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 2005/06, 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 doublecropped wheat/soybean.

Soil testing indicated residual effects from N, P, and S fertilization in previous years at all sites. Significant wheat yield responses were observed at 4, 8, 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. Doublecropped soybean yield responses were significant at 2, 3, and 8 sites for N, P, and S, respectively. Average yield responses for N, P, and S were 141, 369, and 697 kg/ha, respectively. No responses to nutrients other than N, P, and S were determined neither for wheat nor for soybeans.

Differences between the NPS and check treatments have increased with crop year indicating that wheat and doublecropped soybeans are responding to accumulating fertility. Yield differences between the check and NPS treatments were 21 to 53% and 6 to 16% for wheat and doublecropped soybeans, respectively, in 2001 and 2002. Yield differences increased to 60 to 87% and 38 to 48% in the 2005/06 season. All sites will be planted to corn in the 2006/07 season. Argentina-12