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.


14 May 2018

2017 Annual Interpretive Summary

The Regional Consortium of Agricultural Experimentation (CREA), a farmers' organization based in Southern Santa Fe, has established a network of field experiments with the objectives of: (1) determining direct and residual responses to nitrogen (N), phosphorus (P), sulfur (S), and where indicated, to potassium (K), magnesium (Mg), boron (B), copper (Cu), and zinc (Zn); (2) evaluating recommendation methods for N, P, and S fertilization; (3) identifying the degree of deficiency and potential response to nutrients other than N, P, and S; and 4) evaluating the evolution of soil quality under contrasting nutrient management practices. In 2016-17, the two sites under corn-wheat/soybean (C-W/S) rotation were planted to corn, and the three sites under corn-soybean-wheat/soybean (C-S-W/S) rotation were planted to full season soybean.

Adequate precipitation in the 2016/17 season supported high yields in all crops and sites. Corn grain yield responses to N, P, and S were significant at Balducchi and San Alfredo. Responses to NPS averaged 5.9 t/ha (+102%) for both sites. Average response to PS in full season soybean was 386 kg/ha (+9%), but the response was only significant at the Lambare site. There were no significant responses to the other nutrients (K, Mg, B, Cu, and Zn) at any of the sites and crops evaluated this 2016/17 season.

Responses to N were related to available N at planting (soil + fertilizer N) for corn. Pooling data from this season and the previous ones, a critical availability of 166 to 231 kg N/ha to reach corn yields of 10 to 12 t/ha has been estimated. Significant relationships were observed between Bray P-1 soil P concentrations and P responses, with critical P concentrations ranging between 11 and 16 ppm Bray P-1 for the two crops. Below these critical levels, P responses are highly probable. Responses to S were related to pre-plant soil sulfate-S concentrations (0 to 20 cm), with a critical level of 8 to 10 ppm for corn and full season soybean.

There was a special study carried out by the College of Agronomy at the University of Rosario that was featured in Better Crops 2018, #1. It showed that balanced NPS fertilization during 12 consecutive years improved soil organic matter, soil microbial population and enzyme activity, and soil aggregate stability in fields with long annual cropping history and coarse soil texture. However, there were no effects in fields with short annual cropping history and fine soil texture.

For the 2017/18 season, all sites, either under C-W/S or C-S-W/S rotation, will be cropped to wheat/double-cropped soybean.