Maize yield, plant tissue and residual soil N as affected by nitrogen management and tillage systems

Tillage system and fertilizer management is needed to improve sustainable maize production. To investigate the impact of conventional tillage (CT) and no tillage (NT) system on nitrogen (N) application rates and their application at various growth stages (S) on maize production, experiments were conducted at Cereal Crops Research Institute Pirsabak, Nowshera (NWFP), Pakistan, during 2004 and 2005, respectively. Each experiment was consisted of two tillage systems; NT and CT, three levels of nitrogen (N) fertilizer i.e. (60,120 and 180 kg N per ha) and its application at various growth stages (S) i.e. full dose at sowing (S1), full dose at 5 leaves stage of the plant (S2), three equally split doses i.e. at sowing, 5 leaves and pre tasseling stage (S3), two equally split doses i.e. at sowing and 5 leaves (S4), two equally split doses i.e. at sowing and pre tasseling (S5) and two equally split doses i.e. at 5 leaves and pre tasseling (S6). Conventional Tillage resulted lower post harvest soil N. Likewise, CT improved grain yield and tissue N content. Higher grain yield was recorded with 120 kg N per ha. Similarly N applied at various growth stages significantly affected post harvest soil and tissue N content. A full dose of N when applied at 5-leave stage resulted more accumulation of N by plant tissue. Significant interaction among tillage and N was observed for post harvest soil N. Grain yield increased linearly with increase in N level with CT while under NT 120 kg N per ha maximum grain yield was obtained. Interaction of N and its application at various growth stages were significant for grain yield and soil residual N. Interaction of N level and its application at various growth stages were significant for grain yield and post harvest soil N. With 60 kg N per ha, higher grain yield was recorded in interaction with S6, while in case of 120 and 180 kg N per ha, higher grain yield was recorded with S4 and S1, respectively. With 60 kg N per ha, higher post harvest soil N content was recorded at S3, while in case of 120 and 180 kg N per ha, higher post harvest soil N content was recorded with S2 and S3, respectively, while NT with 180 kg N per ha S5 produced the same. CT in interaction with 180 kg N per ha and S3 recorded maximum grain yield while NT with 120 kg N per ha and S6 produced maximum grain yield. It was concluded that CT in interaction with 120 kg N per ha and split application of N showed higher yield. Individually, CT, 120 kg N per ha and split application of N exhibited excellent performance as compared with their associated levels.