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Title: Soil nutrients status after fifty years of tillage and nitrogen fertilization

Author
item Mikha, Maysoon
item OBOUR, AUGUSTINE - Kansas State University
item HOLMAN, JOHNATHAN - Kansas State University

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2018
Publication Date: 7/16/2018
Citation: Mikha, M.M., Obour, A.K., Holman, J.D. 2018. Soil nutrients status after fifty years of tillage and nitrogen fertilization. Communications in Soil Science and Plant Analysis. https://doi.org/10.1080/00103624.2018.1492599.
DOI: https://doi.org/10.1080/00103624.2018.1492599

Interpretive Summary: Long-term studies are valuable for enhancing the knowledge in assessing the impact of management on crop land sustainability. This study assessed the effect of 50 years of nitrogen (N) fertilizer application rates (0, 22, 45 and 67 kg N ha-1) and tillage [clean tillage (CT), reduced tillage (RT), and no-tillage (NT)] on soil nutrients status, soil organic carbon (SOC), and (iii) comparison between the calculation scenarios [Fixed depth and Equivalent Soil Mass (ESM)]. The study was established in 1965 in a dryland winter wheat–sorghum-fallow cropping system near Hays, Kansas at the central Great Plains region. Fertilizer N was the only form of nutrient added throughout the 50 years of managements. The addition of N fertilizer alone resulted in soil nutrient depletion due to nutrient removal by wheat and sorghum grain. The SOC at the surface 0-30 cm was 39% greater than that at subsurface of 30-60 cm depth with both calculation (fixed depth and ESM). The calculation scenarios did not influence the effect of tillage on soil nutrient status. Soil nutrient specifically soil Ca, Mg, and P associated with N rates were no difference than nutrient content associated with control treatment. Crop nutrient removal with wheat and sorghum grain may eventually reduce soil nutrient contents where only N is applied as a soil amendment. Therefore, nutrient addition specifically P should be considered in the future.

Technical Abstract: Long-term studies are valuable in assessing the impact of crop management practices on soil sustainability and function. This study used two calculation scenarios, fixed depth and Equivalent Soil Mass (ESM) to assess (i) soil nutrient status and (ii) soil organic carbon (SOC) as influenced by 50 years of nitrogen (N) fertilizer application rates (0, 22, 45 and 67 kg N ha-1) and tillage [clean tillage (CT), reduced tillage (RT), and no-tillage (NT)] in a dryland winter wheat (Triticum aestivum L)-sorghum (Sorghum bicolor L)-fallow cropping system in the central Great Plains region. The SOM content increased by 33% with NT and RT compared with CT treatment. The SOC at 0-30 cm was 39% greater than 30-60 cm depth with both fixed depth and ESM calculations. The calculation scenarios did not influence the effect of tillage on soil nutrient status. Soil nutrient specifically soil Ca, Mg, and P associated with N rates were no difference than nutrient content associated with control treatment. Crop nutrient removal with wheat and sorghum grain may eventually reduce soil nutrient contents where only N is applied as a soil amendment. Therefore, nutrient addition specifically P should be considered in the future.