A Byproduct Success Story

lncreased Spent Lime Usage in Southern Minn
Affirmed by University/Co-op Research Results

    The spreading of spent lime (more-technically known as Precipitated Calcium Carbonate, or PCC) on upcoming sugarbeet fields has really taken off during the past decade among Upper Midwest beet growers.  Along with increasing pH and influencing the soil nutrients, the spent lime has been demonstrated to reduce the impact of Aphanomyces and Rhizoctonia root rot in infested fields.

Spent beet lime pile. Credit: Southern Minn Beet Sugar Co-op

    The region’s most recently reported research on spent lime’s benefits comes from the Southern Minnesota Beet Sugar Cooperative (SMBSC), where the use of PCC has expanded six-fold since 2001.  Based on this use pattern, the projection is that within five years the Southern Minn factory PCC pile will be reduced significantly beyond what it already has been.  The annual PCC production by SMBSC will be available on a long-term basis for growers to use for their benefit,  
    SMBSC agronomists Mark Bredehoeft and Chris Dunsmore, in conjunction with University of Minnesota soil scientist John Lamb, have summarized five years of studies (2008-12) on the use of PCC.  Their results show increases in sugarbeet and corn yields of 23-36% and 22-35%, respectively, when either four, eight of 12 tons of PCC were applied per acre.  The SMBSC work indicates that PCC applied two years in advance of crop production was the most advantageous, compared to one and three years.
    For sugarbeets, the biggest advantage came when beets were planted in the second year (after soybeans and then corn) following the application of 12 tons of spent lime per acre.  There, beet yields were nearly 27% higher than the mean yield.  When beets were grown in the second year after the application of eight tons of lime, the yields were 20% higher than the mean; after four tons of lime two years previous, the beet yields were nearly 14% greater than the mean.  In all cases, the applied nitrogen rate was 110 pounds per acre on the beets and 140 pounds in the preceding year’s corn.
    The SMBSC research also looked at the effect of PCC on Rhizoctonia.
    A summary of results from 2009 and 2010 shows that when four tons per acre of PCC were applied to soils inoculated with Rhizoctonia solani sub-population AG 2-2 IIB, sugarbeet root yield was 4.3 tons higher than where no PCC was applied to the inoculated soil.  The difference was smaller where sub-population AG 2-2 IVA was inoculated.  There, the benefit from four tons of PCC was just 0.8 ton, well below the least significant difference (LSD at alpha level 0.05) of 3.8 tons.
    In the case where there was no inoculated disease treatment, the yield benefit from four tons of PCC was 2.9 tons per acre, versus where there was no PCC applied.  This increase was not statistically significant, however.

    The investigation, promotion and use success of PCC on crop production has been a collaborative effort by sugarbeet growers, university researchers, agricultural retail industry, crop consultants and the sugarbeet industry.  University researchers John Lamb and Dr. Albert Sims (soil scientist at the University of Minnesota’s Northwest Research and Outreach Center, Crookston) conducted a significant amount of research in cooperation with Southern Minnesota Beet Sugar Cooperative to show the influence PCC can have on crop production — and the benefits to the soil as a natural additive. 
    The agricultural retail industry and crop consultants have taken the time to look at the benefits of PCC with an open mind.  There has been significant communication between the ag industry, crop consultants and SMBSC to provide a quality product to the grower.  The University of Minnesota also has been instrumental in disseminating the information to the agricultural retail industry, consultants and growers. 
    Southern Minnesota growers have accepted the research conducted by SMBSC and the university.  They’ve taken the advice of crop consultants, ag retailers and co-op ag staff and have applied the PCC with much success.  The positive results have led to overwhelming acceptance of PCC application in the region.  This collaborative effort has become a success story highlighting the use of a sugarbeet processing byproduct into a crop production enhancement additive.  It also is an excellent example of how the university, agricultural industry and growers can work together for the benefit of all. — Mark Bredehoeft   

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