Long-term Nutrient Management Network for Southern Buenos Aires Province

In 2007/08, IPNI and Agroservicios Pampeanos (ASP) established a network of field experiments with the objectives of: 1) determining direct and residual responses to N, P, and S; 2) evaluating recommendation methods for N, P, and S fertilization; and 3) identifying the level of deficiency and potential responses to nutrients other than N, P, and S, such as K, Mg, B, Cl^-, Cu, and Zn. Three sites were planted to soybean at Pieres, Tandil, and Tres Arroyos; and one to wheat at Olavarria during the 2009/10 growing season.

Soybean check yields varied from 2,809 to 3,127 kg/ha, and fertilized yields varied from 2,848 to 3,631 kg/ha. Responses were significant to P at Tandil (+332 kg/ha, +11%), and to NPS at Pieres (+607 kg/ha, +22%). The wheat experiment at Olavarria showed a significant response to NPS (+1,295 kg/ha, +27%). Grain yield responses were related to low soil Bray-1 P and sulfate-S levels, and good weather conditions. No responses were observed to nutrients other than N, P, and S. These sites will be planted to wheat during the fourth season of evaluation in 2010/11. Argentina-27