Snow is in the forecast for tomorrow in Maryland, and fields are neither drying out nor warming up quickly. Unlike a living cover or mulch that prevent the soil from drying in spring, low-residue winterkilled cover crops can facilitate faster soil warming and drying. “Low-residue winterkilled” is moderately descriptive, but a photo may do more to illustrate the concept.
Note the difference in the amount of bare soil visible (below). Like the living weeds, a thick mulch covering the soil also prevents rapid drying. Soil conservationists don’t usually recommend leaving soil bare, but the conditions in spring create a quandary- the surface soil needs to dry out for tractor work. Otherwise, traffic and tillage can cause serious structural damage to soil. Besides, what if a low-residue winterkilled cover crop enables no-till planting, thereby reducing soil disturbance?
Radish compared to winter weeds: surface and subsoil moisture
Hot off the dataloggers, data from this year show that surface soil moisture is reduced and subsoil moisture is increased after forage radish compared to winter weeds. Reduced surface soil moisture means that field operations can be carried out without as much structural damage to soil, and increased subsoil moisture means that later season crops may have more of a water reserve.
Because the increased subsoil moisture is likely from water flowing down radish root channels, there is some concern over leaching losses. Planting an early season crop after forage radish is imperative to reduce N losses. Alternating shallow-rooted and deep rooted crops in a rotation may also help to minimize total N losses.