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A BioAg fertility program leads to an increase in organic carbon and related yield response in a Riverland almond orchard.

Aroona, a property near Lyrup in South Australia’s Riverland region, grows 1460 hectares of almonds.

Under the guidance of Orchard General Manager Kelvin Tresize and with the assistance of BioAg Area Manager Phil Toy, Aroona is two years into a four year project involving a 13 hectare demonstration site and a customised fertility program. The first two years of the program have included regular applications of BioAg’s fermented microbial culture Soil & Seed.

The orchard soil is shallow and calcareous so the almond trees have only approximately 400mm where most roots exist. A key aim of the program is to make this layer as healthy and productive as possible.

Aroona can grow 4 tonnes/hectare of almonds using 10 megalitres of water/hectare, which is much better than the industry average. The program aims to maintain or improve water use efficiency.

Kelvin has reported profit improvements as well as improvements in soil carbon levels.

Organic carbon in the orchard soil has increased from 0.4 to 0.79 percent. This coincides with yields up to 93 Kg per hectare better than non-treated areas.

Increasing levels of carbon in the soil show that Soil & Seed has provided an increase in microbial population numbers.

These healthy microbes support trees with nutrition uptake. Tree photosynthesis has removed carbon from the air, which is stored away in the tree roots or in the soil microbes that the trees are interacting with.

As microbes die at the end of their lifecycle, the carbon that was locked up in their cells remains in the soil. This indicates Soil & Seed has initiated and supported well-balanced microbial activity in the soil.

Sustainability is important to Kelvin. ‘I think we have to look beyond seeing soil just as something that holds up horticultural crops. Health of the soil is important for efficient long-term production and a big part of better health is to build organic carbon, which is connected with bio-activity.’

Like many growers, he has an understanding of the part that microbial activity plays in soil health.

‘I believe building up soil biota puts trees in a better shape to withstand heat stress and disease pressure,’ he said.

‘There’s also likely to be more efficient use of applied fertilisers.’

Bio-activity may fluctuate for many reasons. Kelvin has observed that application of herbicides and fungicides can have an impact. Seasonal influences also come into play. With a BioAg fertility program, a grower is able to aim for a base level of activity with carefully measured applications. Application rates, methods and frequency of a given fertility program are informed by soil and tissue test results and the individual grower’s aims for a block.

Orchard General Manager Kelvin Tresize and BioAg’s Phil Toy inspecting almond blossoms at Aroona

The composition of Soil & Seed is controlled and the product can be applied through fertigation. The demonstration site at Aroona is in a section of low-level sprinklers.

Kelvin is also considering drip line application to compare and measure the effectiveness.

Phil Toy from BioAg agrees that the results so far are positive. “It’s not unusual to see real results in the first year of a BioAg fertility program. Further long-term benefits kick in as soil and plant health improve over time. What we have at Aroona is a tangible improvement after two years. Next steps include soil biology tests across the orchard to understand the numbers and types of biology in the soil.

“If this is what we’re seeing after two years, I’m excited about the long term benefits that BioAg can deliver to Aroona during the rest of the program.”

Questions about this article? Keen to see similar results in your orchard? We’d love to talk to you about how you can increase yield while improving the health of your soil.

Stephan Logoida
Horticulture & Viticulture
0428 640 070

Phil Toy
South Aust. Area Manager
0458 440 225