THE CLIMATE KELPIE BLOG: Taking care of the soil takes care of the sugarcane business

Posted by BCG on 19th November 2018

For Michael Waring, a sugarcane grower in Queensland’s Herbert Valley, it is what’s happening below the ground that is the key to the future profitability and sustainability of his business.

“Improving soil health has been very important over the last 10 years. We started by introducing controlled traffic farming in 2009 and more recently have been experimenting with a broader range of fallow crops to improve the soil’s biodiversity. The bigger the range of microbes and other soil organisms, the better it is for the crop.”

Image 1. Michael Waring.

Controlled traffic boosts soil health

Controlled traffic has been a spectacular success in improving both the trafficability of the paddocks and the soil and crop health for Michael. It took several years to implement across the whole farm. “Each year we re-plant around 15 per cent of our land to new sugarcane. Unlike other industries that plant seed, sugarcane is planted as stalks (in 200mm sections called billets) and after harvest each year it regrows from the root system, as ratoons. Traditionally we get around six years from one planting, but it varies depending on the seasons and the how healthy the crop is.”

Since implementing controlled traffic, his soil structure has improved dramatically. “In the past we would have machinery travelling over most of the paddock. With a 24-tonne harvester, it’s detrimental to the crop as well as the soil. Our soils are now more friable and the cane crops are healthier. We have found that the ratoons are lasting longer on controlled traffic. We don’t need to fallow the land as often.”

Climate forecasts influence management plans

Forecasts remain an important part of Michael’s planning for planting, spraying and fertiliser decisions. “When it is a dry year like 2018 we can afford to take a risk on skipping the pre-emergent herbicides. In an average or wetter year, it is important to get the pre-emergent herbicides out straight after planting to provide grass weed control for two or three months in case we can’t get back on the paddock.”

In a dry year Michael prefers to use knockdowns as needed after planting because he knows that he can get onto the paddock to spray if required. Controlled traffic has helped with this both by improving trafficability and reducing the potential to damage crops when spraying after a rainfall event.

Michael uses the Bureau of Meteorology’s 5-day forecast and their seasonal outlook as well as the local two-month forecast from the Herbert Cane Productivity Services.

One chance to reduce nematode numbers

In the last few years Michael has become a lot more interested in what lives beneath the soil surface. One of the drawbacks of growing one crop for six years straight is that it limits the soil’s biodiversity. After participating in a local Natural Resource Management group meeting on soil microflora, Michael decided he could do a lot more to improve his soil health and attended the Australian Biological Farming Conference in 2016.

Michael wants to reduce the number of nematodes, such as the root rot nematode and the root lesion nematode, that can build up and damage sugarcane roots. He has started to experiment with a more diverse range of fallow crop species to improve the soil’s biodiversity.

”During the fallow season, between removing the old ratoons and planting the new cane crop, we usually plant a fallow crop to keep the soil covered and ideally to add back some nitrogen. In the past we have relied on cowpeas or soybean as a fallow crop because they fix nitrogen and are resistant to root lesion nematode.”

‘We’ve been trialing different mixtures of fallow crops to see what will work in the wet tropics.’

One mixture that has been working well is soybean, sunflower and Sunn hemp. Sunn hemp is a legume so it will fix nitrogen and is also showing promise in reducing root knot nematode numbers. Michael says it is still a work in progress. “You need to get the ratio right so that one crop doesn’t smother another one.”

Image 2. To improve soil health Michael has been trialing fallow crop mixtures, such as soybean, sunflower and Sunn hemp.

Reducing nitrogen without reducing yield

In 2014, Michael was able to experiment with reducing his nitrogen fertiliser rates with support from the Federal Government’s Reef Trust. Nutrient runoff is a significant cause of damage to the Great Barrier Reef and has been a focus of the Australian and Queensland governments’ Reef 2050 Plan.

Michael was one of 14 cane growers that participated in Reef Trust Phase 1  – a reverse tender where farmers enter a contract to reduce nitrogen inputs by a set amount each year. He took on a three-year contract to reduce nitrogen inputs by an average of 20 kilograms per hectare. “We only have three years of data, but so far it does not seem to have cost us in yield. Our 2017 harvest was the best we’ve had since 2008, and this year’s crop (2018) should be similar. Both were grown on 120 kg/ha of nitrogen, rather than our old average of 140 kg/ha.”

“We plan to continue using 120 kg/ha. For us having good nitrogen fixation during fallow is an important part of that system. A good soybean crop will usually produce 250 kg/ha of nitrogen when left unharvested. If soybean is only half of our fallow crop mix we should still get 125kg which is enough to supply that first year of nitrogen for the cane crop.”

 

Learn more about Michael’s approach by reading his Climate Champion profile from 2013.

Michael Waring, 0428 771 361, michaelw@terrain.org.au