Jian Liu, Tamie L. Veith, Amy S. Collick, Peter J. A. Kleinman, Douglas B. Beegle, and Ray B.

Transcription

1 Jian Liu, Tamie L. Veith, Amy S. Collick, Peter J. A. Kleinman, Douglas B. Beegle, and Ray B. Bryant Seasonal manure application timing and storage effects on field and watershed level phosphorus losses Supplemental materials: 11 pages, 4 tables, and 4 figures. 1

2 Supplemental Table S1. Manure and chemical fertilizer applications in the WE38 watershed from 2000 to 2010 (water years). Application characteristics Annual range Mean ± SE Animal manure Receiving land Total area (ha) ± 7 Proportion of total cropland area (%) ± 2 Form Cattle slurry (Mg) ± 5 Poultry litter (Mg) ± 23 Swine slurry (Mg) ± 4 All manure (Mg) ± 21 Rate Total N applied (Mg) ± 1.2 Average N rate (kg ha -1 ) ± 8 Total P applied (Mg) ± 0.4 Average P rate (kg ha -1 ) ± 3 Timing Fall (%) ± 2 Winter (%) ± 8 Spring (%) ± 6 Summer (%) ± 3 Method Surface applied with or without incorporation by tillage Chemical fertilizer Receiving land Total area (ha) ± 4 Proportion of total cropland area (%) ± 1 Total fertilizer applied (Mg) ± 3 Form Granules or liquid Rate Total N applied (Mg) ± 1 Average N rate (kg ha -1 ) ± 3 Total P applied (Mg) ± 1.0 Average P rate (kg ha -1 ) ± 5 Timing Fall (%) ± 1 Winter (%) ± 6 Spring (%) ± 6 Summer (%) ± 1 Method Surface applied or irrigated as basal or side-dress All nutrient data were on a dry matter basis. Some fields received repeated applications of chemical fertilizer and manure, and/or different types of chemical fertilizer and manure. Chemical and manure nutrient application rates were calculated based on the area of cropland that received the respective nutrient. Seasons are fall (October to December), winter (January to March), spring (April to June), and summer (July to September) as defined by United States Geological Survey (USGS 2

3 Supplemental Table S2. Topo-SWAT parameter and input values relevant to major hydrological processes and nutrient cycling. Parameter Definition Value Snow SFTMP Snowfall temperature ( C) SMTMP Snow melt base temperature ( C) SMFMX Snow melt factor, June 21 (mm H 2 O/ C-day) SMFMN Snow melt factor, Dec 21 (mm H 2 O/ C-day) TIMP Snow pack temperature lag factor SNOCOVMX Min. snow water content of 100% snow cover 15 (mm H 2 O) SNO50COV Fraction of volume of SNOCOVMX for 50% snow cover Groundwater GW_DELAY Groundwater delay (days) ALPHA_BF Baseflow alpha factor (days) GWQMN Threshold depth in shallow aquifer for return 246 flow (mm) RCHRG_DP Deep aquifer percolation fraction REVAPMN Depth in aquifer for revap (mm) 187 GW_REVAP Groundwater revap coefficient DEP_IMP for Depth to soil impervious layer for topo. index 1164 TI10 10 (mm) DEP_IMP for Depth to soil impervious layer for topo. indices 6000 TI1 - TI9 1-9 (mm) ESCO Soil evaporation compensation factor 0.75 EPCO Plant uptake compensation factor SURLAG Surface run-off lag time (days) 0.15 CN2 Average SCS CN II value (Base CN2 x 65%), distributed by topo. index Variable source water redistribution IRRSC Irrigation code, with IRRNO, to specify 1 irrigation source IRRNO Irrigation source location HRU subbasin number FLOWMIN Min. in-stream flow for irrigation diversions for Calculated by reach TI10 topo. index 10 (m 3 /s) FLOWMIN Min. in-stream flow for irrigation diversions for 100 TI1 - TI9 topo. indices 1-9 (m 3 /s) DIVMAX Max. daily irrigation diversion from reach (mm 2 when DIVMAX >0; 10 4 m 3 when DIVMAX <0) FLOWFR Fraction of flow allowable to apply to HRU 1 3

4 Nutrient-related SOL_NO3 Initial NO 3 concentration in the soil layer (ppm) 20 SOL_ORGN Initial organic N concentration in the soil layer (ppm) 0 (default; SWAT estimation based on soil carbon) SOL_SOLP Initial soluble P concentration in the soil layer 20 SOL_ORGP (ppm) Initial organic P concentration in soil layer (ppm) 0 (default; SWAT estimation based on soil N) PHOSKD P soil partitioning coefficient 175 PSP P sorption coefficient 0.4 PPERCO P percolation coefficient 10 4

5 Supplemental Table S3. Topo-SWAT parameter values for urban land use. Parameter Definition Value by land use Farm structures Paved road Unpaved road FIMP Fraction of total urban impervious area FCIMP Fraction of directly connected urban impervious area CURBDEN Curb length density in urban land type (km ha -1 ) URBCOEF Wash-off coefficient for removal of constituents from impervious area (mm -1 ) DIRTMX Max. amount of solids allowed to build up on impervious areas (kg/curb km) THALF Number of days for 50% build up on impervious areas, i.e. ½ DIRTMX (days) TNCONC Conc. of total N in suspended solids from impervious areas (mg N/kg sediment) TPCONC Conc. of total P in suspended solids from impervious areas (mg P/kg sediment) TNO3CONC Conc. of nitrate in suspended solids from impervious areas (mg NO 3 -N/kg sediment) OV_N Manning s n for overland flow CN2A Curve number (CN), moisture cond. II, hydro soil group A CN2B CN II, hydro. soil group B CN2C CN II, hydro. soil group C CN2D CN II, hydro. soil group D URBCN2 CN II in impervious areas of urban land type

6 Supplemental Table S4. Significant factors and interactions in the complete GLM analysis of field-level management impacts on simulated total and dissolved P loss (only significant components shown). Precipitation amount Total P Dissolved P P value Comparison P value Comparison < High > Low < High > Low Field < STRM > SLOP > FLAT < STRM > SLOP > FLAT Soil cover < Minimal cover = Corn residue > Residue + cover crop < Corn residue > Minimal cover > Residue + cover crop Manure rate < Max > Con < Max > Con Application timing Precipitation amount x Timing < Winter = Fall > Spring < Winter > Fall > Spring No significant interaction < High precipitation: Winter = Fall > Spring; Low precipitation: Winter > Fall > Spring STRM: Field along stream, with a slope of 4%. SLOP: Field far away from stream, with a slope of 16%. FLAT: Field far away from stream, with a slope of 4%. Max: Maximum rate allowed for winter application of slurry in Pennsylvania (3.75 Mg dry weight ha -1 ). Con: Conventionally-applied rate of dairy slurry in the WE38 watershed (2.5 Mg dry weight ha - 1 ). 6

7 Supplemental Fig. S1. Comparison between Topo-SWAT simulated results and measurements. Above: Daily precipitation, observed stream flow, and Topo-SWAT simulated stream flow at the study watershed outlet for calibration ( ) and validation ( ) periods. Below: daily dissolved P loss, which included all days for Topo-SWAT simulation but only the days when stream water was grab sampled for the observational data. Daily P load was calculated by multiplying the P concentration in the grab sample with the total water volume monitored on the same day at the watershed outlet. 7

8 Supplemental Fig. S2. Mean annual field-level dissolved P losses (kg ha -1 ) simulated by Topo- SWAT. Seasonal manure application timings were compared at each level, with significant differences (p < 0.05) between timings identified by different letters (a and b). 8

9 a-1 a-2 a-3 a-4 b-1 b-2 b-3 b-4 9

10 c-1 c-2 c-3 c-4 Supplemental Fig. S3. Some examples of dynamics of cumulative runoff, sediment and P loss as influenced by manure application timing, field conditions, precipitation, and soil cover. (a) Responses of determinants to precipitations for winter manure application to a minimally-covered flat field at a conventional manure rate; (b) Responses of determinants to seasonal manure applications on three field types in low precipitation years, given conventional manure rate and minimal soil cover in non-growing seasons; (c) Responses of determinants to winter manure application in a slopped field with differing soil covers (low manure rate and low annual precipitation). 10

11 Supplemental Fig. S4. Temporal dynamics of total P concentrations in stream flow at the study watershed outlet, as simulated with Topo-SWAT, for four manure storage scenarios: (a) Baseline; (b) 12-month storage (Spring application); (c) 6-month storage (Fall/spring application); and (d) 3-month storage (Four-season application). Inset: Frequencies of daily mean total P concentrations for each scenario. 11