Crop yield and soil fertility as affected by papermill biosolids and liming by-products

Papermill biosolids (PB) in combination with alkaline industrial residuals could benefit agricultural soils while diverting these biosolids from landfill. A greenhouse study was conducted to evaluate the effect of three types of PB at rates of 0, 30, and 60 wet Mg ha -1, as well as five liming by-products at 3 wet Mg ha -1 along with 30 Mg PB ha-1 on crop yield, nutrient accumulation, and soil properties. De-inking paper biosolids (DB, C/N of 65) were applied to soybean [Glycine max (L.) Merr.], and two combined PB (PB1, C/N of 31; and PB2, C/N of 14) were applied to dry bean (Phaseolus vulgaris L.) and barley (Hordeum vulgare L.), respectively. The liming by-products included lime mud (LM), wood ash (WA) from paper mills, commercial calcitic lime (CL), Mg dissolution by-product (MgD), and Mg smelting and electrolysis work (MgSE). Compared with the control, PB2 increased barley yield and total Mg and Na accumulation, and both PB increased plant N, P, and Ca accumulation in barley and dry bean. The impact of DB on soybean was limited. The addition of liming by-products to PB or DB did not affect crop attributes except the combination with MgSE, which severely reduced the growth of dry bean and, to a lesser extent, soybean. Soil NO3-N was immobilized following DB application, whereas there was a net release with both PB. Combining PB and liming by-products produced the greatest changes in soil properties at harvest. Generally, LM and CL raised pH and Mehlich-3 Ca, and MgSE caused a strong increase in Mehlich-3 Mg and Na and water-soluble Cl. When used with appropriate crops, biosolids from paper mills and alkaline residuals other than MgSE can efficiently enhance soil fertility by providing organic C and macronutrients for balanced crop fertilization.