Crop rotation

The practice of alternating the crops grown on a piece of land.
This helps the soil retain the needed nutrients.

Crop Rotation is a common one mana green instant originally printed in the Urza's Legacy expansion for Magic: The Gathering with art by DiTerlizzi. It was reprinted in Duel Decks: Nissa vs. Ob Nixilis with new art by Daniel Ljunggren. Based upon the eponymous practice of cycling agricultural crops, Crop Rotation allows a player to sacrifice a land in play to tutor another land card from their library. It is considered to be an auto-include in any deck that contains Gaea's Cradle. (The reverse would be true except for the cost of acquiring a Gaea's Cradle in the secondary market.) Crop Rotation synergizes with a variety of cards of every type in addition to all utility lands. This provides additional targets based upon the player, additional colors of mana available to the deck, and the strategy involved to achieve the deck's win condition. (For example, when playing my Simic Commander deck, I greatly enjoy casting Crop Rotation on my next turn after transforming Growing Rites of Itlimoc so that I can put Nykthos, Shrine to Nyx into play. Then, casting Eternal Witness to put Crop Rotation back in my hand and recast to put Boseiju, Who Shelters All onto the battlefield and proceed to finish comboing out for the win! Good times, especially when I can pull it off on turn six or seven.) On resolution, at its most simplistic and basic, Crop Rotation is an example of ramp and is almost never a dead draw. There are, however, multiple ways to render it useless by an opponent or one's own game play.

Crop rotation is the agricultural practice of cultivating a different crop on a given tract of land than was just harvested there. It is considered best practice to select a species of plant that is not closely related to the previous crop. The advantages of crop rotation are:

• Different plant species have different requirements for fertilizer and trace minerals. Rotating plant species or, ideally, even plant family, lessens the likelihood of creating nutrient deficiencies.
• Plant pathogens are often fairly specific to a given species and may still be present in the soil. Potato blight and clubroot (affecting cabbage/mustard family) are two such pathogens. Growing an entirely different plant for one or more years (depending on the pathogen) may force new pathogens to "start from scratch".
• In some cases, the cultivation of one crop aids the soil preparation for the following crop. For example potatoes, which are harvested by digging them up, prepare the soil for carrots which require deep loose topsoil.

In a slightly different approach, even livestock may be incorporated into crop rotation. Farmer and rancher Joel Salatin, for example, incorporates cattle and poultry into intensive rotation on pasture. In this case the livestock are rotated rather than the perennial grasses they feed on. Demonstrable benefits for the livestock and the crop that they feed on (in this instance grass) are the result.

Thanks to wertperch for help with details