Plant Vigor and Yield of Perennial Cool-Season Forage Crops When Summer Planting Is Delayed

Abstract

The Cooperative Extension Service in most states recommends dates, in the late‐summer or early‐fall, when perennial cool‐season forage crops should be planted. Planting after the recommended date generally results in less than optimum stand vigor and yield. For many reasons, farmers may wish to plant perennial forages after the recommended date. The objective of this research was to evaluate the performance of forages planted after the recommended latest date. Three perennial cool‐season forage legume and grass species were planted on various dates during August, September, and October in 1991 and 1992 at two locations in Pennsylvania. Development and yield of plants was monitored for 1 year after planting. Plant height in late‐November and percentage ground cover in the spring decreased as planting was delayed after 1 August. Each day planting was delayed after 1 August, total DM yield the following year declined by an average of 158 and 116 lb/acre for alfalfa (Medicago sutiva L.), 105 and 71 lb/acre for red clover (Trifolium pratense L.), 76 and 28 lb/acre for birdsfoot trefoil (Lotus corniculatus L.), and 120 and 63 lb/acre for reed canarygrass (Phalaris arundinacea L.) in central and southern Pennsylvania, respectively. Orchardgrass (Dactylis glomerata L.) yields did not decrease at either location when planting was delayed from early‐ to mid‐August. After mid‐August, however, orchardgrass yield declined by an average of 92 lb/acre for each day planting was delayed. Perennial ryegrass (Lolium perenne L.) yields increased by over 1.0 ton/acre when planting was delayed from early‐August to late‐August. Daily delays in planting perennial ryegrass after late‐August resulted in average yield reductions of 134 lb/acre. In general, planting perennial cool‐season forage crops after 5 September in central and 10 October in southern regions of Pennsylvania resulted in ground cover judged too low for conservation purposes and produced yields that were too low for practical forage harvesting. Accumulated growing degree days (GDD, base 32 °F) from 5 September and 10 October until the first killing frost (temperature ≤27 °F) were approximately 1000 and 230, respectively. Research Question Farmers are frequently faced with planting perennial cool‐season forage crops later in the fall than is recommended. The risks of late planting must be weighed against considerations such as need for forage the following year or ground cover to comply with conservation plans. These are strong pressures on producers to assume greater risk and plant after the recommended date. This study examines the effects on stand vigor and first‐year yield of six cool‐season forage species when planting date was delayed into late‐summer or early‐fall. Literature Summary Recommended planting dates are from early‐August in northern regions through early‐September in southern regions of Pennsylvania. Planting later than these dates causes reduced plant survival, vigor, and yield the following year. In California, alfalfa planted in mid‐October and mid‐Nov...

Revisiting alfalfa planting dates for the semiarid U.S. Southwest

“…This actually occurred on 5 and 8 November in 2014 and 2015, respectively, at Los Lunas, and 22 and 11 November in 2013 and 2014, respectively, at Tucumcari. The −2.8°C temperature is contrary to Wolf and Edmisten (1989), who reported a recommended planting at least 6 wk before the occurrence of 0°C, but consistent to a dormancy‐inducing, or killing frost reported by Hall (1995). Late summer seedings have been consistently successful in the Southwestern United States using −2.8°C as a guideline rather than 0°C, likely because of dry winters with no or minimal frost heaving and soil temperatures that remain warm despite earlier short‐term freezing air temperatures (Wolf et al., 1989).…”

“…(1995) concluded that earlier summer seedings (early vs. late Aug. or late Aug. vs. early Sept.) had greater first harvest and total production year yields in the year after seeding. In Pennsylvania (40–41°N latitude), Hall (1995) reported that there was a 154 kg ha −1 yield loss for every day alfalfa planting was delayed after 1 August. This could be due to a lesser accumulation of total nonstructural carbohydrates (TNC) and vegetative storage proteins (VSP) in alfalfa roots between germination and defoliation or hard freeze, whichever occurred first.…”

“…Otherwise, the harvest was taken just prior to the anticipated −2.8°C as long as it had been 80 d after planting. Any subsequent harvests were taken at intervals of approximately 28–35 d, during early bloom (Hall, 1995), assuring at least a 42‐d rest period between the next‐to‐last harvest and the anticipated −2.8°C (McCordick et al., 2008; Lauriault & Kirksey, 2009), with the final harvest taken just prior to the anticipated −2.8°C. Consequently, in the seeding year, the May plantings at Los Lunas were harvested three times and at both locations and the two June planting dates were harvested twice.…”

“…Alfalfa ( Medicago sativa ) is a small‐seeded perennial forage legume that is broadly adapted to a wide range of soil and climatic conditions and relatively competitive against weeds once established, if properly managed (Summers, 1998). In most regions, alfalfa can be planted in either spring or late summer with a greater degree of success than planting at other times (Hall, 1995; Taylor, Foote, Snyder, Smith, & Templeton, 1972). Generally, spring plantings are recommended when soil temperatures stabilize at ≥ 7°C, while late summer seedings should take place 6–10 wk before the average first autumn temperature of −2.8°C (Lauriault, Sawyer, & Baker, 2003).…”

“…Alfalfa planting dates, particularly for the late summer seedings, are usually determined by elevation and latitude of the planting site, and planting after mid‐September is not recommended at 35–38°N latitudes (Hall, 1995). Generally, late summer seedings have been recommended over spring seedings in the Southwestern United States due to weed competition, irrigation costs, high summer temperatures, winds during establishment, and the perception that yields will be lower from spring seedings; however, yield reductions have been reported in delayed, late summer seeding (Fribourg & Strand, 1973; Hall, 1995; Tesar, 1984). The effect of delayed late summer seeding was greater for alfalfa than other small‐seeded legumes (Hall, 1995).…”