View Full Table | Close Full ViewTable 1.

Soil Survey Geographic Database soils for each field and identification of the field characteristics required for conservation management planning assessment using Natural Resources Conservation Service guidelines. These characteristics include the dominant critical soil and slope representing each field, the field average grain yield, and the residue removal operations.

 
Field Complete list of SSURGO† soils comprising each field (in order of area: high to low) Dominant critical soil for each field from NRCS‡ guidelines Dominant critical slope for each field from NRCS guidelines Field average corn grain yield Residue harvest operations
Mg ha−1
1 84 Clyde silty clay loam, 0–2% slopes 83B Kenyon loam 4.0% 10.85 rake and bale
198B Floyd loam, 1–4% slopes
173 Hoopeston fine sandy loam, 1–3% slopes
83B Kenyon loam, 2–5% slopes
407B Schley loam, 1–4% slopes
175B Dickinson fine sandy loam, 2–5% slopes
41B Sparta loamy fine sand, 2–5% slopes
2 688 Koszta silt loam, 0–2% slopes 688 Koszta silt loam 1.0% 12.60 rake and bale
587 Chequest silty clay loam, 0–2% slopes
3 587 Chequest silty clay loam, 0–2% slopes 587 Chequest silty clay loam 1.0% 12.40 rake and bale
687 Watkins silt loam, 0–2% slopes
88 Nevin silty clay loam, 0–2% slopes
7 Wiota silty clay loam, 0–2% slopes
133 Colo silty clay loam, 0–2% slopes
688 Koszta silt loam, 0–2% slopes
8B Judson silty clay loam, 2–5% slopes
422 Amana silt loam, 0–2% slopes
54 Zook silty clay loam, 0–2% slopes
Soil Survey Geographic Database.
Natural Resources Conservation Service.



View Full Table | Close Full ViewTable 2.

Descriptions and characteristics of the three fields investigated in this study, including field size, crop rotation currently being used, and the tillage practices consistent with Conservation Technology Information Center definitions.†

 
Field Location Area Crop rotation Tillage
ha
1 Cerro Gordo County, Iowa 57 corn–soybean reduced
2 Iowa County, Iowa 19 continuous corn reduced
3 Iowa County, Iowa 77 continuous corn conventional
Definitions from CTIC (2012).



View Full Table | Close Full ViewTable 3.

Identification of the specific field operations and timing of field operations for the continuous corn and corn–soybean crop rotations modeled in this study with reduced tillage assumptions.†

 
Continuous corn Corn–soybean
1 Nov., year 1 chisel plow 20 Apr., year 1 fertilizer application
25 Apr., year 2 fertilizer application 1 May, year 1 field cultivation
1 May, year 2 field cultivation 1 May, year 1 plant corn
1 May, year 2 plant corn 11 Oct., year 1 harvest corn grain direct bale residue
11 Oct., year 2 harvest corn grain DB residue 1 Nov., year 1 chisel plow
15 May, year 2 plant soybeans
1 Oct., year 2 harvest soybeans
Assembled from the Natural Resources Conservation Service operations database.



View Full Table | Close Full ViewTable 4.

Evaluation of residue removal using the subfield model. This table contrasts rake and bale removal without sustainability considerations, rake and bale removal as directed by Natural Resources Conservation Service conservation management planning, rake and bale removal only in areas where the subfield analysis identifies the operations as sustainable, and the conceptual variable-rate residue harvester.

 
Field Total residue available with rake and bale removal if sustainability is not considered Sustainable residue available with rake and bale removal based on NRCS† guidelines Average annual sustainable removal rate with rake and bale removal based on NRCS guidelines Sustainable residue available with selective rake and bale removal‡ Average annual sustainable removal rate with selective rake and bale removal‡ Sustainable residue removal with conceptual variable-rate assumptions Average annual sustainable removal rate with conceptual variable-rate removal assumptions
Mg Mg ha−1 Mg Mg ha−1 Mg Mg ha−1
1 152 0 0.00 35 0.62 133 2.35
2 119 119 6.40 106 5.70 144 7.69
3 387 387 5.06 279 3.65 430 5.62
Natural Resources Conservation Service.
Data from Muth et al. (2012).