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.


04 Jan 2005

2004 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 2003/04, six sites were planted to corn (rotation corn-wheat/soybeans), and five sites to wheat/soybean (rotation corn-soybean-wheat/soybean).

Corn: Significant responses to N were found at four sites, and to PS at all sites. Soil nitrate-N availability at planting explained 49% of corn yield for the 19 experiments during the three growing seasons. Similarly, low soil Bray P (less than 15 to 16 parts per million [ppm]), and low sulfate-S (less than 10 ppm, 0 to 20 cm depth) availability at planting were significantly related to P and S response, respectively. The average yield response to NPS across all six sites was 3,857 kg/ha, a 58% increment over the check.

Wheat: Excellent climatic conditions allowed for high yields and responses to crop fertilization. Average yield responses were: 995, 1,339, 268, and 456 kg/ha to N, P, S, and other nutrients (KMgBCuZn), respectively. Responses to N and P were significant at four of five sites. Two of five sites showed significant responses to S and other nutrients. Grain yield responses to N and P were related to soil nitrate-N and Bray P availability at planting, but there was no relationship between soil sulfate-S availability and crop response to S. The average yield response to NPS for the five sites was 2,392 kg/ha, a 108% increase over the check.

Soybean: Four of the five sites showed significant responses to PS applied to the previous wheat crop. Application of PS for wheat increased doublecropped soybean yields by 363 kg/ha, a 14% increase compared to the check. Data from the 16 experiments conducted over the last three growing seasons indicate that a critical Bray P-1 level of 14 to 16 ppm (at wheat planting) is required to produce doublecrop soybean yields near 3,500 kg/ha., Soybean responses to S are prevalent with sulfate-S concentrations of 10 ppm or less at wheat planting. Argentina-12