2014 ASHS Annual Conference

A multi- disciplinary experiment was initiated in 2008 to study crop yield, soil and plant nitrogen (N) when using organic versus conventional fertility amendments. Tomatoes (Solanum lycopersicum L. ‘Bush Celebrity’) were used to examine the effect of fertility rate (control, low, and high) and source [conventional (Conv) and organic (Org)] in two different production systems [high tunnel (HT) and field (F)].  The experiment was conducted in the summer of 2008-2010 at the KSU Research Center in Olathe in replicated HT and F plots with a consistent management since 2002. The experimental design was a split plot where control plots received no supplemental fertilizer, low plots received a 97 kgN/ ha of pre-plant fertilizer (Conv) or mixed source compost (Org), and high plots received the same pre-plant amendments plus 6.72 kgN/ ha/ week of soluble fertilizers during the growing season (Conv) or fish hydrolyzate (Org). All plots had cover crops of rye (Secale cereal L.) during the winter. Soil NO₃-N and NH₄-N were measured, as well as NO₃-N in leaf petiole sap. Soil NH₄-N and NO₃-N levels were affected by production system, and fertility source and rate, but statistical significance varied by crop and stage. Petiole sap NO₃-N reflected treatment regimes but not necessarily soil N status at each plant stage. Yield of tomato was significantly higher in HT than F. There were no significant differences in tomato yield between Org and Conv in either production system. Tomato yield differences were significant for fertility rate.