Kura clover was successfully established via sod-seeding in different environments. Its establishment and yields were initially inferior to that of red clover and white clover. But, its presence slowly increased in the sward and, by the first harvest of the second post seeding season, it was yielding significantly more than the legume species presently recommended for pastures. Clover establishment increased with increasing intensity of herbicide suppression. Best overall results were obtained with glyphosate at low rate (0.8 kg a.i. ha-1). Paraquat (0.9 kg a.i. ha -1) did not suppress sufficiently the grass population for clovers to establish while glyphosate applied at high rates (3.3 kg a.i. ha -1) led to excessive grass suppression, excessive legume content and temporary weed encroachment. N fertilization at seeding did not consistently increase establishment of sod-seeded Kura clover. Forage quality was positively correlated with clover content.

Herbicide sod suppression during pasture renovation by legume sod-seeding often results in the loss of potentially usable forage, weed encroachment, and inadequate glass-legume ratios. A study was conducted to investigate the viability of sod suppression by sheep grazing or mowing, as alternatives to herbicide, during pasture renovation with no-till seeding of red clover (Trifolium pratense L.) or white clover (Trifolium pratense L.). Sod suppression methods evaluated were: strategically timed mowing or sheep grazing to 5 or 10 cm at seeding and during legume establishment, or similarly managed mowing or sheep grazing with an additional defoliation to 5 cm the previous fall. Additional treatments included suppression by herbicide and, unsuppressed and unseeded controls. Treatments were evaluated by determining clover plant population, botanical composition, forage yield and quality. Physical (mowing or grazing) and herbicide sod suppression resulted in similar clover plant populations; clover yields tended to be higher with herbicide suppression. However, increasing the intensity of physical suppression increased clover yields. Forage quality was increased only with sod suppression by grazing or herbicide when compared with the unimproved control. Although, for grazing this was attributed to a more frequent defoliation regime and not to the renovation itself. Unlike suppression with herbicide, physical suppression did not decrease total seasonal forage yields in the renovation year when compared with controls.

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Manure and underseeded clover are sustainable N sources for spring wheat on gleysolic soils of the St. Lawrence lowlands. Farmers rely on little information to manage adequately, these alternatives to fertilizer N. This study documents in spring wheat red (Triticum aestivum L. cv Algot) (i) the agronomic value of (Trifolium pratense L. cv Arlington); (ii) the impacts of application time and underseeded clover an manure N recovery; (iii) the residual NO3-- in the soil profile that constitutes a potential risk of N transfer from soil to air and water associated to clover alone or combined with manures and, (iv) the use of a plant N availability index. A four year field experiment was established an a St. Urbain clay (Orthic Humic Gleysol) at St. Bruno de Montarville (45°33'N; 73°21'W) in 1993. Ammonium nitrate at 0 to 160 kg N ha--1, swine liquid manure (SLM) and dairy solid manure (DSM) were used either alone or in combination with clover ploughed down in fall as green manure. Manures were applied at pre-seeding, in post-emergence or after harvest. The impact of clover on wheat yield was related solely to an improved N nutrition. Clover supplied fertilizer N equivalents of approximately 30 kg ha --1 to the succeeding wheat crop. Clover combined with manures increased available N in the soil profile so that estimated recovery of manures N was strongly reduced in 1995. Apparent N recovery of SLM was higher than for DSM with values of 5% and 17% in 1994 and 1995 compared to 2 and 4% for DSM. Application time did not significantly affect manure N recovery. Limited risk of N transfer to water and air was associated with post-harvest manure application and underseeded red clover because those practices increased soil profile NO3-- in fall and the end of April. Fluxes of N estimated by NH4+ and NO3 -- sorbed in situ on ionic exchange membranes (IEMs) provided better monitoring of N released by added organic N sources than N extracted by 2M KCl and also were bette