Time to super?

3 posts

Member for

11 years 11 months
Last seen: 08/15/2017 - 15:44
Joined: 11/07/2012 - 16:02

Time to super?

What is the best time to super . Most of the best rain comes (usually) in winter. But 2nd best time is summer, (storms, mostly in Feb). Has't been done for 4/5 years and most of the pasture seems to be Kangaroo Grass, But there are patches of Phalaris and various clovers. Feather grass abounds and there are scaterings of others i can't identify. 

 

Last seen: 03/08/2018 - 21:05
Joined: 10/20/2011 - 16:16

Hi Barra

Applying super(phosphate) will provide both phosphorous and sulphur and a little calcium. All elements are important for plant (and animal) nutrition although the amount of calcium supplied via super is not very much.

The first rule for applying super is to try and apply it when rain will follow. The reason is to ensure stock do not ingest any fertiliser, it is not very good for them.

With regards to phosphorous, the time of the year for application is really somewhat irrelevant, as phosphate applications are really about building up reserves so some gets to spill out for plant growth. The amount of time that phosphorous is in an immediately plant available when applied in a super phosphate form is said to last only days anyhow. There-after it releases due to weathering, microbial action, and due to the action of  the slight acidifying of surrounding soil by plant roots as they feed. This is a long term process.

Sulphur is a bit different. It doesn't get locked up in the soil like phosphorous although will get 'washed away' over time in its sulphate form as is applied in superphosphate. Sulphur is also released to a plant available (but also water soluble)  form  from organically bound forms of sulphur (which are not water soluble) in the soil,  by naturally resident  soil bacteria. In the winter, going into the spring, since it is colder, this microbial process slows down lessening the amount of plant available sulphur in the soil . There is therefore an argument that an application of super in the spring will give greater benefit as the sulphur reserves can be very low. The yellowing of pastures in late winter, especially after alot of rain, is often attributed to low nitrogen, but often, is due to low sulphur as well. That is why if you're applying nitrogen for a pasture boost, using sulphate of ammonia which has both nitrogen and sulphur can give considerably better results than straight urea, which has nitrogen only. Not many understand this unfortunately.

For your situation, where the fertility is so low, probably any application of fert anytime, so long as it soon gets washed in is good.

You should really do a soil test though. There's not much point in applying superphosphate if for example, the soil pH is very low as the phosphorous and sulphur are much less available at low soil pH's. It could be you need to apply lime first.

Hope these comments help rather than confuse

regards

Roger

 

Last seen: 03/08/2018 - 21:05
Joined: 07/23/2013 - 18:26
Hi Barra, Whatever time you choose there is one thing you should do apart from applying the Super and that is to apply soil-microbes. The reason for applying soil-microbes is that the microbes will convert Super into soluble forms for the plant, store any excess reducing any leaching of the Super while increasing supply of other nutrients that may be in your soil such as sulphur, iron and copper. Additionally, as the microbes will source nutrients for your plants, you will be able to reduce the amount of Supper. But, yes there is a but - Make sure you use quality microbes. Check the labels of the product to see what it contains and what strength (how many microbes per gram/ml). Cheers Peter

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