Compaction, cover crops and corn

No tillage has been in place from the 1970s in Brazil and cropping varies depending upon location. The south is very different from this region and height above sea level has a huge effect on climate.  Cuiaba was one of the stop over points on the way up and is only 150 metres above sea level, meaning the heat is quite intense compared to Sorisso which was 400 metres above.

I really wanted to understand what some of these farms have experienced under long-term no-tillage as I considered this would be a good barometer of what effects and benefits there are.  I wasn’t expecting compaction to be an issue, but it was something that appeared to be concerning the best growers and ignored by others.  With sufficient rainfall compaction is less of an issue, but it’s the drought periods that bring the concern, which are becoming slightly longer, and poor root structure hitting compacted layers restricts the access to nutrients water.  This was abundantly clear with some of the root structure of the previous bean crops, roots reaching 10-12 cm and then traveling sideways as the layer was too tight for the roots to penetrate.

Compacted Soil

Above:  Compacted soil layer around 10-12 cm depth.

One supplier I am working with has some great technology and varieties of both corn and soya, but the refreshing approach I found was that they want to see their growers achieving the best performance possible with their products, not just selling seed. One of the team leads I met with had a real passion for soils and soil structure and felt it was important to train their sales team to look closely at soil structure and dealing with compaction. But he wanted them to communicate this to their clients if there is a problem to try and look at how to resolve it to maximise the crop potential. Great commitment to the bigger picture and certainly not something I’ve encountered when it comes to seed sales very often before!

Brachiaria is a widely-grown cover crop used in corn and soya rotations to help improve structure due its root system and also it has the ability to hold on to moisture in the soil (not so much of a problem on my clays in the UK), but it has phenomenal growth rates and grows after the corn has been harvested.  It also can scavenge for nutrients from depth, particularly potassium and nitrogen and it certainly appears to have a role in low fertility soils or where retaining moisture is a problem.   It wouldn’t suit the southern region due to the lower temperatures, but clearly has a prominent role in this region and can be blown in to standing crops.  Nematodes are a big issue for soya beans and this is where crotalaria fits in to the rotation, as it can be planted the same time as the second crop of corn to benefit the following soya crop in the rotation by disaffecting host plants.  Different covers for different reasons.

Some Of The Mato Grosso Team

Above: some of the Mato Grosso team.

I mentioned the ability to grow three crops in one season in my last blog and most people I have met can’t believe we take nearly a whole year to grow one!  I was fortunate to see the growth rates of some of the corn varieties under centre pivot irrigation and it was quite a revelation to see crops at 10, 20 and 30-day growth stages and how fast they grow. The speed of development of some of these varieties is not only phenomenal but it allows them to grow away from problem pests at a far quicker rate than a more standard conventional type.

Below:  Corn 30 days from planting!

Corn 30 Days From Planting

Another fascinating week of visits and I really started to appreciate the vastness of the farming landscape when there is currently 9 milllion hectares of soya beans grown in the Mato Grosso, with a forecast of 12 million by 2022.   It is fairly clear to see the massive potential in Brazil, but there is also a common theme amongst all countries that the race to develop and preserve new technology just gets faster.

Next time: Into the Goias and Minais Gerais states to meet no-till pioneers and discover their keys to success.



Russell McKenzie farms 750ha on predominantly heavy clay on the border between Cambridgeshire, Bedfordshire and Northamptonshire. He grows seed on contract as well as soft and feed wheat, and his usual rotation is wheat, OSR and spring beans. A Nuffield Scholar, Russ has been researching direct drilling in extreme weather in 2013 and 2014.