The U.S. 2016 spring crop sowing campaign is officially underway and corn is already behind schedule, with recent heavy rains being the likely culprit.

On Monday, the U.S. Department of Agriculture reported that corn planting progress is significantly lagging average pace in the southern Mississippi Delta states, including Arkansas, Louisiana, and Mississippi.

In Arkansas, 8 percent of the corn crop has been seeded thus far against a 5-year average of 20 percent. Louisiana's 36 percent falls far short of the 61 percent average and Mississippi has only been able to plant 5 percent of the corn crop compared to an average of 29 percent by this week.

Although the Delta states account for less than 3 percent of U.S. corn production, the start of the spring sowing campaign is always important because it sets the tone for the growing season for the world's biggest producer of corn and soybeans.

Planting pace is crucial every year because it dictates both planted area of each crop and the expected timeframe of yield formation. If corn seeding is delayed sufficiently, farmers may decide to plant soybeans or something else instead, since the growing season for corn is very specifically timed.

Late-planted crops also put a lot of pressure on the harvest because if crops are late to develop, then harvest time will also be pushed further into the autumn, during which the risks of frost or freeze are much higher.

The delay to corn progress in the Delta will be a bigger problem if it translates into their soybean planting window, as Arkansas, Louisiana, and Mississippi account for 9 percent of U.S. soybean production.

The U.S. growing season will be in even further trouble if planting delays begin to surface across the primary corn and soybean states, which at this point in time, is a very real possibility given current conditions and the weather outlook.

When Are the Crops Planted?

Both the pace and timing of U.S. spring planting is mostly dictated by the weather, so progress varies year by year. Of the two primary crops, corn is planted first as it has a shorter planting window.

Typically, corn planting begins in early March in the minor-producing southern states, including Texas and the Delta. The heavy-hitting corn states in the Midwest usually begin in the second or third week of April, and the last week in April is a common start for the northernmost states such as the Dakotas. For the most part, corn planting concludes at the close of May (http://tmsnrt.rs/1oiMGqd).

Soybean planting can proceed as soon as corn is wrapped up. Southern states tend to begin their efforts in April, while planting tends to ramp up in the major states during May. Soybean planting is usually finished by end-June with the wheat-to-soybean double-cropping states in the eastern belt bringing up the rear (http://tmsnrt.rs/1oiMF5P).

Between now and the end of November, the USDA's National Agricultural Statistics Service (NASS) will report planting, growth, and harvest progress every Monday by state. We will not get a gauge on corn progress in major states until that begins, which is likely to be the second or third week in April.

When sowing is delayed, sometimes that means that reporting on the crop is delayed, too. So there is a chance that we will not have a solid national picture of corn planting progress for another month if planting is significantly pushed back in the primary corn growing states, such as Illinois and Iowa.

Active April Could Spell Delays

More spring crop sowing disruptions could be in store across the Midwestern crop belt as April is shaping up to be quite active weather-wise.

Earlier this month, the atmosphere was thrown out of balance by a polar vortex collapse. As a result, storm-inducing low pressure systems will track across the United States more frequently than normal through at least the first half of April.

This could mean that a lot of rain is on the way, but whether it will hamper planting depends on frequency and intensity. Advanced technology and machinery permit farmers to seed cropland quickly, usually allowing them to successfully shoot the gaps of springtime rainstorms.

But even the biggest, fastest planter is no match for a waterlogged field. And given the current state of the soils in part of the Midwest, it would not take an extraordinary amount of rainfall for fields to reach swamp status.

Record or near-record December precipitation ensued across the Midwest, and even though it has been less wet since then, soil moisture still stands near the highest levels in over 30 years in lead corn- and soybean-producing state Iowa and surrounding areas.

Moisture levels are not as extreme in Illinois and points east, but since there are hardly dry soils to be found anywhere in corn and soybean growing states, any amount of persistent spring rainfall could quickly escalate the situation (http://tmsnrt.rs/1RoquW9).

Delta region soils will be soggy again at the end of this week as a storm system is scheduled to sweep across the eastern United States, bringing moderate rainfall to most states east of the Mississippi (http://tmsnrt.rs/22WOYuQ).

Although corn planting will not be in full swing across the United States for another couple of weeks, if a wetter pattern sticks around until then, the primary growing states could run into the same issues that are already present in the south.