Evaluation of the fertilizer value and nutrient release from corn and soybean residues under laboratory and greenhouse conditions

Abstract

Abstract Laboratory and greenhouse studies were conducted on a moderately fertile Taloka (fine, mixed, thermic mollic Albaqualf) silt loam and a low fertility Leadvale (fine‐silty, siliceous, thermic typic Fragiudult) silt loam to evaluate nutrient release and fertilizer value of soybean [Glycine max (L.) Herr.] and corn (Zea mays L.) residues as compared to the inorganic fertilizer 13–13–13–13 (N‐P2O5‐K2O‐S). Residues and the inorganic fertilizer were applied at 50 mg N/kg in a incubation study and at 25 and 50 mg N/kg in a greenhouse study. The incubation study indicted that carbon dioxide (CO2) evolution and nitrogen (N) mineralization followed a identical sequence: soybean > corn residues, similar to residue N concentration and carbon/nitrogen (C/N) ratio sequence. Application of corn residues produced N immobilization in both soils (‐20 mg N/kg soil), whereas soybean increased inorganic soil N in the Leadvale soil (3 mg N/kg soil) and particularly in the Taloka soil (17 mg N/kg soil). The greenhouse study showed the superiority of the inorganic fertilizer over corn and soybean residues for sorghum‐sudan yield, and N, phosphorus (P), potassium (K), and sulfur (S) total uptake. No significant differences were found among the residues and between residues and the control with the exception of the higher soybean rate for total N uptake in the Taloka soil, and the higher corn and soybean residue rate in the Leadvale soil for total K uptake. It also appeared that soybean residues provided a substantial amount of N and S to sorghum‐sudan. Higher rates of both soybean and corn residues constituted a prime source of K, particularly in the Landvale soil which had a low exchangeable soil K level.