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nitrate toxicity levels for plants
I was reading an old TAG issue last night on Cryptocorynes (4:1 I
think) and the author was discussing substrates for Crypts. He was
using sphagnum peat moss in pots. I was wondering about mixing it with
anything else or covering with gravel. Anybody care to describe the
use of peat in substrates especially those designed for a variety of
plants? I suspect peat might have a tendency to decompose a little
faster if mixed with soil. I also suspect that large ratios of peat
might not be suitable for certain plant types.
My question is about nitrate toxicity especially with Crypts. The
author of the TAG article mentioned that certain types of Crypts
didn't grow well in high nitrate environments (i.e. ~100ppm) He
suspected this contributed to Crypt meltdown. I've grown a variety of
Crypts (not as many as the author) in a tank with high nitrates but
found the plants to grow rapidly and they were quite robust. I've not
experienced meltdowns but I doubt that I'm growing anything sensitive.
I also use strong lighting so I suspect this enhances the Crypts'
vitality and health. I suspect that meltdown actually caused by
nutrient deficiencies and poor conditions in general. Any comments?
I was able to previously grow Rotala macranda using a less fertile
substrate with good success however in the highly organic substrate
tank with high nitrate concentrations, it did not grow well and died
out. I wonder if this was due to nitrate toxicity or to an intolerance
for a very low redox potential in the substrate or to a lack of other
nutrients since some other nutrient must have become the limiting
growth factor. It could be that the R mac couldn't get enough iron
from the substrate since I was maintaining relatively low levels of
chelated Fe in this tank and there could have been strong competition
for it. I can't be sure if this was a case of nitrate toxicity or not.
Any comments?
Steve in Vancouver where the heat wave may be ending