Winter biomass potential of four cover crop species: Wheat, rye, triticale, and canola

This study examines variability in predicted aboveground biomass (AGB) of winter cover crops (CCs) across Nebraska, focusing on wheat ( Triticum aestivum L.), rye ( Secale cereale L.), triticale (× Triticosecale ), and canola ( Brassica napus L.). Nebraska's diverse climate, ranging from semiarid to semi‐humid, presents challenges for setting realistic winter AGB goals. The AGB, leaf area index, and plant height were predicted using Agricultural Production Systems sIMulator, calibrated with 2 years of field data from a unique phenotyping experiment. The model reasonably captured overall field‐measured growth trends across species and years, generally comparable with literature‐reported biomass ranges, though over‐ and underpredictions occurred at specific dates, particularly under winterkill conditions. Relative root mean square error for AGB prediction was 20%, 18%, 14%, and 27% for wheat, rye, triticale, and canola, respectively. Early planting (mid‐September) and late termination (early May), on average, increased AGB by 158%, 112%, 131%, and 247% for wheat, rye, triticale, and canola, respectively, compared to shorter growing interval (early October to mid‐April). A review of 17 studies revealed high AGB variability, with overall mean ± standard deviation of 2348 ± 1782 kg ha −1 . Species‐specific AGB ranged from 110 to 6710 (wheat), 190 to 6310 (rye), 750 to 7160 (triticale), and 100 to 2200 kg ha −1 (canola). The “CC growth gap ( β g ),” concept was introduced to quantify AGB losses due to shorter growing interval across climate divisions: 21%–53% for wheat, 27%–67% for rye, 23%–58% for triticale, and 20%–43% for canola. Results underscore the importance of intentional planting and termination timing to optimize winter CC biomass across diverse climates.