Fallow crops for cane farms in North Queensland

Fourth-generation Mossman cane farmer Clint Reynolds has been planting mixed species crops for three years, building on more than 15 years of results from standard cover-cropping on Daintree and Mowbray Valley properties.

The Reynolds' trialled a five-seed mix of tillage radishes, ebony and meringa cowpeas, soy beans,sunflowers and centrosema last year on their 526 hectare Daintree farm and they will also be using sorghum and lab lab this year.

"Up until three years ago we planted fallow crops of legumes or soya beans," Mr Reynolds said.

"While that is better than leaving the ground bare, we were replacing a monoculture with a different monoculture."

Mr Reynolds said he had been to forums and spoken to other growers using mixed species the results spoke for themselves.

He said he was pleased to find earthworms in his sandy soils

recently, and good levels of organic carbon matter.

"The different species bring different benefits," Mr Reynolds said.

"The biggest difference has been in our sandy soils.

"Recent soil tests have confirmed organic carbon levels of 1.8 per cent following one mixed species fallow crop, and we've found earthworms in and around the cane stools.

"That's something we've never seen in our sandy soils. It makes you think you must be doing something right.

"We're planning on cutting back from 140kg to 120kg of bagged nitrogen per hectare this year on the back of our results."

Mossman cane growers Gerard Padovan and Brett Coulthard are also planting multiple species.

Mr Coulthard is using meringa, black stallion and ebony cowpeas, and different varieties of sunflower seeds, after decades of planting either one variety of cowpeas or soya beans.

"This is our second year - the main goal is to try and get more carbon back into our clay soils,'' Mr Coulthard said.

"Another benefit is increasing the strike rate in severe weather conditions."

Mr Padovan's family is trialling a mix of sunflowers and ebony cowpeas on 20 hectares of the farm and are in the process of adding a bean planter to their bed former to reduce the number of passes required once fallow cropping is added to the mix.

"Our mixed fallow was planted four months ago and it is doing its job,'' Mr Padovan said.

"The sunflowers have come through and died off, the beans are still in the ground and we'll be leaving them in as long as possible so the plant cane can feed off the nitrogen.

"Next year we'll be looking at four or five species."

Wet Tropics Sugar Industry Partnership's Laurent Verpeaux said the results were encouraging for farmers.

"Growers only have four to five months in cane crop cycles that can span five to 10 years in this district, but in a short time you can achieve a lot," Mr Verpeaux said.

"Mixed fallow cropping creates habitat and niches for an incredible diversity of soil micro-organisms and bugs that help with nutrient cycling and improve soil structure."

The uptake in the northern Wet Tropics coincides with promising Project Catalyst trials, which began three years ago on Ingham cane grower Lawrence Di Bella's farm.

Soil tests at the site have shown mixed plots have a low ratio of bad nematodes and a high ratio of good nematodes.

Higher nitrogen, potassium and phosphorous counts have also been recorded when crops are mixed, bringing different benefits from each species and in some cases balancing out less favourable traits.

Mr Verpeaux said recent organic carbon results on the Reynolds' farm were also encouraging.

"It is hard to get above two or three percent for organic carbon in the Wet Tropics because of the climate and disturbances created by tillage and compaction,'' he said.

"Organic matter tends to break down more quickly and the key is trying to keep as much as you can as humus.

"Funding programs have been encouraging reduced, zonal or even zero tillage techniques for many years which, when combined with mixed fallow crops, will improve your soil health."