Long-term tillage effects on spring wheat production on three soil textures in the Brown soil zone

Abstract

The adoption of reduced tillage practices has increased markedly on the Canadian prairies in recent years. Producers in the semiarid Brown Chernozemic soil zone require information on how the intensity of tillage will affect moisture conservation and grain yields in the long term. A 12-yr study was conducted in the Brown soil zone of southwestern Saskatchewan on Swinton silt loam (Orthic Brown), Hatton fine sandy loam (Orthic Brown), and Sceptre heavy clay (Rego Brown) to determine the influence of tillage on the production of hard red spring wheat (Triticum aestivum L.) (on the silt loam and clay) and durum (Triticum turgidum L.) (on the sandy loam). The study was conducted with fallow-wheat (F–W) and continuous wheat (Cont W) rotations. The tillage systems were no-tillage (NT), minimum tillage (MT) and conventional tillage (CT). On the sandy soil with its low water-holding characteristics, tillage system did not affect stored spring soil moisture (SSM), nor grain yields, nor grain N. On the silt loam and clay, there were several instances when NT increased stored moisture in the soil, especially on the clay, but the extra moisture conserved was not always associated with increased grain yields. Generally, when significant increases in stored moisture for F–W were accompanied by below-average growing season precipitation (GSP), an advantage in yield accrued to NT. However, when GSP was above average, CT and MT often had greater yields than NT. We rarely observed yield advantages favouring NT on Cont W on the silt loam or on the clay. Our results suggest that wheat grown under NT on the clay has a higher lower limit of available soil moisture than under CT. Generally, grain N concentration was lower for F–W (NT) on the silt loam and clay. This study has shown that mono-culture wheat production in the Brown soil zone was influenced little by tillage system. Key words: Crop rotations, grain protein, soil water, grain production