In New Jersey, soybeans generally do well in terms of productivity, but final yield largely depends on early-season soil conditions, balanced plant nutrition, and timely field management, particularly in sandy soil areas of the Coastal Plain and Southern part of New Jersey.

Importance of early-season establishment

The final yield potential (to be achieved later in the season) of soybean largely depends on how the crop established early in the season. If there is a poor emergence or is nutrient deficiency in early growth stages, it can decrease the final number of pods per acre and slow down the canopy growth. So, primary areas of focus during the early season are:

• To ensure uniformity in planting depth and better seed-to-soil contact for better emergence/stand count.
• To avoid planting into cold/wet soil to save emerging seeds from cold injury.
• To ensure strong nodulation for better rhizobium activity.

Nutrients Management Considerations

Soybeans, being a leguminous crop, don’t need nitrogen (for the most part as they can fix most of their nitrogen needs by themselves), but they need other nutrients:

• Phosphorus for early root development (to absorb water/nutrients and to anchor the plant in the soil) and nodulation. Very high (more than optimum) levels of phosphorus were seen in many New Jersey soils so, no phosphorus fertilizer is recommended for such soils. However, for the soils showing high/optimum phosphorus levels, it is still suggested to apply phosphorus at least in amount equivalent to that is removed by the soybean crop (40 lbs. P₂O₅/acre for a 40 Bu/acre of grain yield).
• Potassium for water regulation and pod fill (determinant of final yield). To the soils showing potassium in high levels, it is still needed to apply 55 lbs. of K₂O/acre for a 40 Bu/acre of grain yield, to account for the potassium removed by the soybean crop. For soils showing below optimum potassium levels, the rate of potassium is recommended to be higher than the 55 lbs. of K₂O/acre, depending on what the yield goal is. For a yield goal of 40 Bu/acre, if potassium levels are below optimum, potassium recommendations are to apply between 70-170 lb. K₂O/acre depending on the potassium levels (180-0 lbs. K/acre) shown in soil test (Mehlich-3). Also, it is important to mention the fields with soybean planted as a double crop, where potassium removal from the preceding small grain crop should be accounted for in fertilization planning by adjusting the soil test potassium results to avoid early season potassium deficiency. For example, a 45 Bu/acre soybean crop removes roughly 100–114 lb. K/acre (120–137 lb. K₂O/acre) from soil when potassium removed by the preceding small grain crop and its straw is also included with the potassium removed by soybean grain.
• Sulfur has been increasingly becoming critical for last two decades, especially in highly leached, low organic matter, and sandy soils because of the decrease in natural sulfur deposits in soil owing to the stricter environmental regulations after the enactment of clean air act of 1990. Sulfur recommendations for soybeans are 20-40 lbs./acre (if broadcasted) or 20-30 lbs./acre (banded).
• Manganese is the micronutrient that is seen deficient in most of the South Jersey’s coarse textured soils. The deficiency is visible in the form of green veins with yellowness appearing between the veins. For soils having the history of Manganese deficiency, recommendations are 15 lbs./acre (broadcast) or 5 lbs./acre (banded) of Manganese, if applied by soil. If a foliar application, recommendations are to apply three times (1^st application as soon as the symptoms appear, 2^nd application on later vegetative stage, and 3^rd at early pod stage) with each application of 0.5-2.0 lbs./acre.
• Maintaining pH between 6.2 and 6.8 is generally good for all nutrient’s availability. However, if pH is outside this range, the nutrients that are present in the soil still become unavailable to the soybean plant.

In many New Jersey soybean fields, mild potassium and sulfur deficiencies are more prevalent compared to visible nitrogen deficiency.

Management specific to the Southern New Jersey Soils

Southern New Jersey’s sandy soils lose nutrients rapidly due to high leaching, lose moisture faster during reproductive stages, and encounter nutrient stress even when soil test results say, “adequate level”. Therefore, split or targeted nutrient management and regular soil testing are very helpful.

In-season crop management

At R1 (flowering stage) to R3 (early pod set stage), it is suggested 1) to be watchful for yellowing on leaves or uneven canopy development, 2) to keep checking if nodulation working effectively (red/pink nodules signify better nitrogen fixation), and 3) to ensure no hidden potassium or sulfur deficiency, especially when high rainfall occurs (high leaching rate).

Takeaways (Summary)

Improved soybean yields in New Jersey are tied to 1) good early season establishment, 2) balanced nutrition of phosphorus, potassium (especially in double-crop soybean), sulfur, and manganese, 3) prudent monitoring of nutrient losses in sandy soils, and 4) timely field scouting during flowering and pod set. Taken together, productivity of New Jersey soybeans relies less on high inputs, but more on early-season balance (nutrition) and timely monitoring.

References

• Huddell, A. M., Thapa, R., Marcillo, G. S., Abendroth, L. J., Ackroyd, V. J., Armstrong, S. D., & Mirsky, S. B. (2024). US cereal rye winter cover crop growth database. Scientific data, 11(1), 200.
• New Jersey Soybean Board. (n.d.). NJ Production Guide. https://njsoybean.org/wp-content/uploads/2022/07/50737-8-New-Jersey-Tech-Transfer-Guide_LR6.pdf
• Rutgers Cooperative Extension. (n.d.). Soil fertility recommendations for soybean (FS102). Rutgers New Jersey Agricultural Experiment Station.
• Heckman, J. R. (1992). Successful double cropping requires adequate soil fertility. The Soil Profile, 2(2). Rutgers Cooperative Extension.
• Sharma, R. K., Cox, M. S., Oglesby, C., & Dhillon, J. S. (2024). Revisiting the role of sulfur in crop production: A narrative review. Journal of Agriculture and Food Research, 15, 101013.