DRYING RATE AND HARVEST LOSSES OF WINDROWED VERSUS DIRECT COMBINED BARLEY

Abstract

Windrowing of cereal crops prior to harvest is reported to hasten drying and reduce losses due to shattering compared to direct combining, but few direct comparisons have been made in barley (Hordeum vulgare L.). Field studies were conducted over 4 yr to compare drying rates and harvest losses in windrowed and standing barley cultivars with varying susceptibility to shattering. Cutting treatments for comparing harvesting losses were initiated when kernel water concentration (KWC) dropped below about 670 g water per kg kernel dry weight, and were continued for 2 wk after combine ripeness (KWC 174 g kg−1). Natural shattering losses and cutting losses were measured at each cutting time, while combine pick-up losses were determined after combining of windrows cut at KWCs greater than 174 g kg−1. Cutting and pick-up losses were independent of harvest time when KWC at cutting was greater than 174 g kg−1. Cutting loss increased after combine ripeness, but was not related to cultivar shattering susceptibility. Combine pick-up losses ranged from 0.4 to 4.3% of yield, and were greater in low-yielding crops than in high-yielding crops. Total harvesting losses for direct combining ranged from 0.1 to 2.8% of yield compared to 0.8–7.7% for windrowing prior to combining in crops harvested at or before combine ripeness. Direct combining 1 and 2 wk later caused increased harvest losses (0.3–20% of yield) which were proportional to cultivar shattering susceptibility. Windrowed barley dried to combine ripeness from 0 to 3 d (mode 1 d) faster than standing barley.Key words: Barley, shattering susceptibility, cutting loss, combine pick-up loss, harvest losses, harvest methods