TILLAGE AND NITROGEN MANAGEMENT IMPACT ON MAIZE

Tillage system and fertilizer-N management are needed to improve sustainable maize production. The objective of the study was to investigate the impact of conventional tillage and no tillage systems, nitrogen rates and its application at various growth stages on maize production. Experiments were conducted at Cereal Crops Research Institute, Pirsabak, Nowshera, Pakistan, for two consecutive years (2004-2005) in a randomized complete block design with split plot arrangement having four replications. Each experiment consisted of two tillage systems i.e. no tillage (NT) and conventional tillage (CT), three levels of nitrogen fertilizer (60,120 and 180 kg ha^-1) and nitrogen application at various growth stages. The combination of tillage systems and nitrogen levels were allotted to main plots while nitrogen application at various growth stages to sub plots. More grains ear^-1 was observed in CT as compared to NT. The number of grains ear^-1 remained at par when N level was increased from 60 to 120 kg N ha^-1 but further increase in N level to 180 kg N ha^-1 resulted in significant increase in grains ear^-1. Number of grains increased when N was applied in split doses as compared to the full (sole) application at sowing or knee high stage and were higher when applied in two splits than three split doses. Heavier grains were produced in CT as compared to NT and with split application of N as compared to sole. Conventional tillage also produced significantly higher grain yield as compared to no-tillage. Year as a source of variation had significant impact on thousand grain weight, grains ear^-1 and heavier and more grains were produced during 2004. Significant interaction among tillage and N was observed for grains ear^-1, grain weight and grain yield. Conventional tillage produced higher grains ear^-1 and heavier grains even with lower dose of 60 kg N ha^-1, while no till required 180 kg N ha^-1 to deliver the same results. Grain yield was highly responsive to increase in N fertilizer up to 120 kg N ha^-1 under conventional tillage system. Further increase up to 180 kg N ha^-1 merely induced any increase in grain yield under CT. In case of no till grain yield decreased beyond 120 kg N ha^-1. Conventional tillage proved superior in terms of grains ear^-1, grain weight and grain yield as compared to no till. Grain yield increased up to 120 kg N ha^-1 but grains ear^-1 and grain weight were higher at the highest dose of 180 kg N ha^-1. Split application of N significantly increased all parameters including yield and yield components as compared to full application of N in single dose.