Answer to Question 1The first phase is shorter-lived and consists of harvested plant materials of new tissue that is not
decomposed. At this stage, soil microbes actively break down plant material particles and tie up much
of the available nitrogen in the soil so that it cannot be taken up by plants. Once on its way to
decomposition, the second form is much more useful to horticulturists as a soil amendment: brokendown
organic debris known as humus. At this point in the life of organic material, microbial activity is
slower and nitrogen is more readily available to the plant. Composting allows for organic materials to
be fully rotted, transitioning microbial activity from being nitrogen-needy to lower levels of activity so
that the benefits of air, water and nutrition can be derived by plant roots.
Answer to Question 2Coarse amendments like sand and perlite are added to increase pore sizes between the particles. Care
should be taken to monitor indoor plant installations over time. Over a period of years, artificial media
will lose air-filled pore spaces and increase water-filled space. This compaction will be detrimental to
plant health because roots need the gas exchange performed in air-filled pores. If plants exhibit
symptoms associated with over-watering and compacted soil is suspected, repot the plants with new,
fresh media.
Biomagnification in a Lake Ontario food chain.
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A 2-fold serial dilution showing the result of moving 0.2 ml of green food coloring successively ...
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