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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS

Location: Agricultural Systems Research Unit

Title: Dryland soil nitrogen cycling influenced by tillage, crop rotation, and cultural practice

Authors
item Sainju, Upendra
item Lenssen, Andrew
item Caesar, Thecan
item Jabro, Jalal "jay"
item Lartey, Robert
item Evans, Robert
item Allen, Brett

Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 13, 2012
Publication Date: August 12, 2012
Repository URL: http://handle.nal.usda.gov/10113/57439
Citation: Sainju, U.M., Lenssen, A.W., Caesar, T., Jabro, J.D., Lartey, R.T., Evans, R.G., Allen, B.L. 2012. Dryland soil nitrogen cycling influenced by tillage, crop rotation, and cultural practice. Nutrient Cycling in Agroecosystems. 93(3):309-322.

Interpretive Summary: Information on soil N storage and mineralization as influenced by management practices is needed to optimize N need for crops, minimize N losses through leaching, volatilization, denitrification, and N2O emission, increase N-use efficiency, and reduce the cost and rate of N fertilization without compromising crop yields and quality. In the northern Great Plains, traditional farming systems, such as conventional tillage with the crop-fallow, reduces soil N storage because of increased erosion and mineralization of organic N and reduction in plant residue N returned to the soil due to absence of crops during fallow. Studies have shown that long-term tillage with crop-fallow has reduced soil N storage by 30 to 50% in the last 50 to 100 years. We evaluated the effects of tillage, crop rotation, and cultural practice on dryland crop biomass (stems and leaves) N, surface residue N, and soil N fractions at the 0- to 20-cm depth in a Williams loam from 2004 to 2008 in eastern Montana, USA. Treatments were two tillage practices (no-tillage [NT] and conventional tillage [CT]), two crop rotations (continuous spring wheat [CW] and spring wheat-barley hay-corn-pea [W-B-C-P]), and two cultural practices (regular [conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height] and ecological [variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height]). Nitrogen fractions were soil total N (STN), particulate organic N (PON), microbial biomass N (MBN), potential N mineralization (PNM), NH4-N, and NO3-N. Crop biomass N was 30% greater in W-B-C-P than in CW in 2005. Surface residue N was 30 to 34% greater in NT with the regular and ecological practices than in CT with the regular practice. The STN, PON, and MBN at 10 to 20 and 0 to 20 cm were 5 to 41% greater in NT or CW with the regular practice than in CT or CW with the ecological practice. The PNM at 5 to 10 cm was 22% greater in the regular than in the ecological practice. The NH4-N and NO3-N contents at 10 to 20 and 0 to 20 cm were greater in CT with W-B-C-P and the regular practice than with most other treatments in 2007. Surface residue and soil N fractions, except PNM and NO3-N, declined from autumn 2007 to spring 2008. No-tillage with the regular cultural practice increased surface residue and soil N storage but conventional tillage with diversified crop rotation and the regular practice increased soil N availability. Without N inputs from crop residue and soil amendments, surface residue and soil N storage decreased but N mineralization increased from autumn to spring.

Technical Abstract: Management practices may influence dryland soil N dynamics. We evaluated the effects of tillage, crop rotation, and cultural practice on dryland crop biomass (stems and leaves) N, surface residue N, and soil N fractions at the 0- to 20-cm depth in a Williams loam from 2004 to 2008 in eastern Montana, USA. Treatments were two tillage practices (no-tillage [NT] and conventional tillage [CT]), two crop rotations (continuous spring wheat [Triticum aestivum L.] [CW] and spring wheat-barley [Hordeum vulgaris L.] hay-corn [Zea mays L.]-pea [Pisum sativum L.] [W-B-C-P]), and two cultural practices (regular [conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height] and ecological [variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height]). Nitrogen fractions were soil total N (STN), particulate organic N (PON), microbial biomass N (MBN), potential N mineralization (PNM), NH4-N, and NO3-N. Crop biomass N was 30% greater in W-B-C-P than in CW in 2005. Surface residue N was 30 to 34% greater in NT with the regular and ecological practices than in CT with the regular practice. The STN, PON, and MBN at 10 to 20 and 0 to 20 cm were 5 to 41% greater in NT or CW with the regular practice than in CT or CW with the ecological practice. The PNM at 5 to 10 cm was 22% greater in the regular than in the ecological practice. The NH4-N and NO3-N contents at 10 to 20 and 0 to 20 cm were greater in CT with W-B-C-P and the regular practice than with most other treatments in 2007. Surface residue and soil N fractions, except PNM and NO3-N, declined from autumn 2007 to spring 2008. No-tillage with the regular cultural practice increased surface residue and soil N storage but conventional tillage with diversified crop rotation and the regular practice increased soil N availability. Without N inputs from crop residue and soil amendments, surface residue and soil N storage decreased but N mineralization increased from autumn to spring.

Last Modified: 8/30/2014
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