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An Organic Fertiliser for Your Garden?

by Gordon Rowland

Responses to the October 2010 ILDA newsletter article 'An Organic Fertiliser for Your Garden', included one reader's dissenting opinion. I published this, and my reply, in the November newsletter, that you may already have seen.

Better late than never, I'm now publishing it on this blog, as I should have in the first place. So you can now share your comments with other readers, in the Comments box at the foot of this page.  

An organic fertiliser for your garden

For many years I used and recommended Nitrosol® and Osmocote Native® fertilisers.

Nitrosol® is an organic liquid fertiliser made from blood and bone. Its major (macro) nutrient (N:P:K) analysis is N (Nitrogen) 8: P (Phosphorus) 3: K (Potassium) 6.

Osmocote Native® is an inorganic slow-release fertiliser. Its N:P:K analysis is N 17.9: P 0.8: K 7.3. These fertilisers both contain trace elements essential to healthy plant growth.

About two years ago, I started experimenting with a new (to me) fertiliser, Seasol Powerfeed®.

PowerFeed® is a concentrated liquid fertiliser made from fish and liquid composts. It contains all the nutrients including trace elements, required for healthy plant growth. It also acts as a clay breaker, improves soil structure, increases flower and fruit yields, stimulates beneficial microbial activity and helps reduce nutrient leaching in sandy soils.

PowerFeed® works even better when used in combination with Seasol® soil conditioner, a liquid seaweed concentrate.

Powerfeed’s N:P:K analysis is N 12: P 1.4: K 7.0, ideal for Australian native plants: sufficient nitrogen, but not so much as to cause weak, sappy growth; low phosphorus in accord with most native soils, insufficient to adversely affect phosphorus-sensitive natives, such as grevilleas and other members of the Proteaceae family. Powerfeed® also includes a fair proportion of potassium.

Seasol Planting Gel® is formulated for establishing new plants, providing slow release essential nutrients while it absorbs, retains and delivers water for up to 5 years.

Over the past two years, results have been so impressive that I now use and recommend only Powerfeed®, Seasol® soil conditioner and, for plant establishment, Seasol Planting Gel®.

'Barry' emailed:

Your article on fertilisers worries me. In it, you mention 4 fertilisers and a planting gel. If you plant native plants suited to your soil and rainfall, you don't need any of this. A bit of water to get them started, that's all.

I do water testing for our landcare group. Our creeks have high phosphate levels, high electrical conductivity and weed plumes - mostly from excess use of fertilisers. Gardening magazines and TV programmes all advocate this or that fertiliser every fortnight to keep your plants looking good. . .

Native plant growers can move away from that philosophy. Grow suitable plants and don't use fertilisers. If, over time, your plant appears to be suffering a shortage of some element, add a little then, not before. And don't plant that species again.

If you could advocate those principles in your newsletters, you would be doing us all a service. . .

And my reply:

I should have made it clear that I don't advocate fortnightly/frequent fertiliser applications, just two applications a year (mid-August and mid-February, maximum) . . .

My additional comments:

By stimulating microbial activity, low-phosphorus organic soil conditioners/fertilisers help recondition disturbed or over-worked garden soils. Contrary to commonly held assumptions, container-grown trees and shrubs are generally much less robust than their wild counterparts. Low-phosphorus organic soil conditioners/fertilisershelp compensate by strengthening their roots, top growth and disease resistance during establishment.


November 2, 2010
Category: Plants and ILDA RSS

1 Posted Comment

(1 awaiting approval)
  • Maree  Apr 16, 2011 @ 2:45pm wrote:

    I agree with you Gordon that nursery-grown plants are not equipped with the same vitality as natural wild native plants. One of the reasons would be that natural soils and their ecosystems come equipped with many fungi that are symbiotic to the native plants. In Australia, we've only described 5% of Australian Fungi so far and very little is known about their ecologies. However, what we do know, is that fungi can have a huge beneficial effect on Plants. For example, protection against pathogenic fungi, increase water and nutrient absorption whilst protecting against dessication, stimulate production of plant growth hormones, condition soil, and, Fungi can even isolate harmful mineral contamination. Artificial fertilisers can harm fungi so all this means that whilst it might be a good thing to just put the plants in the ground, water and forget them - and it may even preserve the natural soil fungi by doing this, it sometimes produces better results by using organic fertilisers such as seaweed extract to boost the plants whilst waiting for natural fungi to help out.

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