Brassica Cover Crops for Nitrogen Retention in the Mid-Atlantic Coastal Plain

• Published in: Journal of environmental quality Vol. 38; no. 2; pp. 520 - 528
• Main Authors: Dean, Jill E, Weil, Ray R
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01.03.2009; American Society of Agronomy
• Subjects: Agricultural practices; Agriculture; Agriculture - methods; ammonium nitrogen; analysis; autumn; Biomass; Brassica napus; Brassica napus - metabolism; coarse-textured soils; Coastal plains; coastal soils; Cover crops; Crops; Drinking water; Dry matter; dry matter content; fallow; forage crops; interspecific variation; Leaching; losses from soil; Lysimeters; Maryland; metabolism; methods; Mid-Atlantic region; nitrate nitrogen; Nitrates; Nitrates - analysis; nitrogen; Nitrogen - metabolism; oilseed crops; Overwintering; planting date; pollution control; Pore water; Raphanus; Raphanus - metabolism; Raphanus sativus; Seasons; Secale; Secale - metabolism; Secale cereale; Shoots; Soil; Soil - analysis; Soil erosion; soil pore water; Soil texture; Soils; species differences; spring; summer; uptake mechanisms; Water; Water - analysis; Maryland; Mid-Atlantic region; USA, Mid-Atlantic Region; ANE, British Isles, England, Essex; ANW, USA, Mid-Atlantic Region; USA, Maryland; ANW, USA, Maryland
• ISSN: 0047-2425; 1537-2537; 1537-2537
• DOI: 10.2134/jeq2008.0066

Received for publication February 5, 2008. Brassica cover crops are new to the mid-Atlantic region, and limited information is available on their N uptake capabilities for effective N conservation. Forage radish (Raphanus sativus L. cv. Daikon), oilseed radish (Raphanus sativus L. cv. Adagio), and rape (Brassica napus L. cv. Dwarf Essex) were compared with rye (Secale cereale L. cv. Wheeler), a popular cover crop in the region, with regard to N uptake ability and potential to decrease N leaching at two sites in Maryland. Plants were harvested in fall and spring for dry matter and N analysis. Soil samples from 0 cm to 105 to 180 cm depth were obtained in fall and spring for NH4-N and NO3-N analyses. Ceramic cup tension lysimeters were installed at depths of 75 to 120 cm to monitor NO3-N in soil pore water. Averaged across 3 site-years, forage radish and rape shoots had greater dry matter production and captured more N in fall than rye shoots. Compared with a weedy fallow control, rape and rye caused similar decreases in soil NO3-N in fall and spring throughout the sampled profile. Cover crops had no effect on soil NH4-N. During the spring on coarse textured soil, pore water NO3-N concentrations in freeze-killed Brassica (radish) plots were greater than in control and overwintering Brassica (rape) and rye plots. On fine textured soil, all cover crops provided a similar decrease in pore water NO3-N concentration compared with control. On coarse textured soils, freeze-killed Brassica cover crops should be followed by an early-planted spring main crop.