Abstract
Excess levels of molybdenum (Mo) are an inherent characteristic of many reclaimed peatlands and other soils in the Irish Midlands. Molybdenum and copper (Cu) interactions, combined with a number of soil factors, can impose a limitation to land use in this area for animal production. An experiment, using four nitrogen fertiliser types and two different phosphate fertiliser rates, was conducted over four years, to determine ways of overcoming this problem in subsequent farming practices. At an annual application rate of 318 kg N/ha, ammonium sulphate and calcium ammonium nitrate plus gypsum reduced molybdenum mean levels in grass herbage to 8.3, 5.6, 2.4, 7.0 and 17.5, 10.2, 5.4, 7.1 (mg/kg), respectively, in consecutive years. For calcium ammonium nitrate and urea applied at the same N rate, resulting Mo mean level were 34.6, 36.5, 28.6, 33.1 and 35.2, 40.5, 29.8, 42.4 (mg/kg) (s.e. of mean = 3.31). Increasing the P application rate from 60 to 180 kg/ha reduced Mo overall mean levels from 26.3 to 16.7 (mg/kg) (s.e. of mean = 2.34). A nitrogen type by phosphorus rate interaction occurred. It reduced Mo from 42.5 to 23.9 and 46.3 to 27.7 (mg/kg) with two N types, (calcium ammonium nitrate and urea), but without significant effect with ammonium sulphate or calcium ammonium nitrate plus gypsum types (s.e. of mean = 4.68). These latter two N forms reduced soil pH by about half a unit over the four years of the trial. The results indicate that permanent benefits can be secured in reducing the Mo content of herbage by these means. The optimum fertiliser treatments, of ammonium sulphate and calcium ammonium nitrate plus gypsum, added over 300 and 150 kg/ha elemental sulphur to the soil. Though favourable in this role, the effects of added S may require further research because it has potential ambivalent effects in the soil-plant-animal system.
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Claims 11
Claim · model-written summary
Ammonium sulphate reduced herbage molybdenum to the reported yearly levels.
- Taxon
- herbagee0
- Treatment
- ammonium sulphatee0
- Outcome
- molybdenum mean levels in grass herbagee0
- Direction
- reducede0
- Value
- 8.3, 5.6, 2.4, 7.0e0
- Qualifier
- 318 kg N/hae0
Not reportedComparator
Verbatim
e0“At an annual application rate of 318 kg N/ha, ammonium sulphate and calcium ammonium nitrate plus gypsum reduced molybdenum mean levels in grass herbage to 8.3, 5.6, 2.4, 7.0 and 17.5, 10.2, 5.4, 7.1 (mg/kg), respectively, in consecutive years.”
Claim · model-written summary
Calcium ammonium nitrate plus gypsum reduced herbage molybdenum to the reported yearly levels.
- Taxon
- herbagee0
- Treatment
- calcium ammonium nitrate plus gypsume0
- Outcome
- molybdenum mean levels in grass herbagee0
- Direction
- reducede0
- Value
- 17.5, 10.2, 5.4, 7.1 (mg/kg)e0
Not reportedComparator
Verbatim
e0“At an annual application rate of 318 kg N/ha, ammonium sulphate and calcium ammonium nitrate plus gypsum reduced molybdenum mean levels in grass herbage to 8.3, 5.6, 2.4, 7.0 and 17.5, 10.2, 5.4, 7.1 (mg/kg), respectively, in consecutive years.”
Claim · model-written summary
Calcium ammonium nitrate produced the reported herbage Mo means.
Verbatim
e0“For calcium ammonium nitrate and urea applied at the same N rate, resulting Mo mean level were 34.6, 36.5, 28.6, 33.1 and 35.2, 40.5, 29.8, 42.4 (mg/kg)”
t0“herbage grown on peatland”
Claim · model-written summary
Urea produced the reported herbage Mo means.
Verbatim
e0“For calcium ammonium nitrate and urea applied at the same N rate, resulting Mo mean level were 34.6, 36.5, 28.6, 33.1 and 35.2, 40.5, 29.8, 42.4 (mg/kg)”
t0“herbage grown on peatland”
Claim · model-written summary
Increasing P from 60 to 180 kg/ha reduced mean herbage Mo from 26.3 to 16.7 mg/kg.
Verbatim
e0“Increasing the P application rate from 60 to 180 kg/ha reduced Mo overall mean levels from 26.3 to 16.7 (mg/kg)”
t0“herbage grown on peatland”
Claim · model-written summary
Increasing P reduced Mo with calcium ammonium nitrate.
Not reportedComparator
Verbatim
e0“It reduced Mo from 42.5 to 23.9 and 46.3 to 27.7 (mg/kg) with two N types, (calcium ammonium nitrate and urea)”
t0“herbage grown on peatland”
Claim · model-written summary
Increasing P reduced Mo with urea.
Not reportedComparator
Verbatim
e0“It reduced Mo from 42.5 to 23.9 and 46.3 to 27.7 (mg/kg) with two N types, (calcium ammonium nitrate and urea)”
t0“herbage grown on peatland”
Claim · model-written summary
The P interaction had no significant effect with ammonium sulphate.
Not reportedComparatorDirection
Verbatim
e0“without significant effect with ammonium sulphate or calcium ammonium nitrate plus gypsum types”
t0“herbage grown on peatland”
Claim · model-written summary
The P interaction had no significant effect with calcium ammonium nitrate plus gypsum.
Not reportedComparatorDirection
Verbatim
e0“without significant effect with ammonium sulphate or calcium ammonium nitrate plus gypsum types”
t0“herbage grown on peatland”
Claim · model-written summary
The latter two nitrogen forms reduced soil pH by about half a unit.
Not reportedTaxonComparator
Verbatim
e0“These latter two N forms reduced soil pH by about half a unit over the four years of the trial.”
Claim · model-written summary
The authors conclude these fertilizers can permanently reduce herbage Mo.
Verbatim
e0“The results indicate that permanent benefits can be secured in reducing the Mo content of herbage by these means.”
t0“herbage grown on peatland”