Corn stover removal for expanded uses reduces soil fertility and structural stability

Corn (Zea mays L.) stover is an asset to recycle essential plant nutrients and buffer soil against natural and human perturbations. Its indiscriminate removal for industrial uses may thus adversely impact soil fertility and productivity. Research data on the impacts of stover removal are needed to establish threshold levels of stover management. Thus, this study documented the 4-yr impacts of a systematic removal of stover on selected soil fertility indicators and structural stability across three contrasting soils in Ohio under no-till (NT) management, including a Rayne silt loam, Celina silt loam, and Hoytville clay loam. Stover was removed at rates of 0, 25, 50, 75, and 100% after harvest for 4 yr. Complete stover removal reduced the total N pool by, on average, 0.82 Mg [ha.sup.-1] in the silt loams but had no effect in the clay loam. It reduced available P by 40% and exchangeable [Ca.sup.+2] and [Mg.sup.+2] and the cation exchange capacity by 10% on the sloping silt loam. Exchangeable [K.sup.+] decreased by 15% on the silt loams for stover treatments [greater than or equal to] 75% removal and by 25% under complete removal on the clay loam in the 0- to 10-cm depth. Stover removal at rates [greater than or equal to] 25% reduced soil macroaggregates (>4.75 mm) by 40% in nearly level soils while 100% removal reduced them by 60% on the sloping soil. Available P and [K.sup.+] were predictors ([R.sup.2] = 0.77) of grain yield while soil organic C (SOC) and total N pools were predictors ([R.sup.2] = 0.45) of stover yield on the sloping silt loam. Based on the data (e.g., SOC pools) from this and previous studies, we determined that only about 25% of stover might be available for removal, and that stover removal has the most adverse impacts on sloping and erosion-prone soils. Abbreviations: CEC, cation exchange capacity; CSL, Celina silt loam; EC, electrical conductivity; HCL, Hoytville clay loam; MWD, mean weight diameter; NT, no-till; SOC, soil organic carbon; SOM; soil organic matter; RSL, Rayne silt loam; WSA, water-stable aggregates.