33
January 2014
Conditions for a successful
adoption of no-till
(Derpsch, 2013)
1. Make sure you use proper seeding technology.
2. On degraded soils, consider a transition through reduced tillage.
3. Produce enough crop residues (>6 tons/ha) and ensure even distribution.
4. Ensure system specific weed control.
5. N-application should adapt to the different nutrient dynamics.
6. Perform systematic and continuous monitoring of the fields.
7. Apply diversity to your rotations.
8. Take advantage of the experience of other producers.
9. Develop creativity and improve the system constantly.
10. Have a positive attitude towards problems. All problems are challenges that can
be overcome.
Q: What is your opinion on row-width and plant population?
A: More soil water will allowmore plants. A slight increase will be possible,
but it depends what you want to achieve. Higher plant population and
better space distribution will give better growth of plants.
Q: What about Sclerotinia: Does CA influence it positively or
negatively and how should it be managed?
A: A monoculture soybean practice is a problem. You must investigate or
consider “stacked rotations”, e.g. two year-two year-two year per crop to
eliminate very persistent diseases. Increasing the carbon content of the
soil will enhance biological control.
Q: Is glyphosate harmless?
A: It is not as harmless as it was thought to be. A recent study in Germany
showed that you need at least two weeks between application and
seeding (of non-Roundup Ready crops). Producers should not rely too
much on one herbicide. Crop rotation forces you to also rotate herbicides,
which you need to aim for.
Q: What is a typical root distribution pattern under CA?
A: Research in Brazil investigated root systems between conventional and
CA systems. The results showed that roots in CA systems are more even
and deeper, as compared to conventional till where roots concentrate on
the upper 20 cm (see
photos
). Researchers and producers should look for
deep-rooted crops and cover crops to produce a lot of vertical channels
in the soil.
Q: Why do we apply more nitrogen (N) under CA during first few
years?
A: There is a lack of N due to immobilisation in CA; tillage increases
mineralisation and quick availability of N. A good practice is to apply
an additional 30 kg/ha of N during the first five years, then the normal
recommended levels after five years. After 20 years of continuous CA and
returning enough biomass to the soil, N rates can generally be reduced.
Q: Should we plant with fertilisers or broadcast in CA systems?
A: After soil has reached equilibrium (balanced nutrient status),
broadcasting is possible. Another possibility is to fertilise those crops
that highly respond to fertilisation (e.g. maize) with a double rate in the
row and not fertilising for instance soybeans that do not respond so much
on direct fertilisation, but take advantage of residual fertilisers in the soil.
The next edition of the CA dialogues with Dr Derpsch will cover the
second event held in Bothaville.
Maize planted in black oats, South America.
No-till soyabeans in maize residues, A de Villiers, South Africa.
Dr Rolf Derpsch
