Crown‐Depth Soil Temperatures and Winter Protection for Winter Wheat Survival

Abstract

AbstractWinterkill of winter wheat (Triticum aestivum L.) can be a serious problem in marginal winter wheat growing areas of the world. Plants that are well hardened or conditioned when entering the winter season may withstand crown‐depth temperatures of about −20°C; less hardened cultivars, about −16°C.Experiments were initiated on a Williams loam (fine‐loamy, mixed Typic Argiborolls) near Sidney, Montana, to establish snow depth and protection requirements, based on a −16°C limit criterion at crown depth (3 to 5 cm), for reasonable assurance of winter wheat survival.Soil temperatures were measured at 0‐, 3‐, 10‐, and 50‐cm depths on fallow soil under various snow depths. In addition, a deep furrow drill was used to seed winter wheat on summer fallow with soil temperatures measured at 0, 3, and 10 cm and in standing stubble with soil temperatures measured at 0‐, 5‐, 15‐, 30‐, 60‐, and 90‐cm depths. Providing no other confounding factors such as snowmelt and subsequent ice‐crust formation are present, about 7 cm of snow is probably sufficient to prevent winterkill even when air temperatures occasionally approach −40°C. The deep furrow drill formed furrows deep enough to trap about 6 to 7 cm of snow. Standing stubble provided additional protection and caught and held snow.