Effectiveness of Silviculture BMPs in Pine Straw Production to Protect Groundwater: 2 nd Year results

Transcription

1 Effectiveness of Silviculture BMPs in Pine Straw Production to Protect Groundwater: nd Year results Patrick J. Minogue, Masato Miwa, Anna Osiecka, Jeffrey L. Vowell, and Roy Lima University of Florida, IFAS, NFREC Florida Forest Service February,

2 Problem Florida pine straw production results in estimated revenues in excess of $ 79 million (Hodges et al. 5). Previous studies have shown needle yields may be increased -5 fold with nitrogen fertilizers (Duryea ). Because of the high revenue potential, growers may be applying fertilizers at luxury consumption rates. Excessive fertilization to increase pine straw yields may be a significant threat to water quality in Florida. Pine straw removal may increase the leaching potential of fertilizers.

3 Current Fertilization BMPs () Maximum elemental N lb/ac over any -yr period 5 lb/ac for any 3-yr period 8 lb/ac during the first -yrs of newly established plantations Maximum elemental P 5 lb/ac over any -yr period 8 lb/ac for any 3-yr period N/A Fertilization guidelines only address traditional forestry applications. Current BMPs recommend soil testing and efficient use of fertilizers Typical pine straw operation: annual raking and fertilization in a 5-year contract or sales by the bale.

4 Objectives Overall: Examine the effects of fertilization and straw removal on soil physical and chemical properties, leaching potential to groundwater, and overall nutrient budgets with contrasting soil nutrient exchange capacity and internal drainage. Specific: Compare soil chemical properties and leaching potential for various diammonium phosphate (DAP) fertilization rates in raked vs. non-raked stands to refine fertilization BMPs.

5 Study Sites Blountstown Site (Pinus elliottii, est. 997) Soil series: Dunbar fine sandy loam (fine, kaolinitic, thermic Aeric Paleaquults) Drainage class: Somewhat poorly drained Subsurface soil CEC: > 5 meq./g Soil depth class: Very deep Slope: -5% P. elliottii SI5: 8 ft Geomorphic setting: Flats of inter-stream divide and low terraces Live Oak Site (P. elliottii, est. 995) Soil series: Alpin fine sand (thermic, coated Lamellic Quartzipsamments) Drainage class: Excessively drained Subsurface soil CEC: <.5 meq./g Soil depth class: Very deep Slope: -5% P. elliottii SI5: 8.5 ft Geomorphic setting: Upland

6 Treatments and Statistical Design Fertilizer (DAP) Treatment: High lb/ac/yr ( lb-n, lb-p) Medium 38 lb/ac/yr (7 lb-n, 7 lb-p) Low 8 lb/ac/yr ( lb-n, lb-p) Control lb/ac/yr Raking Treatment: Annual rake vs. No-rake Statistical Design: Completely randomized design (CRD) with 3 replications Treatment plot layout at Live Oak site

7 Measurements. Periodic soil sampling for nutrient concentration at -, -, -, - 3, 3-8, 8-, and -7 in depths. Monthly surficial groundwater depth and nutrient concentration sampling from treatment area well and distance reference well 3. Continuous monitoring of weather and soil moisture at,,, 3, 8, and inch depths Water and soil samples were analyzed for NH -N, NO x -N, TKN, and TP.

8 Summary of Statistical Analysis: Soil NH -N, NO x -N, TKN, and TP at Blountstown Fertilization had significant effect on NH -N, NO x - Pretreatment First fertilization treatment period (9-) Second fertilization treatment period (-) (8) Source df / N, and 3/3 TP, /7 but / no 8/3 effect /7 /5 on TKN. 3/9 / 5/ 8/3 /7 3/7 NH -N Fert Raking Fert x raking NO x -N Fert < <. <. <. <. <. Raking.3 Raking.3.98 had.58 some.987 effect.8.98 on.78 TKN. in the.583 st.395 year,.75.3 Fert x raking but essentially no effect on the other nutrients. TKN Fert Raking Fert x raking There was no fertilization x raking interaction TP Fert Raking Fert x 3.5 effect raking Bold numbers indicate P<.5.

9 Summary of Statistical Analysis: Soil NH -N, NO x -N, TKN, and TP at Live Oak Fertilization had significant effect on NH -N, NO x - Pretreatment (9-) (-) First fertilization treatment period Second fertilization treatment period (8) Source df / 3/9 3/3 / 5/5 8/ /3 /8 3/8 3/ /9 5/ 8/ / / NH N, and TP (nd year), but essentially no effect on -N Fert 3.79 <.. < <. < Raking TKN. Fert x raking NO x -N Fert < <. <..3 Raking Fert x raking Raking had some effect on TP. Very little or no TKN Fert Raking Fert x effect on the other.359 nutrients raking There was no fertilization x raking interaction TP Fert Raking Fert x effect raking Bold numbers indicate P<.5.

10 Soil NH -N at Different Depths: Blountstown NH -N (mg/kg) st Fertilization nd Fertilization (- in) (-8 in) (8-7 in) lb/ac 8 lb/ac 38 lb/ac lb/ac Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Date (Month/Year) Aug/ Oct/ Dec/ Feb/

11 Soil NH -N at Different Depths: Live Oak 8 st Fertilization nd Fertilization (- in) lb/ac 8 lb/ac 38 lb/ac lb/ac Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Aug/ Oct/ Dec/ Feb/ NH -N(mg/kg) (-8 in) (8-7 in) Date (Month/Year)

12 Soil NO x -N at Different Depths: Blountstown Date (Month/Year) NO x -N (mg/kg) lb/ac 8 lb/ac 38 lb/ac lb/ac Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ st Fertilization Aug/ Oct/ nd Fertilization Dec/ Feb/ (- in) (-8 in) (8-7 in)

13 Soil NO x -N at Different Depths: Live Oak NO x -N(mg/kg) st Fertilization nd Fertilization (- in) (-8 in) (8-7 in) lb/ac 8 lb/ac 38 lb/ac lb/ac Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Date (Month/year) Aug/ Oct/ Dec/ Feb/

14 Soil TP at Different Depths: Blountstown st Fertilization nd Fertilization (- in) lb/ac 8 lb/ac 38 lb/ac lb/ac Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Aug/ Oct/ Dec/ Feb/ TP (ug/kg) (-8 in) (8-7 in) 5 Date (Month/Year)

15 Soil TP at Different Depths: Live Oak TP (ug/kg) st Fertilization nd Fertilization (- in) (-8 in) lb/ac 8 lb/ac 38 lb/ac lb/ac 5 (8-7 in) 5 Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Date (Month/Year) Aug/ Oct/ Dec/ Feb/

16 Groundwater NO x -N Concentration and Long-term Trend Blountstown Live Oak.. Treatment well Reference well NO x -N (mg/l).5..5 NO x -N (mg/l) NO x -N difference (mg/l) Jan Apr Jul Oct Jan Apr Jul Oct Jan. Y=.79 ** +.9 ** Day Jan Apr Jul Oct Jan Apr Jul Oct Jan NO x -N difference (mg/l) Time (Month 9-) Jan Apr Jul Oct Jan Apr Jul Oct Jan. Y=-.3 ** -. ** Day Included Outlier Jan Apr Jul Oct Jan Apr Jul Oct Jan

17 PPT (in) Site Characteristics: Rain, Soil Moisture, and Groundwater Depth Daily PPT (in) Blountstown Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Aug/ Oct/ Dec/ Feb/ Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Aug/ Oct/ Dec/ Feb/ 3 3 Blountstown PPT (in) Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Jun/ Aug/ Oct/ Dec/ Feb/ 3 Live Oak Soil Volumetric Groundwater Level (ft) Moisture (%) 3 3 Dec/8 Feb/9 Apr/9 Soil Volumetric Moisture (%) Groundwater Jun/9 Depth (ft) Aug/9 3 Oct/9 3 Dec/9 Feb/ Date (Month/Year) in in in 3 in 8 in in Trt Well Ref Well Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Apr/ Jun/ Jun/ Aug/ Aug/ Oct/ Dec/ Feb/ Oct/ Dec/ Feb/ in in in 3 in 8 in in Trt Well Ref Well Soil Volumetric Groundwater Level (ft) Moisture (%) 3 3 Dec/8 Feb/9 Apr/9 Jun/9 Aug/9 Oct/9 Dec/9 Feb/ Apr/ Date (Month/Year) Jun/ Aug/ Oct/ Dec/ Feb/ in in in 3 in 8 in in Trt Well Ref Well Date (Month/Year)

18 Conclusions Early results suggest a need for annual N limits rather than 3-year maximums, and continued monitoring is underway to support recommended N amounts for soils representing different leaching potential. A longer period is needed to assess the effect of pine straw removal on soil and groundwater chemical properties.

19 Acknowledgements This project was funded in part by a Section 39 Nonpoint Source Management Program grant from the U.S. Environmental Protection Agency (US EPA) through a contract with the Nonpoint Source Management Section of the Florida Department of Environmental Protection (FDEP). Technical support was provided by National Council for Air and Stream Improvement (NCASI).