Soils in the major corn growing provinces of the Philippines are commonly heterogeneous and require site-specific fertilizer and lime technology that can sustain high yield production and profitability. The objectives of this project were to: 1) determine the level of nutritional constraints in major corn growing areas and the corrective amounts of nutrients and lime required; 2) develop spatial distribution maps of single nutrient availability, pH, and organic matter content; and 3) formulate site-specific fertilizer and lime recommendations for high yield corn production. Field experiments and soil samplings were conducted in the major corn growing provinces (Cagayan, Isabela, Bukidnon, and Misamis Oriental) in the Philippines in 2006 and 2010.

The recommendations are as follows:

- Alluvial silt loam at Enrile, Cagayan, needs 145, 110, and 67 kg/ha of N, P₂O₅ and K₂O, respectively. This soil needs 1 kg/ha each of Zn and Cu.

- Adtuyon clay at Impasugong, Bukidnon, needs 48, 92, and 1 kg/ha of Cu, P₂O₅, and K₂O, respectively.

- Extremely acidic soil at Benito Soliven, Isabela requires 3.6 t/ha CaCO₃.

- Nutrient contents in corn that yields 9.8 t/ha were (in kg/ha): 202 N, 38 P, 151 K, 38 Mg, 26 Ca, 0.5 Zn, and 0.1 Cu. Nutrient contents in grain were (in kg/ha): l04 N, 22 P, 25 K, 14 Mg, 9 Ca, 0.3 Zn, and 0.03 Cu.

- Spatial distribution maps of the test values and corresponding interpolated maps for pH, OM, P, K, Zn, Cu, and B for the four provinces were presented. The maps provided an easier visual assessment of nutritional constraints and a basis for adjusting fertilization and lime rates.

- Site-specific recommendations for N, P₂O₅, K₂O, Zn, Cu, B, and lime for 144 farms were presented.

These recommendations should be circulated for policy and application to corn production in the provinces concerned.