Vegetables can be grown in soils that have not been improved with fertilisers and other soil additives but the size and quality of the resultant crop will be less than if the plant is grown in soils which have been enriched with suitable fertilisers.
The kind of fertilisers I use in my own backyard consist of animal manures, spent mushroom grow bags, home made compost, blood & bone powder and dried, chipped seaweed. Soil amendments used consist of dolomite powder or sulphate of potash.http://hobartkitchengardens.blogspot.com.au/2010/09/ph-and-nutrient-availability.html
Animal manures suitable for direct contact with plant roots include aged bags of sheep and cow manure.Bounce Back is a pelleted manure blend which is certified organic and very convenient to use. 20 kg bags of bounce back can be brought from Waratah.wholesale 1 Tara St South Hobart for $11.30 Mushroom bags can be purchased from smaller nurseries in open top bags much cheaper than the sealed 20 litre bags sold in chain stores like Bunnings and K&D. Spent mushroom bags can give you a bonus crop of mushrooms if you cover the garden bed with straw after incorporating the mushroom bags into the top ten centimetres of soil, just keep up the water and wait for the mulch to rise.
Tasmanian made100% pure Blood & bonemeal can be purchased from Waratah or Roberts rural supplies in 25 kg bags for $30.50. Most blood and bone products on the market are only 60% pure with sawdust making up the rest.
Dried seaweed chips can be brought from Hollanders Imports, 87 Brooker Highway Hobart just before the ABC roundabout.
Ideally these fertilisers would be incorporated into the top 20 centimetre of the garden bed four weeks before planting out but who is that organised. Roots of plants can be burned by chicken manure which is best used as an ingredient in compost, but the inputs mentioned above can be incorporated on planting day without negative affect.
Amounts spread and frequency of application depend on how poor your soil is to start with and what you want to grow. A hand full of manure pellets, blood and bone and seaweed per square metre is good every 6- 12 months will feed most plants. If you are using sheep Manure or mushroom bags then a bag of each per three square metres of garden bed per year will see fantastic crop production. When growing root crops like carrots and parsnips or onions and garlic wait till after a heavy feeding crop like cauliflower or corn has taken many of the nutrients out of your soil, otherwise carrots will fork and onions will not store well.
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