We describe a case study of a forage cropping rotation in New Zealand, demonstrating how simulation models can be used to define the best compromise between the yields of successive crops, and thereby maximise the total yield of the full sequence.
Our results indicate that soil quality, weed management, beneficial insect conservation, and profitability can be maintained in organic systems when periodic tillage is coupled with perennial forage crops in rotation.
Including forages in the crop rotation also led to higher yields in the grain crops planted after the forage, because of less soil disturbance, increased soil organic matter and weed control (Gliessman, 2006).
Davis et al. [95] showed in a nine-year field study in the US corn belt that more diverse rotations including forage legumes enhanced yields of corn and soybean grain by up to 9% and reduced fertilizer application, energy use, and herbicide input significantly.
The reason for the higher erosion rates for the 50 years after 1960 than before was most likely the continued use of moldboard plowing, up and down the slope plowing and the more intensive corn soybean rotation without forages and small grains.
Other researchers have proposed the use of cover crops, synthetic fertilizers, organic fertilizer, manure, liming, agricultural systems and management, agroforestry, forages, compost, crop rotations, and reduced row crop use as ways to sequester SOC.
System efficiency is much lower for N (about 50%) because of gaseous emissions of NH3, N2 and N2O, but it can be improved in different ways by reducing gaseous emissions from the excreta, improving crop N fertilization, and including legume forages in crop rotations (Rigolot et al., 2010).
A six-year trial was conducted for a biennial rotation of four forage crops: oat-sorghum (first year) and ryegrass-maize (second year) in a humid Mediterranean area.
Garabagi et al. (2008) report small expression differences in the D. v. virgifera ortholog of the foraging gene in relation to rotation resistance.
Altogether, the best of the tested strategies is adaptive stocking combined with a rotation that adapts to both spatial forage availability and seasonality.
For example, including forage crops, such as alfalfa, into a crop rotation with corn and soybean had both environmental and economic benefits (Olmstead and Brummer, 2008).
