Too much rain has fallen. Beginning in late autumn 2018, conditions turned wet and have persisted throughout the winter and spring seasons of 2019. For example, the OARDC-Wooster weather station (https://www.oardc.ohio-state.edu/weather1/) registered rainfall on 47 days of the 88-day period April 1 – June 27, totaling 13.4 inches over the period (an average of nearly one-third inch of rainfall per day with rain). Not surprisingly, impacts have been accumulating. Much has been lost directly due to rain and rain-related delays: time, topsoil, fertilizer, targeted levels of stand establishment, and opportunities to start well with weed, pest, and disease management, and other operations. These primary consequences have had secondary ones. Field preparation and stand establishment is always a hectic phase and outcomes are never certain, even in years when weather is largely a neutral factor. Still, routines and schedules can follow a familiar timeline. Not so for many in 2019. Timelines and various common expectations have gone out the window (or, into the drainage ditch, as it were) and management has been more “seat of the pants” than many prefer. We’ve been required to reconsider what to do, when, how, etc.
A Set of Partial Solutions
Conditions can improve with a little cooperation from the weather and strategic action. What follows is a brief overview of factors to consider and steps to take when given a chance: (a) to kick-start or rejuvenate a stand or crop set back by persistently wet or saturated soil since seeding or transplanting or (b) to limit the recurrence of the same problem in future seasons. The amount of detail available for each factor and step could fill at least several VegNet articles. This article is more broad than deep and it draws from experience and excellent references developed through the years by members of the industry and vegetable research-extension community.
1. Surface cultivation. Persistent or pounding rain can lead soil to crust. Crusting prevents seedlings from emerging, air from entering the soil, and some wastes in the soil from leaving it. Breaking the crust with light surface cultivation can help reverse these conditions. Choose the right time and equipment for the operation in order to maximize its benefit while minimizing the potential for creating compaction while heavy equipment is taken across the field with subsurface soil moisture levels still relatively high.
2. Careful cultivation and irrigation. Many now face a situation in which leggy, under-nourished, and generally weak transplants were set into soils wetter than ideal and which remained wet for long stretches thereafter. Not good. Root-shoot ratios are not ideal and root systems may be small and shallow, concentrated near the soil surface. This makes root systems prone to damage due to cultivation and ironically, plants susceptible to LOW moisture stress, especially if weather turns dry AND warm. Keep alert when cultivating, maintain the proper depth and distance from the crop. Also, as we shift toward a more summer-like pattern of scattered but intense rainfall, treat it as an opportunity to encourage root systems to expand and deepen. Doing so may require “weaning” plants off the saturated conditions many have experienced since planting. Guard against strict adherence to irrigation schedules based on a “normal” year with normal stand establishment conditions. Modify how often you irrigate and for how long the water flows each time according to soil and plant conditions, monitoring both carefully. Again, shallow- and small-rooted plants need time to adjust to drier conditions and the process largely cannot be rushed. Consider lengthening the time between irrigations gradually until you are confident the crop has, more or less, fully recovered and “toughened up” and you have reached an adequate level of control over soil moisture and other conditions.
3. Replant. Recall that the growth and productivity of individual plants can hinge on how many neighbors it has and where they are located, i.e., the plant population or density. Compensation allows some crops to produce similar yields across a wide range of plant populations. For these crops, thin stands can be less problematic because yield potential is maintained. However, for non-compensators (e.g., fresh market sweet corn), one less plant clearly results in less yield (e.g., one less ear to sell). Replanting may be more beneficial with crops that do not compensate. Regardless, check records, estimates of days to maturity, etc when selecting varieties and choosing to replant. Also, when replanting flooded-out portions of large plantings, be aware that the crop maturity in these replanted, “pieced in” areas will be different than the main crop but may maintain income potential that would be lost otherwise. These areas may also require slightly different management (e.g., fertilizer, irrigation, protection) than nearby areas planted earlier.
4. Replace. IF and only IF circumstances call for it and allow, replace the vegetable planting with a cover crop, forage/feed crop, or clean fallow program. This step has huge implications for the business and others for the soil. If the very weak or absent vegetable planting can be replaced by clean fallowing or a crop involving less expense, time, and effort but offering some soil building and/or cash-flow potential, this option may represent taking two steps forward starting from one back, i.e., a net gain compared to replanting or continuing with a very weak vegetable crop.
5. Keep planting. Vegetable and grain farmers have been hit hard by the weather so far. One aspect of vegetable farming that can help farmers through these difficult times is that many vegetable crops can be harvest-ready in much less time than full-season corn, soy, and other crops. Enough season remains to plant and harvest a profitable vegetable crop. Talk with your produce buyers. Discuss the possibility of adjusting marketing/delivery scenarios and schedules with, for example, late plantings of early-maturing crops such as sweet corn, green beans, peas, transplanted cole crops, radishes, turnips, daikon radish, zucchini and yellow squash, cucumbers and pickles. Recall that most concentrated-set pickle varieties can be harvested 60 days from planting and northwest Ohio farms traditionally plant through early July.
6. Fertilizer application. Excess rain during stand establishment like many have experienced limits root growth and can allow fertilizer applied before or at planting to leach, runoff, or change form and become unavailable or taken-up less efficiently. Therefore, nutrient deficiencies, especially of nitrogen and potassium, may develop soon after growing conditions improve. Research and experience have shown that applying carefully determined, low amounts of N and K through fertigation, or as a sidedress, broadcast, or foliar treatment, can limit the progression of yield reductions caused by excessive soil moisture. Use plant tissue testing and petiole sap analysis to monitor plant nutrient levels useful in determining if fertilizer applications are needed. Review https://edis.ifas.ufl.edu/pdffiles/EP/EP08100.pdf and similar resources for additional information.
7. Support. Anchoring the plant is one of the six major functions of root systems. Anchoring is difficult in saturated soils and/or when root systems are small, especially compared to the canopy. Don’t underestimate the value of a trellis in supporting upright fruiting crops (e.g., tomato, pepper). It lowers the risk of lodging and wind-whipping (wind-whipping is more likely when transplants were particularly leggy).
For Future Seasons
8. Lengthen rotations and build soil internal drainage and moisture holding capacity. All the familiar approaches – e.g., cover cropping, soil amendments, tiling – apply here. Reduced-tillage approaches are less familiar to some but gaining attention.
Clean fields planted on the flat or then formed into raised beds topped with drip tape and plastic mulch are the current standard among commercial growers throughout much of the world. These standard systems have been very reliable and productive. Reduced-tillage systems, on the other hand, offer various benefits although, historically, their yields are often lower than yields in standard systems. Research by farmers and others has focused on retaining the benefits of reduced-tillage approaches while increasing the yield of systems involving them. For example, at OARDC, we have been investigating whether the use of grafted plants and/or microbe-containing crop biostimulants can enhance yield of tomato grown in a flat-ground, strip-till system. Results have been promising; using one or both treatments has narrowed the gap between yields of the strip-till and standard systems. Regardless, our experience and data collected by others also suggest that soils in strip-till plantings can be more resistant to flooding and resilient when flooding conditions develop.
9. A genetic solution to flooding. Flooding is a problem worldwide in agriculture and plant breeders have taken note. Flooding tolerant rootstocks are available for tomato and ones may become available for other crops that are routinely grafted (pepper, watermelon, cucumber, cantaloupe). Pay attention to flooding tolerance and other grafting-related developments.
10. Study up. It will also remain important to pay close attention to information provided by the climate services community, which includes agroclimatology and other experts. Descriptions of historical trends and projections of future scenarios are constantly improving. My non-expert reading of some recent reports (e.g., see June 8 VegNet) suggests that conditions so far in 2019 are consistent with projections outlined in those reports – e.g., intense rainfall events occurring more often and becoming stronger, allowing for fewer days to complete field work. No one knows for certain that conditions many have encountered so far this season will repeat (weather variability). Still, for planning purposes, a broad reading of various reports can lead one to conclude that conditions so far in 2019 are better viewed as an extreme version of an emerging trend, not a fluke or once in a career scenario.
Brad Bergefurd of OSUE and Jason Cervenec, Education and Outreach Director of the Byrd Polar and Climate Research Center (BPCRC) and Aaron Wilson, Research Scientist with OSU Extension and BPCRC, both with the State Climate Office of Ohio (https://climate.osu.edu/), contributed to this article.