The effect of soil cation balancing on soil properties and weed communities in an organic rotation

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Many organic farmers in Ohio subscribe to soil balancing, or Base Cation Saturation Ratio (BCSR), to manage soil fertility, weeds and crops. BCSR calls for a balanced soil (~70% Ca, ~10% Mg, ~5%K). However, research has not substantiated this claim. An experiment was initiated in 2014 to evaluate the effect of BCSR on weed and crop communities, and soil properties in a 4-crop rotation. The experimental design is a randomized complete block, with 3 BCSR treatments, limestone, limestone with gypsum, GFF (a commercially-available blend from Green Field Farms Cooperative), plus a non-amended control. Soil was sampled in November 2013 and in September 2014, and analyzed for pH, base saturation and nutrient levels. Results of the 2013 samples were used for prescribing amendments applied in April 2014. Additional amendments were applied in fall of 2014. According to 2014 results, soil balance (defined above) was not achieved with the BCSR treatments. Soil pH, percent calcium and potassium were ideal in the gypsum and limestone plots, but magnesium was too high. In GFF plots, pH and percent calcium were too low, while magnesium was slightly elevated. Percent potassium was within the BCSR range, due to GFF’s 0-0-50 component. Aluminum was lower in gypsum and limestone plots, because calcium in these amendments replaces aluminum on soil exchange sites leading to displacement from the root zone. In 2015, we will adjust amendment rates to further balance the soil in treatment plots, and observe the impacts on crop growth and weed communities.



Soil balancing, Weed Control, Organic Weed Control, Soil Amendments