Organic and phosphorus fertilization of corn on limed ultisols
2002
Lapoot, C.R. | Duna, L.V. | Salvani, J.B. (Department of Agriculture, Bulwagan, Malaybalay City (Philippines). Northern Mindanao Integrated Agricultural Research Center)
The long-term effect of chicken manure (CM) and phosphorus fertilization on limed ultisols grown with corn was studied. Findings showed that application of chicken manure increased corn yield. Application of 5 t of CM increased the corn yield by more than 0.5 t from 3.92 to 4.42 t/ha in wet season of 1996; 4.48-5.16 t/ha in 1997; 5.22-6.15 t/ha in 1998; and 4.27-4.98 t/ha in 1999. Application of phosphorus in combination with CM enhanced the yield of corn. At 2.5 t CM, addition of 60, 120, and 180 kg of P increased yield by 1.36 t, 1.70 t and 1.94 t, respectively. At 5 t CM, incremental yields for 60, 120, and 180 kg P were 0.26, 0.53, and 0.88 t, respectively. Application of 60 kg P/ha alone gave the highest return during the dry and wet season croppings. Marginal rate of return (MRR) of 601% and 564% were attained during wet and dry seasons, respectively. Application of 2.5 t/ha CM alone gave MRR of 157%. Both organic and phosphorus fertilizations did not affect amount of exchangeable K. Instead, exchangeable K declined with time brought by declining pH. Application of CM, however, delayed the decline of soil pH from two to three years
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