Soil structural stability following decades of straw incorporation and use of ryegrass cover crops

Abstract Maintaining good soil structural stability is an important element in agricultural sustainability. Incorporation of cereal straw and use of cover crops improve soil structural stability but the long-term individual and interactive effects of these management practices is poorly understood. We examined the impact of four rates of straw incorporation in spring barley (0, 4, 8 and 12 Mg ha−1, annually) combined with a ryegrass cover crop undersown in the barley in spring. Soil was sampled after four decades of treatments in the Askov (Denmark) straw incorporation experiment situated on a sandy loam with 12% clay. We assessed clay dispersibility measured on two macro-aggregate size fractions (ClayDis 1–2 mm and ClayDis 8–16 mm), wet-stability of aggregates, and clay dispersibility of