Abstract
Use of herbicide to terminate alfalfa (Medicago sativa L.), while reducing soil erosion, could conceivably enhance volatile N losses from alfalfa residues. A controlled environment study was conducted to determine the effect of termination method on the quantity of NH 3 volatilized from residues of alfalfa. A factorial combination of two termination methods (chemical, mechanical) and two methods of residue placement (incorporated, surface applied) was applied to alfalfa. Treatments were incubated in a flow-through chamber in the greenhouse for 95 d during which NH 3 and CO 2 evolution was measured periodically. After 95 d, 8% of surface applied legume N was lost as NH 3 in tillage treatments compared to 12% in herbicide treatments. These losses amounted to 3% and 4% of total legume N in tillage and herbicide treatments, respectively. Incorporation of alfalfa residue essentially eliminated volatile N losses. Termination method had comparatively less effect on NH 3 evolution than residue placement although herbicide application tended to increase the proportion of alfalfa N lost via volatilization. Residue incorporation increased cumulative CO 2 evolution regardless of termination method. Results of this study suggest that termination methods in which alfalfa residue is retained on the soil surface may result in significant volatile N losses which could diminish the fertilizer value derived from alfalfa residues. However, these N losses do not necessarily preclude the adoption of herbicide termination of alfalfa given the potential reductions in soil erosion and moisture loss which may be associated with this management practice. Key words: Volatile N losses, NH 3 evolution, termination method, alfalfa, herbicide, tillage, greenhouse
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Claims 8
Claim · model-written summary
Surface residues lost 8% of legume nitrogen as ammonia after tillage, versus 12% after herbicide termination.
- Taxon
- alfalfa
Medicago sativat0 - Treatment
- herbicide treatmentse0
- Outcome
- surface applied legume N was lost as NH 3e0
- Value
- 12%e0
- Qualifier
- 8%e0
- Comparator
- tillage treatmentse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 95 d, 8% of surface applied legume N was lost as NH 3 in tillage treatments compared to 12% in herbicide treatments”
t0“alfalfa”
Claim · model-written summary
Those losses represented 3% and 4% of total legume nitrogen in tillage and herbicide treatments, respectively.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- total legume Ne0
- Value
- 3% and 4%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These losses amounted to 3% and 4% of total legume N in tillage and herbicide treatments, respectively”
t0“alfalfa”
Claim · model-written summary
Incorporating alfalfa residue essentially eliminated volatile nitrogen losses.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Incorporation of alfalfa residuee0
- Outcome
- volatile N lossese0
- Direction
- eliminatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Incorporation of alfalfa residue essentially eliminated volatile N losses”
Claim · model-written summary
Termination method affected ammonia evolution less than residue placement.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Termination methode0
- Outcome
- NH 3 evolutione0
- Direction
- lesse0
- Comparator
- residue placemente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Termination method had comparatively less effect on NH 3 evolution than residue placement”
t0“alfalfa”
Claim · model-written summary
Herbicide termination tended to increase the proportion of alfalfa nitrogen lost by volatilization.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- herbicide applicatione0
- Outcome
- proportion of alfalfa N lost via volatilizatione0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“herbicide application tended to increase the proportion of alfalfa N lost via volatilization”
Claim · model-written summary
Residue incorporation increased cumulative carbon dioxide evolution regardless of termination method.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Residue incorporatione0
- Outcome
- cumulative CO 2 evolutione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Residue incorporation increased cumulative CO 2 evolution regardless of termination method”
t0“alfalfa”
Claim · model-written summary
The authors warned that retaining alfalfa residue on the soil surface may cause substantial volatile nitrogen loss and reduce fertilizer value.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- fertilizer value derived from alfalfa residuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa residue is retained on the soil surface may result in significant volatile N losses which could diminish the fertilizer value derived from alfalfa residues”
Claim · model-written summary
The authors concluded that possible nitrogen losses need not preclude herbicide termination because it may reduce soil erosion and moisture loss.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- adoption of herbicide termination of alfalfae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these N losses do not necessarily preclude the adoption of herbicide termination of alfalfa given the potential reductions in soil erosion and moisture loss”
The same questions in other papers
herbicide · molecular: metabolites · Medicago sativa (alfalfa)Positive and negative results
2 papers in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
2 papers more in this group
See all 6 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.