Jane R. King

Weed Interference, Pulse Species, and Plant Density Effects on Rotational Benefits

Abstract Pulse crop management can increase pulse yields and N fixation, but the effects of previous pulse crop management on subsequent crop performance is poorly understood. Field studies were conducted at three locations, in the Parkland region of Alberta, Canada, between 2004 and 2006. Tannin-free faba bean, narrowleaf lupin, and field pea were planted at 0.5, 1.0, 1.5, and 2.0 times the recommended pulse planting density (PPD), with or without barley as a model weed. Faba bean produced the highest seed yields in higher precipitation environments, whereas pea produced the highest seed yields in lower precipitation environments. Lupin seed yields were consistently low. In the absence of weed interference, faba bean, pea, and lupin N-fixation yields ranged from 70 to 223, 78 to 147, and 46 to 173 kg N ha−1, respectively. On average, faba bean produced the highest N-fixation yield. The absence of weed interference and a high PPD increased pulse seed and N-fixation yields. Quality wheat crops were grown on pulse stubble without additional N fertilizer in some site–years. Management practices that increased N fixation resulted in only marginal subsequent wheat yield increases. Subsequent wheat seed yield was primarily influenced by pulse species. Pea stubble produced 11% higher wheat yields than lupin stubble but only 2% higher wheat yields than faba bean stubble. Consistently high wheat yields on pea stubble may be attributed to synchronized N release from decomposing pea residues with subsequent crop N demand and superior non-N rotational benefits. Nomenclature: Barley, Hordeum vulgare L.; field pea, Pisum sativum L.; narrowleaf lupin, Lupinus angustifolius L.; tannin-free faba bean, Vicia faba L.; wheat, Triticum aestivum L

Seeding rate effects in oat-berseem clover intercrops

The sustainability of cereal cropping systems may be improved by the addition of legumes. The effects of seeding rate were studied for intercrops of berseem clover (Trifolium alexandrinum L.) and oats (Avena sativa L.). Bigbee berseem clover, an annual forage legume, was intercropped with oats on a Black Chernozemic soil at Edmonton, Alberta, in 1996 and 1997. Berseem dry matter (DM) yields were greatly reduced by increasing oat plant density. There was a linear decline in berseem DM with increasing oat DM or oat tiller density. The relationship between oat plant density and berseem DM was nonlinear and varied between years and harvests. Berseem yield reductions varied from 44 to 82% with target densities of 100 oat plants m-2. Effects of berseem seeding rate (BSR) on oats varied between years. Increasing BSR from 6 to 24 kg ha-1 decreased oat tillering, oat DM and oat plant DM by 22–51, 0–57 and 8–51%, respectively, and increased oat tiller DM by 0–18%, with oats at 10 to 20 plants m-2. Differences betwe...

The green manure value of seven clover species grown as annual crops on low and high fertility temperate soils

Annual and perennial clover species may differ in green manure value. Seven clover (Trifolium) species were grown as annual crops on low fertility (Breton) and high fertility (Edmonton) soils in Alberta. Four annual clovers [balansa (T. michelianum Savi), berseem (T. alexandrinum L.), crimson (T. incarnatum L.), and Persian (T. resupinatum L.)], three perennial clovers [alsike (T. hybridum L.), red (T. pratense L.), and white Dutch (T. repens L.)] and a non-legume reference crop [fall rye (Secale cereale L.)] were ploughed-down as green manure in autumn, and followed by barley (Hordeum vulgare L.). Annual clovers had greater biomass yields than perennial clovers, and berseem clover had the highest yield. At Breton, mean biomass N content was greater for perennial clovers (2.9 g N kg-1) than annual clovers (1.9 g N kg-1). Clover biomass at Breton yielded an average of 77 kg N ha-1, with N derived from the atmosphere averaging 88% by N difference method and 75% by 15N natural abundance method. At Edmonton, ...

Glyphosate Can Reduce Glyphosate-resistant Canola Growth After Individual or Sequential Applications1

Greenhouse experiments were conducted to determine whether multiple applications of glyphosate and time of glyphosate application with regard to the crops growth stage had a significant effect on the growth and development of glyphosate-resistant canola. Glyphosate was applied as single applications at the two-, four-, or six-leaf stage of canola; as sequential double applications at the two- and four-, two- and six-, and four- and six-leaf stages of canola; and as a triple application at all three stages. Of the plant growth parameters measured, single applications of glyphosate resulted in significant reductions to stem weight and shoot weight compared with nontreated plants, and multiple applications of glyphosate caused significant reductions to leaf area, leaf weight, stem weight, and shoot weight. Single applications of glyphosate were less injurious to glyphosate-resistant canola compared with multiple applications, and canola growth parameter reductions were greatest after earlier glyphosate applications. Nomenclature: Glyphosate, canola, Brassica napus L. Additional index words: Crop injury, herbicide-resistant crop, leaf stage, multiple application. Abbreviations: EPSPS, 5-enolpyruvylshikimate-3-phosphate synthase; RH, relative humidity.

Above and below-ground competition between Kura clover (Trifolium ambiguum) and meadow bromegrass (Bromus biebersteinii): A greenhouse study

Kura clover (Trifolium ambiguum) is a perennial legume that shows potential for use in pasture mixtures in western Canada. Previous studies have shown that early growth of kura clover is reduced when grown in mixtures with grass species. A greenhouse study examined the relative importance of above- and below-ground competition on growth and development of kura clover when grown with a grass species. Kura clover plants were grown in pots with meadow bromegrass (Bromus biebersteinii) and barriers were put in place to remove all competition, shoot competition, root competition, or to allow full competition. After 12 wk, plants were harvested. Height, leaf area, leaf number, leaf dry weight, and root/crown dry weight were measured. Kura clover leaf number and leaf area were greatest when roots did not interact with meadow bromegrass roots. Vegetative biomass of kura clover doubled when there was no root competition. Shoot competition did not alter leaf number, leaf area, or leaf biomass. Successful establishm...