Variety trial

One of the pieces of the ECHO internship is a variety trial or research project conducted by concurrent interns over the course of a few months during the second half of their year on the farm.  Laura Catherine and I chose from a list of projects put together by farm staff as worthy candidates for study.  Our decision was to continue the research begun by two interns in 2009 regarding potting soil mixes, amendments and plant growth.

The goal of the original experiment was to find easily produced homemade potting mixes that could approximate the commercially available peat-moss-based mixture that ECHO currently uses in its greenhouse.  The 2009 experiment focused on plant growth over a three week window and concluded with as many new questions as it answered.  We chose to focus on one of those unknowns: the water retention of the top performing mixes.

Our experiment involved measuring the top three homemade mixes from the 2009 trial for evaporation rates and total water retention graphed against dry weight.  We then seeded up 200 repetitions of three types of seed (grain, vegetable and fruit tree) in the three mixes along with a control.  A total of 1600 seeds were planted.  After three weeks, we measured plant weight, length and color.

Measuring plant weight

We then selected the top performing mix to be amended with sugarcane bagasse (pulverized sugar cane stalks left over from the extraction process).   We mixed bagasse in at 25%, 50% and 75% by volume and repeated a 200 repetition planting for vegetable and grain seed for a total of 1200 seeds.  The results of this second phase were unexpected and dramatic.  No matter the concentration of bagasse, the seedlings 'ran out of steam' after about two weeks of growth and began to stagnate.  The control mixture with no bagasse continued to grow as in the first phase of our trial.

Tray on the right has 0% bagasse

The reason for this is uncertain, but could have something to do with the non-sterile nature of our potting mix and the subsequent use of much available nitrogen by micro-organisms beginning to break down the bagasse.

One key aspect of the bagasse mixtures LCC and I were unable to measure was the water retention during periods of high plant respiration and evaporation.  This experiment should be conducted again in Aug/Sep to see if the bagasse truly acts as a volumizer.

New experiences in the last week:

1. Ate a canistel

This is not my hand.

2. Planned to eat a kumquat

3. Made chili from scratch
4. Sent my 5DII to Canon for repair (that is weak for a camera with only 3,000 shutter actuations)
5. Distinguished by taste and color seven cultivars of grapefruit (I say I can, don't make me prove it)