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Aboveground and Root Decomposition of Cereal Rye and Hairy Vetch Cover Crops.

Sievers, T. and Cook, R. L.. 2018.


Synchronizing cover crop decomposition and nutrient release with cash crop uptake can provide benefits to agroecosystems but can be difficult to implement. The objectives of this study were to quantify the aboveground and belowground decomposition and nutrient release of two cover crops, hairy vetch (Vicia villosa Roth) and cereal rye (Secale cereale L.), after termination with herbicides through a 16-wk period during the cash crop growing season using litterbags and intact root cores. Plant Root Simulator probes monitored mineral N in the soil. Hairy vetch aboveground (k = 0.4505) and root (k = 0.6821) biomass decomposed at a faster rate than aboveground (k = 0.1368) and root (k = 0.1866) biomass of cereal rye. Hairy vetch had higher initial N content in aboveground (41.9 g kg-1) and root (16.5 g kg-1) biomass than cereal rye (11.5 and 8.3 g kg-1, respectively). Hairy vetch had a lower C to N ratio than cereal rye in both aboveground (9.52 vs. 34.72) and root biomass (17.31 vs. 40.31) contributing to decomposition differences. Hairy vetch rapidly decomposed after cover crop termination in the spring, therefore growers should consider delaying termination of this cover crop until close to cash crop planting to decrease the risk of N loss. Cereal rye residues decompose much slower and may also immobilize N because of its high C to N ratio. A better understanding of how aboveground and belowground cover crop characteristics influence decomposition will help to optimize cover crop nutrient release with cash crop uptake.

Key Words

ARC, Agronomy Research Center; PRS, Plant Root Simulator.