Irrigated Crop Rotations

Corn-Harvest-lftGrowing different crops on the same field in a preplanned succession is known as crop rotation. Crop rotation seeks to balance the different fertility demands of various crops to avoid excessive depletion of soil nutrients. It also helps avoid or reduce the buildup of pathogens (diseases) or other pests (insects). 

By rotating crops, irrigated farmers can keep their fields under continuous production, without the need to let them lie fallow. This practice reduces the need for additional fertilizers or herbicides; both of which are expensive. 

Some farmers take it a step further by growing crops for the sole purpose of improving soil characteristics. They leave the crop unharvested, allowing it to become incorporated into the soil and add nutrients and organic matter (known as ‘green manure’). Once the unharvested crop is tilled in, soil microorganisms aid can the decomposition of this fresh material. The vegetation degradation allows the nutrients held within the green manure to be released and made available to the succeeding crop. 

Wheat-2-lftBrian Drouhard uses green manure and rotational strategies to improve his crop quality and yield on DNR-managed land he leases in Franklin County. “Including a mustard crop into our cropping system adds cost but I prefer to think about it as an investment; an investment that pays dividends including increased organic matter, improved water holding capacity, reduced erosion, better soil fertility and greater disease control.”

In the long run, Brian and other farmers who practice crop rotation expect to reap the benefits of better soil and a reduce need for fertilizers and herbicides.

Toby McKay
Tri-Cities Unit Land Manager, SE Region