Reduced Tillage in the Fraser Valley

For the first time, several Fraser Valley corn producers attempted to grow corn with reduced tillage this year . The fields varied in soil type, amount of tillage used and previous crop and so did the results.

In preparation for corn planting, most farmers plough, disc and harrow their fields, working the field 3-6 times. The intention of this ‘conventional’ tillage is to eliminate weeds, prepare a good seed bed, loosen the soil to help corn roots grow, eliminate compacted areas and level the surface. Loosening soil can also help it dry faster and a drier soil warms up more quickly.

The effect of tillage on seed bed deserves some consideration. Corn seed is large and requires a planting depth of 2.5-6 cm (1-2.5 in) with good soil contact all around the seed. Corn planters are designed to cut a groove into the soil, deposit seed into the groove, then cover the groove. These planting operations are more easily accomplished in a cultivated field with loose soil.

In un-tilled fields, a cutting disc mounted in front of the openers assists penetration into the soil and cuts through trash on the soil surface. However, even more difficult than opening the furrow is closing it. Corn seed in an open furrow is exposed to birds and rodents and will not absorb water rapidly.

At Agassiz, we have found that the solution to closing the furrow is to cultivate a narrow (7 cm or 3 in) band of soil prior to creating the furrow. This is accomplished with special concave and fluted disks, mounted in front of the openers (see photo). The depths of the disks must be set to match seeding depth, so that the seed furrow can be easily closed by the packing wheels. Because of this cultivation, we prefer the term ‘minimum-till’ to ‘zero-till’. Overall, seeding must be done more slowly in un-tilled than in tilled soil.

On the coarse-textured soils at the Pacific Agri-Food Research Centre at Agassiz, minimum-till corn has consistently yielded as well as, or slightly better than, tilled corn. Also, the minimum-till corn matured earlier and contained more grain. In other regions, performance of minimum tillage has improved over years .

How well did reduced tillage work on Fraser Valley farms in 2001? In two side-by-side comparisons by a farmer near Rosedale, yield, maturity and grain yield were somewhat better for reduced-tilled corn than conventionally tilled corn. This farmer had a bumper crop of 20 t/ha of dry matter (9 T/ac) with over 27% dry matter content. ‘Reduced tillage’ in these fields meant reducing the number of cultivations rather than ‘minimum-tillage’.

On a nearby farm, corn grown with no tillage yielded 30% less than with conventional tillage (11.7 vs 17.4 t dry matter /ha or 5.2 vs 7.7 T/ac). This fine-textured field was planted with a planter that did not have the ‘cultivating’ disk (see photo), so the furrows were left partially opened. The same type of planter was used in south Rosedale to plant corn directly into winter wheat stubble sprayed with Roundup. Uneven germination in this field caused the farmer to cultivate and replant. This farmer planted corn directly into winter wheat in another field that ranged in texture from heavy to light. A side-by-side comparison of no-till and conventional tillage on the lighter part of the field produced almost identical yield, dry matter and grain for the two management systems (15.4 t dry matter/ha or 6.9 T/ac with 26% dry matter content).

A sandy field near Chilliwack emerged well, had few weeds and produced a respectable yield of 15.9 t/ha (7.1 T/ac) at 28.0% dry matter and just under 40% grain. The farmer states that he is pleased with the overall results but suggests that headlands should be tilled to reduce compaction.

What are the lessons learned from the 2001 experience? Planting corn with reduced tillage seems advantageous. Planting minimum-till must be done carefully with the right tools so that seed placement is uniform and seed furrows are well covered. More testing needs to be done under different soil and cover crop conditions.

S. Bittman, AAFC, Agassiz.

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