Response of maize (Zea mays) and okra (Abelmoschus esculentus) intercrop relayed with cowpea (Vigna unguiculata) to different levels of cow dung amended phosphate rock

Field trial was conducted at the Institute of Agricultural Research and Training, Moor Plantation, Ibadan, Nigeria in 2002 and 2003 to assess the effect of Ogun rock phosphate (ORP) amended with cow dung(CD) manure on the growth and yields of maize and okra in intercrop relayed with cowpea on an Aquic Arenic Haplustalf. Significant treatment effects were observed in plant height and leaf area of maize and okra whereas stem girth was not significantly affected in either crop. The percentage leaf P concentration of maize, okra and cowpea were significantly (P < 0.05) affected by treatment application.The percentage ranged from 0.18 - 0.48 and 0.24 - 0.45 in maize, 0.20 - 0.39% and 0.21 - 0.40% in okra and 0.16 - 0.40 and 0.18 - 0.42% in cowpea in 2002 and 2003, respectively. Increase in available P inamended ORP over sole ORP ranged from 44 - 71%, 40 - 71%, and 50 - 67% in the 2nd, 3rd and 4th sampling period. The ORP + 4 t/ha CD gave the highest P content of leaf in all the crops and in bothyears. The complementary use of Ogun rock phosphate with 3 t ha-1 cow dung manure produced the highest yields of maize (3.2 and 2.3 t ha-1), okra (1.6 and 2.5 t ha-1), and cowpea (1.8 and 1.9 t ha-1) in2002 and 2003, respectively