Abstract
In citrus orchards, nitrogen uptake efficiency (NUE) is between 40 to 60% where any excess of nitrate is subjected to leaching below the rooting zone. The compound, 3,4-dimethylpyrazole phosphate (DMPP) inhibits the nitrification process in soil thus reducing/delaying nitrate leaching. The objective of this study was to evaluate the performance of DMPP added to ammonium sulphate (AS+DMPP), compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN), in fertigation of bearing orange trees grown outdoors in drainage lysimeters. Fertilizers were 15N-labeled to trace N through soil-plant-drainage system. Soil was sampled monthly from April to December and trees were destructively harvested in December. In trees fertilized with AS+DMPP, increased biomass was observed with a more profuse development of root system and higher fruit yield. Fertilizer 15N uptake significantly increased with DMPP addition. In AS+DMPP amended soils, increased values of -15N and lower -N concentrations were recorded from April to June as evidence of the inhibitory effect of DMPP on the nitrification process during this period. In CPN and AS fertilized soils, 15N losses in drainage solutions represented 9-10% of the fertilizer supplied whereas less than 3% was leached when DMPP was added. At the end of the cycle, highest NUE was recorded in the AS+DMPP treatment (69%), while CPN and AS had lower values (61% and 54%, respectively). Therefore, the use of DMPP enables a more efficient utilization of the fertilizer-N in citrus trees, minimizing the risk of nitrate-N pollution in groundwater. However, DMPP supply should be considered during spring fertilization, since high temperatures of summer months significantly reduced its activity.
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Claims 10
Claim · model-written summary
AS+DMPP increased orange tree biomass.
Verbatim
e0“In trees fertilized with AS+DMPP, increased biomass was observed”
e1“compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN)”
e2“bearing orange trees”
Claim · model-written summary
AS+DMPP produced a more profuse root system.
Verbatim
e0“In trees fertilized with AS+DMPP, increased biomass was observed with a more profuse development of root system”
e1“compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN)”
e2“bearing orange trees”
Claim · model-written summary
AS+DMPP raised fruit yield.
Verbatim
e0“In trees fertilized with AS+DMPP, increased biomass was observed with a more profuse development of root system and higher fruit yield”
e1“compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN)”
e2“bearing orange trees”
Claim · model-written summary
DMPP addition significantly increased fertilizer 15N uptake.
Verbatim
e0“Fertilizer 15N uptake significantly increased with DMPP addition”
e1“compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN)”
e2“bearing orange trees”
Claim · model-written summary
AS+DMPP soils had increased -15N values during April to June.
Verbatim
e0“In AS+DMPP amended soils, increased values of -15N and lower -N concentrations were recorded from April to June”
e1“compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN)”
e2“bearing orange trees”
Claim · model-written summary
AS+DMPP soils had lower -N concentrations from April to June.
Verbatim
e0“In AS+DMPP amended soils, increased values of -15N and lower -N concentrations were recorded from April to June”
e1“compared to ammonium sulphate (AS) and calcium-potassium nitrate (CPN)”
e2“bearing orange trees”
Claim · model-written summary
DMPP reduced fertilizer 15N loss in drainage to less than 3%, versus 9-10% with CPN or AS.
Verbatim
e0“In CPN and AS fertilized soils, 15N losses in drainage solutions represented 9-10% of the fertilizer supplied whereas less than 3% was leached when DMPP was added”
e1“bearing orange trees”
Claim · model-written summary
AS+DMPP gave the highest nitrogen uptake efficiency, 69%, versus 61% for CPN and 54% for AS.
Verbatim
e0“highest NUE was recorded in the AS+DMPP treatment (69%), while CPN and AS had lower values (61% and 54%, respectively)”
e1“bearing orange trees”
Claim · model-written summary
High summer temperatures significantly reduced DMPP activity.
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high temperatures of summer months significantly reduced its activity”
e1“citrus trees”
Claim · model-written summary
The authors recommend DMPP supply during spring fertilization.
- Outcome
- DMPP supply should be considered during spring fertilizatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DMPP supply should be considered during spring fertilization”
e1“citrus trees”
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