‘Advanced’ Soil Health Strategies

Mark Liebig

USDA-ARS-NGPRL

 

Summary of dryland cropping systems

 

Carbon Sequestration Potential, High or Low?

 

 

 

 

 

 

 

 

 

 

Soil Quality Evaluation
Long-term cropping systems study
Mandan, ND

§    The continuous crop, no-till management system enhanced the capacity of soil to function.

§     Withstand erosion

§     Facilitate water transfer

§     Provide a source for plant nutrients

Continuous crop, no-till management creates a more sustainable agriculture

Carbon is sequestered…
Soil quality is improved…
What is it worth?

An increase of 893 lbs/ac (1 Mg C/ha) increased spring wheat grain yield by 14-35 lbs/ac (Bauer and Black, 1994; Diaz-Zorita et al., 2002).

Assume:

•      Carbon accretion of 238 lbs C/ac and a 1,300 ac farm

Increase in income from increased crop yield over ten years (cumulative) ≈  $15,000 – $38,000

 

 

Take home message…

ü    No-till with continuous cropping is the most effective dryland cropping system for sequestering carbon.

 

ü    Carbon Sequestration =       Increased Organic Matter = Improved Soil Quality =                     A more resilient, sustainable cropping system

 

No-Till and Soil Acidity

16 Years of No-till:
Effects on Soil pH

Depth (inches) 1983        1999       

0-3                  6.48         5.98

3-6                  6.40         6.38

6-12                 6.70         6.79

12-18               7.18          7.19

18-24               7.65         7.69

 

16 Years of No-till:
Effects on Soil pH

N rate     0-3”        

LOW        6.22

MED        6.06

HIGH       5.73

 

No-till: Effects on Soil pH

Depth (inches) Wheat             Crambe           

0-2                  6.09                 6.26

2-4                  5.93                 6.03

4-8                  6.25                 6.31 

8-12                 6.62                 6.67

 

Grazingland Management:
Effects on Soil pH

         Fert. Crested         Heavily        Moderately

Property      Wheatgrass  grazed         grazed        

Soil pH                  5.10   6.62             6.44  

Exch Ca+2 (cmol/kg)     6.39   12.06           11.37 

CEC (cmol/kg)            10.44 18.21            17.29

Organic C (Mg/ha)     28.6   28.4             22.8  

 

Effects on soil environment
(i.e., So what?)

•     Short-term

–    Decrease in divalent cations on exchange sites.

–    Decreased CEC.

–    Compromised capacity to cycle N.

–    Reduced effectiveness of certain herbicides.

•     Long-term

–    Changes in mineral structure (enhanced weathering).

Managing Soil Acidity

•     Deep plowing

–    24-30 inch tillage depth

–    Brings calcium-rich soil to surface

–    Also cures sodic claypans

Managing Soil Acidity

•     Lime

•     Livestock

•     Legumes

Crop Selection and Sequencing

The Cost of Nitrogen

$515/ton

N Management Considerations

•     Soil water status?

•     Extractable soil N?

•     Previous crop residue effects on N mineralization/immobilization?

 

 

Previous Crop

Depletion (cm)

mid-May – mid-Sept, 2002 – 2004

Soil water (cm)

April, to 1.8 m

2003 - 2005

Difference (cm)

from sunflower

SUNFLOWER

13.5

35.0

0

CORN

12.6

39.6

4.6

SP. WHEAT

10.6

45.1

10.1

CANOLA

10.0

41.3

6.3

MILLET

9.6

41.5

6.5

CHICKPEA

8.5

39.0

4.0

LENTIL

8.1

42.2

7.2

DRY PEA

5.0

45.3

10.3

 

N Management Considerations

•     Soil water status?

•     Extractable soil N?

•     Previous crop residue effects on N mineralization/immobilization?

Great Plains Cropping Systems

Crop diversification is a tool to reduce production risks

Spring Wheat Yield after
Selected Crop Sequences
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

Take home message…

ü    Determine productivity potential based on current status in soil     (i.e., available water, soil test N, mineralization/immobilization potential).

 

ü    Annual legumes can fix own N and have proven resilience, but there are other options.