Reducing Nonpoint Source Pollution through Effective Ditch Management

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Brandon Hall
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1 Reducing Nonpoint Source Pollution through Effective Ditch Mngement Meliss Huert DNREC Division of Wtershed Stewrdship Dringe Progrm University of Delwre

2 Artificil Dringe in Delwre Engineered system to remove excess wter Ditches Chnnelized strems Tile drins Required for lnd use in mny res Poorly drined soils High wter tles 2

Tx Ditch 101 1951 Dringe Lw Governmentl sudivision of the stte Formed through Superior Court Powers relted to mintennce of dringe

3 Tx Ditch Dringe Lw Governmentl sudivision of the stte Formed through Superior Court Powers relted to mintennce of dringe Mnged y elected lndowners 234 Tx Ditch Orgniztions responsile for mintining 2,000 miles of chnnel providing enefit to >100,000 people. 3

4 Concerns with Artificil Dringe Conduits for nutrient nd sediment pollution Eutrophiction of Chespeke nd Delwre Inlnd Bys Accumultion of vegettion nd sediment requires mintennce Impcts from current mintennce prctices on wter qulity re unknown 4

5 Minor Mintennce Activities Deteriorted pipe replcements nd clering Bever dm removl Annul mowing Weed wiper r Control woody vegettion Mintin cler Rights-of-Wy 5

6 Mjor Mintennce Tx Ditch Dip Out Dredging of ditch Performed s needed (15-20 yers) Spoils plced on djcent field nd spred Vrile timing etween steps Difficult to know nutrient loss from spoil nd mended soils 6

7 Reserch Ojectives Chrcterize djcent field nd spoils for potentil loss prior to incorportion Determine potentil P loss from spoil mended res Gol: Determine method to predict P loss from mended res 7

Study Site Selection 7 of 15 tx-ditches scheduled for dip-out in 2013-2014 were selected Only portion of ditch mintined

8 Study Site Selection 7 of 15 tx-ditches scheduled for dip-out in were selected Only portion of ditch mintined t time Segments rnged from km ( mile) Lnd use in proximity to dip-out ws minly griculturl or forested 8

9 Soil Smpling Collected soils from djcent fields prior to dip Collected representtive spoil smples from piles plced on smpled fields Site 4A Site 4B 9

Lortory Anlysis Chrcterize field nd spoil for potentil loss prior to incorportion Simulte chisel plowing of field nd corresponding spoil Mix t 3

10 Lortory Anlysis Chrcterize field nd spoil for potentil loss prior to incorportion Simulte chisel plowing of field nd corresponding spoil Mix t 3 different rtios (1S:7F, 3S:5F, nd 7S:1F) Determine nd mintin field cpcity of field-spoil mixtures Collect nd chrcterize susmples t 2 time intervls (2 nd 30 dys) 10

11 Chrcteriztion of Field nd Spoil Averge Mehlich 3 P Concentrtions (mg kg -1 ) *Numers ove re M3-PSR vlues Field Soils Spoil Sediments Agronomic Threshold A 1B 1C 2 3A 3B 4A 4B 5A 5B 6A 6B 7 Ditch Site 0.04 Environmentl Risk >

12 Chrcteriztion of Field nd Spoil Averge Wter Extrctle P Concentrtions (mg kg -1 ) Field Soils Spoil Sediments Environmentl Risk A 1B 1C 2 3A 3B 4A 4B 5A 5B 6A 6B 7 Dich Site 12

13 Amended Field Soils- 2 Dy Results Averge Mehlich 3 P Concentrtions (mg kg -1 ) Incorportion decreses Mehlich 3 P Field Soil 1S:7F 3S:5F 7S:1F Agronomic Threshold c 1A 1B 1C 2 3A 3B 4A 4B 5A 5B 6A 6B 7 Ditch Site c 13

14 Amended Field Soils- 30 Dy Results Averge Mehlich 3 P Concentrtions (mg kg -1 ) Field Soils 1S:7F 3S:5F 7S:1F Agronomic Threshold A 1B 1C 2 3A 3B 4A 4B 5A 5B 6A 6B 7 Ditch Site 14

15 Amended Field Soils- 2 Dy Results Averge Wter Extrctle P Concentrtions (mg kg -1 ) Incorportion decreses Wter Extrctle P Field Soils 1S:7F 3S:5F 7S:1F Environmentl Risk c d c c c c c d d c d c c 1A 1B 1C 2 3A 3B 4A 4B 5A 5B 6A 6B 7 Ditch Site c d c d c d 15

16 Amended Field Soils- 30 Dy Results Averge Wter Extrctle P Concentrtions (mg kg -1 ) Field Soils 1S:7F 3S:5F 7S:1F Environmentl Risk A 1B 1C 2 3A 3B 4A 4B 5A 5B 6A 6B 7 Ditch Site 16

17 Incution Conclusions Incorportion reduces potentil risk of P loss from mended res More effective t reducing WEP thn M3-P Difference not lwys significnt so need to determine optimum spreding depth Next steps: Investigte properties of field nd spoil smples to determine effective spreding depth for ditch sites Regression nlysis Provide recommendtion 17

18 Reserch Ojectives nd Gol Chrcterize ditch ottom sediments to determine potentil relese of P to overlying wters Quntify P removl from mintennce Overll Gol: To provide recommendtion tht improves current mngement 18

19 Ditch Core Sediment Smpling Collect intct sediment core smples within ech ditch 0-5, 5-15, 15+ cm 19

(M3-P), EPA 3050 -P Soil texture nd sequentil

20 Chrcteriztion of Core Smples Chrcterize P in sediments Wter solule P (WSP), Mehlich 3 P (M3-P), EPA P Soil texture nd sequentil P frctiontion Quntify P removl during mintennce 20

21 Ditch Core Sediments: Mehlich 3 P cm Generlly Mehlich 3-P decresed with core sediment depth nd following mintennce Mehlich 3 P (mg kg -1 ) cm 5-15cm sediments t times possessed gretest concentrtions >15 cm Pre-dredging 1 yr fter dredging 2 yr fter dredging Those sediments possessed 0-5cm sediments in excess of gronomic needs 21

22 Ditch Core Sediments: Wter Extrctle P (WEP) 22

23 Ditch Core Sediments: Mehlich 3 Phosphorus Sturtion Rtio Averge Mehlich 3 PSR Vlues 23

24 Ditch Core Conclusions Enrichment of P in top 0-5cm sediments Excessive levels oserved M3 PSR elow environmentl risk threshold ut it is importnt to note tht chnnel conditions re different thn field Next steps: Clculte totl P removed from mintennce ctivity Provide recommendtion 24

25 Thnk you for your time nd ttention. Questions or Comments? 25

Enhancing Botanical Composition and Wildlife Habitat of Pastures in South Central Iowa through Soil Disturbance by Mob-grazing of Beef Cattle

Enhancing Botanical Composition and Wildlife Habitat of Pastures in South Central Iowa through Soil Disturbance by Mob-grazing of Beef Cattle Animl Industry Report AS 66 ASL R2888 214 Enhncing Botnicl Composition nd Wildlife Hitt of Pstures in South Centrl Iow through Soil Disturnce y Mo-grzing of Beef Cttle Justin J. Bisinger Iow Stte University,