POPCORN YIELD AND NUTRIENT COMPOSITION AS AFFECTED BY NITROGEN FERTILIZATION AND LIMING IN CALABAR, NIGERIA

Zea mays L. everta (Popcorn) is a relatively new maize sub-species that is being introduced into the cropping system of arable crop farming in Calabar, Nigeria. Its productivity can, however, be impeded by low N concentration in the soil and high soil acidity that already affect the yield of conventional maize grown in the study area. Therefore, a two year trial was conducted at the Teaching and Research Farm of the University of Calabar, Nigeria to determine the effects of nitrogen and liming rates on growth, yield and nutrient composition of popcorn (Zea mays L. everta). A 3 x 4 factorial experiment in a randomized complete block design with three replication was used while treatments consisted of four levels of nitrogen (0, 40, 80 and 120 kg N ha-1), applied as urea (46% N) and fitted in a factorial arrangement with three levels of lime (0, 500 and 1000 kg ha-1) applied as calcium trioxocarbonate (iv) (CaCO3). Results indicated that all plant parameters examined were significantly (p=0.05) higher with the application of 80 kg N ha-1 and 500 kg ha-1 lime rates than other N and lime rates. Grain yield performance was in the order 80 > 120 > 40 > 0 kg Nha-1, which corresponded to 23.78, 33.55, 50.32% during 2009 and 15.14, 36.41 and 76.76% in 2010 above the 120, 40 and 0 kg N ha rates of N applied, respectively. Also, an increase of 20.0 and 24.83% in 2009, and 9.09 and 18.03% in 2010, in grain yield were observed when 500 kg ha-1 lime rates was applied and out-yielded both the 1000 kg ha-1 and control rates, respectively in both years. The application of lime at 1000 kg ha-1 resulted in significantly (p=0.05) higher N and Ca uptake in crop in both years. The P and Mg concentrations were highest from plants treated with 500 kg ha -1 lime. Effect of liming was not significant (p=0.05) in 2009, but was statistically at par at 0 and 500 kgha-1 lime rates and significantly (p=0.05) higher than tissue K content at 1000 kg ha-1 liming rates in 2010. The effect of lime was not consistent in both years but N xLime (L) interaction was significant while 500 kg ha-1 liming rate was most promising. Maize grain yield performance was better and most rewarding with the application of 80 N ha-1 while grain yield was best when 500 kg ha-1 lime rates was applied, Therefore, application of 80 kg Nha-1 and 500 kg ha-1 of lime are recommended for a profitable popcorn production in Calabar, Nigeria.