title: The kill date as a management tool for cover cropping success.
abstract: Integrating cover crops (CC) in rotations provides multiple ecological services, but it must be ensured that management does not increase pre-emptive competition with the subsequent crop. This experiment was conducted to study the effect of kill date on: (i) CC growth and N content; (ii) the chemical composition of residues; (iii) soil inorganic N and potentially mineralizable N; and (iv) soil water content. Treatments were fallow and a CC mixture of barley (Hordeum vulgare L.) and vetch (Vicia sativa L.) sown in October and killed on two different dates in spring. Above-ground biomass and chemical composition of CC were determined at harvest, and ground cover was monitored based on digital image analysis. Soil mineral N was determined before sowing and after killing the CC, and potentially mineralizable N was measured by aerobic incubation at the end of the experiment. Soil water content was monitored daily to a depth of 1.1 m using capacitance sensors. Under the present conditions of high N availability, delaying kill date increased barley above-ground biomass and N uptake from deep soil layers; little differences were observed in vetch. Postponing kill date increased the C/N ratio and the fiber content of plant residues. Ground cover reached >80% by the first kill date (∼1250°C days). Kill date was a means to control soil inorganic N by balancing the N retained in the residue and soil, and showed promise for mitigating N losses. The early kill date decreased the risk of water and N pre-emptive competition by reducing soil depletion, preserving rain harvested between kill dates and allowing more time for N release in spring. The soil potentially mineralizable N was enhanced by the CC and kill date delay. Therefore kill date is a crucial management variable for maximizing the CC benefits in agricultural systems.
authors.affiliation: School of Agriculture Engineering, Technical University of Madrid, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Alonso-Ayuso
authors.affiliation: School of Agriculture Engineering, Technical University of Madrid, Madrid, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Gabriel
authors.affiliation: School of Agriculture Engineering, Technical University of Madrid, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Quemada
mesh_terms: D000383:Agriculture / Q000379:methods*; D018533:Biomass; D018556:Crops, Agricultural / Q000737:chemistry / Q000254:growth & development*; D005308:Fertilizers; D008903:Minerals / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D014867:Water / Q000032:analysis; D014887:Weather
chemical_list: D005308:Fertilizers; D008903:Minerals; D012987:Soil; D014867:Water; D009584:Nitrogen