The tolerance of spring wheat and barley to post-emergence harrowing
Use of herbicides in certain situations may not always be appropriate for controlling weeds because of cost or improper crop stage. Crops produced without the use of herbicides require alternative weed-control methods. A 12-yr study was conducted at Indian Head, Saskatchewan, under weed-free conditions to determine the tolerance of spring wheat and barley, with or without ammonium phosphate fertilizer placed with the seed, to post-emergence harrowing. Barley and spring wheat harrowed with diamond-toothed harrows as it was emerging, at the 1.5-leaf stage, or at the 2.5-leaf stage in the absence of weeds produced yields similar to those from a non-harrowed check when averaged across years and fertilizer treatments. Ammonium phosphate fertilizer placed with the seed significantly increased yields of both barley and spring wheat (averaged across years and harrowing treatments) but did not alter the tolerance of barley and spring wheat to post-emergent harrowing. This implies that a delay between seeding and harrowing due to rain or using a harrowing operation to break a surface crust should not result in yield losses for barley and spring wheat.Key words: Triticum aestivum L., Hordeum vulgare L., cultural control, organic production phosphorus