Recently we have been doing soil pH tests at Roogulli to see what progress has been made with the acid soils. The results offer some hope for improving the soil without the expense of applying lime or gypsum.
The story so far...
In 1998 when we took over care of the 25 acre property the improved pastures had been dusted with superphosphate every two years for at least 20 years. The top area near the house was grazed mainly by horses and had patches of salt scald. The area closer to the creek was more or less permanently grazed to the ground by sheep, had active erosion gullies and an abundance of Serrated Tussock and Gorse. This was a land management regime commonly used in the Canberra region at the time and is still followed today on many rural properties.
With our arrival, grazing and superphosphating stopped. The Phalaris was vigorous and with good rain it grew to eyeball height (about 1.5m) in the top areas in the first spring. This was great for kids playing jungle games but hard to walk through. We started slashing the grass each year. To our unpracticed eyes there didn't appear to be many other grass species. It is hard to know now whether this was really the case or just a lack of skill in recognizing grass species on our part. Over the following years, helped along by the extended drought, the Phalaris gradually became less vigorous.
Lab soil tests in Spring 2006 for the paddock where our house, kitchen garden and new food forest are now located gave a pH (CaCl2) of 4.5 for the top 10cm of soil. This is equivalent to a water pH test result of 5.5 which is quite acid but not unusual in this region.
In 2008 we began grazing again using alpacas and llamas and applying our gradually expanding knowledge of rotational grazing techniques. The kitchen garden was also started with composts, alpaca poo, green manures and mulches repeatedly added to the paddock soil to increase the amount of organic material in the soil. Hens have been grazing one section of pasture on a rotational basis. The food forest has only recently begun with the first planting in Winter of 2012.
It occurred to us that it might be interesting to retest the soil pH after all this activity. At no stage have we added lime or gypsum. We tested using a Manutec Soil pH Test Kit which is not nearly as accurate as a lab test but much quicker. As best we can find out, this is a water pH test.
On the left is the test from the kitchen garden with a result that looks like about pH 5.5 - 6. In the centre is the sample from the food forest which looks decidedly more acidic, around pH 4.5 - 5.This area is near the kitchen garden and the soil is similar to the soil that the kitchen garden started with. On the right is the result from the pasture where the hens graze. This result is similar or maybe slightly higher in pH than the kitchen garden test.
It is difficult to compare these results with the lab tests from 2006. The good news is that it appears that the organic soil improvements in the kitchen garden and the rotational grazing by hens on pasture may have some effect on the pH in our soils. They both appear better options for soil improvement than the infrequent mowing regime that has been applied in the past to the food forest area and it will be interesting to see what happens to the pH in this area as the serious mulching activity kicks in as part of building up the food forest.
And now for some more pH tests in the paddocks... it is amazing how much a simple test like this can help with understanding what is going on in our soils.