Final answer:
An irrigated annual forage combination that could be double cropped in a single pivot is rye followed by sorghum sudangrass. This system utilizes land efficiently and promotes sustainable agriculture by improving soil health and biodiversity.
Step-by-step explanation:
An irrigated annual forage combination would consist of a succession of crops that are planted and harvested within a single year and are capable of thriving with supplemental watering. Based on the crops mentioned, option b. Rye and sorghum sudangrass double cropped in a single pivot would be an appropriate combination. Rye, which is a cool-season cereal crop, can be planted first and harvested in the spring, followed by sorghum sudangrass, a warm-season forage, planted in the same pivot after the rye is harvested to take advantage of the remaining growing season. This double cropping system optimizes the use of land and can improve soil health, increase biomass production, and offer a sustainable way to manage resources.
Double cropping is a form of crop rotation, which has several advantages including the disruption of pest cycles, an increase in biodiversity, improvement of soil nutrients, and reduction in dependence on chemical inputs such as pesticides. Other forms of crop management that aim to enhance productivity and sustainability include intercropping, where different crops are grown together in proximity to benefit each other and the ecosystem.