The effect of tillage implement selection and timing of sweet clover plowdown on succeeding spring wheat yields

Non-Peer ReviewedA three-year field study was conducted on a Dark Brown Chernozemic soil to assess the impact of time of sweet clover incorporation and tillage implement used on succeeding wheat yields . During year 1 wheat was under-seeded to clover and in year two the clover was incorporated on either June 15, July 1, or July 15. Five tillage implements were evaluated: (a) Moldboard plow, (b) Rotavator, (c ) Tandem disc, (d), Offset disc, and (e) Deep tillage cultivator. In the spring of year three, each treatment was seeded to wheat. Over the duration of the study small, usually insignificant differences in year three wheat yields occurred related to incorporation implement. Time of Sweet clover incorporation during year two was a significant factor with June 15 treatments, resulting in 8 and 16 % greater year three grain yields than the July 1 or July 15 dates, respectively. Sweet clover dry matter production, measured at the early date of incorporation, was reduced by 32 % when compared to either of the two later incorporation dates. Mineral nitrogen, determined to a depth of 60 cm in year three immediately following wheat seeding, was 82, 75, and 62 kg ha-1 representing the June 15, July 1, and July 15 incorporation dates, respectively. It is concluded that the choice of implement selected for sweet clover incorporation is not critical, however the timing of plow-down is important and should be relatively early in order to maximize succeeding grain production