means of growing fertilisers at our disposal. Give it a go and you’ll be amazed at the results.