Skip to main content
ARS Home » Plains Area » Akron, Colorado » Central Great Plains Resources Management Research » Research » Publications at this Location » Publication #335555

Research Project: Adaptation of Dryland Cropping Systems for the Central Great Plains Region to Extreme Variation of Weather and Climate

Location: Central Great Plains Resources Management Research

Title: Changes in soil surface chemistry after fifty years of tillage and nitrogen fertilization

Author
item Obour, Augustine
item Mikha, Maysoon
item Holman, Jonathan
item Stahlman, Phillip

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2017
Publication Date: 8/29/2017
Publication URL: http://handle.nal.usda.gov/10113/5801878
Citation: Obour, A.K., Mikha, M.M., Holman, J.D., Stahlman, P.W. 2017. Changes in soil surface chemistry after fifty years of tillage and nitrogen fertilization. Geoderma. 308/46-53. doi:10.1016/j.geoderma.2017.08.020.

Interpretive Summary: Knowledge gained on the long-term effects of crop management practices on soil fertility is critical in developing nutrient management strategies to optimize crop yields. This study examined the long-term effects of nitrogen (N) fertilizer application (N rates of 0, 22, 45 and 67 kg N ha-1) and tillage intensity [conventional tillage (CT), reduced tillage (RT) and no-tillage (NT)] on soil phosphorus (P), micronutrients and soil acidity in a dryland winter wheat–sorghum -fallow cropping system. Results showed soil organic matter (SOM), iron (Fe) and zinc (Zn) concentrations were greater under NT compared to CT or RT. Similarly, NT has 34% higher (32 mg kg-1) available P compared with CT and 19% higher available P compared with RT treatment in the upper 7.5 cm soil depth. After 50-yr of tillage and N fertilizer applications, pH in the surface 7.5 cm declined with increasing N application, particularly with 67 kg N ha-1 rate. In general, soil pH was lower with NT (pH = 5.7) compared with CT (pH = 6.3) and RT (pH = 6.2) treatments. Iron and manganese (Mn) concentrations increased with increasing N rate. These increases were probably related to the decrease in pH as N application rate increased. Based on our findings, growers adopting NT need to monitor changes in soil surface chemistry and take necessary corrective measures such as liming to maintain satisfactory pH and nutrients levels to optimize crop yields.

Technical Abstract: Knowledge gained on the long-term effects of crop management practices on soil fertility is critical in developing nutrient management strategies to optimize crop yields. This study examined the long-term effects of nitrogen (N) fertilizer application (N rates of 0, 22, 45 and 67 kg N ha-1) and tillage intensity [conventional tillage (CT), reduced tillage (RT) and no-tillage (NT)] on soil phosphorus (P), micronutrients and soil acidity in a dryland winter wheat (Triticum aestivum L) –sorghum (Sorghum bicolor L) -fallow cropping system. Results showed soil organic matter (SOM), iron (Fe) and zinc (Zn) concentrations were greater under NT compared to CT or RT. Similarly, NT (32 mg kg-1) increased P accumulation in the upper 7.5 cm soil depth compared to CT (21 mg kg-1) or RT (26 mg kg-1). After 50-yr of tillage and N fertilizer application, pH at the soil surface (0 to 7.5 cm) declined markedly with increasing N application, pH ranged from 6.1 with the control to 5.5 when 67 kg N ha-1 was applied. Averaged across N rates, soil pH was lower with NT (5.7) compared to CT (6.3) and RT (6.2) treatments. Iron and manganese (Mn) concentrations increased with increasing N application rates, probably due to the decrease in pH associated with N application. Based on our findings, growers adopting NT need to monitor changes in soil surface chemistry and take necessary corrective measures such as liming to maintain satisfactory pH and nutrients levels to optimize crop yields.