By Sjoerd Willem Duiker
This spring has brought a lot of rain, some of which came down in heavy downpours. The rain is a blessing but can be a curse too.
Recharging soil water reserves is a blessing. This sets the stage for success with cover crops that have put on a lot of growth and may have been managed with new techniques such as ‘planting green’. The replenishment of soil water reserves has removed any concerns about depletion of soil water by the growing cover crops and this water will now be conserved by the the dead cover crop mulch if it is left on the surface. The reason is that the carpet of mulch helps conserve water by reducing evaporation. This will help weather summer water deficits which can be just around the corner, even after the plentiful rains.
A fully canopied corn crop uses about 0.25 inches of water per day. Our best soils (e.g. Hagerstown silt loam) store no more than 7 inches of plant available water in the top 50” of the soil. If the profile is entirely saturated, it would take about 28 days to deplete all the plant available water in full summer. However, the crop will already start experiencing mild drought stress if 50% of the plant available water is depleted. That explains why we say in PA that we are never more than 3 weeks away from a drought! In fact, many of our soil types don’t nearly store that much water due to shallowness or coarse fragment content, so there drought is always near, making it essential to not waste any drop.
Soil erosion is a curse. It may have been severe this spring if the soil was left beat up, starving, and naked (that is experienced tillage). Because such a large proportion of our soils are HEL (Highly Erodible Land) this spring has been another reminder of the importance of keeping the soil undisturbed and covered by living vegetation or dead mulch.
Incidental transfer of manure is another curse. It may have happened if manure was applied to the surface instead of placed under the soil. If manure is surface applied in the spring, and runoff does occur, then there is a large likelihood that part of that surface manure disappears to the stream. If runoff occurs a longer time after manure application, this is not likely to happen. This spring, therefore, a good case can be made for the benefits of manure injection with low-disturbance injectors.
Soil compaction threat, is another curse. The high moisture content makes the soil highly sensitive to be compacted. This is a threat to be watched for by avoiding heavy machinery in the field, using tires inflated to low pressures or tracks, and closely monitoring the effect of hoofs on the soil if you are grazing animals in your fields.