Abstract
Abstract High rates of N fertilizers and limited crop uptake of N during the growing season can result in excessive accumulation of soil nitrate (NO − 3 ). Soil NO − 3 can be decreased with efficient cropping systems. Experiments were conducted in Connecticut from 1987 through 1990 on a Paxton fine sandy loam soil (coarse‐loamy, mixed, mesic Typic Dystrochrept) to determine the effects of N rate and cropping system on soil NO − 3 . Orchardgrass ( Dactylis glomerata L.), red clover ( Trifolium pratense L.), a double‐crop system of oat ( Avena sativa L.) followed by tyfon [ Brassica rapa L. × B. pekinensis (Lour.) Rupr.], maize ( Zea mays L.) followed by a cover crop of winter rye ( Secale cereale L.), and a fallow system received preplant N at 0, 112, 224, 336, and 448 kg ha −1 . Each system was evaluated for two consecutive growing seasons and repeated three times. Nitrogen was applied only in the first growing season. Soil NO − 3 at the first autumn sampling generally increased for all systems as N rate increased. Mean spring soil NO − 3 levels were only 23% of previous autumn NO − 3 levels. By the second autumn sampling, soil NO − 3 values were near background levels except in the fertilized fallow system. At the two highest N rates, oat‐tyfon produced the smallest overwinter change in soil NO − 3 storage. An oat‐tyfon double crop, orchardgrass, or red clover system should decrease soil NO − 3 more effectively than maize or a noncropped fallow when soil NO − 3 accumulations are greater than those produced from N inputs equivalent to 224 kg ha −1 .
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Claims 5
Claim · model-written summary
Soil nitrate at the first autumn sampling increased with N rate in all cropping systems.
- Taxon
- Orchardgrass
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Dactylis glomeratae0 - Treatment
- N ratee1
- Outcome
- Soil NO − 3 at the first autumn samplinge1
- Direction
- increasede1
- Qualifier
- for all systemse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Orchardgrass ( Dactylis glomerata L.), red clover ( Trifolium pratense L.)”
e1“Soil NO − 3 at the first autumn sampling generally increased for all systems as N rate increased”
Claim · model-written summary
Mean spring soil nitrate was about 23% of the previous autumn level.
- Taxon
- OrchardgrassDactylis glomeratae0
- Outcome
- Mean spring soil NO − 3 levelse2
- Direction
- lowerinferrede2
- Value
- 23%e2
- Comparator
- previous autumn NO − 3 levelse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Orchardgrass ( Dactylis glomerata L.), red clover ( Trifolium pratense L.)”
e2“Mean spring soil NO − 3 levels were only 23% of previous autumn NO − 3 levels”
Claim · model-written summary
By the second autumn sampling, soil nitrate values were near background levels except in the fertilized fallow system.
- Taxon
- OrchardgrassDactylis glomeratae0
- Outcome
- soil NO − 3 valuese3
- Qualifier
- near background levels except in the fertilized fallow systeme3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Orchardgrass ( Dactylis glomerata L.), red clover ( Trifolium pratense L.)”
e3“By the second autumn sampling, soil NO − 3 values were near background levels except in the fertilized fallow system”
Claim · model-written summary
At the two highest N rates, the oat-tyfon system produced the smallest overwinter change in soil nitrate storage.
- Taxon
- oat
Avena sativae4 - Treatment
- oat‐tyfone4
- Outcome
- overwinter change in soil NO − 3 storagee4
- Direction
- smalleste4
- Qualifier
- At the two highest N ratese4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“At the two highest N rates, oat‐tyfon produced the smallest overwinter change in soil NO − 3 storage”
Claim · model-written summary
An oat-tyfon double crop, orchardgrass or red clover should decrease soil nitrate more effectively than maize or a noncropped fallow when soil nitrate accumulation exceeds that from 224 kg ha-1 of N input.
- Taxon
- oatAvena sativae5
- Outcome
- decrease soil NO − 3 more effectivelye5
- Qualifier
- when soil NO − 3 accumulations are greater than those produced from N inputs equivalent to 224 kg ha −1e5
- Comparator
- maize or a noncropped fallowe5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“An oat‐tyfon double crop, orchardgrass, or red clover system should decrease soil NO − 3 more effectively than maize or a noncropped fallow when soil NO − 3 accumulations are greater than those produced from N inputs equivalent to 224 kg ha −1”