Drought frequently limits alfalfa (Medicago sativa L.) herbage productivity during mid‐summer in the North Central USA, but the productivity of other legumes during drought is unknown. We determined the effect of drought on the herbage yield and quality and stand persistence of birdsfoot trefoil (Lotus corniculatus L.), cicer milkvetch (Astragalus cicer L.), red clover (Trifolium pratense L.) and alfalfa. Legumes were established on a sandy, mixed, Udorthentic Haploborolls and subjected to two soil water regimes promoting ‘droughted’ and ‘well‐watered’ (control) plant growth. Mid‐day stem pressure potentials for droughted and control plants ranged from −1.3 to −3.8 MPa and −0.1 to −1.4 MPa, respectively. When drought occurred throughout growth, legume herbage yields of droughted alfalfa, birdsfoot trefoil, cicer milkvetch, and red clover averaged 33, 21, 19, and 13% of their respective controls. Average herbage yield of droughted alfalfa was 120% greater than yields of birdsfoot trefoil and cicer milkvetch, and 165% greater than red clover yield. Averaged for all harvests and species, whole herbage acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin (ADL) concentrations were reduced by 30 to 4870, 26 to 46%, and 0 to 49%, respectively, when drought occurred throughout growth. Effects of drought on lignin in NDF and crude protein concentration were not consistent. Droughted alternative legumes produced herbage with lower ADF, NDF, and ADL concentrations than alfalfa. Improved quality in droughted legumes was related to greater leaf:stem weight ratio, delayed maturity, and often higher quality in both the leaf and stem fractions compared to the control treatment. Although drought reduced the herbage yield of all legumes, alfalfa has the greatest yield potential in drought.

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...

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