Regional Maize Grain Yield Response to Applied Phosphorus in Central America
Raun, William R. | Barreto, Hector J.
Maize (Zea mays L.) in Central America is commonly grown under continuous cultivation and on marginal lands where restricted use of conservation practices and fertilizers limit productivity. Maize grain yield response to P source, rate, and method of application was evaluated at 33 locations in Central America. Soil orders included Andisols, Inceptisols, and Ultisols. Treatments included rock phosphate (RP) applied broadcast preplant without incorporation at rates of 13 and 26 kg P ha⁻¹, triple superphosphate (TSP) band-applied at planting at rates of 13 and 26 kg P ha⁻¹, TSP broadcast preplant at 26 kg P ha⁻¹, and a check where no P was applied. All treatments received 100 kg of N ha⁻¹ as urea applied in split applications and 30 kg S ha⁻¹ as CaSO₄.2H₂O. Averaged over locations, maize grain yield increased 0.38 and 0.74 Mg ha⁻¹ when 13 and 26 kg P ha⁻¹ was band-applied as TSP and increased 0.21 and 0.16 Mg ha⁻¹ when RP was broadcast at the same rates. All P treatments had a probability (PR) >0.61 of outperforming the unfertilized check. Triple superphosphate band-applied at 26 kg P ha⁻¹ offered the greatest probability (0.69) of an economicr esponse to P fertilizer across environments. Stability analyses and analyses of yield differences suggest that response to applied P was independent of environment for the sites evaluated. The consistent response to applied P across a wide range of environments demonstrates that P is a limiting element for maize production on marginal lands in Central America and that the probability for economic response to applied P is high. Contribution from the Int, Maize and Wheat Improvement Ctr. (CIMMYT).
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