Cropping: 30 zero-till lessons learned

By DairyBusiness staff

Earlier this year, international pioneer for Zero Tillage (ZT), John Landers of Brazil, spoke to a group of farmers at Tom Barcellos’ ranch near Porterville. He talked about the advantages of adopting zero-tillage farming practices.

Barcellos has been involved in zero-till farming for several years and is considered one of the leaders of that practice in California and the West.

“We’ve reduced trips through the fields from 10 to as few as three,” said Barcellos, referring to planting, fertilizing, weed control and harvest.

“The expense of time, labor, equipment and fuel are cut significantly,” said Matt Kidder, who works closely with Barcellos. Kidder said this year they followed a wheat crop with zero-till corn for silage.

Landers provided the following 30 lessons learned during zero-till production and research with the system in Brazil. While some of his lessons learned are related to farming in the tropics, most all will translate into practices in North America.

Landers’ lessons include:

1. Adoption of Zero Tillage (ZT) must be on a soil with all physical and chemical limitations removed – hoe and plough pans especially need to be removed by cultivation.

2. Generation of adequate biomass (>6 ton/ha/yr) and vigorous root development are crucial to restructuring of soil, which takes time – old root holes and crumb structure accumulate and create high rainfall infiltration.

3. Long term fertilizer strategy should be to fertilize the system and not the individual crop – only attainable with high fertility status but gaining much planting time with no plant fertilizer.

4. Crop rotations must contain a gramineous summer crop for adequate biomass production – inclusion of a leguminous cover crop enhances carbon sequestration by removing nitrogen (N) deficiency;

5. Marking techniques for spraying must be adapted to the ZT situation, where wheel marks are indiscernible, especially in the wet-dry tropics.

6. Phosphorus and potassium status improve under Zero Tillage and should permit reductions in the use of these nutrients.

7. On the other hand, surface crop residues sequester nitrogen (when surface-applied) and N rates on maize and upland rice need to be increased by 25% to 30% in the early years of ZT.

8. Surface-applied urea suffers losses up to 70% without rain under ZT conditions in the tropics because crop residues may contain urease, which volatilizes the fertilizer as ammonia – N side-dressings should be incorporated.

9. Water economy under sprinkler irrigation varies from about 15% to 25% in tropical regions, depending on the thickness of the crop residue.

10. Diseases, pests and weeds are controlled in the first instance by rotations.

11. Integration of crops and pastures in a rotation reduces pest, disease and weed levels and increases total income and profit for both, also recuperating soil structure.

12. Low application rates of desiccant herbicides after the summer crop help reduce weed problems in the following second crop, with benefits for the next summer crop  –  such additional herbicide costs should be imputed to this crop.

13. Cover crops preceding main crops reduce and sometimes eliminate post-plant herbicide requirements, e.g., early millet before soybeans – only feasible on later planted crop.

14. Rolling of black or white oats  (Avena strigosa and A. sativa) between panicle initiation and the milk stage kills the crop without recourse to herbicide. This does not function with pearl or finger millet, with tillers of different ages.

15. Grazing or cutting of millets before panicle initiation provokes re-sprouting and tillering, “perennizing” the plant.

16. Soybeans can be successfully zero tilled into degraded or native pasture providing a small tine is used (12/15 cm deep).

17. Only 70% of soil cover eliminates most erosion – elimination of replanting and gullying reduce costs.

18. If the timing of entry into ZT coincides with the need for heavy replacement costs of tillage machinery or tractors, considerable economy can accrue to the non-purchase of this equipment and purchase or adaptation of ZT planters and/or drills instead.

19. Either plant immediately after desiccation (before green plants lose turgidity) or wait until the residue is dry and brittle – wilted green stalks are hard to cut and “hairpin” into the seed slot; this is more a problem of systemic herbicides.

20. Planting before desiccation is risky because if weather or breakdowns impede application until seedling emergence, the extra costs or yield penalties are high.

21. With considerable green matter being desiccated, planting should be delayed up to three weeks, to avoid alelopathic breakdown products from residue decomposition, especially of roots.

22. Decompaction should never be necessary with adequate biomass generation – in Brazil, with high biomass generation, a heavy clay soil has been continuously zero-tilled for 35 years and tests with subsoiling have been inconclusive.

23. In an extreme case where ZT was started without removing a hardpan, a chisel plough or subsoiler, fitted with a trash disc, will leave up to 70% or more of the residue on the surface.

24. Weed fallow is very variable and generates low biomass – it is a last resort.

25. Slug problems can occur under tropical irrigated conditions and sub-tropic conditions with high biomass – carbaryl or other baits are effective but labour intensive. A high amount of sugar in residues may encourage slugs – e.g. millet better than maize, try beetroot as a trap crop.

26. Maintenance liming can be applied on the soil surface and should be reduced compared to CT, max 1-2 ton/ha, depending on texture.

27. Over liming in surface applications leads to micro-nutrient imbalance (e.g. of manganese in soybeans or zinc in maize) this effect also appears to favor nematodes.

28.  Even distribution of residues is essential for good planting – use straw choppers when biomass is high, spreaders with low biomass – with windrows of residues plant diagonally to clear the planter/drill.

29. All problems are challenges to be overcome.

30. There are no limits to a farmer’s creativity.