Open Access

ARTICLE

Comparative effectiveness of two phosphorus sources for wheat in southwestern Buenos Aires (Argentina)

by Ron MM, T Loewy

Departamento de Agronomía, Universidad Nacional del Sur, Altos del Palihue, 8000, Bahía Blanca, Argentina.

Address correspondence to: María de las Mercedes Ron, Fax 054-0291-4595127; Phone 054-0291-4595126; e-mail:

Phyton-International Journal of Experimental Botany 2017, 86(all), 68-73. https://doi.org/10.32604/phyton.2017.86.068

Abstract

In the southwest of Buenos Aires Province (Argentina) nitrogen (N) and phosphorus (P) deficiencies are important wheat yield limiting factors. The objective of this paper was to report on the comparative effectiveness of diammonium phosphate (DAP) and triple superphosphate (TSP) in the area covering a range of soils and years. Between 1983 and 1992, 13 experiments were carried out in farmer’s fields. Soils were classified as Ustolls and Udolls. The design of the experiments was of complete randomized split blocks. Horizontal treatments were P-sources (DAP and TSP) and rates (0 to 135 kg/ha). Vertical treatments were check and a single rate of urea N applied at sowing or tillering. Yield response to horizontal treatments was significant in four experiments carried out in the Ustolls. DAP and TSP were compared by the calculation of efficiency ratio (ER) and substitution value (SV), defined as the ratio of TSP/DAP rates rendering the same yield response. ER of DAP to TSP was between 0.82 and 1.28. In two of the four experiments, the SV value was above the quotient between their respective prices, estimated in around 1.1. This means that, in those sites, DAP was not only more effective than TSP but also a more profitable source. SV seems a more useful parameter than ER because it applies to the full range of fertilizer rates. Regardless of statistical significance yields were around 60 kg/ha higher for DAP on an average of all experiments and fertilizer rates.

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