Nutrient Uptake by Ryegrass Cultivars and Crabgrass from a Highly Phosphorus‐Enriched Soil

Abstract

Long‐term poultry litter application to crop and pasture lands may result in the buildup of nutrients, particularly phosphorus (P) in the soil. Poultry producers use poultry litter in place of chemical fertilizers to grow crops or forages for grazing and hay production. Cool‐season annual ryegrass (Lolium multiflorum) and warm‐season crabgrass (Digitaria ciliaris) are annual forages commonly grown in the southeastern region of USA. The combination of two forages gives year‐round pasture for a forage‐livestock system. A study was initiated to evaluate the P uptake efficiency of five ryegrass cultivars (Marshall, Rio, Jackson, TAM 90, and Gulf) grown during the winter and spring followed by the annual crabgrass variety Red River during summer. The experiment was conducted during the 2000 and 2001 growing seasons in Mize Mississippi on a highly P enriched Ruston silt loam soil. The ryegrass was grazed during winter then harvested once in early June. Cultivar Rio produced the greatest dry matter (DM) in both growing seasons. In 2001, due to optimum soil moisture conditions, cultivars Gulf and TAM 90 produced more DM than 2000, an extremely dry year. In 2001 crabgrass planted after TAM 90 produced significantly greater DM (7565 kg ha⁻¹) than crabgrass following the other ryegrass cultivars. Cultivar Marshall was the most effective in removing P from soil in 2000 (7.38 kg ha⁻¹), while Rio was superior in 2001 (8.73 kg ha⁻¹). In general, crabgrass was more effective in P removal than ryegrass cultivars tested. Therefore, the combination of ryegrass followed by crabgrass may provide an effective forage‐livestock management system in the southeastern states.