93.9 BayFM Geelong
Vegetables have undergone amazing changes since we started selective breeding and cultivating them a relatively short time ago. These creations are hungry little monsters and need fertile soil and good nutrition. With Australian soils being low in some nutrients, kitchen gardening can be a disappointing experience if you don't know a little about how to feed your veggies.
Signs your veggies aren't receiving enough nutrition vary. Although, generally yellowing of older leaves, poor growth rates and pale colour gives you indications that something isn't right.
It's also important to remember that plants can only uptake nutrients when their water supply is sufficient i.e the nutrients become absorbable when soluble. It also helps to explain why liquid type fertilisers tend to give you faster results.
The Big 3
Major nutrients (as distinct from minor or trace nutrients) are so called because of the quantity required. Nitrogen, Phosphorus and Potassium or (N), (P) and (K) have hugely impacted Australia's capacity to grow food. Phosphorus especially is in low supply in Australia's soil and this explains why phosphorus-rich grey water will kill your native plants - they're simply not used to it. But this abundance of nutrients has caused problems when mixed with existing river systems (think weeds and algae) as nature adapts to uptake the new found fertility. Additionally as soil biology has decreased with large scale herbicide, fungicide and pesticide use, much of the nutrition is now 'locked up' in the soil.
The answer? Compost. As is the answer to so many food growing problems, adding organic matter to feed the soil helps to unlock the fertility as well as drastically reduce the amount of fertiliser needed.
Organic vs Synthetic
One advantage of buying synthetically produced fertiliser off the shelf is that you can readily read the amount of major nutrients in contains. They'll often be listed in ratios following the (N), (P), (K) order e.g. a good measure for standard vegetables is (5:6:4).
Of course if you're purchasing chicken manure off the side of the road, it's near impossible to know what ratios are in it. Plus it could be mixed with different litter such as wood shavings or straw which will also impact nitrogen levels.
As a general rule, grain eating birds will produce much higher nutrient manure than grass eating ruminants such as cows and sheep. But the very important advantage of using animal manures is that you also get benefits to your soil structure. Not only are the fertilisers, they are also fantastic soil conditioners and help to encourage life within our soils.
Processed organic fertilisers such as blood and bone and pelletise chook manure (dynamic lifter) will often include major nutrient ratios on their packaging, providing a good compromise between fresh manure and synthetic fertilisers.
To good to flush!
Ending on perhaps a controversial note…we all have one incredibly high value source of liquid fertiliser that we flush away several times a day. For example, did you know that 95% of excess human nutrients pass through our urine? How to do it? Well, this stuff is so good that you need to dilute it. Every heard the story about urinating on lemon trees? Well for every person that's told me it's a good idea, another has told me ''their sons killed a tree doing that!" You need to ensure you dilute the urine with about 9 parts water for every part of urine. A large bucket with a lid in the bathroom is all that's needed for dilution. Avoid splashing the (sterile) urine mix over the tops of plants instead aiming at the drip zone. Check out this example of Swedish knowledge being used in Ethiopia:
Incredibly urine is so high in nutrients that one person can provide liquid fertiliser for 300 - 400 square metres every year! Maybe it should be (N) (Pee) (K)!
Andrew Lucas comes to BayFM.com.au with a wealth of fruitful gardening experience!
His interest in food gardening started as a cook, but whilst on a trip through eastern Europe in 1999 he became fascinated with the incredibly productive and beautiful urban veggie patches present in most communities. Returning inspired, he dug up his own back yard upon returning and hasn't look back since! Specialising in kitchen gardens it's no surprise our gardening guru lives in Geelong's north-west where he picks up tips from the locals - many of whom bring decades of productive gardening knowledge from Europe and Asia.
You can read his full profile here.