Abstract
In irrigated apple orchard systems, the magnitude and timing of plant demand for nitrogen (N) and retention of N in the root zone to allow root interception are important factors for efficient management of N fertilizer. Results from five experiments in high-density plantings of apple ( Malus domestica ) on dwarfing (`Malling 9') rootstocks are reported. All experimental plots received daily drip irrigation and N applied through the irrigation system (fertigation) with different regimes according to experimental design. Labelled fertilizer applications, whole tree excavation and partitioning and removal of N in fruit and senescent leaves were used to assess tree N demand. Nitrogen requirements ranged from 8 to 40 lb/acre (8.8 to 44 kg·ha -1 ) over the first 6 years after planting and N use efficiency was often low (<30%), likely because supply exceeded demand. Annual growth is supported by N remobilized from storage and taken up by roots. Root uptake of labelled fertilizer was negligible during early spring and the commencement of rapid uptake was associated with the end of remobilization and the start of shoot growth, rendering prebloom fertilizer applications ineffective. Thus timing of N supply to periods of high demand is crucial for improving efficiency. Comparisons were made to determine the effects on N leaching and tree N utilization of irrigation scheduled to meet evaporative demand and irrigation applied at a fixed rate. Water losses beneath the root zone were greater for fixed rate than scheduled irrigation during the coolest months (May, June and September) of irrigation application. Nitrogen leaching followed a similar pattern during times of N fertigation (May and June). Greater N use efficiency was also measured for trees when irrigation was scheduled to meet evaporative demand rather than applied at a fixed rate. The most N efficient management system was for trees receiving a low [50 ppm (mg·L -1 )] fertigated N supply, at 0 to 4 or 4 to 8 weeks following bloom with scheduled irrigation.
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Claims 11
Claim · model-written summary
Apple nitrogen requirements ranged from 8 to 40 lb/acre over the first six years.
- Taxon
- Apple
Malus domesticat0 - Outcome
- Nitrogen requirementse0
- Value
- 8 to 40 lb/acree0
- Qualifier
- first 6 years after plantinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen requirements ranged from 8 to 40 lb/acre (8.8 to 44 kg·ha -1 ) over the first 6 years after planting”
t0“Apple”
Claim · model-written summary
Nitrogen use efficiency was often below 30 percent.
- Taxon
- AppleMalus domesticat0
- Outcome
- N use efficiencye0
- Direction
- lowe0
- Value
- <30%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N use efficiency was often low (<30%), likely because supply exceeded demand.”
t0“Apple”
Claim · model-written summary
Annual apple growth draws on stored and root absorbed nitrogen.
- Taxon
- AppleMalus domesticat0
- Outcome
- Annual growthe0
- Qualifier
- N remobilized from storage and taken up by rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Annual growth is supported by N remobilized from storage and taken up by roots.”
t0“Apple”
Claim · model-written summary
Root uptake of labeled fertilizer was negligible in early spring.
- Taxon
- AppleMalus domesticat0
- Outcome
- Root uptake of labelled fertilizere0
- Direction
- negligiblee0
- Qualifier
- early springe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root uptake of labelled fertilizer was negligible during early spring”
t0“Apple”
Claim · model-written summary
Rapid nitrogen uptake began with the end of remobilization and start of shoot growth.
- Taxon
- AppleMalus domesticat0
- Organ / stage
- shoot growthe0
- Outcome
- rapid uptakee0
- Direction
- rapide0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“commencement of rapid uptake was associated with the end of remobilization and the start of shoot growth”
t0“Apple”
Claim · model-written summary
Prebloom fertilizer applications were ineffective.
- Taxon
- AppleMalus domesticat0
- Treatment
- prebloom fertilizer applicationse0
- Outcome
- ineffectivee0
- Direction
- ineffectivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“rendering prebloom fertilizer applications ineffective.”
t0“Apple”
Claim · model-written summary
Fixed rate irrigation caused greater root zone water losses than scheduled irrigation in cooler months.
- Taxon
- AppleMalus domesticat0
- Treatment
- fixed ratee0
- Outcome
- Water losses beneath the root zonee0
- Direction
- greatere0
- Qualifier
- coolest months (May, June and September)e0
- Comparator
- scheduled irrigatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water losses beneath the root zone were greater for fixed rate than scheduled irrigation during the coolest months (May, June and September) of irrigation application.”
t0“Apple”
Claim · model-written summary
Nitrogen leaching followed the fixed rate irrigation water loss pattern during fertigation.
- Taxon
- AppleMalus domesticat0
- Outcome
- Nitrogen leachinge0
- Qualifier
- N fertigation (May and June)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen leaching followed a similar pattern during times of N fertigation (May and June).”
t0“Apple”
Claim · model-written summary
Scheduled irrigation gave greater tree nitrogen use efficiency than fixed rate irrigation.
- Taxon
- AppleMalus domesticat0
- Treatment
- irrigation was scheduled to meet evaporative demande0
- Outcome
- N use efficiencye0
- Direction
- Greatere0
- Comparator
- applied at a fixed ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Greater N use efficiency was also measured for trees when irrigation was scheduled to meet evaporative demand rather than applied at a fixed rate.”
t0“Apple”
Claim · model-written summary
Low nitrogen fertigation with scheduled irrigation was the most nitrogen efficient system.
- Taxon
- AppleMalus domesticat0
- Treatment
- low [50 ppm (mg·L -1 )] fertigated N supplye0
- Outcome
- N efficient management systeme0
- Direction
- moste0
- Qualifier
- 0 to 4 or 4 to 8 weeks following bloom with scheduled irrigatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The most N efficient management system was for trees receiving a low [50 ppm (mg·L -1 )] fertigated N supply, at 0 to 4 or 4 to 8 weeks following bloom with scheduled irrigation.”
t0“Apple”
Claim · model-written summary
Nitrogen supply should be timed to high demand to improve efficiency.
- Taxon
- AppleMalus domesticat0
- Outcome
- timing of N supply to periods of high demande0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Thus timing of N supply to periods of high demand is crucial for improving efficiency.”
t0“Apple”
The same questions in other papers
irrigation · nutrient: efficiency · Malus domestica (apple)Results agree
2 papers in the same direction as this paper
- positive
- positive
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.