The merits of biological vs chemical fertilisers measured over 3 years across 2 replicated trial sites
Two replicated soil health sites at Willow Creek and at Yundi on the Fluerieu Peninsula of SA contained 4 soil health treatments, 1 farmer method and a control. They were monitored to find differences in soil health, plant health, feed quality, biomass and soil moisture.
This aim was to find and provide a better regional understanding of the impact of the alternative and chemical fertilisers on soil moisture holding capacity, growing season length, soil acidity and other soil health parameters such as microbial properties (mainly bacteria and fungi), organic C and pasture health and production.
We found that the cost of biological treatments compared well with chemical treatments and can be applied in larger rates biannually saving on application cost. In addition, the biological soil health treatments made substantial improvements in soil health and plant health and the biomass and feed testes compared well with chemical treatments The cost of biological treatments compared well with chemical treatments and can be applied in larger rates biannually saving on application cost. Specifically, the biological soil health treatments:
• made a bigger difference when soil organic carbon was lower (such as at Yundi compared to Willow Creek)
• built soil carbon when the soil organic C was lower
o plant mineral uptake
o nitrogen availability and mineralisation
o phosphorus availability
o pH, and
o soil health indicators such as bacteria and fungi numbers.
• There were statistical differences in plant feed test results when comparing those treated with biological fertilisers vs chemical treatments.
• The cost of the minerals added to the treatments were in most cases beneficial as they were taken up by the plants.
• Some mineral elements where lacking in the soil need re application each year, while others do not. This is a case by case basis and there is more information in the report.
• The additional cost of biochar added to the FFF/S treatment Oct have played a role in improving soil moisture and mineral availability, biomass, soil health and pH as this treatment was overall the better of the biological treatments.
Full report can be found HERE
Soils Research Review – Fleurieu region
We have conducted a comprehensive “Soils Research Review” of soils trails, research and demonstration sites in the Fleurieu region including those relevant to the region. The review outlines the main outcomes of each project and gaps and recommendations for future soils research in the region. Click here for a copy of the report – Soils Research Review
We conducted a Biochar Trial under non irrigated pasture. With 100 and 200kg of biochar with 100 and 200kg of Single Super. The full report can be found here
Overall the biochar had a positive effect on both the plant biomass and minerals in the soil, with a statistical difference was detected in the plant minerals caused by biochar.
The biochar in general improved pasture biomass. In many cases the half fertiliser rates (100kg of urea) showed similar growth to the full fertiliser rates (200kg of Urea) indicating that the biochar may be holding nutrients in the soil allowing greater pasture growth.
Over 8 reliable pasture cuts there was more often an interaction between biochar rates than there were fertiliser rates and sometimes an interaction between both. When the seasonal factors were not limiting (ie November) it was more difficult to find a statistical difference.
There was a general pattern of mineral retention in the soil with added biochar and the mineral retention was higher in the soil with half fertiliser treatments rather than full fertiliser treatments. These results were not statistically analysed.
PLANT TISSUE TESTS
There was an increase in the amount of manganese in the plant tissue in the biochar treatments. This was the only statistical difference in minerals found in the plant tissue caused by biochar.
No significant differences due to the biochar treatment were detected with the feed test result. Higher fertiliser rate had a small effect on increasing fibre but reducing fat content.
This biochar video shows the trial being sown and discusses the trial.
Precision pH and Electro Magnetic Mapping Demonstration
Soil acidity is recognised as a major land degradation issue in the Fleurieu region. Historically, liming has occurred on a paddock by paddock basis and no account has been taken of pH variations across paddocks. pH mapping has the ability to determine in – paddock variation and lead to improve liming strategies which are both more cost effective and efficient in the treatment of soil acidity. This new technique will be undertaken on 10 paddocks on at least 5 farms. We expect this will be on around 300ha. Key aims will be to provide information on how well this new practice works in this region. This will include the accuracy of the technique and whether useful differences are observed and, if so, what landscape patterns are evident. For this reason, demonstrations will be undertaken on a range of different properties, soils and grazing regimes.
On each paddock evaluation of pH zones determined will be undertaken. In addition to producing the precision pH maps, evaluation work will be focussed on whether there is a relationship between surface pH zones identified and the pH in the 10-20cm layer ( i.e. subsurface acidity), and whether distinct landform patterns occur within the region so variation in pH can be estimated in other paddocks without the need for further testing.
The precision pH mapping machine has the capacity to undertake Electro Magnetic (EM) mapping at the same time. EM scanning should reflect the soil types, depth and depth to rock and clay so an evaluation of this technique will also be made. This may assist with the identification of moisture storage capability of different soil profiles.
The pH mapper results across the 10 paddocks and report can be found here.
Replicated soil health trial Willow Creek
Alternative soil health treatments across a replicated trial showed promise in building soil health. When compared to an unfertilised control, biologically treated plots showed improved mineral uptake, nitrogen use efficiency, pH and soil health indicators over a one-year period. The cost of the minerals added to the treatments were in most cases beneficial as they were taken up by the plants. The additional cost of biochar added to one treatment may have played a role in improving soil moisture and mineral availability and pH. Unfortunately, we did not find any statistical differences in plant biomass or feed value between treatments possibly due to the season and the method of analyses. A full copy of the report can be found here
Yundi Soil Health Trial
An additional soil health trail has been set up and monitored at Yundi. Initial results suggest that alternative soil treatment can increase a soils capacity to hold moisture. For more details click here
5 Soil Health Case Studies
This project aims to provide a better regional understanding of the impact of the alternative and chemical fertilisers on soil moisture holding capacity, growing season length, soil acidity and other soil health parameters such as microbial properties (mainly bacteria and fungi), organic C and pasture production. The methods are used:
• Five paired case study sites on farmer properties measuring soil health (paired means one site has a soil health or chemical treatment and the other a control). The treatments here have been established for a minimum of five years. It is important to note that the paired site is either a different paddock on the same farm or a different farm (next door). All paddocks are adjacent to their comparison. Care was taken to choose similar pasture species and soil types, but the grazing management was not the same and soil health treatments also different.
There was a range of grazing strategies and this influenced soil health and plant available water. The soil health was generally better where there were alternative fertilisers, however the soil health was well supported where there was a high grazing pressure and low grazing days. The soil biology was not as good where there was low ground cover and less plant species diversity.
The cation exchange capacity (CEC) was always higher on the biological sites supporting the transfer of nutrients from the soil to the plant. Denitrification was higher on high chemical N input sites. The pH of the soil was better in biological side irrespective of liming treatment
The report highlights the importance of grazing management, ground cover, and mix of pasture species in conjunction with biological fertilisers to support soil health. The final report needs a few small final edits pending feedback from the case study farmers and can be found here
Soil Moisture Probes
At each of our replicated soil health trials and case study sites we have a soil moisture probe and a probe also into the control. There are 5 sensors on each probe down to 5 depths. We measure Plant Available Water (PAW), soil moisture, soil temperature and rainfall. The soil moisture probe data can be viewed here
For other soil moisture data information:
Link into the Barossa Improved Grazing group data here
Link into the SAMDB NRM network here