Term
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Definition
| The process of ammonia diffusion from the soil surface to the atmosphere |
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Term
| ammonia volatilization is a complex process often associated with... |
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Definition
| surface-applied animal manures and N fertilizers |
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Term
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Definition
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Term
| For ammonia volatilization to occur, ammoniacal N (NH4+ and NH3) must be... |
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Definition
| either initially present in the applied material, or generated during manure or fertilizer transformations |
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Term
| when animal manures can release additional ammoniacal N |
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Definition
| during organic N decomposition (N mineralization or ammonification) |
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Term
| a fertilizer that contains ammoniacal N |
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Definition
| some such as ammonium nitrate |
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Term
| a fertilizer that can release ammoniacal N after application to soil |
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Definition
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Term
| some environmental factors that generally enhance the conversion of organic N from
fertilizers or manures to NH4+ |
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Definition
| higher temperature and soil water content |
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Term
| what higher temperature and soil water content does for the conversion of organic N from fertilizers or manures to NH4+ |
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Definition
| generally enhances the conversion of organic N from fertilizers or manures to NH4+ |
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Term
| The ammoniacal N from animal manures or fertilizers is initially released into ______, where it is partitioned into ______ |
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Definition
the soil solution
NH4+ and NH3 |
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Term
| The ammoniacal N from animal manures or fertilizers is initially released into the soil solution, where it is partitioned into NH4+ and NH3 depending on... |
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Definition
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Term
| pH and temperature vs. amount of NH3 |
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Definition
| As pH and temperature increase, the proportion found as NH3 increases |
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Term
| effect of rain, irrigation, or tillage on ammoniacal N |
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Definition
| any rain, irrigation, or tillage that moves the ammoniacal N into the soil usually enhances adsorption of NH4+ and eliminates or reduces NH3 losses |
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Term
| what has to happen for NH3 to be lost as gas |
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Definition
| some of the NH3 dissolved in the soil solution has to be converted to gaseous NH3, a process that is controlled by Henry’s Law constant |
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Term
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Definition
| describes the proportion of NH3 that is in the soil air compared to the adjacent soil solution |
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Term
| some reasons NH3 volatilization increases when soil temperature rises |
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Definition
1) the conversion of organic N to NH4+ increases
2) the proportion of total ammoniacal N as NH3 increases
3) the proportion of NH3 in the soil air increases. |
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Term
| the effect of the decomposition of animal manures and the hydrolysis of urea fertilizers |
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Definition
| consume H+ ions from the soil, which in turn can lead to a pH increase |
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Term
| hydrogen buffering capacity (HBC) vs. NH3 loss |
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Definition
| soils with a large HBC commonly show smaller NH3 losses than soils with a small HBC |
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Term
| some reasons losses of NH3 are increased in wetter areas |
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Definition
1) release of NH4+ from organic sources such as urea is enhanced under wetter conditions
2) a greater proportion of the NH4+ is not adsorbed by the soil exchange sites and remains in the soil solution at higher soil water contents. |
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Term
| why some plant damage may occur if urea is banded with the seed |
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Definition
| because of ammonium toxicicity |
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Term
| why the rate of urea hydrolysis matters |
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Definition
| because a fast rate reduces the time available for urea and ammoniacal N to diffuse deeper into the soil when surface-applied |
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Term
| objective of this lab number 7 |
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Definition
| to evaluate the effect of soil water content and temperature on ammonia volatilization from surface-applied urea. |
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