Volume 61, Number 1, March 2024

The annual accumulation of precipitated calcium carbonate (PCC) in sugar processing factory stockpiles in the Northwest U.S. sugarbeet growing area creates problems related to storage requirement and environmental related issues. Utilizing this PCC for agricultural use may provide a long-term solution to this problem but applying PCC or other lime materials to Northwest U.S. agricultural soils is not a common practice. In other areas of the U.S., PCC is routinely used to ameliorate the negative effects of low pH on crop growth, however this is not the case in the Northwest U.S. sugarbeet growing area due to soils typically having high pH. An alternative agricultural use for PCC needs to be found. Recently concluded research in southern Idaho has demonstrated that PCC application of rates up to 90 dry Mg ha^-1 (40 dry tons ac^-1) on calcareous soils does not negatively affect crop growth or yields in common crop rotations. An alternative reason for PCC application may be to supply phosphorus (P) and other nutrients as a fertilizer. The PCC in this study had average P and K concentrations of 12.4 kg P₂O₅ Mg^-1 (24.8 lbs P₂O₅ ton^-1) and 2.05 kg K₂O Mg^-1 (4.1 lbs K₂O ton^-1). Data from this and other research studies suggests that PCC and P fertilizer likely have equivalent plant P availability. This study also assumed that the K in PCC was equivalent to K fertilizer. Across all crops assessed in this study [sugarbeet, corn, spring malt barley, and potato (Russet Burbank)], as P and K fertilizer prices increased from 2018 and 2022, the value of P and K in PCC increased from $13.94 Mg^-1 ($12.65 ton^-1) to $28.15 Mg^-1 ($25.54 ton^-1) and $1.31 Mg^-1 ($1.19 ton^-1) to $3.16 Mg^-1 ($2.87 ton^-1), respectively. Averaged across all acres and selected crops in the Amalgamated Sugar Company (ASCO) growing area, substituting PCC for fertilizer P and accompanying K could have resulted potential savings of between $96 ha^-1 ($39 ac^-1) in 2018 to $198 ha^-1 ($80 ac^-1) in 2022. Substituting PCC for fertilizer K could have resulted in potential savings of between $84 ha^-1 ($34 ac^-1) in 2018 to $190 ha^-1 ($77 ac^-1) in 2022. Alternate uses, transportation and application costs need to be accounted for to fully understand the full PCC value. Because ASCO is a grower owned cooperative, PCC utilization strategies are economically important for sugarbeet growers.

Sugarbeet production, including pre-season tillage and late-season soil inversion to lift beets, leaves soil vulnerable to wind erosion by removing all residue cover from soil. The integration of cover crops and strip tillage can provide protection of soils from wind erosion in sugarbeet fields, while also potentially improving soil health, decreasing water erosion, and nutrient losses. However, it’s critical to show that these practices do not carry risk of lowering profits by diminishing yield and quality. Here, we evaluated the effect of strip-tillage with and without cover crops prior to sugarbeet on sugarbeet yield and quality parameters. We performed replicated strip trials on three growers’ fields in Western Minnesota, using production-scale equipment and grower best management practices, and found no effect of strip-tillage with or without cover crops in yield, sucrose %, sucrose purity, or extractable sucrose (P>0.10 for all variables). This indicates that adopting strip-till and cover crops practices poses little risk to on-farm profit.

Precipitated calcium carbonate (PCC) lime is a byproduct of sucrose extraction from sugarbeet processing factories in Idaho. Each year 351,000 Mg PCC is produced and stockpiled at sugarbeet factories in Idaho. There currently are no large-scale disposal strategies for the PCC and these stockpiles continue to grow each year. The simplest solution would be to apply more of the PCC directly to agricultural fields each year, however the effects of PCC on high pH soils and southern Idaho crop rotations are not well understood. A study was conducted at the USDA-ARS laboratory in Kimberly, ID to determine the effects of PCC application to an alkaline silt loam soil on sugarbeet, dry bean and barley production and soil properties. Three PCC treatments (rate and timing) and an untreated control were compared.  The PCC had no effects on crop production factors and most soil properties. The only significant effect of PCC treatments was an increase in soil phosphorus (P) concentrations compared to the control. This indicates the PCC can serve as a P fertilizer. For all three crops in this study, PCC was applied at rates that resulted in applied P levels that were 1.6 to 5.3 times greater than even the highest published recommended P rates. Compared to the control, bicarbonate soil P concentrations increased by 25% and 73% for the final PCC application amounts of 26.9 Mg ha^-1 (6.7A treatment) and 89.7 Mg ha^-1 (6.7A and 89.7T treatments), respectively. The PCC used in this study can safely be applied (at rates up to 87.9 Mg ha^-1) to heavier textured alkaline soils in the local growing area. Disposing of PCC in this way represents a viable strategy for reducing PCC stockpiles.