EFFECTS OF ROW SPACING, SEEDING RATE AND NITROGEN ON YIELD OF BARLEY AND WHEAT UNDER ZERO-TILL MANAGEMENT

Adopting water-conserving tillage practices on the Canadian prairies w ill protect the soil against erosion while conserving soil water. The use of tall-standing stubble to conserve water creates a dilemma for p roducers because maximum yields can only be obtained with narrow rows, and tall stubble may limit the use of narrow row spacings. A 4-yr stu dy on a thin Black clay soil investigated the effects of three row spa cings (10, 20 and 30 cm), six seeding rates (34, 67, 100, 134, 168 and 202 kg ha(-1) for wheat and 27, 54, 81, 108, 134 and 161 kg ha(-1) fo r barley) and two rates of N (low and high) in hard red wheat (Triticu m aestivum L.), durum (Triticum durum L.) and barley (Hordeum vulgare L.) using a continuous cropping, zero-till production system. The yiel ds of cereals were maintained with 30-cm row spacing over a wide range of growing conditions under zero-till management. Durum had a 5.8% yi eld advantage and barley a 2.4% advantage for the 30-cm row spacing ov er the 10-cm row spacing. The number of plants established and the num ber of spikes produced decreased as row spacing increased for all crop s. But wider row spacing resulted in more kernels produced per spike, which, in the case of barley and durum, more than compensated for the lower number of spikes. Increasing seeding rates significantly improve d grain yield in all crops and years because more spikes were produced . Grain yield was related to the reciprocal of seeding rate. The few r ow spacing x seeding rate interactions observed in 2 of 12 cases sugge st that seeding rates need not be adjusted for changes in row spacing. The results obtained have important implications for equipment design and the ability to more easily handle high-crop-residue situations.