Published August 26, 2019 | By Mike Petersen
Tillage by a tractor pulling some sort of an implement has its ramifications, good or detrimental. Earthworms also in a manner till the soil, they are tunnelers seeking other critters (nematodes, amoeba, fungi, bacteria, and protozoa) as food sources along with exuded proteins, sugars and carbohydrates of all kinds left from plant roots.
I have been reading partially for recreation and also to bring you more “soils stuff” from written materials that I subscribe to or access via libraries [call me old fashion] or get via interviewed articles in Agricultural magazines. So I read some incredibly interesting information from Dr. Paul Hepperly a scientist that has had a tenure at The Rodale Institute, Ohio State University regarding worms that live and work in our soils.
1. Worms love soybeans, high nutritive value
which aids in worms in reproduction and vigorous life
2. Plowing is very hard on worm habitat – usually 50% less populations than conservation tillage systems.
3. Worm castings aid in carbon sequestering and stabilizing carbon in soils – castings are up to 26% carbonaceous material.
4. Worm castings are rich in calcium which is important to nutrient uptake from roots.
5. In moderately acid to acid soils calcium is important to helping soil structure and aggregation
6. Worm castings are rich in iron in an available form, chelated
7. Earthworms lay cocoons which contain 1 to 5 eggs
8. Each cocoon goes through a gestation period of 1-5 months depending upon worm species
9. Baby worms hatch, are active immediately and become sexually mature within 3-12 months
10. Worms can produce 10 pounds of organic amendments in 1 season
11. Worms are active 2 times during a year; spring and then when soils cool back down after a warm summer – they prefer soils that are 48 to 63 degrees F.
12. Synthetic fertilizers can be detrimental to worms and toxic – especially ammonia
13. Nitrogen in the worm castings is in the nitrate form rather than ammonium
14. In acidic soils liming will aid worm populations, reproduction and worm activity
15. Manuring when possible greatly aids the population of earthworms, both the vertical and horizontal burrowing worms due to the enrichment of animal gut species of microbes passed out thru manure.
16. Worms recycle manure into the soil beyond the soil surface taking it deeper into the soil profile
While we were out this spring (May and June) getting data to study soil compaction in very moist soils, we did some worm counts per square foot. Strip Tilled soils at least 5 years running we were counting 10 to 18 worms. Direct Seeded fields (No-Till) we counted 12 to 20 worms per square foot. In the Conventionally tilled soils, so many less, 1 to 9 worms. We also found worm cocoons, the most we found in the strip tilled fields, 2 to 7 cocoons/sq.ft.. Now one has to be looking very closely when you dig to see the little cocoons. See the picture below.
As you can see with the man’s fingers the cocoons are quite small, probably 3/16ths of an inch up to 1/4 inch. They are usually laid in the upper 10 inches of the soil profile in a warm environment but not hot. I have seen earthworm cocoons not fair well in soils that reach 110 to 140 degrees F.
A wonderful scientist from Quebec, Odette Menard affectionately called ‘The Earthworm Lady’ whom I have met and had long discussions personally has studied earthworms at night being sexually active on the soil surface in a variety of soil residue conditions and all the incredible tunneling they do. She has said “Soil health isn’t just about the chemical make-up,” says Ménard. “The challenge is to talk about the soil with respect to its physical and biological properties.” And that’s where earthworms become important. These creatures help to aerate the soil, build and maintain soil structure, increase hydrology, improve nitrogen efficiency and reduce pests and diseases. Ménard also says farmers often worry earthworm tunnels will increase the chance of nutrient leaching within their soils, but that’s not the case. In fact, since earthworms stay close to living plant roots – often within one inch – their tunnels support overall root development. “More holes in the soil means the soil is actually in better shape,” she says. “And the better the soil, the more root development, counterbalancing leaching.”
For all of us to realize that with Strip-Till we can aid worms in their effectiveness in our soils. It has been studied in the last 3 years that cover crops in No-Till and Strip-Till systems even provide more gains to growers in all kinds of climatic environments. A couple years back when we at Orthman had the Bill Orthman farm as a experimental station to study strip-till effects for the beneficial fact finding and support of the Orthman Strip-Till Method; I carried out earthworm counts with a couple of our interns. We were 6 years into Strip Tilling at the time and we were counting 15 to 32 earthworms per square foot, calculate that out per square yard using the average of what we counted, that is 620 worms being busy. That is 3,005,640 worms per acre folks if everything stayed equal. That is one whale of a lot of worms. We also measured that summer soil infiltration rates; strip-tilled soils with high numbers of earthworms in those clay loam soils was 2.95 inches/hour compared to the normal USDA-NRCS Soil Survey data at 0.6 inches/hr. for a clay loam soil. The advantages of combining worm tunnels and strip-till which is much less disturbing than conventionally tilled soils with plows or disk-ripper implements and a field finisher of some sort.