Predicting cereal cover crop biomass using shoot length in California vegetable systems

To better understand cover crop benefits and receive nitrogen scavenging credits for cover cropping, farmers need simple and robust methods of predicting cover crop biomass production. A new regulation focused on improving nitrogen management on over 200,000 ha of irrigated land in the central coast of California motivated us to evaluate if the shoot length of rye (Secale cereale L., 'Merced') and triticale (x Triticosecale Wittmack, 'Pacheco') could predict shoot biomass. Field samples for rye (n = 162) and triticale (n = 126) were collected at various developmental growth stages from organic and conventional vegetable farms and planting date trials, across multiple soil types, planting times, row spacings, and plant densities. Main shoot length was well-correlated with oven-dry shoot biomass for rye (r(2) = 0.87) and triticale (r(2) = 0.88). This provides farms in California and beyond with a simple, robust method to estimate cover crop shoot biomass.