Could tropical storm Isaac actually help break US drought?

Tropical storm Isaac is bearing down on the Gulf Coast, but once it gets inland, it is expected to bring much needed rain to drought-hit farmlands.

Although tropical storm Isaac is causing evacuations and is expected to lead to power outages when it comes ashore, there may be a silver lining for drought-pressed farmers farther inland.

After the storm leaves the coast, it is expected to move north, dumping heavy rain up the Mississippi Delta.

Although it is probably too late to help this year’s harvest, agricultural experts say the rain could help recharge the soil for next year’s crop in Illinois, Indiana, and Ohio. It could also add needed water to the river systems that drain into the Mississippi. And by adding moisture to the air, the storm may also set the stage for more rain in the future in some drought-effected areas.

“Everyone will welcome this rain,” says Dale Mohler, senior meteorologist at Accuweather State College, Pa. “The benefits outweigh the negatives.”

Mr. Mohler forecasts the southern part of the Mississippi Delta could receive four to eight inches of rain and the more northern areas could get two to three inches.

The storm arrives, however, at the point when many crops are being harvested. As of last week, the US Department of Agriculture (USDA) reported the cotton crop is nearing maturity, corn is ready to be harvested, and soybeans are just about ready, as well. Farmers in Arkansas, Kentucky, and Tennessee are right in the middle of their harvest.

“Isaac will be a challenge for those crops ready to be harvested,” says Bill Lapp, president of Advanced Economic Solutions, an agricultural consulting firm in Omaha, Neb. “The rain is an insult to injury here.”

In addition, Mr. Lapp worries that if Isaac still has a wind field when it reaches the farm areas, the gusts may knock down crops already weakened by the minimal moisture, increasing the harvest losses.

On Aug. 20, the USDA estimated the yield on the corn crop would be down 13 percent, the lowest production since 2006. On Monday, Pro Farmer, a trade publication, estimated the soybean crop would be worse than government estimates.

Normally, rain at this time of year would be welcome, says Chad Hart, an agricultural economist at Iowa State University in Ames. But the drought caused crops to mature earlier than normal. “July is crucial for corn, August for soybeans,” says Mr. Hart. “Rain is less beneficial now because the crops are too far along.”

On the other hand, the rain from Isaac could benefit many farmers getting ready to plant their winter wheat crop, especially those in southern Illinois and Indiana. “This is the perfect storm for winter wheat,” says Hart.

If the rains continue for a few days, he is hopeful it will soak into the ground, helping to get the moisture level back up. “Going into this year, you could dig down five feet in Iowa and still find no moisture,” he says. “My guess is that Indiana is the same, so Isaac is tremendous opportunity for some good soaking rain that will help next year.”

Hart is also optimistic that the humidity from Isaac may help to stem the drought. “Basically, the idea is that we get most of our moisture out of the Gulf of Mexico,” he explains. “If it crosses really dry land, it loses the moisture so the more humidity we get, the more chances for storms that are beneficial.”

The heavy rains will also help to replenish some of the area's rivers, where the dry conditions have caused shoaling in narrow channels. The Army Corps of Engineers has been busy dredging channels to keep the barges moving. “The rain should open up some shipping lanes that have slowed because of the drought,” says Hart.

The exception is that Isaac could cause some bottlenecks in New Orleans. On Monday, the Coast Guard said it will evaluate the river after Isaac passes to make sure passage is safe. In the meantime, the Port of New Orleans shut down until after the storm passed.