Winter Cereal Canopy Effect on Cereal and Interseeded Legume Productivity

Abstract

Interseeding red clover (Trifolium pratense L.) or alfalfa (Medicago sativa L.) into winter cereals in the North Central United States can provide forage and a green manure crop. We hypothesized that winter cereal canopy traits such as leaf area index (LAI) and whole plant dry matter (DM) would infl uence interseeded legume establishment and productivity, yet the eff ect of canopy traits on resource competition in intercropping systems is not well understood. Th is study was conducted from 2005 to 2007 to evaluate the impact of diverse cereal canopy traits on the establishment of frost-seeded legume intercrops. In March, red clover and alfalfa were frost-seeded into three winter wheat (Triticum aestivum L.) and three triticale (X Triticosecale Wittmack) varieties selected for diff erences in maximum LAI, plant height, and DM. Across three growing seasons, the cereals produced a range of LAI from 2.1 to 6.2 and whole plant harvest DM of 817 to 2029 g m -2 . In the 2 yr with legume data, densities were infl uenced by cereal 1 yr and DM was aff ected by cereal both years. Alfalfa and red clover densities were similar, yet DM production was 42% higher in red clover 40 d aft er grain harvest. Th e presence of a legume intercrop did not aff ect grain yield, but reduced weed densities and weed DM 40 d aft er harvest. Producers implementing this intercrop may select cereal varieties based on grain yield, but must be cautious of varieties known to produce above normal LAI values because of the potential to reduce legume productivity.

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…Interseeding or relay cropping is a common approach to successfully establishing and gaining the benefits of a cover crop in regions with shorter growing seasons, and has received a certain amount of attention in the NGP (e.g. Bruulsema and Christie 1987; Thiessen Martens et al 2001;Blaser et al 2011).…”

Expanding Red Clover (Trifolium pratense) Usage in the Corn–Soy–Wheat Rotation

“…In contrast, the light compensation point for alfalfa is 13% [41]. Blaser et al suggest that this factor explains the observed difference in dry matter production between red clover and alfalfa [34]. The impact of this factor is further demonstrated in a study by Gist and Mott [40].…”

“…Ease, equal to RC [34] Slow to establish, weak seedlings [27] Less competitive than RC [35] Vigorous, easy to establish [27] Easy to establish [27] Slow to establish, but persistent [29] Years to establish, then competitive [27] Lifespan/persistence Short-lived perennial, 2-4 years [31] 3-20 years [27] 10+ years [36] Perennial [28] Biennial [27] 1-5 years [27] Perennial [29] 5-20 years [27] Regrowth From crown, high recovery rate [37] From crown [27] From crown [27] Stolons and self-seeding [28] From crown [27] From crown [27] Rhizomes, slow recovery [29] Stolons, slow recovery [27] Competitive capacity High [27] High [27] Moderate [27] Moderate [27] Moderate [27] Persistent and hardy [29] Moderate [27] Drought tolerance Moderate [31] High [27] Moderate [27] Low [36] High [27] Prefers cool, wet conditions [27] Moderate, goes dormant [29] Moderate, goes dormant in drought [27] Shade Red clover germinates in temperatures as low as 5 °C [39] and continues to grow at temperatures above 32 °C, though growth is slowed [40]. It thrives where conditions are shady, cool, and moist [3].…”

“…Studies examining the impact of germinating red clover in an established crop, such as red clover under-seeded to winter wheat [34] or red clover inter-seeded with corn [9], have shown no significant negative impact on grain yields. However, in the proposed system, red clover's spring re-growth occurs alongside corn germination.…”

“…Although red clover germinates and sprouts, competition for moisture and nutrients delays flourishing until after the wheat is harvested. Forty days after cereal harvest, Blaser et al measured a two-fold to thirty-fold increase in red clover root dry matter, a 64% increase in root length, and an average shoot: root ratio rising from 8.5 to 11.2 [54]; red clover dry matter production was essentially constant, regardless of winter cereal seeding density [55]; and red clover dry matter production was found to be 42% higher than alfalfa [34].…”