Impact of Long-Term Manure and Mineral Fertilization on Accumulation of Non-Structural Carbohydrates in Lucerne Forage

Abstract

Fertilization management affects both productivity and nutritive value of forage legumes. However, there are few studies about changes in lucerne non-structural carbohydrates under long-term fertilization. The aims of this study were to compare the effects of mineral fertilization and organic manure on lucerne plant parts (leaf, stem) starch and water-soluble carbohydrate (WSC) accumulation in association with canopy structure following 60 years of different fertilization management approaches. Treatments investigated were: two contrasting levels of mineral N, P2O5 and K2O application (0:0:0 and 91:71:175), each with and without farmyard manure. Changes were mainly reflected in WSC content where intensive mineral fertilization consistently reduced the stem and forage WSC in contrast to unfertilized control or manure alone. These changes could be associated with a dilution effect presented by the highest increase of maximal stem length at these treatments. Manure improved leaf and forage WSC despite the associated increase in maximal stem length and leaf weight ratio, probably as a result of improved soil environment together with the potentially increased presence of arbuscular mycorrhizal fungi. Results showed that manure fertilization has potential for improvement of lucerne WSC, despite some negative relationships between lucerne canopy traits and sugar content.