Aim

To assess and measure pasture dry matter response over time, comparing BioAg treatments (annual and biennial) with annual treatments of single super phosphate (SSP).

The trial showed that the use of a slow release fertiliser based on “reactive phosphate rock” as used in BioAgPhos® and Superb® has an accumulative effect over time, continual applications either annually or biennially work to improve pasture dry matter production. The trial showed that Superb® produced more dry matter than conventional P and S fertilisers, though on a statistical basis they would be considered equal. It is clear that Superb® performed as well as traditional fertiliser in a modest rainfall pasture system.
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Introduction

Phosphorus (P), sulphur (S) and calcium (Ca) are all-important nutrients for a quality pasture.

P is essential for plant growth. It plays a role in photosynthesis, respiration, energy storage and transfer, cell division, cell enlargement and many other vital plant functions. Phosphate helps promote early root formation and growth, it is a large contributor to yield and profitability in pastures and crops and it assists in the transportation of nutrients.

S is used by plants to help with nitrogen metabolism, enzyme activity and protein and oil synthesis. It also helps stimulate soil biology, rumen biology and helps maximizes wool tensile strength.

Ca is also important in root and shoot stimulation, helps with the mechanical strength of the plant (integrity and selectivity of cell membranes), activates several enzyme systems, helps neutralise organic acids within the plant, is essential for good seed set in subterranean clovers. It can also help stimulate microbial activity and molybdenum availability.

Both Single Super Phosphate (SSP) and Superb (BioAg) supply these three main ingredients.

SSP has been the mainstay of pasture production in Australia for a long time, but with changing ideals in agricultural communities, the use of “non-chemical” based fertilisers is rising. Superb is a blend of 2 naturally occurring products, being BioAgPhos (derived from reactive phosphate rock) and Gypsum.

BioAgPhos® is a unique fertiliser that provides pastures and crops with an immediate and continuing source of plant-available phosphate. It is made by digesting reactive phosphate rock (sourced from Algeria) with our proprietary microbial culture, which is designed to further break down the rock and improve nutrient availability to plants.

Methodology

The trial site selected and soil tested in 2014 and then again in 2018 to look at nutrient run-down Treatments were then applied (hand spread) based on district standard treatment (125kg/ha SSP – 11kg phosphorus (P) per hectare per year):

  • Nil
  • SSP – annual application
  • Superb – annual application
  • Superb – biennial application
  • BioAgPhos (BAP) – annual application
  • BioAgPhos (BAP) – biennial application

The trial site did offer the opportunity to include 6 other replicated treatments; these were used to research other treatments and had no impact on the aim, purpose or conclusions of the trial.

Plots were mown on a cut and carry basis (i.e. all mown material was removed from plots). No stock grazing was allowed although there was some accidental grazing from lambs in the spring of 2016 – two cuts were lost.

Treatments were re-applied as needed on an annual or biennial basis.

Total of 22 cuts were taken over a 4 year period finishing in the autumn of 2018.

Forage quality tests were also taken in the spring of 2017 – results also available in discussion.

Trial designs

Results and discussion

At the end of the trial the two Superb® treatments produced more dry-matter than SSP.

SSP produced the third highest amount of dry matter, better than both BioAgPhos® treatments while all treatments out-performed the nil treatment.

The treatments containing Sulfur (SSP and the two Superb® treatments) were significantly better than the straight phosphate products (BioAgPhos®).

Sulphur is an integral part of every living cell and a constituent of 3 of the 21 amino acids that form proteins.

Sulphur is also a constituent of enzymes and vitamins (thiamin and biotin), it is essential for nitrogen fixation in legumes.

It is also a necessary for chlorophyll formation.

This shows the importance of sulphur in pasture production and how, when combined with phosphorus, you can increase pasture dry matter production

graph showing cumulative effects

LSD = 507

Although there was no statistical difference between the two Superb® treatments with that of SSP, the trend showed that the longer the trial went the better the dry matter responses were to a slow release phosphate fertilizer (cumulative graph).

SSP was the better performer for the first 6-12 months of the trial.

From then on Superb® led dry-matter cuts.

The annual treatment of Superb® did slightly out-perform the biennial treatment in the first three years although the biennial treatment provided the best cumulative response in the last year of the trial.

The use of a slow release fertiliser based on “reactive phosphate rock” as used in BioAgPhos® and Superb® has an accumulative effect over time. Continual applications either annually or biennially work to improve pasture dry matter production.

The trial showed that Superb® produced more dry matter than conventional P and S fertilisers, though on a statistical basis they would be considered equal.

It is clear that Superb® performed as well as traditional fertiliser in a modest rainfall pasture system.

Cost comparison

Based on the dry matter production over 4 years the cheapest option is to spread Superb on a biennial basis (both on a per hectare price and on a cost of extra dry matter produced).

Also evident from the table is that with hay at a cost of anywhere between $150 and $300 per tonne of dry matter, i.e. 15-30c/kg DM – it is much cheaper to grow your own forage.

table showing costs of various treatments

Appendix

Climate – average temperature and rainfall figures (BOM)

Nutrient removal

The pasture was made up of primarily sub clover and improved grasses (phalaris and ryegrass).

The plots were all cut and the clippings weighed and exported off the site (there was no animal grazing and thus no effluent (urine or faeces) recycled back on to the plots).

A large amount of nutrient was therefore exported off the plots.

In general for every 1 tonne of dry matter removed per hectare (as hay).

Over the length of the trial, based on the two Superb® treatments and the SSP treatment, the average dry matter removed was 15649 kg.

This represents a nutrient removal over the length of the trial of about 407kg nitrogen, 47kg phosphorus, 344kg potassium, 39kg sulfur, 149kg calcium and 63kg magnesium.

We were applying 11kg P per annum (equivalent) with fertiliser, i.e. 44kg P per plot was applied over the length of the trial, just under what we took off as dry matter, but there was quite a decline in the soil P levels based on Colwell P measures (refer soil test results).

What happened?

Given the reduction in P levels for all treatments it would appear we applied less than the required maintenance levels, in practice annual or biennial soil tests would pick this up and nutrient application adjusted accordingly.

A significant decline was seen in potassium levels from the original soil test results – due to the total removal of dry matter.

Sulfur levels did improve over time with the addition especially with the addition of the fertilisers containing sulfur.

trial plots with hay

Soil tests (Environmental Analysis Lab – Lismore)

Feed Quality Results (October 2017 – Forage Lab Australia)

The results indicate an improvement in crude protein when using sustained release fertilisers – Superb® and BioAgPhos®) -which in turn delivered a higher Relative Feed Value.

In addition there was an increase in the feed’s calcium content when using Superb®.

These aspects will be evaluated further in future trials.

Phosphate (P) Cycle

Sulphur (S) cycle

Potassium (K) Cycle

Acknowledgements

BioAg would like to acknowledge the help of McGeechan Farm Supplies (Crookwell) and its staff for its help throughout the trial and to Mick McGeechan for hosting BioAg and allowing the trial to go forward.

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