Spring Seedbed Characteristics After Winterkilled Cover Crops.

Winter cover crops can be problematic for early spring vegetable production in the Mid-Atlantic because many cover crops hinder spring field work with high residue mulches that immobilize nutrients, decrease soil temperature, and increase soil moisture content. These effects are disincentives to cover crop adoption by farmers. We compared spring seedbed conditions and subsequent cash crop performance after winterkilled cover crops in Maryland’s Coastal Plain and Piedmont regions for two seasons. The four cover crop treatments were: oats (Avena sativa L.), a traditional high-residue winterkilled cover crop; forage radish (Raphanus sativus L.), a low-residue winterkilled cover crop; a combination of oats and radish; and no cover crop. Spinach was planted in March using no-till and conventional planting techniques for each cover crop treatment. Continuous monitoring of soil moisture at 5 cm showed that following each rain event forage radish decreased the time required to reach 80% of the plastic limit, an estimate of soil workability. For three out of four site years, forage radish plots were higher than oats plots in soil nitrate (0-20 cm) at spinach planting time and during the initial spinach growth period. For all four site years, soil nitrate in forage radish plots was higher than in no cover crop plots. The magnitude of nitrate differences varied with site and year. Soil sulfate-S (0-20 cm) was 3 mg kg-1 higher in forage radish plots throughout the February-May period () in all four site years. Spinach performance, quantified by emergence and yield, was greater after forage radish.  Our data show that low-residue winterkilled cover crops such as forage radish can provide the environmental benefits of high residue cover crops while facilitating, rather than hindering, early season cash crop production. Given a sufficient cover crop stand in fall, no-till planting without herbicides is feasible for spinach following a forage radish cover crop.