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Kansas

Everyone is always talking about how quick nitrogen leaches thru the soil..What i'd like to know is how fast does it do this? 2 days....4 days....6 days...??? I know your type of soil is the biggest facter (sand,loam,clay) but is there a chart or table telling a person how fast it leaches? Was just curious....Thanks for your replies. Shawn.

5/15/2002 10:27:09 PM

Garden State Pumpkins

Hey Shawn, I don't know of any chart that will give that type of information. Just below on this page, alexsdad asks the question I have my soil test NOW WHAT..Gordon gave me alot of links to read. They were great. if somewhat over my head. but the leaching of nitrogen isn't draining out of the soil but the availability of nitrogen in the soil, it's conversion to plant usable nitrogen and then it breaks down and becomes unusable again...or something along those lines...take a look at those links...Chuck

5/16/2002 7:15:51 AM

southern MN

The process of leaching nitrogen depends not only on your soil type but also what form the nitrogen is in, temp, and rainfall.

Only nitrogen in the form of nitrate NO3 can leach and nitrogen in the form of ammonia NH3 can be lost to volatilization. Inorganic fertilizer that you apply is in between NO3 and NH3 and depending on the conditions the reaction can go either way it is called the nitrification/denitrification process.

The process of converting nitrogen to a form that can be lost is done by bacteria. The warmer the soil the quicker the bacteria works at converting the nitrogen. However soil temps below 50 degrees almost stops the bacteria process. That is why you don't see farmer putting anhydrous on their fields till late fall (ideally it should be done in the spring but with time constraints many just do it in the fall). Also farmers now have a product called N-serve which helps slow down the bacteria process.

Rainfall, without a downward movement of water there will be no leaching. All the nitrogen can be in the NO3 form (still available to the plant but capable of being leached)but without the downward movement of water it will remain where it was. Usually it the heavy rains that do the most leaching because it comes all at once.

Soil types also play a role, coarse soils (sand) when saturated will leach the NO3 and fine soils (clay) when saturated is subject to denitrification (converting NO3 to N2 not useable)

5/16/2002 10:46:30 AM

southern MN

To put this all in prespective in a real world example: Here in southern MN (we have webster clay loam soils) the farmers put their Nitrogen fertilizer on as anhydrous ammonia (NH4) which is readily avialable to plants. It is not recommended that they apply the anhydrous until after Oct. 30 (the long term average for soil temp below 50 degrees). Most farmers did this, however we had an unusually warm fall and most areas the soil temp did not drop below 50 until almost Dec. in Oct. the soil temps were still in the 70's. It was estimated that with these conditions the majority of the NH4 was already converted to the NO3 (leachable). However, we have not had alot of heavy rains (about average rainfall) so the majority of the N is still there in the root zone. We have lost some of the N to denitrification but if we had recieved a 2-3" rain we would be looking at reapplying or adding a N fertilizer because of leaching.

I hope this helps and if you are dealing with N in the form of manure look up the article in the how to section on nutrient analysis of manure, there is discussion on N in manure.

5/16/2002 10:46:54 AM

Garden State Pumpkins

You guys are great...See Shawn that's what I meant but Wango understands it...Now about that Cation exchange %
chuck

5/16/2002 12:46:50 PM

Cornwall UK.(50N 5W)300ft.

At this time of the year I put Ammonium Nitrate on fields of grass every 4-5weeks after that time its either been washed out used by the plant or lost into the atmosphere and needs another dressing.In this situation you have to time it so that it is applied just before it rains so that it is washed into the soil but hopefully not so much rain that it is washed away.If you put it on a dry field and it doesn't rain you lose most of it.

5/16/2002 7:10:54 PM

southern MN

An Iowa State University publications put the rates for loss of N at:

From leaching: one inch of infiltrating water will move nitrate down the in the soil 1" for clay loam and 2.5" in sandy soils

from denitrification in waterlogged soils with a soil temp above 60 degrees and a pH of 7 and a readily available energy source (carbon): 100 lbs of nitrate in 5 days

The fact sheet is about Nitrogen use in corn
http://www.extension.iastate.edu/Publications/NCH55.pdf

5/17/2002 1:19:59 PM

Kansas

Hey guys , thanks for the information. This was a question i've been wanting to ask for some time and now i'm glad i finally did. Thanks a million. Shawn.

5/17/2002 1:24:25 PM