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Title: Soil fertility status in Ohio and Indiana and the effect of soil fertility on soybean grain yield in Ohio.
Abstract: Soil fertility is one of the major factors that influences soybean [Glycine max (L.) merr] grain yield. Two experiments were completed in Ohio and Indiana with the objectives 1.) to assess the status of soil fertility in each state, and 2.) to determine the impact of soil fertility on soybean grain yield in Ohio. Sampling was conducted from 2013 through 2015 in Ohio resulting in 624 total samples, and from 2010 through 2014 in Indiana resulting in 483 total samples. In both states, soil P, K, pH, Ca, Mg, organic matter (OM), cation exchange capacity (CEC), and soil texture were measured. Plant nutrient concentrations for P, K, N, Mg, Ca, and S were also measured in the leaf tissue. In Ohio, 35% and 21% of the soil samples collected were below the state-established critical levels (CL) for P and K, respectively. Additionally, in Ohio, 18% of soil samples had a pH <6.0, and 29% had a pH > 6.8. In Indiana, 30% and 41% of the soil samples collected were below the CLs for P and K, respectively. Also, 22% of soil samples had a pH <6.0, and 19% had a pH > 6.8. For the leaf tissue analyses, < 10% of samples were below the sufficiency range for any nutrient except for N in Ohio where 14% of samples were below sufficiency and K in Indiana where 38% of the leaf tissue samples were below sufficiency. In Ohio, soybean grain yield was reduced by 7 and 4 bu/acre when soil P and K were below the CL, respectively. An increase in CEC of 1 meq/100 g soil resulted in a decrease in yield of 0.4 bu/acre. Low leaf tissue P, K, and N levels resulted in yield reductions of 16, 12, 8 bu/acre respectively. To prevent yield loss, producers should soil and tissue sample to monitor fertility levels and maintain levels within the state guidelines.