Abstract
A pot trial was conducted under greenhouse conditions to assess the effect of humic acid (HA) application in combination with rock phosphate (RP) on the plant phosphorus (P) nutrient use efficiency (NUE), in comparison to the performance of struvite (ST) and triple superphosphate (TSP) amended plants. A sandy soil, exhibiting a low P content, was used in combination with a lignite derived, liquid humic acid product, with a HA content of 4.8 %. Nine groups of perennial ryegrass (Lolium perenne L.) were set up as experimental plants, in replications of six, each containing 4.5 kg air dry soil with a P supply of 27 mg P kg-1 soil, causing P deficiency during the experiment. HA was applied at rates of 1, 30 and 100 mg kg-1 soil, directly to the soil as coated RP or as foliar application. Aboveground biomass was harvested biweekly, five times in total. Amendment performance was evaluated by analysing plant biomass, soil pH, plant phosphorus-, carbon-, nitrogen-, iron-, zinc-, manganese- and boron contents. The label doses of 1 mg kg-1 soil as well as 100-fold increases in HA concentration didn’t result in a significant difference in plant shoot or root growth and P NUE compared to untreated plants. Positive trends were displayed at higher foliar application rates. Plant tissue micronutrient concentrations of HA treated samples were generally lower and partly significantly lower than the control. The detected effects were accredited to the hormone-like influence of HA on plants’ metabolism and the ability to alter soil conditions. The lack of calcium in ST amended samples resulted in better plant P availability, significantly higher P uptake and better shoot biomass development. Trends show that ST could be applied in combination with HA to further increase plants P NUE in the future.
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Claims 8
Claim · model-written summary
Humic acid at the label dose of 1 mg kg-1 soil and at a 100-fold higher concentration produced no significant difference in ryegrass shoot or root growth and P nutrient use efficiency compared with untreated plants.
- Taxon
- perennial ryegrass
Lolium perennee0 - Treatment
- label doses of 1 mg kg-1 soil as well as 100-fold increases in HA concentratione1
- Outcome
- plant shoot or root growth and P NUEe1
- Direction
- no_changeinferrede1
- Comparator
- untreated plantse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“The label doses of 1 mg kg-1 soil as well as 100-fold increases in HA concentration didn’t result in a significant difference in plant shoot or root growth and P NUE compared to untreated plants”
Claim · model-written summary
Positive trends were displayed at higher foliar humic acid application rates.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- higher foliar application ratese1
- Outcome
- Positive trendse1
- Direction
- Positive trendse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“Positive trends were displayed at higher foliar application rates”
Claim · model-written summary
Plant tissue micronutrient concentrations of humic acid treated plants were generally lower than the control and partly significantly lower.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- HAe1
- Outcome
- Plant tissue micronutrient concentrationse1
- Direction
- lowere1
- Qualifier
- partly significantly lowere1
- Comparator
- the controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“Plant tissue micronutrient concentrations of HA treated samples were generally lower and partly significantly lower than the control”
Claim · model-written summary
The authors attribute the detected humic acid effects to its hormone-like influence on plant metabolism and its ability to alter soil conditions.
- Taxon
- perennial ryegrassLolium perennee0
- Compound
- HAe1
- Outcome
- detected effectse1
- Qualifier
- hormone-like influence of HA on plants’ metabolisme1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“The detected effects were accredited to the hormone-like influence of HA on plants’ metabolism and the ability to alter soil conditions”
Claim · model-written summary
Struvite-amended plants, lacking calcium, showed better plant P availability.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- ST amendede1
- Outcome
- plant P availabilitye1
- Direction
- bettere1
- Qualifier
- lack of calciume1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“The lack of calcium in ST amended samples resulted in better plant P availability, significantly higher P uptake and better shoot biomass development”
Claim · model-written summary
Struvite-amended plants showed significantly higher P uptake.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- ST amendede1
- Outcome
- P uptakee1
- Direction
- highere1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“The lack of calcium in ST amended samples resulted in better plant P availability, significantly higher P uptake and better shoot biomass development”
Claim · model-written summary
Struvite-amended plants showed better shoot biomass development.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- ST amendede1
- Outcome
- shoot biomass developmente1
- Direction
- bettere1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“The lack of calcium in ST amended samples resulted in better plant P availability, significantly higher P uptake and better shoot biomass development”
Claim · model-written summary
Struvite could be applied in combination with humic acid to further increase plant P nutrient use efficiency.
- Taxon
- perennial ryegrassLolium perennee0
- Outcome
- ST could be applied in combination with HA to further increase plants P NUEe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“perennial ryegrass (Lolium perenne L.)”
e1“Trends show that ST could be applied in combination with HA to further increase plants P NUE in the future”
The same questions in other papers
ammonium magnesium phosphate hexahydrate · growth · Lolium perenne (perennial ryegrass)Results agree
1 paper in the same direction as this paper
- 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.