Abstract
Summary. This study aimed to define the effect of differing rates of nitrogen application and lock up length on harvested material for silage in south-western Victoria. At 2 sites in south-western Victoria, 140, 3 by 2 m plots of predominantly perennial ryegrass pasture were randomly allocated, within 4 replicate blocks. Five nitrogen fertiliser rates (0, 25, 50, 75, 100 kg N/ha) in combination with 7 lock up lengths were randomly allocated to the 35 plots within each replicate. Nitrogen was applied 1 week after initial lock up (September 10, site 1; September 12, site 2) and harvesting commenced 3 weeks after initial lock up. For each treatment and harvest date, dry matter yield and botanical composition were determined and samples of total pasture and the ryegrass fraction were collected and chemically analysed for dry matter digestibility, crude protein, neutral detergent fibre, water-soluble carbohydrates and mineral content. Metabolisable energy was derived from dry matter digestibility. Increasing rates of nitrogen increased herbage dry matter yield regardless of length of lock up. The yield response was greatest 8 weeks after initial lock up at both sites (site 1, 26 kg DM/kg N; site 2, 14.9 kg DM/kg N). Subsequent regrowth of pasture was increased by nitrogen application over shorter lock up lengths (weeks 3 and 4). Botanical composition was unaffected by treatment during the harvesting period or in the subsequent autumn. Application of nitrogen gave rise to a linear increase in pasture metabolisable energy and crude protein content at both sites until week 5. Thereafter, this response diminished and by week 8 there was a decrease in metabolisable energy and crude protein content. Neutral detergent fibre content was relatively unaffected by nitrogen application until week 8 of the study, at which point there was a linear increase. Application of nitrogen reduced the water-soluble carbohydrate content of pastures throughout the sampling period. It is concluded that application of nitrogen to a mixed sward locked up for silage can increase dry matter yield and, provided pasture is harvested before ryegrass ear emergence, can also have a positive effect on metabolisable energy and crude protein. Given that the decision for removing paddocks from the grazing rotation is based upon pasture growth and stocking rates, the use of nitrogen fertilisers on higher stocked farms could lead to increased dry matter yield over shorter lock up periods. On farms with lower stocking rates shorter lock up periods may allow for pastures to be returned to the grazing rotation earlier, or provide the opportunity for a second harvest of pasture for silage.
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Claims 13
Claim · model-written summary
Increasing nitrogen raised herbage dry matter yield regardless of lock-up duration.
- Taxon
- perennial ryegrass pasturee1
- Treatment
- Increasing rates of nitrogene0
- Outcome
- herbage dry matter yielde0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Increasing rates of nitrogen increased herbage dry matter yield regardless of length of lock up.”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
The largest yield response at site 1 was 26 kg DM/kg N eight weeks after lock-up.
Verbatim
e0“The yield response was greatest 8 weeks after initial lock up at both sites (site 1, 26 kg DM/kg N; site 2, 14.9 kg DM/kg N).”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
The largest yield response at site 2 was 14.9 kg DM/kg N eight weeks after lock-up.
Verbatim
e0“The yield response was greatest 8 weeks after initial lock up at both sites (site 1, 26 kg DM/kg N; site 2, 14.9 kg DM/kg N).”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
Nitrogen increased subsequent pasture regrowth with shorter lock-up periods.
- Taxon
- pasturee0
- Treatment
- nitrogen applicatione0
- Outcome
- Subsequent regrowth of pasturee0
- Direction
- increasede0
- Qualifier
- weeks 3 and 4e0
Not reportedComparator
Verbatim
e0“Subsequent regrowth of pasture was increased by nitrogen application over shorter lock up lengths (weeks 3 and 4).”
Claim · model-written summary
Treatments did not affect botanical composition during harvest or the following autumn.
- Taxon
- perennial ryegrass pasturee1
- Treatment
- treatmente0
- Outcome
- Botanical compositione0
- Direction
- unaffectede0
Not reportedComparator
Verbatim
e0“Botanical composition was unaffected by treatment during the harvesting period or in the subsequent autumn.”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
Nitrogen linearly increased pasture metabolisable energy through week five.
- Taxon
- pasturee0
- Treatment
- Application of nitrogene0
- Outcome
- pasture metabolisable energye0
- Direction
- linear increasee0
- Qualifier
- until week 5e0
Not reportedComparator
Verbatim
e0“Application of nitrogen gave rise to a linear increase in pasture metabolisable energy and crude protein content at both sites until week 5.”
Claim · model-written summary
Nitrogen linearly increased pasture crude protein through week five.
- Taxon
- pasturee0
- Treatment
- Application of nitrogene0
- Outcome
- crude protein contente0
- Direction
- linear increasee0
- Qualifier
- until week 5e0
Not reportedComparator
Verbatim
e0“Application of nitrogen gave rise to a linear increase in pasture metabolisable energy and crude protein content at both sites until week 5.”
Claim · model-written summary
At week eight, metabolisable energy decreased.
Verbatim
e0“Thereafter, this response diminished and by week 8 there was a decrease in metabolisable energy and crude protein content.”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
At week eight, crude protein content decreased.
Verbatim
e0“Thereafter, this response diminished and by week 8 there was a decrease in metabolisable energy and crude protein content.”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
Nitrogen had little effect on neutral detergent fibre before week eight.
- Taxon
- perennial ryegrass pasturee1
- Treatment
- nitrogen applicatione0
- Outcome
- Neutral detergent fibre contente0
- Direction
- relatively unaffectede0
- Qualifier
- until week 8e0
Not reportedComparator
Verbatim
e0“Neutral detergent fibre content was relatively unaffected by nitrogen application until week 8 of the study, at which point there was a linear increase.”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
At week eight, neutral detergent fibre rose linearly with nitrogen.
- Taxon
- perennial ryegrass pasturee1
- Treatment
- nitrogen applicatione0
- Outcome
- Neutral detergent fibre contente0
- Direction
- linear increasee0
- Qualifier
- week 8e0
Not reportedComparator
Verbatim
e0“Neutral detergent fibre content was relatively unaffected by nitrogen application until week 8 of the study, at which point there was a linear increase.”
t0“pasture”
e1“predominantly perennial ryegrass pasture”
Claim · model-written summary
Nitrogen reduced pasture water-soluble carbohydrates throughout sampling.
- Taxon
- pasturese0
- Treatment
- Application of nitrogene0
- Outcome
- water-soluble carbohydrate contente0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“Application of nitrogen reduced the water-soluble carbohydrate content of pastures throughout the sampling period.”
Claim · model-written summary
Harvest before ryegrass ear emergence to gain energy and protein benefits from nitrogen.
Verbatim
e0“provided pasture is harvested before ryegrass ear emergence, can also have a positive effect on metabolisable energy and crude protein.”
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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.