Soil Health Movement and Research in New Mexico

New Mexico Organic Farming ConferenceFebruary 15, 2019

New Mexico Organic Farming ConferenceFebruary 15, 2019

Contact Information:Extension Plant Sciences

New Mexico State University Las Cruces 

Email: jidowu@nmsu.eduPhone: 575‐646‐2571

WhatisSoilHealth? Ability of the soil to support crop growth … (Power & Myers, 1989)

Capacity of the soil to function in a productive and sustained manner … (NCR‐59 Madison WI, 1991)

The capability of the soil to produce safe and nutritious crop …. (Parr et al., 1992)

Fitness for use (Pierce & Larson 1993)

% organic matter

pH

Salinity/Sodicity

Different soil Nutrients

Aggregation/Structure

Water infiltration

Water retention

Soil Compaction

Soil Erodibility

Physical Chemical

Biological

Carbon sequestration capacityMicrobial abundance and activity in the soil Nutrient cycling capacity

Soil Health Functions

A combination of soil physical, biological and chemical functions

HowHealthy/SickisaSoil?

1. How do we measure the problem?

2. What can we do about it?

3. If you can’t measure it, you can’t manage it

Howdowestudysoilhealth

1. Potential soil health measurements that can separate between management systems

2. Measurements can vary with climate, agroecosystems and management systems – How do we handle this?

3. Selection of indicators and testing their relationships to soil performance

Objective: To Develop a Quantitative Assessment of Soil Health

Potentialsoilhealthmeasurementsthatcanseparatebetweenmanagementsystems

Step One

Started out with a total of 40 soil measurements(Physical, Chemical & Biological)

PotentialSoilHealthIndicators

Physical – 10 Measurements 1. Mean Weight Diameter of Dry Aggregates (mm)2. Dry Aggregates > 2mm (%)3. Dry Aggregates < 0.25mm (%)4. Sand (% )5. Clay (% )6. Silt (% )7. Available Water Capacity (cm3/cm3)8. Wet Aggregate Stability (%)9. Bulk Density (Mg/m3)10. Penetration Resistance (psi)

Start out with many measurements – Physical, Chemical Biological

PotentialSoilHealthIndicators Chemical – 13 Measurements 

1. pH2. EC (dS/m) (Salinity)3. Sodium Adsorption Ratio4. Nitrate Nitrogen (mg/Kg)5. P (mg/Kg)6. K (mg/Kg)7. Ca 8. Mg9. Na 10. Zn 11. Mn 12. Fe 13. Cu 

PotentialSoilHealthIndicators Biological – 13 Measurements 

1. Permanganate Oxidizable Carbon (Active carbon in the soil)2. Soil Organic Matter3. Total Microbial Biomass4. Diversity Index5. Total Bacteria Biomass6. Actinomycetes Biomass7. Gram (‐) Biomass8. Gram (+) Biomass9. Rhizobia Biomass10. Total Fungi Biomass11. Arbuscular Mycorrhizal Biomass12. Saprophytes Biomass13. Protozoa Biomass14. Undifferentiated Biomass15. Fungi:Bacteria16. Predator:Prey17. Gram(+):Gram(‐)

Measurementscanvarywithclimate,agroecosystemsandmanagementsystems–Howdowehandlethis?

Step Two

Soil Health Sampling Sites in NMSoil Health Sampling Sites in NM

Replicated Research Sites

Grower Site

Sampled across different agroecosystems and

management systems at both research sites and

growers’ fields

20

50

80

0 ‐ 5 cm 5 ‐ 15 cm

Bacteria (%)

TFG POC ALF CTC CTS CWO

Results from Los Lunas Ag. Sci. Center

TFG: Tall fescue grass; POC: Peach orchard; ALF: Alfalfa; CTC: Conventional tillage – clay ; CTS: Conventional tillage – sand; CWO: Cottonwood orchard.

200

400

600

0 ‐ 15 cm 15 ‐ 30 cm

Active Carbon (mg/kg)

TFG POC ALF CTC CTS CWO

0

2000

4000

6000

0 ‐ 5 cm 5 ‐ 15 cm

Microbial Biomass (ng/g)

TFG POC ALF CTC CTS CWO

B BB

B B

A

abb b

bab

a

0

2

4

0 ‐ 15 cm 15 ‐ 30 cm

Soil Organic Matter (%)

TFG POC ALF CTC CTS CWO

AB AA

BC

A

C

abaa ab

bcc

A

C CCBC

ABCa

abab

ab abb

AB AABBC

DCD ns

Results from Los Lunas Ag. Sci. Center

13

0

0.7

1.4

0 ‐ 15 cm 15 ‐ 30 cm

Mean Weight Diameter (mm)

TFG POC ALF CTC CTS CWO

0.2

0.4

0.6

0 ‐ 15 cm 15 ‐ 30 cm

Available Water Content (cm3/cm3)

TFG POC ALF CTC CTS CWO

ABBB B

AAB

ns

TFG: Tall fescue grass; POC: Peach orchard with clover; ALF: Alfalfa; CTC: Conventional tillage – clay ; CTS: Conventional tillage – sand; CWO: Cottonwood orchard.

AAB

ABCABC

C BC

aaa

ab

bb

Selectionofindicatorsandtestingtheirrelationshipstosoilperformance

Step Three

Selection Criteria for Soil Health Indicators

Sensitivity to land management

Precision of measurement method

Relevance to important functional soil process

Ease and cost of sampling

Cost of analysis

15

Someoftheselectedindicators

• Biologically Active Carbon (POXC)• Easily decomposable portion of organic matter • Active carbon is an indicator of microbial activity of the soil

• Soil Organic Matter• Total amount of organic residue in the soil• Organic matter impacts several soil properties

Physical root proliferation: (Bulk Density, Penetration resistance, Organic matter)

Soil Structure: (Organic matter, Dry Aggregate Distribution, Aggregate Stability)

Soil Erodibility: (Dry Aggregate Distribution, Aggregate Stability, Organic matter)

Soil Salinity/Sodicity: (Electrical Conductivity, Sodium Adsorption Ratio)

Soil Moisture: (Aggregate Stability, Organic matter, Soil Texture, AWC)

Nutrient retention and release: (Organic matter, Soil texture, Soil Nutrients)

Biological activity: (Total microbial biomass, Organic Matter, POXC)

Indicatorsexpressingsoilperformance

ScoringCurveforPOXCScoring functions allow us to interpret the laboratory values

0

10

20

30

40

50

60

70

80

90

100

350 370 390 410 430 450 470 490 510Permanganate Oxidizable Carbon (mg/kg)

Percentile

EXCELLENT = 4

LOW = 1

MEDIUM = 2

GOOD = 3

WorkinProgress:

Visually enhanced report format

Easy to read

Easy to understand

Suggestion of management options when there are problems

Development of farmer friendly assessment framework: