Lime vs Fertiliser Experiment / Demonstration

A demonstration of the effect of lime versus fertiliser on grass growth on acid pasture

As I mentioned before in my allotment diary,  I've set up a demonstration / experimental plot to show the effect of lime and fertiliser. The land here is pasture that has not been cultivated as such for many years, probably since the war. All it has had is sheep eating the grass and supplying some manure in return.

It's very acid, pH is as a low as 4.5 in places. There's more info on lime here: Garden Lime but in a nutshell, lime raises the pH making the soil more alkaline and less acid which enables plants to extract nutrients more easily.

Lime is, in my opinion, very under-used. I've seen people on plots chucking more and more manure and fertiliser on yet not getting the results they could have because the soil is acid. The old boys would have said the soil was sour, which is very apt.

Initially I was going to do a very rough and ready demo but since we've got the space I thought I'd do it properly. I've roped off 9 squares, 2 metres to a side, in a large square which is 6 metres to a side.

Using 9 plots will equalise the effects of different light, soil, water etc and, for all practical purposes, be a fair guide.

The plots getting lime will receive 250 grams per square metre (roughly 8 oz per square yard) of ground limestone. So 1kg over the 4 square metres.

For fertiliser I'm using simple fish, blood and bone at a rate of 125 grams per square metre (approx. 4oz per square yard) – 500 grams per 4 square metre plot. This has an NPK ratio of 5:5:5 (see this article: Fertilisers)

Since the test plots just have grass on them and are acid, the ideal fertiliser would have been Nitrate of Chalk aka Nitro Chalk – NPK Ratio 27:0:0 Grass loves nitrogen and Nitrate of Chalk also contains lime so reduces acidity. It's a good fertiliser for brassicas as well, which need high nitrogen and a high pH. But I wanted to compare fertiliser vs lime and a combo will just confuse the issue.

The control plots will get nothing, of course. The lime and fish, blood & bone were spread by hand late yesterday and the torrential rain this morning will have washed them in.

Demonstration Plot

I did have an email suggesting this was a waste of time as the results were a foregone conclusion, but I think that's missing the point. My experience is people go with what they think unless you can prove a different method works better to them.

This is as much as demonstration as an experiment. Of course, I could be proved wrong. Wouldn't be the first time.