Dr Christine Jones on where the additional nutrients come from

DR CHRISTINE JONES' TESTIMONY BEFORE AUSTRALIAN SENATE STANDING COMMITTEE ON CLIMATE CHANGE, TRANSPORT AND AGRICULTURE 30 JULY, 2008

Dr Jones—When we measured the nutrient levels in his paddock this year prior to him sowing his crop [again], the phosphorous levels had gone up by a factor of five. The agronomist actually thought there was a laboratory error in the data. We relooked at that and at bare areas compared with areas under the grass, and it was correct that available phosphorous had gone up by a factor of five.

Senator HEFFERNAN—And that is the microbes releasing it.

Dr Jones—Yes. Phosphorous fertilisers had been used over time, under 15 years of zero till in that area, and they just formed a phosphorous bank that had been inaccessible. A fortune has been spent on phosphorous fertilisers. That farmer will not need to apply phosphorous fertiliser, we do not know for how long but for several decades, because the microbes are releasing what has been built up. You mentioned before the issue with your conventional zero till and why it is that carbon does not work, nitrogen does not work and phosphorous does not work. Nothing works because you have to have a microbial bridge between plants and minerals in the soil. Plants cannot actually access those unless that is in place. Normally the carbon from plants feed the microbes that in turn bring nutrients back to the plants. We have destroyed all those associations in soil by loading it with toxic chemicals, basically. What has been in favour of its adoption is not only climate change but the rapidly increasing price of phosphorous, nitrogen and herbicides. That has encouraged farmers to look for alternatives to that system.