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Brassica Cover Crops for Nitrogen Retention in the Mid‐Atlantic Coastal Plain
Author(s) -
Dean Jill E.,
Weil Ray R.
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0066
Subject(s) - raphanus , cover crop , brassica , agronomy , secale , shoot , soil water , lysimeter , leaching (pedology) , environmental science , biology , horticulture , soil science
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 NH 4 –N and NO 3 –N analyses. Ceramic cup tension lysimeters were installed at depths of 75 to 120 cm to monitor NO 3 –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 NO 3 –N in fall and spring throughout the sampled profile. Cover crops had no effect on soil NH 4 –N. During the spring on coarse textured soil, pore water NO 3 –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 NO 3 –N concentration compared with control. On coarse textured soils, freeze‐killed Brassica cover crops should be followed by an early‐planted spring main crop.