Effect of Harvest Processes on the Nutritive Value of Kentucky Bluegrass Residue from Seed Harvest

Abstract

Kentucky bluegrass (Poa pratensis L.) fields were historically burned following seed harvest to remove post‐harvest residue and maintain stand productivity, but regulations were imposed on field burning. Reduced‐burn or non‐burn production systems remove residue in part by baling, and the baled residue is often utilized for forage. It was unknown if harvest processes (swathing, combining seed, and baling) and the time between combining and baling affected forage nutrient content. Experiments at two locations evaluated the effect of harvest method and timing on crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin, and 48‐h in vitro true digestible dry matter (IVTDDM). At the Potlatch, WA, experiment, CP decreased by 8 g/kg DM, IVTDDM decreased by 38 g/kg DM, NDF increased by 48 g/kg DM, ADF increased by 26 g/kg DM, and lignin did not change before and after swathing. Forage nutrient content did not change between before and after combining seed or baling. At the Pullman, WA, location, IVTDDM decreased by 1.8 g/kg/day DM, NDF increased by 2.8 g/kg/day DM, ADF increased by 1.4 g/kg/day DM, lignin increased by 0.2 g/kg/day DM, and CP was unchanged when baling was delayed 23 days after seed harvest. Baling Kentucky bluegrass residue soon after combining with as much leaf content as possible will result in the highest nutritive value.

Residue removal and nitrogen cycling in burn and non‐burn Kentucky bluegrass seed production systems

“…Open field burning of bluegrass residue, often done in late summer or early fall (mid‐August to late September), may result in the release of plant available nutrients at a critical time for Kentucky bluegrass growth and reproduction (Holman & Thill, 2005b; Holman, Hunt, & Thill, 2007). Nonthermal systems that leave more residues and nutrients on the surface may favor microbial immobilization of N during this same period (Holman et al., 2011). Fertilizer regimes in nonthermal systems, therefore, may need to be altered to better simulate this release of N. A better understanding of N processes in both burned and nonthermal residue systems is necessary to optimize N fertilization in Kentucky bluegrass systems, minimizing losses and increasing profitability.…”

Burn and mechanical residue removal methods on production‐life of Kentucky bluegrass

“…Nonthermal residue management, therefore, generally results in premature stand decline as compared with field burning. In addition, postharvest residue is low in forage nutritive value, economic value, and demand (Holman, Hunt, & Thill, 2007; Holman, Hunt, Johnson‐Maynard, et al., 2007; Holman et al., 2011), all of which are disincentives to manage postharvest residue other than through field burning.…”