Abstract
To address the conflict between soil degradation and sugarcane productivity in South China karst regions, this study investigated the coordinated regulatory effects of fertilization practices on sugarcane yield, soil enzymatic activities, and ecological stoichiometry through nitrogen-potassium coupling experiments, establishing a theoretical framework for precision nutrient management. A field experiment evaluated the soil enzymatic activities, nutrient concentrations, ecological stoichiometry indices, and sugarcane productivity across eight nitrogen-potassium application ratios (N 0 K 0 to N 3 K 2 ). The direct and indirect effects of fertilization measures were quantified using structural equation model (SEM), grey relational analysis and path analysis. The results showed that the high nitrogen and high potassium treatment (N 3 K 2 ) achieved maximum sugarcane yield (91.05 t ha -1 ), representing a 55.25% increase over the control, but leading to soil acidification (pH 4.57). Optimal nitrogen use efficiency (38.47%) occurred under the low nitrogen and high potassium treatment (N 1 K 2 ), exceeding conventional fertilization by 21.41%. Path analysis revealed that urease exerted the strongest direct yield effect (1.977), while total potassium demonstrated the highest grey correlation degree (0.911). The medium nitrogen and high potassium treatment (N 2 K 2 ) exhibited optimal soil fertility (IFI = 0.57) with significantly higher total base ions (0.48 Cmol kg -1 ) compared to other treatments. The ecological stoichiometric characteristics showed that the soil in the study area was in the state of nitrogen limitation (nitrogen-phosphorus ratio = 1.89) and phosphorus efficiency (carbon-nitrogen ratio = 9.56-23.25). Structural equation modeling revealed nutrient cycling influenced sugarcane yield through enzymatic regulation (total effect = 0.702). This study established an acid soil ternary regulation framework integrating enzyme activity, nutrient cycling, and stoichiometric balance, while recommending the optimization scheme of nitrogen-potassium ratio (N:K 2 O ≈ 1:1.5) for southern sugarcane cultivation. The ammonium nitrogen activation coefficient (> 1.5%) and carbon-phosphorus ratio (< 25%) were identified as pivotal fertility monitoring parameters, offering theoretical foundations for precision fertilization and sustainable soil management in karst areas.
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Claims 13
Claim · model-written summary
High nitrogen and potassium produced maximum sugarcane yield of 91.05 t ha -1, 55.25% above control.
Verbatim
e0“the high nitrogen and high potassium treatment (N 3 K 2 ) achieved maximum sugarcane yield (91.05 t ha -1 ), representing a 55.25% increase over the control”
Claim · model-written summary
High nitrogen and potassium acidified soil to pH 4.57.
Not reportedTreatmentComparatorDirection
Verbatim
e0“but leading to soil acidification (pH 4.57)”
t0“sugarcane”
Claim · model-written summary
Low nitrogen and high potassium gave 38.47% nitrogen use efficiency, 21.41% above conventional fertilization.
Verbatim
e0“Optimal nitrogen use efficiency (38.47%) occurred under the low nitrogen and high potassium treatment (N 1 K 2 ), exceeding conventional fertilization by 21.41%.”
t0“sugarcane”
Claim · model-written summary
Urease had the strongest direct yield effect, 1.977.
Not reportedTaxon
Verbatim
e0“Path analysis revealed that urease exerted the strongest direct yield effect (1.977)”
Claim · model-written summary
Total potassium had the highest grey correlation degree, 0.911.
Not reportedTaxon
Verbatim
e0“total potassium demonstrated the highest grey correlation degree (0.911).”
Claim · model-written summary
Medium nitrogen and high potassium gave optimal soil fertility index of 0.57.
- Treatment
- medium nitrogen and high potassium treatment (N 2 K 2 )e0
- Outcome
- soil fertilitye0
- Direction
- optimale0
- Value
- 0.57e0
Not reportedTaxonComparator
Verbatim
e0“The medium nitrogen and high potassium treatment (N 2 K 2 ) exhibited optimal soil fertility (IFI = 0.57)”
Claim · model-written summary
Medium nitrogen and high potassium gave higher total base ions of 0.48 Cmol kg -1.
Not reportedTaxonTreatment
Verbatim
e0“with significantly higher total base ions (0.48 Cmol kg -1 ) compared to other treatments.”
Claim · model-written summary
Study area soil showed nitrogen limitation with nitrogen-phosphorus ratio 1.89.
Not reportedTaxon
Verbatim
e0“the soil in the study area was in the state of nitrogen limitation (nitrogen-phosphorus ratio = 1.89)”
Claim · model-written summary
Study area soil showed phosphorus efficiency with carbon-nitrogen ratio 9.56-23.25.
Not reportedTaxon
Verbatim
e0“phosphorus efficiency (carbon-nitrogen ratio = 9.56-23.25)”
Claim · model-written summary
Nutrient cycling influenced sugarcane yield through enzymatic regulation with total effect 0.702.
Verbatim
e0“Structural equation modeling revealed nutrient cycling influenced sugarcane yield through enzymatic regulation (total effect = 0.702).”
Claim · model-written summary
Authors recommend N:K 2 O ≈ 1:1.5 for southern sugarcane cultivation.
Verbatim
e0“recommending the optimization scheme of nitrogen-potassium ratio (N:K 2 O ≈ 1:1.5) for southern sugarcane cultivation.”
Claim · model-written summary
Ammonium nitrogen activation coefficient above 1.5% was identified as a fertility monitoring parameter.
Verbatim
e0“The ammonium nitrogen activation coefficient (> 1.5%) and carbon-phosphorus ratio (< 25%) were identified as pivotal fertility monitoring parameters”
Claim · model-written summary
Carbon-phosphorus ratio below 25% was identified as a fertility monitoring parameter.
Verbatim
e0“The ammonium nitrogen activation coefficient (> 1.5%) and carbon-phosphorus ratio (< 25%) were identified as pivotal fertility monitoring parameters”
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