Does winter cereal rye seeding rate, termination time, and N rate impact no‐till soybean?

Abstract

Some farmers who use cover crops (CCs) have moved from CC preplant kill (PK) to delayed CC termination, called planting green (PG). We conducted a study to explore if soil conditions and crop production can be optimized by manipulating winter cereal rye (Secale cereal L.) seeding rate and spring N topdress rate for these two termination times. Treatments were arranged in a split‐split plot, randomized complete block design with four replications for three years at two Pennsylvania locations. Main plots were seeding rate (34, 67, and 134 kg ha−1, or 1x, 2x, and 4x, respectively), subplots were termination timing (PK and PG), and sub‐subplots were N rate (34 and 67 kg ha−1, or low and high, respectively). Planting green nearly doubled rye biomass at both sites, and at Landisville the high N rate accumulated 17% more biomass than the low N rate, while there was no biomass N rate effect in PK. Soil in PG was 7–15% drier at planting, up to 7% wetter later, and up to 0.9–1.3 °C cooler compared with PK at both sites. Soybean (Glycine max L.) yield was reduced by 3–4% when PG was paired with the high N rate across seeding rates at Rock Springs and with the 1x seeding rate at Landisville compared with other treatment combinations. Soybean population was not impacted by treatments. We conclude rye seeding and N topdress rates of 34 kg ha−1 in PG can maintain similar conditions and soybean yield equivalent to PK, thereby reducing seed and N costs.

Cereal rye cover crop seeding method, seeding rate, and termination timing effects corn development and seedling disease

“…(2009) suggested that more tillering by the CR cover crop planted at the low SR likely compensated for growth. Similarly, Reed and Karsten (2022) did not report a significant effect on CR biomass from increasing seeding rates. According to them, the increased competition between plants in higher populations can reduce individual plant size which can be translated into similar amounts of CR biomass.…”

“…Similarly, Reed and Karsten (2022) did not report a significant effect on CR biomass from increasing seeding rates.…”

“…These results confirm the high degree of impact on biomass production from both main effects, mainly due to the prolongation of the growing window in both fall and spring seasons. In a study published by Reed and Karsten (2022), termination timing had a significant impact on CR biomass. It was the only main effect that significantly increased biomass in both locations of their experiment.…”

Cereal rye seeding rate does not affect magnitude of weed suppression when planting green within Mid-Atlantic United States

“…The lack of weed suppression differences among seeding rates may be attributed, in part, to the lack of an observed cereal rye biomass response among seeding rates. Similarly, Reed and Karsten (2022) showed no biomass response to increasing cereal rye seeding rates from 34 to 134 kg ha −1 when evaluating delayed termination (i.e., planting green) effects on soybean performance in Pennsylvania. Yet, a positive relationship between crop sowing density and weed suppression is well-described in the literature for small grain cash crops (Mohler 2001) and remains an important component of multi-tactic weed control in low-input systems (McCollough and Melander 2022).…”

“…In summary, our results suggest that there is no reason to increase cereal rye seeding rates for weed suppression services or decrease seeding rates for agronomic reasons (i.e., soybean population and yield) when employing planting-green tactics in no-till soybean production within the Mid-Atlantic region. Growing evidence suggests that expanding the growing season window to accumulate GDDs, including use of delayed termination tactics, is a more important driver of cereal biomass production than seeding rate (Essman et al 2020;Feyereisen et al 2006;Mirsky et al 2017;Reed and Karsten 2022;Schramski et al 2021;Vollmer et al 2020). Most growers manage cover crop termination adaptively and do not have a singular focus on weed suppression benefits, nor target specific cover crop biomass thresholds before planting.…”