Resumo

MORENO RESQUIN, Higinio et al. Potassium fertilization in no-till mechanized farming of eastern Paraguay. Investig. Agrar. [online]. 2012, vol.14, n.1, pp.41-49. ISSN 2305-0683.

Continued land use and new varieties with high yielding potential creates the need to apply potassium fertilizer in agricultural systems under no-till farming in eastern Paraguay. The objectives of this research were to evaluate the effect of potassium fertilization on the yield of wheat, corn and soybeans, and determine the critical level of potassium in the soil. Six experiments were conducted on-farm in Caaguazú, San Pedro and Amambay. The experimental design was a randomized block with three replications. Treatments consisted of five doses of K₂O (0, 25, 50, 75 and 100 kg ha^-1), broadcasted at planting using potassium chloride. Wheat was planted in the winter of 2009 and soybeans and corn in the summer 2009 – 2010. Crops responded to the application of potassium and the degree of response was inversely related to interchangeable K⁺ at the 0 –10 cm soil depth. The critical K⁺ level was 0.17 cmol_c kg^-1. On average, the dose for maximum yield was 63 kg K²O ha^-1. When data from this research was grouped with other recent studies, the critical general level for potassium was 0.16 cmol_c kg^-1. The results contributed to improve K fertilization recommendations in eastern Paraguay.

Palavras-chave : Critical level; calibration; analysis of potassium.

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