OPTIMIZING WINTER CEREAL RYE MANAGEMENT: PRECISION PLANTING, SEEDING RATE, AND CULTIVAR SELECTION FOR BIOFUEL AND FORAGE PRODUCTION

Author

Katherine Baker, Southern Illinois University CarbondaleFollow

Date of Award

12-1-2025

Degree Name

Master of Science

Department

Plant, Soil, and Agricultural Systems

First Advisor

Brevik, Eric

Second Advisor

Sadeghpour, Amir

Abstract

Winter rye (WR; Secale cereale L.) is recognized as a versatile and resilient cover crop that significantly enhances environmental sustainability and farm profitability in corn (Zea mays L.)–soybean (Glycine max L.) rotations. Its rapid fall growth, winter hardiness, and adaptability to a variety of soil types make winter rye an optimal choice for mitigating soil erosion, minimizing nutrient losses, and yielding biomass that can be used for forage or biofuel production. As a winter cereal, winter rye offers a multitude of ecological advantages, including the enhancement of soil organic carbon, nutrient recycling, improvement in soil quality, suppression of weeds, and reduction of runoff. These ecosystem services are essential for addressing nutrient loading in the Upper Mississippi River Basin (UMRB), where challenges such as nitrate-nitrogen (N) and phosphorus (P) losses persist. Despite these advantages, adoption of WR prior to corn remains limited in the U.S. Midwest due to economic and agronomic constraints. The costs associated with planting WR, combined with potential yield penalties in subsequent corn crops, discourage many farmers. These penalties are often linked to N immobilization, interference with corn establishment, and increased pest or disease pressure. To improve adoption, we propose harvesting WR for forage or biofuel to offset input costs. The focus of our research was improving WR management systems to offset the costs of WR implementation, while maintaining forage and biofuel qualities necessary for WR harvest and processing. We hypothesized that implementing novel WR planting techniques (Chapter 1), lowering WR seeding rates (Chapter 2), and using an open-pollinated WR cultivar (Chapter 2) would yield the necessary forage and biofuel qualities in WR biomass with the most economic benefits. Within Chapter 1, the novel planting approach, precision planting (skipping the cash crop row; STCR- to create non-intersecting zones of WR and corn growth), was studied. This approach was implemented to reduce the costs associated with planting of WR and to alleviate the negative impact of WR on following corn. We conducted five site-years of field experiments in southern Illinois to compare the impact of STCR versus conventionally planted (intersecting rows of WR with cash crop; NP) WR on biomass, biofuel and forage quality, and economic benefits (potential savings in seed costs with potential for increase in quality of biomass for sale). Our results indicated that STCR had a similar leaf area index (LAI) (1.96) and biomass yield (2.52 Mg ha-1) to NP (1.72 and 2.33 Mg ha-1, respectively). Cellulose and holocellulose (cellulose + hemicellulose) concentrations of WR, which are associated with higher ethanol production, were increased by STCR relative to NP. However, hemicellulose and lignin concentrations were similar between the two planting methods. The STCR decreased forage quality, potentially through increased tillering due to the reduction in seeding rate by skipping the cash crop row. Relative forage quality (RFQ) was lower with STCR than with NP. However, the RFQ in STCR was high enough (>151) that it did not influence its economic value. Thus, we recommend STCR over NP for biofuel and forage production. Similarly, in Chapter 2, we conducted two trials in southern Illinois to evaluate the effects of seeding rate and cultivar on WR yield, quality, and economic benefits. Study A tested four seeding rates (34, 56, 84, 112 kg ha-1) with six replicates, while study B evaluated two cultivars (Guardian open-pollinated rye vs. PROGAS hybrid rye) at two seeding rates (67 vs. 101 kg ha-1) with four replicates. Results of study A showed that every 10 kg ha-1 increase in seeding rate increased WR biomass yield by 0.07 Mg ha-1. However, higher seeding rates reduced forage quality, decreasing crude protein (CP), total digestible nutrients (TDN), and relative forage quality (RFQ), while increasing cellulose, hemicellulose, and holocellulose contents, which are desirable for biofuel production. In study B, PROGAS (hybrid rye) generally outperformed Guardian (normal rye) in yield, particularly in 2021, across seeding rates, with taller plants exhibiting higher lignin, cellulose, hemicellulose, and holocellulose but lower RFQ. Hybrid rye was less cost-effective for forage production compared to normal rye. We recommend lower seeding rates of normal rye for forage production to optimize quality and hybrid rye at higher seeding rates for biofuel production to maximize biomass yield. These findings highlight the trade-offs between yield and quality in WR management, offering producers tailored strategies to enhance the profitability of their operation. Together, these findings demonstrate that WR management in corn-soybean systems involves balancing trade-offs among biomass yield, quality, and profitability. Farmers targeting forage should prioritize Guardian rye at lower seeding rates to maximize nutritive value and cost efficiency. Conversely, those seeking biomass for biofuel should consider the PROGAS hybrid rye at higher seeding rates to capitalize on increased lignocellulosic content. The STCR planting method presents an innovative, cost-effective approach that maintains yield potential while improving biofuel quality and reducing input costs. Overall, integrating optimized seeding rate, cultivar selection, and precision planting strategies can make WR a more economically viable and environmentally sustainable component of corn–soybean rotations. These management adaptations not only support profitability but also contribute to soil and water quality goals in the Upper Mississippi River Basin, aligning agronomic performance with regional conservation priorities.