Question for Soil Scientists / Agronomists / Farmers About Rain on Nearly Frozen or Frozen Soil

[Chitowncy]

I was wondering if the rain last night / early today "soaked into" the ground or did it mostly run-off into our waterways and cause more erosion? It seems the ground is generally dry and could use more moisture, both for farmers and natural areas or even people's lawns. When the ground seems like it's nearly frozen - and this map suggests soil temperatures around central Iowa were 33 degrees Farenheit https://mesonet.agron.iastate.edu/agclimate/soilt.php - does that act as a defense or shield prohibiting water from soaking in like we sorely need around central Iowa?

I was hoping this rain arrived before the ground would freeze as it always appeared to me that rain, however rare, on frozen ground was often briskly washed into gulleys and waterways and could even lead to flash floods in our man-made world where we just have more and more concrete, and also not enough no-till and conservation practices to protect and preserve soil. It was almost like the ground was impervious once it was frozen.

That's just my general and anecdotal observation though that it appeared the gulleys and streams were full this morning after the heavy rain, so I wanted to know what the experts on here would say about the rain yesterday / today. Was it good and did it "soak-in" to the ground or were the benefits lost and it mostly just quickly flushed off the land due to nearly frozen or in some cases frozen soil?

Would love to hear the expert opinions on this topic.

 

[BCClone]

The top of the ground is frozen so most is generally running off. The warmer rain might thaw a smidge of the top out where the snow cover is gone so a little might soak, but not much. Erosion should not be a concern since the ground is solid. I'm located along the MN border so I can't speak for southern or central iowa.

 

[BWRhasnoAC]

Can't be frozen that deep can it? We haven't been that cold for very long at least here in Iowa. It's been pretty mild besides that ridiculous crap we had come through.

 

[Agclone91]

Can't be frozen that deep can it? We haven't been that cold for very long at least here in Iowa. It's been pretty mild besides that ridiculous crap we had come through.

Dry soil freezes faster than wet soil, and we are plenty dry. NWS shows ~8" frost depth by Camp Dodge as of 1/2.

 

[8bitnes]

First 2-3" in the corn and bean fields were real sloppy yesterday as they soaked up some of it, but ground was solid beneath that. Also, the rain came across a 12+ hours long event so runoff and erosion will not be too awful. It definitely helped more than it hurt

 

[isufbcurt]

Hopefully it's running off to fill my upper pond back up

 

[Chitowncy]

Dry soil freezes faster than wet soil, and we are plenty dry. NWS shows ~8" frost depth by Camp Dodge as of 1/2.

Interesting. So, what my intuition tells me probably happens when the ground is completely frozen (like in a typical late January) and a rain occurs, it will just run-off without soaking in much, correct?

Love all the diverse experts and knowledge on this board. Thanks in advance, amigos.

 

[CyCrazy]

Interesting. So, what my intuition tells me probably happens when the ground is completely frozen (like in a typical late January) and a rain occurs, it will just run-off without soaking in much, correct?

Love all the diverse experts and knowledge on this board. Thanks in advance, amigos.

Yes, my yard in Ames is thawing out, my sump pump is running quite a bit.

But yes frozen dry soil will always lead to runoff.

 

[Agclone91]

Interesting. So, what my intuition tells me probably happens when the ground is completely frozen (like in a typical late January) and a rain occurs, it will just run-off without soaking in much, correct?

Love all the diverse experts and knowledge on this board. Thanks in advance, amigos.

There's always other factors that can come into play, but yes, generally speaking your thought process is accurate.

 

[cycloner29]

Been a lot of wind erosion. All the snirt (snow and dirt) you see driving on roads where the snow drifts look black.

 

[JM4CY]

Been a lot of wind erosion. All the snirt (snow and dirt) you see driving on roads where the snow drifts look black.

Why aren’t more people talking about this? This feels way worse than most years. Probably due to that week of bad wind. The front of my house is beyond filthy.

 

[KidSilverhair]

Why aren’t more people talking about this? This feels way worse than most years. Probably due to that week of bad wind. The front of my house is beyond filthy.

I’ve done a bit of driving between CR/Fairfield/Ames/Boone this past week, and the amount of topsoil I’ve seen blown into the ditches on top of the snow is distressing. I thought current farming practices were designed to prevent a lot of that?

 

[cowboycurtis]

I’ve done a bit of driving between CR/Fairfield/Ames/Boone this past week, and the amount of topsoil I’ve seen blown into the ditches on top of the snow is distressing. I thought current farming practices were designed to prevent a lot of that?

It really sucks to see all that dirt blowing in the ditch. It was a really bad combination of not much snow cover and 3 days of terrible wind. 30 years ago the ditches would fill with dirt all the time. Now we don’t see it that often, took a crazy amount of wind. There is way more residue on the surface to stop runoff and wind erosion than 30 years ago.

 

[Stormin]

Rain and snow in winter are beneficial for recharging the soil water table. Ground can be frozen and runoff can occur. But those runoffs refill our creeks and rivers as they melt. As the soil warms and the snow melts, that now unfrozen soil acts like a sponge and sucks up water. Tillage today utilizes residue and the uneven surfaces that result from the tillage. The openings created trap moisture and snow for infiltration rather than runoff. We are much better off today than in years past because of conservation tillage and residue management.

 

[AuH2O]

I’ve done a bit of driving between CR/Fairfield/Ames/Boone this past week, and the amount of topsoil I’ve seen blown into the ditches on top of the snow is distressing. I thought current farming practices were designed to prevent a lot of that?

It does, and had we had this combination of dry weather and wind 30 years ago it would’ve been way worse. There’s still too much old school tilling, but it’s way better than it used to be. When I drive up north I see some really bad fields, hilly, stripped clean of residue. Thankfully those are more the exception than the norm. However, it should never happen, and should be illegal.

 

[BCClone]

It does, and had we had this combination of dry weather and wind 30 years ago it would’ve been way worse. There’s still too much old school tilling, but it’s way better than it used to be. When I drive up north I see some really bad fields, hilly, stripped clean of residue. Thankfully those are more the exception than the norm. However, it should never happen, and should be illegal.

I file a manure management plan with the DNR every year. While I rarely moldboard plow, (I will do it every great once in a while if trash gets too heavy due to being continuous corn) my plan has it in to cover myself. All the models that are ran that I'm required to submit, show that I could moldboard plow and would still be creating topsoil. So those 7 out of 8 years that I don't, means I'm HIGHLY restoring topsoil to the earth. So lets be careful on broad brushes.

 

[NWICY]

Been a lot of wind erosion. All the snirt (snow and dirt) you see driving on roads where the snow drifts look black.

Lack of snow cover then multiple days if 30-40 mph winds will do that. The snow before Xmas might have been 2 or 3 inches in my area but it really just blew into big drifts once it found something to catch against. Driving hwy 20 in Central Iowa the only snow cover left is in the fence rows and ditches. Fields are basically bare again.

 

[BCClone]

Lack of snow cover then multiple days if 30-40 mph winds will do that. The snow before Xmas might have been 2 or 3 inches in my area but it really just blew into big drifts once it found something to catch against. Driving hwy 20 in Central Iowa the only snow cover left is in the fence rows and ditches. Fields are basically bare again.

Snowing here right now. We definitely have snow cover, not a lot but still have it.

 

[AuH2O]

I file a manure management plan with the DNR every year. While I rarely moldboard plow, (I will do it every great once in a while if trash gets too heavy due to being continuous corn) my plan has it in to cover myself. All the models that are ran that I'm required to submit, show that I could moldboard plow and would still be creating topsoil. So those 7 out of 8 years that I don't, means I'm HIGHLY restoring topsoil to the earth. So lets be careful on broad brushes.

I'm referring to some specific sites that I see as I get through Hamilton, Webster, and Kossouth Co. mostly. Some big, bare slopes close to drainage. Whether it meets a DNR plan or not, it's common sense that some of these that I see are runoff nightmares. Now we see WAY less of this these days, which is great. But these are obvious problems that have great public cost.

And there are two aspects to consider. There's the rebuilding aspect, which is important, but there's prevention of the nutrients and sediment loss to water bodies in the first place.

Frankly based on some of the things the DNR puts out publicly from time to time, it seems like they are treading lightly in terms of water quality statements. But when Naig describes calling out phosphorous levels in rivers "propaganda" it's not hard to see why.

Practices have come a long way, but there is so much more uninterrupted land in production now that it isn't enough. The benefits of having way more small farms with more groves and even fence lines breaking things up is greatly understated in my opinion. Practices have gotten better, but we aren't seeing the results in the water quality.

 

[Turn2]

Rain and snow in winter are beneficial for recharging the soil water table. Ground can be frozen and runoff can occur. But those runoffs refill our creeks and rivers as they melt. As the soil warms and the snow melts, that now unfrozen soil acts like a sponge and sucks up water. Tillage today utilizes residue and the uneven surfaces that result from the tillage. The openings created trap moisture and snow for infiltration rather than runoff. We are much better off today than in years past because of conservation tillage and residue management.