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sorry rope and timmy, its a well documented fact that plants will have measureable amounts of nitrates in their leaves, especially in high fert / low light conditions.....

....I think its a storage mechanism, and when there is insufficient lihgt to make use of it then it remains.

From http://www.soil.ncsu.edu/publications/S ... AG-439-14/

Inorganic Chemical Effects: Health Concerns from Nitrate
Human Health Problems

Humans ingest nitrates from food and water. Once nitrate enters the body of humans older than six months, it is steadily absorbed from the digestive tract and excreted in the urine. Healthy human adults can consume fairly large amounts of nitrate with little harmful effect.

Infants under six months, however, are susceptible to nitrate poisoning because their undeveloped digestive tracts possess bacteria that convert nitrate into nitrite, which is toxic. When nitrite enters the bloodstream, it reacts with oxygen-carrying hemoglobin and forms a compound called methemoglobin. This compound reduces the blood's ability to carry oxygen. As oxygen levels decrease, infants may show signs of suffocation, a condition called methemoglobinetnia.

The most conspicuous symptom of methemoglobinemia is bluish skin, most noticeably around the eyes and mouth. If detected rapidly, methemoglobinemia can be successfully treated with an injection of methylene blue, which changes methemoglobin back to hemoglobin. Untreated, the condition is extremely serious: death occurs when 70 percent of the body's hemoglobin has been converted to methemoglobin.

While rare, infant deaths from methemoglobinemia (or blue baby syndrome) have been linked to high levels of nitrate in well water. Doctors recommend using bottled water to make formula when nitrate levels exceed the drinking water standard set by the Public Health Service: 44 parts per million (ppm) of nitrate (NO3). This level is equivalent to 10 ppm of nitrate-nitrogen(NO3-N). With one possible exception, no breast-fed infants have developed methemoglobinemia, probably because the mother excretes nitrate so rapidly

Water with a high amount of nitrates can be very harmful to humans and livestock alike. When nitrates are consumed in water they are converted to nitrites. Nitrites take away oxygen in the blood and are responsible for many stillbirths and abortions

Maybe that's why many vegetables are harvested early morning, after perhaps the plant processes during the night have off-gassed a degree of nitrates through conversion.... must be a reason for it... anyone know?

Quote:

Normally because the plants look better and last longer if they are picked before absorbing the "field heat" during the daytime.(they are in better nick

) Otherwise they are all limp and unappetising.
Also easier to pick them when it is cool, gotta look out for the workers eh.

Author:	Notable [ Apr 8th, '08, 12:43 ]
Post subject:	Nitrates in Food
Has anyone done any research about nitrate content in the food we produce. Nitrates can be toxic to humans, and one of the problems with commercial agriculture is high nitrate levels due to the amount of artificial fertilizers , which are mainly nitrogen based. As we use Ammonia/ Nitrite/ Nitrate as our fertilizer, do the plants have high levels of same? cheers Rodney

Author:	RupertofOZ [ Apr 8th, '08, 13:06 ]
Post subject:
Rodney most "complete" agricultural fertilisers actually provide/have a very high proportion, often 50%, of nitrogen in the ammonium (NH4+) (usually urea) based form rather than predominantly the nitrate (N03) form.... The nitrate conversion is actually/subsequently done within the plant itself... hence there can be residual nitrate levels.... For this very reason most hydroponic fertilisers are completely different and are a "nitrate" NO3 formulation and "complete" fertilisers are avoided like the plague.... Similarly in an AP system nitrates are available for plant uptake directly as an NO3 ion in the nutrient water itself.... IMHO, the plants will only take up the nitrates needed and residual nitrate levels would be minimal... as they are in hydroponically grown vegetables.

Author:	timmy [ Apr 8th, '08, 13:45 ]
Post subject:
there shouldn't be any residual nitrate as the plant will only absorbe what it needs, and we certainly aren't spraying concerntrate all over them.

Author:	steve [ Apr 8th, '08, 15:14 ]
Post subject:
sorry rope and timmy, its a well documented fact that plants will have measureable amounts of nitrates in their leaves, especially in high fert / low light conditions. As to what level our plants have? i dont know. I'm sure a quick search will find the acceptable level. I dont think its the nitrates that are the problem, but the nitrites that will form when foods are cooked. remember nitrate are an oxidising agent, hence giving up the oxygen and becoming nitrite (or even further in inorganic situations) anyone tried applying a flame to a mixture of sulfer carbon and sodium nitrate? LOL IMO the amount of nitrites that butchers put into your meat is more of a concern AND it gives you an excuse to only very lightly cook your greens (the way it should be!) i only think that its the leafy greens and specifically spinach that give the probs with nitrate storage, I think its a storage mechanism, and when there is insufficient lihgt to make use of it then it remains. i recon a $1 donation by each active member should buy us a lab test of a sample

Author:	RupertofOZ [ Apr 8th, '08, 15:50 ]
Post subject:
Steve wrote: sorry rope and timmy, its a well documented fact that plants will have measureable amounts of nitrates in their leaves, especially in high fert / low light conditions..... ....I think its a storage mechanism, and when there is insufficient lihgt to make use of it then it remains. Pretty much what I said/meant Steve.... high "complete" fertilisers, usually urea based, ammonia - uptake and conversion in plants.... And you're probably right that under certain conditions, particularly low light where sugar conversion and other plant chemistry conversions are correspondingly slowed.... the nitrates probably are "stored" if the plant is harvested at that stage.... Hydroponic fertilisation however as I said "deliberately" avoids the use of such high fertilisers for that reason..... I'd suspect that in low light, low photosynthesis periods, nitrates may also be stored in plants in an AP system given our direct high nitrate environment.... Maybe that's why many vegetables are harvested early morning, after perhaps the plant processes during the night have off-gassed a degree of nitrates through conversion.... must be a reason for it... anyone know? Would make for interesting experiment as you say Steve.

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Author:	RupertofOZ [ Apr 8th, '08, 15:52 ]
Post subject:
Actually, thinking about it, I think this aspect of nitrate content/storage was one of the things that Wilson Lennard looked at in terms of basil production in AP.... and in particular shelf life and presentation.....anyone got his paper?

Author:	RupertofOZ [ Apr 8th, '08, 16:00 ]
Post subject:
Quote: From http://www.soil.ncsu.edu/publications/S ... AG-439-14/ Inorganic Chemical Effects: Health Concerns from Nitrate Human Health Problems Humans ingest nitrates from food and water. Once nitrate enters the body of humans older than six months, it is steadily absorbed from the digestive tract and excreted in the urine. Healthy human adults can consume fairly large amounts of nitrate with little harmful effect. Infants under six months, however, are susceptible to nitrate poisoning because their undeveloped digestive tracts possess bacteria that convert nitrate into nitrite, which is toxic. When nitrite enters the bloodstream, it reacts with oxygen-carrying hemoglobin and forms a compound called methemoglobin. This compound reduces the blood's ability to carry oxygen. As oxygen levels decrease, infants may show signs of suffocation, a condition called methemoglobinetnia. The most conspicuous symptom of methemoglobinemia is bluish skin, most noticeably around the eyes and mouth. If detected rapidly, methemoglobinemia can be successfully treated with an injection of methylene blue, which changes methemoglobin back to hemoglobin. Untreated, the condition is extremely serious: death occurs when 70 percent of the body's hemoglobin has been converted to methemoglobin. While rare, infant deaths from methemoglobinemia (or blue baby syndrome) have been linked to high levels of nitrate in well water. Doctors recommend using bottled water to make formula when nitrate levels exceed the drinking water standard set by the Public Health Service: 44 parts per million (ppm) of nitrate (NO3). This level is equivalent to 10 ppm of nitrate-nitrogen(NO3-N). With one possible exception, no breast-fed infants have developed methemoglobinemia, probably because the mother excretes nitrate so rapidly And from Wiki ... Quote: Water with a high amount of nitrates can be very harmful to humans and livestock alike. When nitrates are consumed in water they are converted to nitrites. Nitrites take away oxygen in the blood and are responsible for many stillbirths and abortions So yep, agree with Steve... it's the conversion to nitrites that's probably the concern...

Author:	Axl [ Apr 8th, '08, 16:18 ]
Post subject:
Quote: Maybe that's why many vegetables are harvested early morning, after perhaps the plant processes during the night have off-gassed a degree of nitrates through conversion.... must be a reason for it... anyone know? Normally because the plants look better and last longer if they are picked before absorbing the "field heat" during the daytime.(they are in better nick ) Otherwise they are all limp and unappetising. Also easier to pick them when it is cool, gotta look out for the workers eh.

Author:	steve [ Apr 8th, '08, 16:49 ]
Post subject:
they also weigh more because of the higher water content, so be happy when you buy wilted veggies from the store! lol

Author:	Food&Fish [ Apr 8th, '08, 17:51 ]
Post subject:
Axl wrote: Quote: Maybe that's why many vegetables are harvested early morning, after perhaps the plant processes during the night have off-gassed a degree of nitrates through conversion.... must be a reason for it... anyone know? Normally because the plants look better and last longer if they are picked before absorbing the "field heat" during the daytime.(they are in better nick ) Otherwise they are all limp and unappetising. Also easier to pick them when it is cool, gotta look out for the workers eh. Ah that explaines it when i was a kid we used to pick our watermelons around midnight [ from the italians tobbaco farm ] best watermellons we ever had

Author:	EllKayBee [ Apr 9th, '08, 07:38 ]
Post subject:
Shame on you F&F, you should be setting an example not putting bad ideas into the younguns heads here

Author:	Sleepe [ Apr 9th, '08, 08:33 ]
Post subject:
Think the answer is no Rodney You'd kill the fish first.

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