Do Cover Crops Really Steal Moisture?

This article is based on Tyler Tobald’s “Cover Crops Use Zero Moisture” video. You can watch the video here. 

For years, Tyler Tobald wrestled with the argument that cover crops use up all the moisture for your cash crops. In 20 years of no-till and 15 years of cover cropping, he witnessed a different reality. Tobald farms in north central Kansas at JTAG Farms and finds that properly managed cover crops don’t actually steal moisture, they improve the soil water holding capacity. Unfortunately, this anecdotal evidence isn’t entirely convincing to many farmers so Tobald decided to gather some data. 

Putting Cover Crops to the Test

Tobald set up an experiment to monitor soil moisture levels on cover cropped soils using probes. He started on a 132 acre field that came out of winter wheat in mid-June 2025 with a solid 50-bushel crop. Following harvest, he planted a 55-species cover crop mix on July 9th and the field wasn’t treated with any fertilizer, herbicide or other inputs. Tobald mentioned this field has been in cover crop and no-till practices for the past 20 years as well. 

Two moisture sensors from Grow Guru were already buried in this field, measuring available water every 30 minutes from 6 inches down to 42 inches deep. One sensor, Lee's East, had the cover crop growing directly over it. The other, Lee's West, was a control area that Tobald kept sprayed down to bare ground all summer to mimic a fallow period and kill any living weeds that might skew the moisture readings.

Graphic 1: Moisture Sensor Data from Lee’s East field where the cover crop was grown

Graphic 2: Moisture Sensor Data from Lee’s West field where the ground was left fallow and any weeds were chemically terminated

Cover Crop = Livestock Feed

Tobald also planned to graze the cover crop. He ran 91 cow-calf pairs on this field starting November 30th, with cows averaging 1,300 lbs and calves averaging around 600 lbs. They grazed through a weaning period, a brief move to his parents' place a mile west, and back again before the cows finally came off January 5th.

Working through the animal unit math and forage intake estimates on the conservative side 3.5% of body weight for pairs, 2.25% for dry cows Tobald calculated roughly 125,000 pounds of forage consumed. That’s about 63 tons of forage produced by the post-wheat cover crop. 

Using Missouri Extension's silage valuation tool at $136 per ton, that's $8,524 worth of feed. Grown and harvested on-site, with no mechanical harvesting equipment whatsoever. The cows walked in, ate it, and left behind their own fertilizer.

The cover crop seed cost about $30 an acre, for a total of $3,960. Tobald acknowledges he's not counting planting costs, but argues those roughly cancel out against what you'd spend planting silage corn. And unlike silage, the cover crop left behind legumes fixing nitrogen, deep-rooted radishes mining subsoil nutrients, and rapeseed making phosphorus more available for the next cash crop. None of that showed up in the feed value calculation.

Evaluating the Moisture Sensor Data

At the surface level, Lee's West (bare ground) had 7.71 inches of readily available water at 92% full. Lee's East (cover crop) had 7.29 inches at 88% full. A 0.42-inch difference in favor of the bare ground. At 6 inches deep, Lee's East had 4-hundredths of an inch more water than Lee's West. At 10 inches, Lee's East was still ahead, by a tenth of an inch. It's only at 18 and 26 inches that Lee's West edges forward by 0.18 inches and 0.09 inches respectively, which Tobald argues are marginal differences.

The real gap opens up at 34 and 42 inches. Lee's West shows significantly more water at those depths. But there's a reason for that, and it has nothing to do with cover crops: Lee's East hits sand and rock just past 34 inches. It's a limestone hill. The sensors aren't comparing apples to apples at those depths, they're comparing two different soil profiles.

Strip out those bottom two levels where the soil differences make the comparison obsolete, Lee's East, the cover cropped side, actually has more available moisture than Lee's West by about two-tenths of an inch.

The bare ground lost more water to evaporation over the summer. With no canopy and no residue, the soil surface was exposed to sun and heat all season. Photos of the Lee's East transmitter show it buried under a thick, dense mat of cover crop, shading the ground, holding moisture and slowing evaporation.

The Bottom Line

Tobalt is careful not to oversell the numbers. He got 12 to 15 inches of rain from planting to turnout more than a typical Kansas summer, which probably explains why the cover crop grew tall enough to hide cows. While the cover crop probably won’t produce 63 tons of forage every year, it doesn't change what the sensors showed.

He's also clear that cover crops don't work everywhere the same way. Twelve inches of annual rainfall calls for a different plan than 36 inches. His argument is that a properly managed cover crop, one that gets killed by a hard freeze before it hits the grain-filling stage and draws down deep moisture reserves, won't rob the soil profile of valuable moisture. The crop builds canopy, adds tonnage, fixes nutrients, and then stops before it consumes more water than it’s helping preserve.

In 2026, Tobal plans to plant corn with GPS-guided yield mapping on both sides to see whether 15 years of cover cropping left the soil in better shape to produce a cash crop. The moisture sensors will keep running.

With the moisture sensor data, Tobald is more confident than ever that well managed cover crops don’t actually steal moisture, but rather help the soil conserve valuable rainfall for the upcoming crop.