Anne Lee

A long-running farm-based study to compare the Albrecht Kinsey soil fertility approach with a more conventional approach hasn’t shown any major positives but it hasn’t shown any significant negative impacts either.

Back Track Dairies has been operating its two adjacent farm units under the different fertiliser approaches since 2012.

The 155ha Whakapono is run under the Albrecht Kinsey approach while the 210ha Waiora has been run using conventional fertiliser recommendations.

Jeremy Casey and Kim Solly farm the operation as an equity partnership and embarked on the comparative study so they could see for themselves if there were any positive or negative effects.

Jeremy says he’s been buoyed by the fact there aren’t any significant negatives and though they’re not major in terms of production or profit, the positives that he sees in animal health and the ability to keep nitrogen applications low, are enough for them to continue using the approach even though the funding for the study has come to an end.

The couple became interested in the Albrecht Kinsey approach through Kim’s father who supplies agricultural dolomite, rich in magnesium and calcium.

Calcium and magnesium are central to the Albrecht Kinsey fertiliser approach in that it aims to maintain the soil so its cation exchange capacity is saturated to 80% with about 68% of that coming from calcium and 12% from magnesium.

The theory is that at that level the soil structure and soil biology are improved which boosts crop yields and quality.

Most conventional scientists dismiss the concept that it adds any benefits over fertiliser recommendations which are typically made based on plant requirements and pH.

But Jeremy and Kim’s quest to compare the system side-by-side attracted interest from the science community and in 2013 with the help of retired Lincoln University emeritus professor Tony Zwart a steering committee was set up and funding gained so that robust measures could be taken each year.

Since then Plant and Food scientists, Lincoln University, DairyNZ, Ballance Agri-Nutrients, Macfarlane Rural Business and Dairy Condition Monitoring have all played a role in monitoring and measuring numerous parameters and metrics including soil fertility, soil biology and structure, pasture growth and quality, animal production, animal health and financial performance.

Ballance Agri-Nutrients has provided the conventional fertiliser recommendations while Don Hart from Top Soils has carried out the Albrecht Kinsey recommendations.

United States-based Neil Kinsey has also visited the property several times.

Soil test analysis was carried out at both Hill Laboratories in New Zealand and Perry Labs in the US.

The types of fertiliser applied under the Albrecht Kinsey approach have included conventional fertilisers such as magnesium, potassium sulphate, sulphate of ammonia and elemental sulphur as well as guano (dicalcic phosphate) and dolomite (both magnesium carbonate and calcium carbonite) with Jeremy and Kim steering away from using other “biological” soil additives such as humates so as not to confound the results.

At the start, with funding looking limited for the study, the decision was made to try and get the Albrecht Kinsey farm run to the desired base saturation levels as quickly as possible.

That meant high rates of fertiliser were applied, and after the first two seasons the total fertiliser spend over that time was about $1000/ha more than on Waiora.

In the last two seasons the fertiliser rates on Whakapono have been reduced but throughout the study more calcium, sulphur and magnesium has been applied while phosphorous and nitrogen applications have been lower.

Over the last three seasons the difference in fertiliser cost has averaged $158/ha with Whakapono the more expensive.

The couple have run the farms at a 3.3- 3.4 cows/ha stocking rate – slightly lower than has been typical in Canterbury, particularly over the first few years.

They’ve also been comparatively low nitrogen users too on both farms although Whakapono consistently lower than Waiora.

Results have shown that despite using about 20% less nitrogen fertiliser Whakapono has kept pace with Waiora on milk and overall pasture production.

Throughout the study Whakapono has had slightly more clover present in pasture swards.

Last season Jeremy purposely increased the amount of nitrogen used on Waiora to better represent a more typical Canterbury situation.

That helped push the Overseer nitrogen loss rates up for the conventionally run farm taking it well above Whakapono for the first time in the study. (see more on nitrogen leaching on page 59).

Plant and Food measures of soil structure in terms of penetration resistance, macroporosity and aggregate stability have shown no significant differences between the farms but there have been more earthworms and other soil invertebrates in the Whakapono soils.

The only problem is there are also more invertebrates of the undesirable type too with more grass grub and clover root weevil.

Plant and Food has also carried out soil chemistry testing – independent of the conventional and Albrecht Kinsey advisers to the farms.

Soil carbon content has increased to more than 3% on both farms.

There has been some noticeable difference in animal health particularly around calving time.

Jeremy has frequently found he’s needed to take more preventative measures on Waiora than Whakapono when it comes to downer cows.

Across the whole study period though, there’s been no significant difference in overall animal health.

Reproductive performance in terms of three-week submission rate has typically been about 3% ahead on Whakapono and empty rate has been consistently 1-2% lower on Whakapono.

“At the start I thought that if we came to the end of the trial period and things like production and profit were sitting fairly equal but the environmental footprint was better – then that would be a good outcome.

“We’ve been able to show there’s no negatives really and we’ve been able to match production and profitability now using less nitrogen, relying more on the extra clover we grow.”

In retrospect the only thing he’d change would be the speed they aimed to get to the Albrecht Kinsey prescribed percentage base saturation levels.

“I think we’d have done that a bit more slowly so the cost wouldn’t have been all upfront.”

Jeremy and Kim are now looking at sowing more diverse pastures on Whakapono and including species such as cocksfoot, meadow fescue, birdsfoot trefoil and timothy as well as some herbs.

They’re interested in estimating their greenhouse gas emissions more closely and looking at the effect of diverse pastures on soil carbon measures.

Both units will continue to be managed separately in terms of fertiliser regimes and much of the farms’ data will continue to be monitored as part of other projects including DairyNZ’s Meeting a Sustainable Future project.