Chile Day 5

The role of earthworms in agriculture and
the environment

Yesterday I gave my talk. It was due to start at 1200 and we started, according to Chilean tradition as Alexander informed me, at about 1215. There was a good turn out, 50 plus people. I talked and was translated for about 45 minutes and then we had over 30 minutes of questions. I was very impressed by the number of student questions - far more than I usually get in UK seminars. Many thanks are particularly due to Kooichi Vidal who translated as we went along.

Yesterday I also completed the introduction of the paper and Pedro and Jose worked on regressions and tables for the results section.

Today, the main order of business was a field visit with some undergraduates to a contaminated site that people are using phytostabilisation on. Alexander was keen we set an example on timing. The trip was scheduled to leave at 1430. At 1435 we started to go to the bus.....prompt for Chilean time.

Phytoremediation has two main forms - in the first you use plants to extract contaminants from the ground. This is called phytoextraction. It works really well in the lab. and usually doesn't work in the field. The other main methods is phytostabilisation. This just involves getting plants to grow on "nasty" soil to stop the soil blowing away as dust and causing health problems when it is inhaled by people.

The copper smelter in the background
with the degraded "soil" in front

The site we looked at is on the Puchuncavi, down wind of a copper smelter. The soil is developed on old sand dunes. The fumes from the copper smelter acidified the soil and deposited lots of copper and some arsenic. The plants died and the organic matter content of the soil slowly went down.

Gully erosion - the soil is effectively
 sand with few if any roots to hold it
together. Gullies develop when it rains.

The soil now is pretty much sand and subject to lots of erosion.

Alexander's field trials. Along the
 fence are sandy "control" plots - the soil
as is. The plots in front of the people  had
organic matter added allowing plants to
re-establish.

Alexander has run several field trials here. He tried growing plants to take up the copper out of the soil but the copper stayed put. However he was able to add organic matter to the soil which helped plants grow and thus reduce erosion - an example of phytostabilisation.

Some of the pretty yellow flowers
growing on the site.

On the way back alexander spontaneously said that he would buy the students dinner (and the bus driver) so we stopped in Con Con for some Empanada - effectively Cornish pasties, very tasty.

We also made some more progress on the paper and discussed some other things we needed to do before writing it up fully.

Last day tomorrow.