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

The Regional Consortium of Agricultural Experimentation (CREA), a farmers’ organization based in Southern Santa Fe, has collaborated with IPNI with support from AgroServicios Pampeanos, to establish a network of field experiments with the objectives of: 1) determining direct and residual responses to N, P, S, and where indicated, K, magnesium (Mg), boron (B), copper (Cu), and zinc (Zn); 2) evaluating recommendation methods for N, P, and S fertilization; and 3) identifying 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 2006/07, five sites within a corn-wheat/soybean rotation (C-W/S), and four sites within a corn-soybean-wheat/soybean rotation (C-S-W/S) were planted to corn.

Soil testing indicated residual effects from N, P, and S fertilization in previous years at all sites. Significant corn yield responses were observed at 8, 5, and 3 sites for N, P, and S, respectively. Nitrogen and P responses were related to soil nitrate-N and Bray-P levels, respectively, but S response did not relate to soil sulfate-S availability. Average yield responses for N, P, and S were 3635, 2175, and 737 kg/ha, respectively. No responses to other nutrients than N, P, and S was determined for corn.

Differences between the NPS and check treatments have increased with crop year indicating that corn is responding to accumulating fertility. Yield differences between the check and NPS treatments were 81% and 64% for corn, respectively, in corn-wheat/soybean rotation (C-W/S) and corn-soybean-wheat/soybean rotation (C-S-W/S). Yield differences increased to 64 to 81% and 58 to 64% in the 2006/07 season compared with 2004/05 season. Five sites will be planted to wheat and the other four will be planted to soybean 2006/07 season. Argentina-12