Corn Nitrogen Management Following Daikon Radish and Forage Oat Cover Crops

Abstract

Core Ideas Daikon radish and forage oat cover crops following winter wheat sequestered residual autumn soil NO3–N levels. Nitrogen availability to the ensuing corn crop may be reduced when preceded by radish or oat cover crops. When using radish or oat cover crops, increased 5×5 starter rates (> 45 kg N ha‐1) may be required if full SD is delayed until V11. Radish and oat cover crops preceding corn did not provide a subsequent N fertilizer replacement value but may still be effectively utilized as soil conservation tools. Cover crops (CC) preceding corn (Zea mays L.) may influence subsequent nitrogen (N) availability, but it is not clear whether N strategies require adjustment. Field studies conducted in 2015 to 2016 evaluated the effects of a daikon radish [Raphanus sativus (L.)], forage oat [Avena sativa (L.)], and no CC following winter wheat [Triticum aestivum (L.)] on soil chemical properties, corn growth, grain yield, and profitability. Nitrogen management strategies were equalized to 179 kg N ha–1 and included pre‐plant incorporated (PPI) N, poultry litter (PL) PPI (61 kg N ha–1) plus sidedress (SD) N V11, starter N (45 kg N ha–1) subsurface banded (5 cm below and 5 cm beside the seed, 5×5) followed by V4, V11, or V4 plus V11 SD, and a zero N control. Cover crops reduced autumn soil NO3–N levels 78 to 84% relative to no CC but occasionally reduced N during critical corn uptake periods. Cover crops did not increase soil base cation availability to the ensuing corn crop. When 5×5 starter was followed by full SD at V11, CCs reduced yield 3.2 to 3.9% and profitability 11.8 to 13.2% compared with no CC indicating reduced efficacy and possibly greater 5×5 requirements to maintain yield potential until SD time. In the zero N control, CCs reduced grain yield 11.8 to 14.2% and increased yield response to N 63 to 79% suggesting reduced N availability. Radish and oat CCs provided a trap crop for autumn residual N, but N management strategies may need to account for reduced N availability.

Radish and annual ryegrass alter corn yield response to nitrogen rate

“…As suggested by polynomial regression analysis, it may even take more than the recommended rate of N to maximize corn yield following radish. This observation is consistent with a study conducted in Michigan (Rutan & Steinke, 2019), which recommended additional starter fertilizer in corn following a radish cover crop. In the current study, the P fertilizer applied at corn planting also contained a small amount of N.…”

“…A study in Wisconsin found that radish following winter wheat captured Nr (19.7–202 kg ha −1 ), but subsequent corn yield response was unaffected (Ruark et al., 2018). Likewise, Rutan and Steinke (2019) found that radish captured Nr in the fall (189 kg ha −1 ) but did not assure additional N was available for the subsequent corn crop. A study conducted the Pacific Northwest, which is typically drier and milder compared with the northern Corn Belt, reported that annual ryegrass added 18–42 kg N ha −1 yr −1 but did not increase subsequent corn yield (Kuo & Jellum, 2000).…”

Soil bacterial community composition following cover crops and corn nitrogen management

“…Plants can modulate microbial community composition through litter quality, root morphology, and rhizodeposition, and may depend on the growth stage (Berg & Smalla, 2009;Cavaglieri et al, 2009;Chaparro et al, 2012;Cleveland et al, 2014). However, radish and oat CCs have reduced N availability to the ensuing corn crop and require CC-specific N strategies (Rutan & Steinke, 2018a).…”

“…In Michigan, growers have utilized different strategies when applying corn N to synchronize N availability with uptake. On medium-textured soils of the Northern Corn Belt, fertilizer strategies often include a single pre-plant incorporated (PPI) N application or split applications where starter fertilizer at planting is followed by in-season sidedress (SID) (Rutan & Steinke, 2018a, 2018b. Surface broadcast or subsurface banded are two N placements that are widely used but that may impact soil bacteria differently.…”

“…To ensure winterkill, CCs were terminated with glyphosate in the autumn after 79-83 d of growth (3 Nov. 2014, 4 Nov. 2015. Nitrogen management strategies were initiated at corn planting and consisted of five strategies previously investigated for the Northern Corn Belt and a zero-N control (Rutan & Steinke, 2018a, 2018b. Nitrogen strategies were balanced to the Michigan 2015 recommended maximum return to N rate of 179 kg N ha −1 (https://www.canr.msu.edu/soilfertility/Files/Articles/ General-Soil-Fertility/2015%20MRTN%20N%20Rates%20 for%20Corn.pdf, Michigan State University, East Lansing, MI; verified 26 June 2021) and consisted of urea-N PPI (46-0-0), dried poultry litter (4-3-2) PPI at 2.2 Mg ha −1 (61 kg N ha −1 first year available N) plus V11 SID N, and 5 × 5 starter N (45 kg N ha −1 urea ammonium nitrate [UAN; 28-0-0], hereafter referred to as 5 × 5) followed by SID N at V4, V11, or split (50:50) V4 and V11.…”