Pedosphere 30(6): 747--758, 2020
ISSN 1002-0160/CN 32-1315/P
©2020 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Nitrogen fertilization and potassium requirement for cereal crops under a continuous no-till system
Allison J. FORNARI, Eduardo F. CAIRES, Angelo R. BINI, Adriano HALISKI, Lucas TZASKOS, Helio A. W. JORIS
State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900(Brazil)
      Nitrogen (N) and potassium (K) are the most required nutrients for corn and wheat production. Increasing the N application rate usually boosts crop yields. However, many uncertainties remain for K management. Potassium deficiency results in yield losses, but K application rate based on the percentage of K+ in the cation exchange capacity (CEC) is doubtful, especially in soil with high CEC. A field trial was conducted to examine the effects of KCl application before sowing corn and wheat, by raising the percentage of K+ in CEC at pH 7.0 (CECpH7.0) to approximately 2.5%, 3.5%, and 4.5%, and adding N as a topdressing (75, 150, and 225 kg ha-1 to corn and 40, 80, and 120 kg ha-1 to wheat) on the nutrition and yield of corn and wheat under a continuous no-till system (30 years). Exchangeable K+ content increased in the topsoil (0-20 cm depth) up to 7.2 mmolc dm-3 after K application at the highest rate, which, however, did not result in significant increases in nutrient uptake and yields for both corn and wheat. The N application rate positively affected the uptake and removal of all macronutrients by corn and wheat. Applying N as a topdressing increased yields of corn and wheat by up to 83% and 22%, respectively. Our results suggest that in the soil with a high CECpH7.0 (162.1 mmolc dm-3), the recommendation for K application made by considering the percentage of K+ in the CECpH7.0 may result in excessive application of K fertilizer to crops with high K-recycling potential grown under a continuous no-till system.
Key Words:  cation exchange capacity,crop K demand,K recycling,N requirement,Triticum aestivum L.,Zea mays L.
Citation: Fornari A J, Caires E F, Bini A R, Haliski A, Tzaskos L, Joris H A W. 2020. Nitrogen fertilization and potassium requirement for cereal crops under a continuous no-till system. Pedosphere. 30(6):747-758.
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