Exploration of Responses to Potassium in Western Uruguay

Several regions of Uruguay has recently shown K deficiencies and responses. This project looks to determine the different areas with K deficiency, evaluate responses in the main field crops, and provide information on K soil testing.

IPNI-2007-URY-2

24 Jan 2013

2012 Annual Interpretive Summary


This research is based on previous observations of K deficiency and responses in field crops grown within the northwestern Uruguay region. Data from the first three years of field work and other studies, including 50 experiments under wheat, barley, maize, soybean, sunflower, and sorghum crops, indicated a critical K range of 0.30 to 0.40 cmol/kg (117 to 156 ppm), below which there is a high probability of response to K fertilization. Integration of soil survey data with this field work has allowed researchers to estimate that an area of 4 million ha is potentially K deficient in Uruguay.

Field work in the 2011-12 growing season included six trials in western Uruguay - five under full season soybean and one under maize. Grain yield responses to K fertilization averaged 577 kg/ha (+11%) for maize and ranged from 109 to 413 kg/ha (+3 to 14%) for soybean, according to soil exchangeable K levels. A long-term field experiment has been initiated in 2012 to evaluate soil K dynamics under crop rotations of western Uruguay.

As part of the activities of the project, results for the first three years of this project were presented and discussed at a seminar organized at the College of Agronomy of Universidad de la Republica at Montevideo (Uruguay) on 25 April 2012. Also, an article was published in Better crops with Plant Food magazine, and other presentations were made at the 19th ISTRO Conference. Uruguay-02