Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 1995
Publication Date: N/A
Technical Abstract: The effects of N fertilization versus no-fertilization were compared from 1988-1993 in a long-term cropping and tillage experiment on Pullman clay loam at Bushland, TX. Nitrogen (35-45 kg/ha) was applied as ammonium nitrate or as 31-0-0 liquid at planting for grain sorghum [Sorghum bicolor (L.) Moench] and winter wheat (Triticum aestivum L.) grown in wheat-fallow (WF), continuous wheat (CW), wheat-sorghum-fallow (WSF), and continuous sorghum (CS) sequences with stubble-mulch (SM) tillage and no-tillage (NT) management. Dryland wheat grain or biomass yields did not respond to fertilizer addition during any year for any combination of sequence and tillage. However, fertilizer applications increased average grain yields 39% (1.1 Mg/ha) on CS-SM plots and 54% (1.2 Mg/ha) on CS-NT plots. Biomass yields increased similar percentages. Sorghum grown in the WSF sequence did not respond to N addition. The N-mineralization capacity of Pullman soil did not sustain the N- requirement for the greater production in the CS sequence, but provided sufficient N for sorghum in the WSF sequence and for wheat in all sequences.