The Effect of Crop Establishment System On the Nitrogen Use Efficiency of Winter Wheat In Ireland.

Winter Wheat production in Ireland is typically a high-input system with average yields of 8.8t/ha and N inputs of 190kg/ha. Although ploughing (P) to a depth of 200mm followed by a secondary cultivation combined with sowing is the dominant establishment system, shallow non-inversion minimum tillage (MT) is also practised.  Straw incorporation (+S) as a method of increasing soil organic matter content is sometimes practised. This study examined the effects of cultivation systems, straw incorporation and nitrogen rate on the nitrogen uptake and grain yield of winter wheat (cv. Alchemy) grown in the south east of Ireland.

Field experiments were conducted in 2009 and 2010 on a medium textured clay loam. A 4 x 5 factorial experimental design was used with four establishment systems (MT; MT+S; P; P+S) and 5 N rates (0, 140, 180, 220, 260 kg/ha) with 4 replications. Crop N uptake (CNU) was recorded during the growing season. Harvest measurements included grain and straw N uptake, grain yield and grain protein. Statistical analysis was carried out by analysis of variance using Genstat. 

 In 2009 the MT treatment had an increasing CNU as the season progressed with a significantly higher uptake than the P treatment at GS 65 and 75. However, cultivation system had no significant effect on grain yield or total N uptake at harvest. Due to poor crop establishment with MT in 2010, the P treatments had a higher CNU at GS 24, 28, 32 and 47. Although there was no difference in CNU at GS 65 or 70 the P treatments had a significantly higher grain yield and total N uptake than the MT at harvest. Straw incorporation had little effect in both seasons.

 These field experiments indicate that the impact of MT on yield and N uptake parametres is season and weather dependent.