ENHANCING MAIZE YIELD WITH NITROGEN MANAGEMENT AND TILLAGE SYSTEMS

An investigation on the impact of conventional tillage (CT) and no tillage (NT) system on nitrogen (N) application rates and their application at various growth stages (S) within these tillage systems on maize production, experiments were conducted at Cereal Crops Research Institute Pirsabak, Nowshera (NWFP), Pakistan, during 2004-05, 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 ha-1) 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).\ud \ud Conventional Tillage enhanced emergence and resulted lower harvest index and post harvest soil N. Likewise, CT improved germination %age, delayed silking, produced taller plants, more leaves per plant, higher leaf area, higher placement of ear, increased plants and ear at harvest, more grains ear-1, heavier grains, higher shelling %age, grain yield, stover yield, biological yield, grain moisture content and tissue N content. Nitrogen increased germination %age, plant height, leaf area, ear height, number of plants and ears at harvest, shelling %, stover yield, biological yield and grain moisture. Higher grain yield and harvest index was recorded with 120 kg N ha-1. Similarly N applied at various growth stages significantly affected grains ear-1, 1000 grain weight, shelling %age, grain moisture content, post harvest soil and tissue N content. Application of N at pre tasseling significantly improved grain ear-1 and shelling %age. A full dose of N when applied at 5 leaves stage resulted more accumulation by plant tissue. Significant interaction among tillage and N was observed for days to 75% silking, leaves ear height, grains ear-1, grain weight, grain yield, biological yield, harvest index, grain moisture content and post harvest soil N. CT produced higher grains ear-1 with 60 kg N ha-1 , while NT produced with 180 kg N ha-1. Grain yield increased linearly with increase in N level with CT while under NT 120 kg N ha-1 maximum grain yield was obtained.\ud \ud The T and N application at various growth stages revealed that more grains ear-1 were produced at S5 at both the tillage systems. In case of NT; the lowest number of grains ear-1 was produced at S4 while CT produced the lowest number of grains ear-1 at S1. CT at S3 recorded heavier grain while NT at S6.\ud \ud Interaction of N and its application at various growth stages were significant for ear height, gains ear1 , grain weight, shelling %, grain yield, stover and biological yield, grain moisture content and soil residual N. Each parameter increased with 180 kg N ha1 at S2,S6 S5,S1,S1,S4,S3 and S3, respectively.\ud \ud Interaction of N level and its application at various growth stages were significant for ear height, grains ear-1, and 1000 grain weight, shelling %, grain yield, stover and biological yield, grain moisture content and post harvest soil N. With 60 and 180 kg N ha-1, higher grains ear-1 and 1000 grain weight were recorded in interaction with S6. With 60 kg N ha-1, higher grain yield was recorded in interaction with S6, while in case of 120 and 180 kg N ha-1, higher grain yield was recorded with S4 and S1, respectively. With 60 kg N ha-1, higher biological yield was recorded in interaction with S6, while in case of 120 and 180 kg N ha-1, higher biological yield was recorded with S5 and S3, respectively. With 60 kg N ha-1, higher post harvest soil N content was recorded at S3, while in case of 120 and 180 kg N ha-1, higher post harvest soil N content was recorded with S2 and S3, respectively. while NT with 180 kg N ha-1 S5 produced the same. In case of 1000 grain weight, CT in interaction with 180 kg N ha-1 and S1 recorded maximum 1000 grains weight while NT did the same with 180 kg N ha-1 and S6. CT in interaction with 180 kg N ha-1 and S3 recorded maximum grain yield while NT with 120 kg N ha-1 and S6 produced maximum grain yield. CT in interaction with 60 kg N ha-1 and S6 recorded maximum harvest index while NT with 120 kg N ha-1 and S4 gave maximum harvest index.\ud \ud It was concluded that CT in interaction with 120 kg N ha-1 and split application of N showed higher yield and yield attributes. Individually, CT, 120 kg N ha-1 and split application of N exhibited excellent performance as compared with their associated levels