Forage production and quality of several crop rotations and pastures in northwestern Spain

Multiple cropping has been used for many years to increase production in temperate areas of Europe where the growing season is favourable and is important when land area is limiting.
The purpose of this 3-year study was to determine how several different cropping systems affected forage production potential at three rainfed locations in northwestern Spain (Galicia). The cropping systems compared were: single crop maize; double crop systems of maize-rye, maize oats+ vetch, and maize-Italian ryegrass; three crops in a two-year rotation of maize-Italian ryegrass (12-months) forage rape; 2-year pasture maize and two contrasting 3-year grass-legume mixtures.
There was an increase in dry matter (DM) production as cropping intensity increased. The one-year double cropping systems always yielded more than three crops in two years, which in turn outyielded single crop maize or 3-year pastures. The highest DM yields were 20–9 t ha-¹ from the maize-oats-I-vetch rotation. Maize was the principal crop determining total production, yielding about 70% of the total DM for the double cropping systems. The maize component gave similar annual yields in the multiple crop and maize-pasture rotations, but the use of maize allowed double cropping, which increased production compared with 3-year pasture.
Forage rape gave the highest in vitro dry matter digestibility (IVDMD) of 773–815 g kg-¹ while the oats-I-vetch mixture gave the highest crude protein (CP) concentration (105-217 g kg-¹). The maize crops had the lowest CP content (62-76 g kg-¹) though digestibility was high (653-713 g kg-¹).