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

The Regional Consortium of Agricultural Experimentation (CREA), a farmer organization based in Southern Santa Fe, has collaborated with IPNI to establish a network of field experiments with the objectives of: 1) determining direct and residual responses to N, P, sulfur (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 experiments evaluated check (CK), PS, NS, NP, NPS, and NPS + KMgBCuZn treatments. 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 at all sites. Excellent climatic conditions allowed for record corn grain yields which ranged between 5.4 to 10.1 t/ha for the CK and 11.4 to 16.4 t/ha for the NPS treatments. Significant corn yield responses to NPS, NP, NS, N, P, and other nutrients were observed at 2, 6, 3, 1, 1, and 1 sites, respectively. Considering the 31 sites/year over the five corn seasons of the network, corn yields and corn N responses have been significantly related to soil pre-plant nitrate-N availability, and corn yields of 10 t/ha could be obtained with soil nitrate-N levels of 140 to 150 kg/ha (0 to 60 cm). A soil Bray P-1 critical level of 15 mg/kg has been established below which corn P responses are highly probable. For S, sites with soil pre-plant sulfate-S levels below 10 mg/kg generally show corn yield responses greater than 300 kg/ha. Sites will be planted to wheat/soybean in the C-W/S rotation and to full season soybean in the C-S-W/S rotation, in the 2007/08 season. Argentina-12