Soil Moisture Differences in No-Till Crops

Speaker 1: And as soil moisture becomes a greater concern, no till cropping becomes more attractive. Earlier this year we met with extension soil and water conservation specialist Jason Warren to explain why.

Jason, here at [inaudible 00:0015] we’ve got quite a bit of research going with no till right here. Talk to us, what do we got here with these crops?
Speaker 2: Real quickly we’ve got some soy beans, corn, sun flowers, sorghum, some of which are double crop, some of which are full season, early planted crops, and then we have wheat. Some of these plots are in continuous wheat, cultivated continuous wheat and then some of them are in continuous no till wheat. What we’ve been looking at here recently in these plots is soil moisture content because we want to answer the question how do these more intense cropping systems such as double-crop soy beans or sorghum, how does that impact soil moisture and how will it impact the following crop, not only from a yield perspective but then to learn how moisture and the dynamics of changing soil moisture after rain fall events or after tillage impacts soil moisture for potential use by the next crop.
Speaker 1: And that’s something a lot of people have on their minds right now. We’ve had some really hot temperatures in the last few weeks, we’ve had some good rain falls earlier this week. What do we expect to see conventional to no till in terms of that soil moisture?
Speaker 2: One thing we’ve recently done is a data analysis on the no till continuous wheat versus the conventional tillage wheat. That allows us to look at the summer fallow period and see how we recharge that soil after the wheat comes off and how we lose water during these 100 – 105 degree days. What we find is when we till soils we open that soil up, we remove the surface residue and we increase evaporative water loss. In general an easy role of thumb is in cultivated land we can get, in say a two inch rain fall we get nice good infiltration, but then a week later we can have an inch less water in the top 15 inches due to evaporative water loss compared to the no till, and that difference will be maintained until it rains again, it recharges both systems to an equal amount and then we have a drying effect in the cultivated land that dries it out to a greater degree than our no till land.
Speaker 1: So we’re looking at a much more fluctuating system in the conventional.
Speaker 2: That’s really a good take home message is no till provides a more stable system with respect to soil moisture because you don’t get those dramatic fluctuations in soil moisture at the near surface.
Speaker 1: I guess it’s sort of an insurance system at that.
Speaker 2: To some degree yes it is. Even talking to producers, they’ll tell me that while their yields may not have increased but they very much stabilized compared to when they were in a cultivated system, but that’s even more important as we move westward. Here in Lahoma we’re right around the 30, 35 inch annual rain fall. As you move westward toward the Texas panhandle you get less and less rain fall and these kind of analyses become more and more important, particularly if you’re trying to intensify your crop rotation because as we move westward we need to depend more on subsoil moisture than we do as we move eastward. So some of these analyses become very important.
Speaker 1: What you’re saying with no till is that when you’re depending on that subsoil moisture you’re going to have more consistent year to year level throughout the cropping season.
Speaker 2: To some extent. Given that everything is equal and the only variable is tillage you’re going to have a more consistent elevated amount of moisture, and it’s mainly due to the surface soil drying out and wetting up and drying out during dry periods and rain fall periods. You don’t get that dramatic drying in no till that you do in cultivated systems.

Everybody can observe that when you cultivate, it dries out.
Speaker 1: Okay. It’s good information. We’ll be keeping an eye on it.
Speaker 2: All right. Thank you, sir.