Yield and arbuscular mycorrhiza of winter rye in a 40-year fertilisation trial

Abstract

The impact of different fertilisation treatments on soil organic matter, available soil nutrients, mycorrhizal and root properties, as well as on the yield response of winter rye (Secale cereale) was studied in a long-term field trial in Austria under dry site conditions. Winter rye has been grown since 1906 in soils treated with easily soluble mineral fertiliser, farmyard manure, and in an unfertilised control. We found the soil organic matter to be 96% higher in the plots fertilised with farmyard manure compared with easily soluble mineral fertiliser. Available soil phosphorous and potassium contents were at least 136% higher in both fertilised treatments than in the unfertilised control. Arbuscular mycorrhizal colonisation (+46%) of winter rye roots by indigenous arbuscular mycorrhizal fungi, arbuscule frequency (+20%), and the length of the extraradical arbuscular mycorrhizal mycelium (+18%) were higher in the unfertilised control and reduced in the NPK treatment compared with the farmyard manure treatment. The average grain yield of winter rye from 1960 to 2000 increased in all treatments. This increase was higher in the fertilised treatments, +41% for farmyard manure and +60% for easily soluble mineral fertiliser, than in the unfertilised control. Two main effects presumably accounted for the continuously increasing average winter rye yield in all fertilisation treatments: (1) the use of modern winter rye varieties with a higher nutrient efficiency; and (2) an ongoing atmospheric nitrogen deposition. We conclude that the preferential application of farmyard manure, typical for low-input farming systems, resulted in increased levels of soil organic matter, arbuscular mycorrhizal colonisation and arbuscule frequency, supporting soil fertility by an enhanced crop nutrient uptake by arbuscular mycorrhizal fungi under dry site conditions, thus promoting crop yield stability and sustainable plant growth.