Soil Management and Crop Biomass Removal Impacts on Soil Organic Matter Content

Krisztina Eleki, Richard M. Cruse, László Fodor, Lajos Szabó, and Sándor Holló

?????????????????????????Can we remove crop biomass and conserve soil organic matter content (humus)?

Why is this an important question?The U.S. government “Vision for Bioenergy and Bio-based Products in the United States” – from biomass by 2030

5% of power, 20% of transportation fuels and 25% of chemicals

Why is this an important question?Much of biomass will come from agricultural land

What do we understand?Soil Organic Matter very important

SustainabilitySoil qualityCrop productionSoil and water conservation

What do we understand?Soil organic matter if organic matter added*Soil organic matter if biomass removed*

* For simple cropping systems – one or two crop, one or two fertilizer management treatments

We do not understand interactions!Crop typeCrop rotationsFertilizer management – root mass and microbial

activity

Manure applications – organic matter additions

Tillage – microbial activity

Root morphology (form) effects

Key – seeking evidence Can we harvest crop biomass?

IF YES

How much can we harvest? What is best management?

ObjectiveDetermine the effect of management practices on Soil Organic Matter (SOM) change with time

Crop rotationFertilizer managementManure applicationCrop biomass removal

MethodsLocation – Kompolt, Hungary, Rudolf Fleischmann Research Station - 47°45' N and 20°15' E Multifactor experiment – four replications

Crop rotations (main plots) - 3Fertilizer rate (splits of main plots) - 12Fertilizer management (second split) - 3

Methods (cont.)Fertilizer rates – 12

Commercial fertilizer ratesManure applicationBiomass removal vs. no removal

Methods (cont.)Experiment 1961 – 2001SOM measured: 0 – 30 cm depthAnalysis of Variance

Results

Year Effect - Not Significant

2.4

2.5

2.6

2.7

2.8

2.9

3

1961 1969 1977 1981 2001

Year

SO

M (

%)

Results

Fertilizer vs. No Fertilizer

2.65

2.75

2.85

2.95

1969 1977 1981 2001

Sampling Years

SO

M (%

)

Fertilizer

P < 0.0008

1961 SOM = 2.58%

ResultsCrop Rotation Effects

2.60

2.65

2.70

2.75

2.80

2.85

2.90

2.95

3.00

1969 1977 1981 2001

Sampling Years

SO

M (%

)

Cont. Corn

Four Crop Rotation

P = 0.08

1961 SOM = 2.58%

Results

Fertilizer Management Effects

2.70

2.75

2.80

2.85

2.90

2.95

3.00

1969 1977 1981 2001

Sampling Years

SO

M (%

)

4 YR Corn, 4 Alfalfa

Yearly Application

4 YR app., 4 YR none

P < 0.0001

Results

Biomass and Manure Effects on SOM

2.7

2.75

2.8

2.85

2.9

2.95

1 2 3

Treatment

SO

M (

%)

No Manure Biomass Removal

Manure – 35.2 Mg/haBiomass Removal

No Manure Biomass Incorp.

P < 0.0008

ConclusionsRotations ????

Fertilizer management

Manure applications

Biomass removal

Next StepTest 2 soil carbon models against this dataUse best model to estimate SOM change across landscape in Iowa

With different managementWith biomass removal