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.


06 Jan 2009

2008 Annual Interpretive Summary

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, S, and where indicated, to K, Mg, B, Cu, and 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. In 2007/08, three sites within a corn-wheat/soybean (C-W/S) rotation were planted to wheat/soybean, and four sites within a corn-soybean-wheat/soybean (C-S-W/S) rotation were planted to full season soybean.

After 7 years of experimentation, grain yields in the continuous check treatment showed the effect of depleted soil N, P, and S reserves, reaching only 36%, 56%, and 82% of the yield obtained in the continuous NPS treatment for wheat, double-cropped soybean, and full season soybean, respectively.

For wheat, average responses to N, P, and S were 2,100, 1,930, and 102 kg/ha, respectively. A significant response to NP was observed at all three sites. Considering the seven seasons and 28 sites under wheat, significant relationships were established between grain yield and soil N supply as predicted by soil nitrate-N at sowing + fertilizer N rate. Use of 130 to 140 kg/ha allowed for high grain yields of 4,000 kg/ha. A critical level of 15 to 20 ppm Bray 1 P has been established below which wheat P responses are highly probable.

For full season soybean, average responses to N, P, and S were 178, 554, and 416 kg/ha, respectively. For double-cropped soybean, average responses to N, P, and S were 517, 1,757, and 595 kg/ha, respectively. Out of the seven sites under soybean, six showed significant yield responses to P and four showed responses to S. Considering the 31 sites under soybean during seven seasons, a critical level of 13 ppm Bray 1 P has been established below which soybean P responses are highly probable. A critical level of 10 ppm sulfate-S has been estimated below which soybean S responses are highly probable.

Sites will be planted to corn in the C-W/S rotation and to wheat/soybean in the C-S-W/S rotation during the 2008/09 season. Argentina-12