Organic and phosphorus fertilization of corn on limed ultisols

Lapoot, et al. (DA-NOMIARC) studied the long-term effect of chicken manure (CM) and phosphorus fertilization on limed ultisols grown with corn.

Findings

• 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.

Source: PCARRD, 2002. Highlights 2001, Los Banos, Laguna.

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