Establishing a Plant Nutrition Network for the CREA Region in Southern Santa Fé

On-farm field experiments establish as a long-term network in 2000, to evaluate responses to N, P, and S in wheat, soybean, and maize in the southern Santa Fe and Southeastern Cordoba regions. Evolution of soil properties are evaluated periodically in teh different treatments.


01 Apr 2006

2005 Annual Interpretive Summary

The Regional Consortium of Agricultural Experimentation (CREA), a farmers’ organization based in Southern Santa Fe, is collaborating with INPOFOS Southern Cone with support from AgroServicios Pampeanos, to establish a network of field experiments. The objectives are: 1) determine direct and residual responses to nitrogen (N), phosphorus (P), sulfur (S), and where indicated, potassium (K), magnesium (Mg), boron (B), copper (Cu), and zinc (Zn); 2) evaluate recommendation methods for N, P, and S fertilization; and 3) identify the level of deficiency and potential response to nutrients other than N, P, and S. The six fertilizer treatments are: 1) check, 2) PS, 3) NS, 4) NP, 5) NPS, and 6) NPS + KMgBCuZn. In 2004/05, five sites were planted to soybean within a corn-wheat/soybean rotation, and four sites to corn within a corn-soybean-wheat/soybean rotation.

Excellent climatic conditions allowed for high soybean yields in 2004. Soil testing indicated residual effects from P fertilization in previous years at all five sites. The average yield response to NPS across all five sites was 591 kg/ha, a 15% increase over the check. Significant yield responses were observed at 3 and 2 sites for P and S, respectively. Phosphorus responses were related to soil Bray-P levels, but S response did not relate to soil sulfate-S availability. Greater differences between treatments in 2004/05 than in 2001/02 indicates that full-season soybeans are responding to accumulated fertility in the P+S treatments.

Significant responses to N, P, and S were found at all four corn sites for 2004. The average yield response to NPS across sites was 4,629 kg/ha, a 64% increase over the check.
Each kg of applied N, P, and S contributed to 19, 45, and 61 kg of corn, respectively. Considering the four seasons of corn experiments, yield responses to N were related to soil nitrate-N availability (0 to 60 cm depth) and yields of 10,000 kg/ha could be reached with 177 kg/ha of available N at planting (soil N + fertilizer N). Similarly, low soil Bray P...less than 15 to 16 parts per million (ppm)...and low sulfate-S availability (less than 10 ppm, 0 to 20 cm depth) at planting were related to P and S response. No responses to nutrients other than N, P, and S were determined. Argentina-12