Evaluation of Tillage, Crop Rotation, and Cover Crop Impacts on Corn Nitrogen Requirements in Southeastern South Dakota

<p>Nitrogen (N) is a vital factor of corn (Zea mays) production. Previous work in South Dakota has shown that there is uncertainty as to whether nitrogen requirements are the same for corn raised under no-till (NT) versus conventional till (CT) production systems. The objective of this study was to evaluate whether N requirements continue to be greater under long-term NT versus CT production systems in southeastern South Dakota, while also considering effects from cover crops and crop rotation. This was a two year study conducted at the SDSU Southeast Research Farm near Beresford, SD; it was superimposed on a long-term rotation and tillage study established in 1991. Treatments included applied N rates of 0, 40, 80, 120, 160, and 200 lbs N acre-1. Rotations were: corn/soybean (Glycine max) and corn/soybean/small grain; the three-year rotation was split additionally by ‘cover crop’ and ‘no cover crop’ treatments. Parameters measured included: soil plant analysis development (SPAD) chlorophyll readings, normalized difference vegetation index (NDVI) readings, ear leaf N content, total plant N uptake, yield, test weight, moisture, and grain protein. In 2014 small plot results were quite variable due to 13.5” of rainfall in June; the 2015 growing season was mild, producing more representative yields. Both N rate and tillage showed significant impacts on yield in the 2014 and 2015 three-year rotation. In 2014, spring soil nitrate levels tended to be 50 lbs ac-1 less in the ‘cover crop’ verses ‘no cover crop’ treatments, but there were no significant yield differences between cover crop treatments. Nitrogen that was not available in the spring likely became available later when cover crop residue decomposed. No-till corn was generally more sensitive to N application in the 2015 two-year rotation than CT corn, however, optimum N rates were the same across tillage regimes. In this study, long-term NT soils did not consistently require more N than CT soils. More research needs to be conducted to further define N recommendations and the impact of cover crops and crop rotation on soil N credits.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - Open Access

Discipline thesis:degree_discipline

Plant Science

Year dc:date.available

2016

Author dc:creator

• Berg, Sara Louise

Contributors dc:contributor

• Peter Sexton

• corn
• fertilizer
• nitrogen
• no-till
• South Dakota
• tillage
• Agricultural Science
• Agriculture
• Agronomy and Crop Sciences
• Plant Sciences

Licence

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/1017

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-2016