Yield and yield components of maize as influenced by row arrangement, nitrogen and phosphorus levels in maize (Zea mays L)/ castor (Ricinus communis) mixture

Field experiment was conducted at Institute for Agricultural Research farm Samaru, Zaria in Nigeria during 2007 to 2009 rainy seasons. Treatments consisted of factorial combinations of three alternate row arrangements of maize: castor in 1:1, 1:2 and 2:1, four levels of nitrogen (0, 40, 80 and 120 kg N ha -1 ) and three levels of phosphorus (13, 26 and 39 kg P ha -1 ), in a split plot design with three replication. Nitrogen and phosphorus fertilizer were assigned to the main plots and row arrangements to the sub-plots. Row arrangement of 1:2 significantly increased cob weight, while 2:1 increased 100- grain weight and yield of maize. Applied 40 kg N ha -1 resulted in significantly heavier cob diameter and grain yield in 2009. Application of 80 kg N ha -1 increased cob diameter and weight in 2007. Cob weight in 2009, 100- grain weight and yield in 2007 responded up to 120 kg N ha -1 . Application of 39 kg P ha -1 was observed to increased 100- grain weight, while grain yield did not responded beyond applied 26 kg P ha -1 . Maize can be intercropped with castor at 2:1 row arrangement with application of 120 kg N ha -l plus 26 kg P ha -l .