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Soil and Water Quality with Miscanthus on a Louisiana Coastal Plain Hillside L. Gaston and W. Felicien LSU AgCenter School of Plant, Environmental and Soil Sciences. Rationale Marginally productive land used for pasture and timber may be more productive with non-pasture, biomass grasses - PowerPoint PPT Presentation
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Soil and Water Quality with Miscanthus on aLouisiana Coastal Plain Hillside
L. Gaston and W. Felicien
LSU AgCenterSchool of Plant, Environmental and Soil Sciences
Rationale Marginally productive land used for pasture and timber may be more productive with non-pasture, biomass grasses
Good for the landowner / producer and local community Positive direction with respect to energy dependency and climate change Depends on sustainable production without negative environmental effect
Objectives YieldNutrient dynamicsSoil qualityWater quality
Overview of the Experiment Location, Field Plot Design, Study Components and Methods
Location LSU AgCenter Calhoun Research Station, Calhoun, LA Western Coastal Plain MLRA 133B Ruston-Lucy Association, Hilly – a sandy loam, acidic soil
Specific site had not be used for years
Field Plot Design Miscanthus giganteus transplanted spring 2009 @ 1 plant m-2
Treatments applied 2010 RCB design 3 replications with blocks perpendicular to slope (high, middle and low) Plots 5 m x 5 m with 2 m border between plots and 5 m buffer between blocks Treatments include
Inorganic N @ 80 and 160 kg ha-1
N-based poultry litter @ 80 and 160 kg ha-1
No fertilization controlNo miscanthus, no fertilization = native vegetation control
Harvest fall to winter for biomass productivity and tissue composition
Runoff Water Quality Sub-plots (3/4 m x 2 m stainless steel, 10 cm walls, 5 cm deep trough with drain)
In all poultry litter, no fertilizer control and native vegetation plots (12 sub-plots) Parameters include volume, TS, DS, SS, COD, DOC, NH4
+, NO3-, TP, DRP and pH
All runoff > ~ 200 mL analyzed Begun after treatments applied 2010
Soil Quality Extractable nutrients, OC and FDA hydrolysis Sampling in late winter before re-growth
Results
Yields
Treatment 2010 2011---------- Mg ha-1 -----------
0 N 5.79 a 6.81 a 80 N inorganic 4.49 a 4.99 a160 N inorganic 7.36 a 7.82 a 80 N poultry litter 7.30 a 7.98 a160 N poultry litter 7.81 a 8.69 a
Low yields and no effect of fertilizer rate or source
Nutrient Removal in Harvest
2011
Treatment Ca Mg P K S-------------------- kg ha-1 --------------------
0 N 11.0 2.4 0.7 11.1 2.0 80 N inorganic 10.2 1.0 0.6 9.4 1.8160 N inorganic 12.9 2.0 0.3 16.1 2.6 80 N poultry litter 16.9 1.8 3.0 20.3 3.2160 N poultry litter 9.8 1.8 4.4 18.3 2.5
Negligible depletion of soil nutrients
2010 similar
Soil Quality Parameters
OC
Treatment 2012 2011 2010 2009-------------- % --------------
0 N 0.80 a b c 0.80 a 80 N inorganic 0.67 b c 0.78 a160 N inorganic 0.65 c 0.74 a 80 N poultry litter 0.88 a 0.94 a160 N poultry 0.88 a 0.84 a
Native vegetation 0.83 a b 0.82 a
Average 0.79 0.82 0.78 0.81
FDA Hydrolysis
Treatment 2012 2011--- micromoles g-1 h-1 ---
0 N 0.17 a 0.13 a 80 N inorganic 0.17 a 0.16 a160 N inorganic 0.16 a 0.12 a 80 N poultry litter 0.16 a 0.14 a160 N poultry 0.12 b 0.13 a
Native vegetation 0.16 a 0.15 a
Runoff Water Quality
2010
Treatment TS DOC NH4+ NO3
- TP DRP---------------------------- kg ha-1 ----------------------------
0 N 32 a b 9 b 0.3 a 0.1 a 0.3 a 0.2 a 80 N poultry litter 42 a b 7 b 0.2 a 0.2 a 0.3 a 0.3 a160 N poultry 25 a b 8 b 0.3 a 0.1 a 0.5 a 0.4 a
Native vegetation 64 a 20 a 0.5 a 0.2 a 0.3 a 0.2 a
2011
0 N 34 a 4 a 0.2 a 0.1 a 0.1 a 0.1 a 80 N poultry litter 13 a 2 a 0.1 a 0.1 a 0.1 a 0.1 a160 N poultry 19 a 5 a 0.2 a 0.1 a 0.3 a 0.3 a
Native vegetation 35 a 11 a 0.2 a 0.5 a 0.1 a 0.1 a
Discussion
Some indication that miscanthus performs better at lower landscape position,or performs worst at higher position
Block 2010 Yield 2011 Yield ------------ Mg ha-1 ------------
High 4.82 a 4.78 bMiddle 7.38 a 9.31 aLow 7.79 a 7.69 a b
Runoff depth follows this trend but differences are not significant
Little runoff from high position at this site is consistent with measured KSAT
KSAT = 12.3 ± 6.0 cm h-1 (single ring method)
Fast topsoil drainage may reduce available water in absence of less permeable subsoil
Yield data are inversely related to depth to Bt
Depth to Bt Horizon (cm)
0 20 40 60 80 100
Yie
ld (
Mg
ha-1
)
0
4
8
12
R2 = 0.74
Negative relationship between miscanthus yield and depth to the Bt horizon. Data exclude plots from which sample to 1 m could not taken due to wetness (lowest block). Three plots from the highest block had no Bt within 1 m. Depth to these in this figure and the regression was taken as 100 cm.
Relative Depths to Bt Horizon within Treatments
0.0 0.4 0.8 1.2 1.6 2.0
Rel
ativ
e Y
ield
s w
ithin
Tre
atm
ents
0.0
0.4
0.8
1.2
1.6
2.0
2.4
R2 = 0.93
Negative relationship between relative yields of miscanthus within treatments and relative depths to Bt within plots of the same treatment –normalized yields and depths to Bt within treatments.
Subsoil fertility may contribute, however, there is no significant relationship between topsoil chemical fertility and yields
Seep areas below lowest block indicates fairly shallow saturation
Further Planned Work
Depth to saturation unknown –install wells to determine behavior
Fertility level at site is low to very low for common pasture grassesRaise baseline fertility and continue
Summary
Yields of miscanthus are low, e.g., 7.3 ± 3.5 Mg ha-1 in 2011, third year
Water may be limiting miscanthus and soil heterogeneity obscuringtreatment effects
In contrast, second year (2011) yields of switchgrass at this site were23.5 ± 3.8 Mg ha-1
Miscanthus appears to be neutral in effect on measures of soil and water quality, i.e., the same as diverse, open-land vegetation
Loss of nutrients in runoff is negligible from miscanthus, even wherepoultry litter is applied at ~ 3 and 6 Mg ha-1
Presumably due to low high infiltration and low soil fertility