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Green fields eclipsing the brown
On cover crops, clean drinking water, and the new look of the Corn Belt in early spring
The average date of the last frost in most places in Iowa happens around the middle of April, though in some northern parts of the state, that average last frost happens sometime in early May. That date can feel impossibly late following a long-lingering winter (perhaps even moreso after more than one "false spring"), but it's the climatological reality. And it constrains choices like when to plant corn in the state -- a decision bounded on the other end by the date when it's too late to plant before risking losing the harvest to arrival of the next winter.
■ These constraints typically leave Iowa (and much of the rest of the Corn Belt) looking pretty barren for about half of the year. That vista has started to change, though, with the increasing adoption of cover crops -- plants seeded in the ground after the cash crops (usually corn and soybeans) have been harvested in the fall. Where cover crops are planted, it's become increasingly common to see green in the fields well outside the usual seasons.
■ The adoption of cover crops is the kind of easily-overlooked development that deserves both attention and applause. Plants like cereal rye (the most popular cover crop in Iowa) keep soil nutrients from leaching away when the snow melts, while helping to reduce soil erosion and build up helpful organic matter. Some even help to choke out weeds until the next year's cash crop can be planted.
■ In modern terms, it's still a new practice -- almost no cover crops were planted in Iowa a decade ago, and now they're planted on more than 2 million acres annually.
■ It's not just aesthetically pleasing; soil preservation is an important tool for reducing toxic runoff into the rivers and streams that not only eventually flow into the Gulf of Mexico, but that also serve as a major source of drinking water along the way. It's going to take a while to really establish the practice and to make sure that the right incentives are in place for all of the stakeholders involved (farmers, governments, consumers, and water-drinkers, just for starters), but it's a challenge well worth undertaking.