Poultry litter and nitrogen fertilizer effects on productivity and nutritive value of crabgrass

Abstract Crabgrass ( Digitaria spp.) is deemed as a productive and nutritious warm‐season annual forage for livestock in the U.S. transition zone. However, there limited information about nitrogen (N) source rate effects on productivity nutritive value of crabgrass North Carolina. Herbage accumulation (HA), N removal, crude protein (CP), total digestible nutrients (TDN), tissue nitrate (NO 3 − ) concentrations were evaluated 2 yr (2020 2021) two physiographic regions (Piedmont Coastal Plain). Treatments five rates chemical fertilizer (up to 480 kg ha −1 ), plant‐available from broiler poultry litter 472 399 2020 2021, respectively), one control (zero N). Overall responses not different between sources. At Plain, HA increased 4,990 dry matter (DM) plateaued at 7,136 DM an agronomic optimum (AONR) 198 (SE = 49) . Piedmont, erratic, estimation AONR was possible, values approximately half or less those Plain. Removal linearly associated with HA. Increasing had marginal positive effect CP (ranged 126 154 g no TDN (averaged 626 ). Tissue NO below toxic threshold feeding livestock. Poultry effective crabgrass. Nitrogen more apparent crabgrass’ productivity; generally high regardless source.