Efficacy of Recalcitrant Carbon Soil Amendment to Improve Zea Mays Yield in Poor Quality Sandy Loam Soils.

A recalcitrant carbon (RC) product, comprised of approximately 49% carbon, 38% water, and 13% various minerals and trace elements including: iron, zinc, manganese, sulfur, boron, and molybdenum, was field tested on Zea mays for yield response. The study was designed as a strip plot with four replications. Strips received either 0, 7.17, 14.35 or 21.52 Mg ha^-1 RC. Four nitrogen (N) rate/timing treatments were studied as a randomized complete block applied within RC strips (201.75 kg ha^-1 at V3, 201.75 kg ha^-1 at V6, 100.87 kg ha^-1 at V3 and V6, and an untreated control). Plots were established in similar, loamy soils (Myatt loam and Stough sandy loam) at Mississippi State University’s R.R. Foil Plant Science Research Center. Soil samples collected prior to treatment indicated soil organic matter (SOM) and cation exchange capacity (CEC) averaged 1.3% and 5.0 cmol_c/kg, respectively. Mean clay concentrations were 9.09% while mean sand concentrations were 66.13%. Treatment effects on yield were assessed using the generalized linear model (GLM) in SAS, no interactions were observed. Recalcitrant carbon rate, N timing, and replication effect significantly affected yield (P<0.05). The greatest mean grain yields were measured in the 21.52 Mg ha^-1 RC treatment. There were no significant differences attributed to the timing of N application, except for the zero-N control. Yield data were reassessed excluding the zero-N treatments. The 21.52 Mg ha^-1 RC application yields remained significantly greatest and only the replication effect and RC rate were significant when the zero-N data were excluded.