Elemental disorder – tu much jin?
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In this second instalment of the Chinese five elements posts, we'll talk about 土 (tu, earth), the most commonly-used medium for plant growing, and mineral nutrients (including metals, jin, 金).
Plants can be temperamental little things and getting the right pairing can be important. Then there are fertilizers and nutrients to consider. Your average garden center can be quite daunting on first visit with the array of soils and supplements. So where do you start?
KISS
Keep it simple soil. We’re working on guides to help you, categorising plants by (amongst other things) how nutrient-demanding they are. But a safe bet is to get a good – ideally natural – general compost and go for plants that grow together naturally to hedge your bets. So what grows together naturally I hear you ask?
Just add peas and carrots...
There are some great graphics on companion planting out there, but a fun ‘hack’ is to look at repeated and old combinations in food recipes. Italians love tomatoes, basil and garlic, and they all grow very well together in a fantastic symbiosis. The tomato reaches for the sky, the garlic burrows into the soil and the basil sits in the middle ground, maximizing the precious space in your urban garden. Similarly Northern European hardier veg – like broccoli, cabbage, cauliflower and kale – often go well together. Peas and carrots, unsurprisingly make a happy couple!
Nutrient nerdery
The plants have their friends in your all purpose compost, but what about all those minerals and metals? Well, let’s first think about what a plant needs to grow (beyond carbon, oxygen and hydrogen, or C02, H20 and O2 to really be nerdy)? They need primary nutrients: nitrogen, phosphorous and potassium.
- The air is circa 79% nitrogen but sadly not all plants can benefit from that, except legumes, like beans which are able to absorb and process atmospheric nitrogen. In nature the most common sources of nitrogen are organic waste (animal and plant) and rain (when some of the atmospheric nitrogen makes it into the soil). If you've bought compost made of decomposed plant and animal matter, that’s a great start.
- Compost will also help with phosphorous content, as that’s most commonly produced by plant matter processed by animals, or poo(p) as most of you will know it. In a subsequent experimenting post we’ll discuss some ways to make your own compost easily and at home.
- Potassium is a little trickier, it’s common in clay soils (see below), but in many other soils it’s added as potash. Potash is generally mined, or plant ashes soaked in a pot of water can produce potash. If you’re feeling bold, perhaps you want to try that, but it might be easier to find a sustainable source of potash! Fish scraps and seaweed are one such sources, although a little pungent in a small space.
The secondary nutrients are calcium, magnesium and sulphur. For brevity’s sake, calcium is thankfully normally present in most decent bought composts, as is sulphur (found commonly in organic waste). Rather than buy magnesium fertiliser, a potential alternative is to dissolve a tiny bit of Epsom salts (1-2 teaspoons per gallon of water).
Micro-nutrients include zinc, copper, iron, manganese, boron, molybdenum, sodium, and chlorine. But we’ll save that for another time. The key thing to remember is that with primary nutrients the more the merrier, same for secondary nutrients, generally.
Can’t I just dig it up?
If you fancy just digging some soil from near where you live, go for it, but make sure you understand the soil type. Here’s a quick guide to them:
- Clay soil: uncannily like clay you played with in school; lumpy, sticky when wet and very hard when dry. Clay holds water so careful not to drown your plants.
- Sandy soil: feels like sand! And like sand it dries quickly and drains quickly, so don’t underwater with this soil. It’s often nutrient-poor, so you’ll need to get your nutrient nerdery on.
- Silt soil: drains similarly quickly to sand, but retains more moisture and is nutrient-richer. It often feels smooth to the touch but can get compacted easily.
- Peaty soil: an organic matter bonanza but sadly as its acidic it inhibits further decomposition and therefore lacks nutrients. Like clay in the water retention stakes.
- Chalky soil: stony and free-draining but lacking some micronutrients which stunt growth. Should feel like ground chalk.
- Loamy soil: everyone’s favourite, with good drainage, moisture retention and nutrient-packed.
Microscope and hairnet not really necessary for this test...
If you’re still unsure try this: put your soil into a small jar, filling it a third, then add water and shake very well. Leave it overnight. Loam, the holy grail of soil nerds, should result in quite clear water with layered particles at the bottom and some very fine particles at the top. Clay and silt soils will leave the water cloudy with the residue at the bottom. Peat soils will also leave the water cloudy (a little less so than clay) but with a lot floating at the top. Sandy soils will result in clear water and most the particles at the bottom. Chalky soils will leave the distinctive white grit at the bottom and grey water.
Buy cr*p and dead stuff
In conclusion, I would always opt for compost-rich soils with lots of organic matter, including poo(p) is possible and sprinkle it with dead-stuff (burned and soaked plant matter, fish and seaweed principally). If you have pets take care with fish bone meal, it can be a delicious treat, but potential harmful, especially if you’re adding other fertilisers or pesticides.
From poo(p), up next in the final instalment of the elemental trilogy we’ll torture the metaphor further as we talk about fire (huo, 火), in this case, the sun and how to maximise light in an urban garden.