Soil Health and

Ecosystem Services

Cynthia A. Cambardella, USDA-ARS-NLAE

Soil Quality

“…capacity of soil ecosystem to function …”

Maintain productivity & biodiversityStore and cycle nutrients

Regulate & partition water flowFilter, buffer & detoxify

SIMBIOS Centre, UK

Soil biology

Decompose organic matterStabilize organic matter

Cycle nutrientsBuild soil structure

Biodegradation

ECOSYSTEM SERVICES

Source: freshwaterwatch.thewaterhub.org

Soil Health

Ecosystem ServicesActivity of

soil organisms

Soil Quality

Soil Properties

Soil biology

Adair County

LTAR Site

Long-Term AgroecologicalResearch (LTAR) Site Neely-Kinyon Research Farm, Greenfield IA

Started in 1998 Kathleen Delate, ISU, PI

Cindy Cambardella, ARS, co-PI

Southern IA Drift Plain

Soil cores in fall every year

after harvest from each plot

to a depth of 15 cm

Composted animal manure

organic corn and oats

28% Urea: conventional corn

Fall 2014 Organic Conventional

SOC (g/kg)* 24.6a 23.1b

TN (g/kg) 2.4a 2.3b

POMC (g/kg) 3.2a 2.4b

MBC (mg/kg) 452a 372b

PotMinN (mg/kg) 54a 43b

InorgN (mg/kg) 3.1a 3.2a

Macroaggs (%) 24a 22a

* Depth 0-15 cm

Means followed by same letter within a row are not different at 95%

Fall 2014 Organic Conventional

pH* 6.9a 6.3b

Bray P (mg/kg) 69a 22b

K (mg/kg) 266a 217b

Mg (mg/kg) 400a 338b

Ca (mg/kg) 3702a 3105b

EC (µS/cm) 186a 143b

BD (g/cm3) 1.22a 1.26a

* Depth 0- 15 cm

Means followed by same letter within a row are not different at 95%

Organic soils had

> total soil C & N

> biologically active soil C and N

> plant nutrients (P,K,Mg)

< soil acidity

= aggregate stability

= bulk density

than conventional soils.

Soil Health Summary

LTAR 1998-2014

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IN N

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)

Conventional Organic

36% more biologically active N in organic surface soil in fall 2010

N Mineralization Potential

Adopting organic farming

practices could help reduce N

loss to surface water??

What if…..

Pros: extended rotations,

small grains, cover crops, no

fertilizer N

Cons: tillage, cultivation,

animal manure

Boone County

OWQ Site

Organic Water Quality Research (OWQ) SiteISU Ag Engineering and

Agronomy Research Farm Boone IA

Des Moines Lobe

Started in 2012 Cindy Cambardella, ARS, PIKathleen Delate, ISU, co-PINIFA

Field History

No chemicals since 2006

Planted to oat/alfalfa 2006-2011

Pre-2006, conventional corn-soybean

Soils

Clarion: fine-loamy mixed, mesic Typic Argiudoll

Canisteo: fine-loamy mixed, mesic Typic Haplaquoll

Webster: fine-loam, mixed, mesic Typic Haplaquoll

Monitoring Sump

Flow Barrier

(2.4 m deep)

Non-perforated pipe

(1.2 m deep)

30 Plots (30.5m x 30.5m)

Perforated pipe

(1.2 m deep)

N

*Perimeter tile drain (0.15m diam)*

*Tile drain (0.08 m diam)

at N and S end of each plot*

*Plastic flow barrier

at E and W end of each plot*

*Tile water from 3 plots routed each

sump pit*

Install Tile Drains: Fall 2011

Cropping Systems

Organic C-S-O/A-A

Organic pasture/hay(alfalfa, fescue, timothy, orchard grass)

Conventional C-S

Randomized block design

5 replicates per system

Continuous tile flow monitoring

Tile water quality samples

collected weekly

Fertility

Dairy compost before organic

corn (170 kgN/ha)

and oats (57 kgN/ha)

28%UAN before conventional

corn; side dress (170 kgN/ha)

Weather station on site

with continuous monitoring

Weed Management

Spring chisel plow/disk

Rotary hoe and cultivator ~3X

Walk soybean every other week

Herbicide in conventional

Prefix®, soybean; Lumax®, corn

Soil CO2 flux every other week

during growing season

Monitoring

Tile flow and drainage water NO3-N

Soil profile NO3-N (to 120 cm) in spring and fall

Soil health (to 15 cm) in fall after harvest

Growing season soil CO2 flux

Soil Health Measurements

Total soil C&N; microbial biomass C&N; N mineralization

potential; soil enzyme activity; inorganic N, P, K, Mg, Ca;

aggregate stability; pH; EC; bulk density

microbial community structure and function

Plant Measurements

Yield; plant populations; total aboveground biomass C&N;

weed density; insect pest and disease populations; stalk nitrate

Precipitation

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Mar Apr May Jun Jul Aug Sep Oct

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cip

ita

tio

n, c

mAverage 2012 2013 2014

March-October

Average 75.8 cm

2012 45.9 cm

2013 57.2 cm

2014 86.9 cm

2012: dry, warm spring- dry, hot summer

2013: wet, cool spring – dry, hot summer

2014: normal spring – very wet summer

Tile Flow 2013

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Conv C-S Org C-S-O/A-A Org Pasture

Peak tile flow and rainfall were correlated in 2013

April-May rainfall 29.3 cm

∑ Annual tile flow

Conv C-S: 170,096 liters

Org C-S-O/A-A:192,839 liters

Org Pasture: 179,333 liters

No tile flow after August 1

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Conv C/S Organic C/S/OA/A Organic Pasture

Tile Drainage Water Nitrate N 2013

NO3-N concentrations: <5ppm in early spring; increase to

~30ppm corn-soybean

Tile Flow 2014

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Conv C-S Org C-S-O/A-A Org Pasture

Tile flow peaked early July and late August, following 22 cm of

rain in June and 20 cm of rain in August

∑ Annual tile flow

Conv C-S: 203,948 liters

Org C-S-O/A-A:207,507 liters

Org Pasture: 100,570 liters

Tile Flow Didn’t Stop

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itra

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Conv C/S Organic C/S/OA/A Organic Pasture

Tile Drainage Water Nitrate N 2014

Overwinter Nitrate N concentrations from Nov 28, 2014 – Mar 25, 2015

Conventional C-S 13.0, Organic C-S-O/A-A 3.8, Organic Pasture 0.3 ppm

Tile Drainage Water Nitrate N 2014

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Conv C/S Org C S

Comparing Organic C and S to Conventional C-S

Tile Drainage Water Nitrate N 2015

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N, p

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Conv C-S Org C-S-O/A-A Org Pasture

Org C-S-O/A-A stable since late Aug 2014 at ≤5 ppm; Conv C-S ranged

from 10 ppm to more than 20 ppm during same time period.

Compost applied

Crop N Loss NO3-N Conc

2012 kgN ha-1 mg N liter-1

Organic C-S-O/A-A 7.9 8.8

Conventional C-S 10.1 10.9

Organic Pasture 7.0 3.3

2013

Organic C-S-O/A-A 17.7 8.8

Conventional C-S 34.7 19.4

Organic Pasture 9.5 6.3

2014

Organic C-S-O/A-A 14.5 7.2

Conventional C-S 34.4 18.1

Organic Pasture 1.2 1.3

∑ 2012-2014

Organic C-S-O/A-A 40.1

Conventional C-S 79.2

Organic Pasture 17.7

OWQ Summary

Tile water flux varied with rainfall

Tile water nitrate N concentrations were

highest for the conventional corn-

soybean rotation for all years

Tile water N loading loss from 2012-

2014 from organic C-S-O/A-A was 50%

lower than conventional C-S

Adair County

Org Veg Site

Organic Vegetable Research, Neely-Kinyon

Research Farm, Greenfield, Iowa

Southern IA Drift Plain

Started in 2010 Kathleen Delate, ISU, co-PI

Cindy Cambardella, ARS, co-PINIFA

Tomato-Sweet Corn- Pepper

Rotations

Randomized Block Design

4 replicates

Fall Planted

Rye/Hairy Vetch Cover Crop

Spring Applied

Composted Dairy Cattle Manure

Chisel Plow Tillage

Roller Crimper

Soil cores (0-15 cm)

in fall 2010-2014

Plot size 0.60 m X 0.46 m

2 CO2 collars per plot

-close to plant

-max dist from plant

CO2 flux every 2 weeks

Apr-Oct 2012-2014

Lysimeter buried at

100 cm in center of

each plot

Soil water sampled

every 2 weeks Apr-Oct

2011-2014

CO2

Lysimeter access port

lysimeter

Two plots per port

Fall 2014* T2 T3 T5

SOC (g/kg)* 26.8c 30.7a 29.0ab

TN (g/kg) 2.7bc 3.0a 2.9ab

POMC (g/kg) 3.8b 5.7a 6.0a

MBC (mg/kg) 220b 283a 286a

PotMinN (mg/kg) 54.3b 70.4a 70.2a

Macroaggs (%) 15.0c 27.0a 21.4b

T2 = No Cover Crop, Till

T3 = Cover Crop, No-Till

T5 = Cover Crop, Till

Till vs No-Till: T3 vs T5

Cover crop vs No Cover Crop: T2 vs T5

* after peppers

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Lysimeter: Pepper 2014

Till Notill

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Lysimeter: Sweet Corn 2013

Cover Crop No Cover Crop

NO3-N lower with cover crops

in all crops in all years

NO3-N lower under no-till

in all crops in all years

Lysimeter NO3-N to estimate N leaching potential

Average growing season

CO2 flux higher with cover

crops in both rotations in all

years

Cover crop: 0.74 g CO2/m2/h

No cover crop: 0.51 g CO2/m2/h

Average growing season

CO2 flux higher under no-till

in both rotations in all

years

Till: 0.47 g CO2/m2/h

No-till: 0.67 g CO2/m2/h

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Sweet Corn CO2 Flux 2013

NCC C T NM

CC C T NM

No Cover Crop

Cover crop

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Tomato CO2 Flux 2013

CC C NT NM

CC C T NM

No till

Till

Soil Respiration as an estimate of Microbial Activity

Org Veg Summary

Soil health was greatest in cover crop

plots amended with compost by the end

of the 2nd growing season and

remained stable through the fall of

2014.

Nitrate-N leaching below the rooting

zone was consistently lower with cover

crops for all crops in all years

Soil respiration, quantified as CO2 flux,

was consistently higher under reduced

tillage for all crops in all years.

Overall Conclusions I

Organic grain cropping rotations in

Iowa are stable and resilient systems

Enhance soil health

Retain C and nutrients

Maintain crop yield

Organic C-S-O/A-A rotations show

great promise to improve surface water

quality in Iowa

Reduce tile drainage water [NO3-N]

Reduce annual N loading loss

Overall Conclusions II

Organic vegetable rotations that utilize

fall-planted cover crops and composted

animal manure increase overall soil

health, enhance microbial activity,

increase C sequestration, and reduce N

leaching loss from the rooting zone

Cynthia A. Cambardella, PhDUSDA-ARS

National Laboratory for Agriculture and the Environment

2110 University Blvd. Ames, IA 50011

Email: cindy.cambardella@ars.usda.gov

515-294-2921