Effects of rock phosphate amended with poultry manure on soil available p and yield of maize and cowpea

Abstract

The effect of rock phosphate (Sokoto and Ogun rock phosphates) amended with poultry manure on soil
available phosphate (P) and yield of maize and cowpea grown sequentially was evaluated for four
cropping seasons. The results obtained showed superiority of single super phosphate (SSP)
application over either Sokoto or Ogun rock phosphates. However, complementary application of the
Sokoto and Ogun rock phosphates with poultry manure increased maize plant height by 12 and 6, and
19 and 8%, respectively. Also, percent phosphorus contents in maize and cowpea leaf tissues
increased respectively by 33 and 22, and 22 and 25% in 2000, and by 25 and 6, and 16 and 18%,
respectively in 2001. Maize grain yield was increased by 33 and 26, and 18 and 25%, respectively, while
that of cowpea was increased by 25 and 32, and 49 and 38% in 2000 and 2001, respectively when
compared with application of rock phosphate alone. Single super phosphate treated soil had the
highest residual P values in all the three sampling periods. The effectiveness of rock phosphate as a P
sources for crop production was remarkably enhanced by solubilizing effect of poultry manure. Its low
rate (2 t ha-1) in combination with rock phosphate gave almost similar effects like higher rates (3 and 4 t
ha-1) of applications.