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Agronomic Crops Network

Ohio State University Extension


If You Planted and Heavy Rainfall Affected Your Fields…

According to the USDA-NASS report for the week ending 05/14/23, 26% of Ohio’s corn and 28% of Ohio’s soybean acres were planted. About 8% of corn and soybean was reported emerged. Ohio’s planting (and emergence) progress is coming along for both corn (Figure 1) and soybean (Figure 2) crops. However, there are still significant acreages to be planted yet, and weather does not always help.


Figure 1. Plant stands of recently emerged and early planted corn in Ohio under surplus water conditions.


Figure 2. Plant stands of recently emerged and early planted soybean in Ohio under surplus water conditions.

Heavy rainfall (1-2 inches of rain) events were reported for some areas of Ohio last week. Heavy rainfall can negatively affect planted and emerged fields, planted and non-emerged fields, and yet-to-be-planted fields. If you are in one of the areas with concerns about heavy rainfall, below is a summary of topics that one should consider (Table 1).

Table 1. Topics, considerations, and takeaways for corn and soybean fields are affected by heavy rainfall this season. If you are interested to learn more about these topics, access any of the linked articles.




Soil crusting

Heavy rainfall and warmer temperatures build conditions for soil crusting. Soil crusting is a hard layer on the soil surface due to rapid drying. Soils prone to crusting are tilled fields, low cover crop residue, fine soil textures, and soils with low organic matter. Soil crusting can affect seedling emergence, reduce plant stands and vigor, and limit water infiltration.

Some alternatives: 1) planting deeper for better seed/soil contact + access to moisture; 2) reduced or no-till systems for more residue in the soil surface; 3) rotary hoe in the crusted layer (if crop is germinated and still below ground, damage to seedlings may occur); 4) a row crop cultivator if the crop is tall enough.

Crops under water

In corn, waterlogged conditions during vegetative stages can limit yield potential by reducing yield components and nutrient losses. Soybean tends to be more sensitive to flooding stress during the reproductive stages than vegetative ones.

Crop Stage is critical for recovery. Management options to address flooding in the short term are limited; understanding the potential impacts can help prepare and plan for management adjustments in the future.

Replanting decisions

For corn, 50% emergence can be expected following accumulation of 150 soil GDDs from planting, 5-7 days under normal conditions (longer under cold/wet). For soybean, assess stands no earlier than the VC growth stage. Visual stand assessment at the VE growth stage often underestimates the number of plants.

Our 101 recommendation is to wait… Crop stands should be assessed after ‘stable’ and ‘better’ conditions (e.g., warmer temperatures and adequate soil moisture). Often, hasty decisions are not the best. Low stands planted early can yield comparable to more stands planted late (e.g., replanted).

Nitrogen management for corn

Wet conditions make us consider adjustments to reduce nutrient and crop losses. Understanding corn’s morphological, developmental, and physiological responses is critical for preparing and adjusting to such conditions.

For applications yet to happen, here is a list of adjustments to consider:
Adjusting nitrogen fertilizer application timing, fertilizer sources, and fertilizer placement/method. Other tools include crop insurance, better hybrids, cover crops, and the use of drainage.

General planting recommendations

Plant corn 1.5 – 2 inches deep. Depending on the hybrid and environment, recommended plant populations (or final stand) have ranged from 24,000 to 34,000+ plants per acre. Plant soybeans 1 – 1.5 inches deep with tillage. If soybeans are no-till, ¾ - 1 inch deep is recommended. About 100,000 – 120,000 plants per acre are recommended as the target plant population in soybean when planting in May.

Planting corn and soybeans after soil temperatures reach the 50°F mark is recommended. Measure soil temperatures ½ - 2 inches below the soil surface in the early morning. Generally, early planting comes with risks (e.g., late spring frost, insect/disease losses, and slug damage). However, timely planting is essential to maximize yields.

The bottom line is that seed damage due to abiotic factors can affect seedling vigor, plant growth, and crop establishment, ultimately reducing crop stands and yields. We recommend weighing the above considerations if you are affected by heavy rainfall this crop season.

For more planting and other Agronomic Crop Updates, follow the C.O.R.N. Newsletter or visit the Ohio State Agronomy YouTube channel.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.