It will probably come as news to many farmers and pure shock to others. But long-term no-till usually solves, rather than causes, soil compaction problems.
That's the bottom line of a recent five-year study examining no-till and soil compaction by University of Kentucky (UK) soil scientists.
“A lot of farmers have been concerned that, with tractors and other heavy loads, you get some compaction in no-till as in conventional till. But you never work it out with tillage, so it would build up in time,” notes Lloyd Murdock, UK soil scientist.
“From what we have found in our studies, that just isn't true,” the veteran no-till researcher adds. “The fact is, no-till soil is more resistant to compacting, and it rebounds more quickly than conventional-till if it does get compacted by heavy trafficking when it's wet.”
Why? First, no-till increases organic matter in soil dramatically, greatly increasing the number of earthworms that tunnel the soil. It also increases numerous other biological activity by organisms.
Soil structure improves because the system of soil pores improves. And those pores aren't destroyed by tillage. No-till soil becomes strong enough to reduce crushing, which translates to compaction. It's also firmer, enabling it to carry heavier equipment loads.
In the study, some treatments were severely compacted to a depth of 12"; others were left untouched. In compacted treatments that were tilled, soil was disked, removing compaction to a 6" depth. In no-till treatments, crops were planted into the severely compacted ground.
Predictably, the first year was a disaster for no-till, with only a 2% yield of what it was in non-compacted areas. In the tilled treatments, yield was about 75% of the non-compacted area.
The second year, no-till areas recovered rapidly, yielding 80% of the non-compacted area. That jumped to about 90% the third year. It remained in the low 90% range the final two years of the study.
It took the tilled treatments until the third year to reach 80% and the fifth year to reach about 90%.
“Actually, the no-till recovered from the very severe compaction faster than where it had been tilled,” Murdock points out. “I imagine further recovery above the 90% level will be slow in both cases. But the facts are that no-till recovers from compaction faster than conventional till and resists compaction more effectively in the first place.”
That's no news to veteran no-tillers. Consider Richard Dickinson, who now farms with his son, Paul, near Guthrie, KY. He started working into no-till about 30 years ago.
“I can't say that I've noticed a compaction problem with no-till,” Dickinson says. “I believe that if you use continuous no-till on 100% of your ground, the soil structure will improve and take care of itself. That's what I've observed.”
Dickinson admits to cheating a bit some years back — he worked down corn stubble to sew winter wheat into in the fall. He then wised up and started no-tilling his wheat, too.
“Now, I believe we were shooting ourselves in the foot by working those corn stalks. Since we went 100% no-till, the soil benefits began to show up. By tilling those corn stalks, we were destroying much of what we built up with the no-till.”
Dickinson and Murdock both urge farmers new to no-till to be patient.
“It takes time for soil structure to improve with no-till. You may experience a bad first or second year,” Dickinson says, “but if you stick with it, you'll start to see the real benefits.”