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Farming Practice Comparisons in South Dakota: A case study across the fence and implications for the future

Introduction

Tractor planting seed in a no-till field.
(USDA NRCS South Dakota photo)

A long debate has been whether soil health systems that eliminate tillage and include cover crops can show financial returns when compared to the conventional systems. Part of the reason that this debate cannot be fully resolved is that farmers are generally not willing to share their financial information with others, and therefore, the lack of comparison information left the farmers, researchers, and conservationists in the dark about the financial performance of different farm production systems. Emerging carbon issues and opportunities recently have added another layer to this debate and may challenge farmers to re-consider their farm’s financial status under different production systems. Many private firms are seeking ways to pay producers to adopt practices that provide carbon storage in the soil, which will cause farmers to wonder whether accepting carbon payment provided for adopting conservation practices are in their best interests.

This extension paper intends to provide some new insights on the financial and carbon storage comparisons between neighboring farms using conventional versus conservation practices (mainly no-till and cover crops). A farming system study conducted in 2018-2019 compared farming practices. Conventional and no-till paired farms at four locations across South Dakota answered many questions concerning the financial inputs made into their systems and compared field yields. Due to confidentiality, this report shows average values for each system and not individual data and farm locations. To determine carbon intensity (g C/bu) for corn under different production systems, the Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies carbon model (abbreviated as GREET) was used.

Summary

Bar graph illustration across the fence corn systems comparisons in South Dakota using the CREET C model, surveying four locations with two farms at each location. For a detailed description of this graph and data set, please call SDSU Extension at 605-688-6729.
Figure 1. Across the fence corn system comparison in South Dakota. GREET C model (2022rev.1). Four locations, two farms at each location.

Conventional and no-till farm average values for corn production appear in Table 1. Farm size, corn yield, nutrient rates (Nitrogen, Phosphorus, and Potassium) and herbicide use are very similar between the conventional and no-till farms. However, differences occur with the amount of diesel used per acre and equipment investment per acre. The conventional farms used almost twice as much diesel compared to no-till farms and have $225 more equipment investment (dollars per acre, or $/a). These results suggest that new producers could avoid high equipment expenses and investments by adopting conservation farming systems. Similarly, existing conventional farms could also reduce equipment inventory by converting to conservation systems.

The evaluated conventional and no-till corn production data, as determined by the GREET carbon model, is shown in Figure 1. The result from our study shows that conventional system had no contributions to soil carbon (abbreviated as C); whereas, the no-till system contributed 4,231 grams of C/bu of corn. Both farming systems had similar carbon intensity values for the management practices that appear as emissions. The net total carbon emitted is the key value for whether a farming system has carbon to sell or offset carbon released from non-farm carbon emitting entities. The model showed the conventional system did not store any carbon. The no-till system stored soil C because of no soil disturbance and some cover crop contributions; however, the net carbon is still positive (2629 g/bu for corn). The carbon emitted into the atmosphere from diesel refinement and use on the farm, carbon energy used to manufacture fertilizers and steel for equipment, as well as other inputs listed are still keeping the conservation farms from attaining carbon neutrality.

Table 1. Across the Fence (side-by-side) tillage system comparison in South Dakota.

Category
Conventional
No-Till
Cropland acres
1588
1456
Corn yield
184
185
Diesel/a
5.4
2.8
N rate (lbs/a)
162
167
P2O5 rate (lbs/a)
63
57
K2O rate (lbs/a)
35
53
Herbicide (oz/a)
82
85
Cover crop use (number of farms)
0/4
3/4
Manure/livestock integration (number of farms)
0/4
1/4
Equipment ($/a)
581
356

Average values from 4 CT/NT farm across the fence comparisons.

What does this mean to South Dakota farmers?

Farmer standing in a no-till field.
(U.S. Department of Agriculture photo)

If the GREET model is utilized to determine carbon emissions or soil storage, and farmers want to change practices for carbon payments, system-wide changes are necessary to accomplish this. However, if the no-till (soil health focused) farms cannot become carbon neutral or negative (Figure 1), there is still no extra carbon to offer for offsets to industries without first offsetting carbon emitting by farming practices.

What could the future look like?

The carbon and greenhouse gas issues probably are not going away and could continue to influence agriculture. In the future, farms maybe expected to address their carbon emissions. Stored soil carbon created from conservation cropping systems will likely become increasingly important for on-farm carbon neutrality credits in the new carbon accounting system proposed to guide business and tax structures in the future.