Environmental Chem

[gyourkoshaven]

I'm not sure about the first one, but the answer to the 2nd question I do know. Synthetic fertilizer advantages are that they can provide a lot more phosphorous and potassium than compost, and they can provide only what is necessary for the soil, since the creators design them that way.

[Phenylethylamine]

I'd guess that irrigation can damage topsoil by washing it away, or leaching minerals out of it, or causing it to become overly waterlogged... some or all of those.

[2win]

Thanks. That's what my partner and I came up with, but our coach and teammates said we needed to have someone verify that.

[kjhsscioly]

for the first, erosion is a huge problem with irrigation, especially when farmer plant fields every year without crop rotation. Also, if the water is tainted, it can result in plants with hazardous minerals in them (lead, mercury, and others)
for the second, it is most likely that they can provide a more targeted mix of N-P-K than organic fertilizers can, i.e plant specific, or nutrient specific. They are also usually stronger and for commercial farming, give bigger results.

[2win]

ah, okay, thanks!
btw, does your username mean katy junior high school science olympiad? if not, then never mind.

[kjhsscioly]

not even close, though it is a very generic name

[2win]

oh,ok, i was just curious.
another question: when testing soil pH with a probe, do you have to mix the soil with distilled water? or is that just for testing with pH paper?

[kjhsscioly]

this is from http://www.ehow.com/how_4781811_use-ph-meter.html
step1
Make sure that the pH probe you are using has been stored in a storage solution or a pH 4 solution. If this is not the case, soak the probe in distilled water for at least 24 hours.
Step2
Check that the meter is set in pH mode, and then rinse the probe of your meter in distilled water. Shake it off before placing it in a pH 7 solution for calibration.
Step3
Let the probe remain in the solution for at least 30 seconds to allow time for the meter to stabilize, and then adjust the meter so that it reads pH 7.
Step4
Rinse once again and then place it into a pH 4 solution, giving time for the meter reading to stabilize. Adjust the meter so that it reads pH 4. Your meter has now been calibrated.
Step5
Rinse the probe once again as you have done before and shake off any excess liquid. The probe is now ready to be placed in your sample liquid.
Step6
After allowing the pH reading to settle as you have done before, take the pH reading of your sample.
Step7
Store the probe in storage solution or a pH 4 solution when finished measuring.

[2win]

Thank- you once again. My coach didn't know about the calibration thing.

[emilyy18]

zOMG you have to do all that before using a probe!! Supposedly we are using probes in competition, how do you know they calibrated it beforehand for you, and they did so correctly!? ahh