If you listen closely, you can almost hear the crops and garden plants gasping for breath!
Torrential and repeated rains throughout Indiana have left many farmers and gardeners in dire straits.
What had been shaping up to be a fairly decent season has quickly turned into a nightmare, with crops under water in many locations.
Everyone knows that plants need water to survive and grow, but there is a point where there is too much of a good thing.
Inundation of the plant, total immersion of many plants, is tolerable only for a very short time before damage occurs … think hours.
Even once the water recedes, or if the plants were never inundated but are sitting with their roots in saturated soil, the damage can be almost as severe. Roots need not only water, but also oxygen, to take up nutrients and grow.
Once the pore spaces of the soil fill with water, the air is displaced. The roots effectively suffocate, and the plants they serve begin to shut down.
Photosynthesis (food production) slows, respiration (food consumption) continues and the plant begins a spiral of starvation and, oddly, dehydration. It becomes subject to a variety of root rot pathogens, which see this as a great opportunity to do what they do best.
Even if flooding doesn’t kill plants outright, it may have a long-term negative impact on crop performance.
It is extremely important that flooded produce be properly washed to reduce contamination.
Washing can reduce the amount of silt on the crop along with the bacteria that it bears, but washing alone or even scrubbing will not reliably reduce food-borne pathogens adequately.
Crops typically consumed raw and growing where flooding has come from offsite via streams or river overflow should generally be considered as green manure or compost and not be consumed.
Many of the crops across Indiana have an off-green or yellowish color. These plants are suffering from various nutrient deficiencies — nitrogen, phosphorus, potassium and perhaps others — even though the soil contains adequate amounts. But the main deficient element is oxygen.
One element that is not patient for the return of drier conditions is nitrogen. Flooded and saturated soils lead rather rapidly to significant losses of this element, essential for plant growth, by a couple of avenues.
Denitrification occurs when bacteria in saturated soil change nitrate to a gaseous nitrogen, which moves into the atmosphere. Conversely, excess water moving through the soil profile will take soluble nitrate down out of reach of shallow-rooted crops. The net result is that once the soil dries, there may be little nitrogen left for the plant to use to regrow. That, coupled with subsequent disease pathogens, may make the damage seem to worsen even after conditions improve.
As is obvious to all, what is needed now is several rain-free days so the soils can drain and draw in air to stimulate root growth. Unfortunately, the flooded fields often develop a hard surface layer that prevents air from entering.
The two most important things growers can do to aid recovery is 1) as soon as the soil can be worked, till the soil lightly to break up sealed surfaces and allow air to enter the soil, and 2) sidedress with nitrogen, up to 50 pounds of it per acre, perhaps during the tillage operation or, if conditions do not allow for soil applications, apply a foliage application.
Even assuming fields and gardens could be worked and planted today, it is too late to replant many vegetables. At best, we are looking at only 80 to 90 days before a likely frost. Crops that could be planted for a fall harvest include snap beans, fresh market beets, broccoli, cauliflower, cucumbers, summer squash, zucchini, leafy crops (lettuce, spinach, etc.), and radishes.
Rather than let productive fields go to weeds for a season, use the opportunity to plant a cover crop or green manure to improve future drainage, capture residual fertility or add nitrogen and smother the weeds that we know will fill the void if given the opportunity.
Resist the urge to replant immediately; give the soil a chance to dry out first. Working wet soil will have long-lasting effects of soil compaction.
When the soil is ready, choices include sudangrass or sorghum-sudan hybrids, buckwheat, cowpeas, annual alfalfa — Nitro. Just like tools in a tool box, each cover crop has its unique purpose. The choice is yours, but please don’t allow weeds to be your cover crop!
Sadly, we may not know the full effect of flooding until long after the water recedes, but it is fortunate that we seldom see this scale of soil saturation and flooding for this duration.
We can certainly hope that these are once-in-a-lifetime conditions and an unfortunate experience that we can share with grandchildren someday, along with contrasting stories of the 2012 drought.
If farming and gardening were easy, everyone would want to do it!
Roy Ballard is an agriculture and natural resources educator with the Hancock County office of Purdue Extension (www.extension.purdue.edu/hancock). Contact him at 317-462-1113 or [email protected].
