Research conducted by NSW Department of Primary Industries using a leading Pioneer® brand corn has highlighted the benefits of including corn as part of a cotton rotation.
Principal Research Scientist, Dr Nilantha Hulugalle, of the Australian Cotton Research Institute, said the project was initiated to see whether the bulky corn crop delivered more organic matter to the soil. It also followed anecdotal evidence from growers who had achieved higher yields from a corn / cotton rotation compared to a cotton /cotton rotation.
This scenario was tested last season by Dr Hulugalle by sowing back-toback cotton and a cotton-corn-cotton sequence under conventional-and minimum-tillage (permanent beds). The highest yield in that comparison was with cotton-corn-cotton minimum tillage with the cotton achieving 10.1 bales per hectare compared to the yield of cotton in the cotton rotation at 9.0 bales per hectare. In the conventional tillage scenario, the cotton following corn produced 9.8 bales per hectare compared with cotton after cotton at 8.2 bales per hectare.
“The initial stand out result is that the cotton treatment that included corn significantly outperformed their counterparts in yield,” Dr Hulugalle said.
Yield increases in the corn rotation ranged from 12 per cent through to more than 21 per cent and added significantly to the gross margin, with an extra $697 per hectare achieved in the maximum tillage scenario and an extra $389 in the minimum tillage crop.
“It is looking very promising and the results are quite substantial.” He said a lot of growers he worked with had mentioned corn was one of the best rotations and the trials backed this up.
“The results are just so striking,” he said. “In all our treatments following corn, the cotton yields increased.
Included in the research was a study looking at the soil carbon numbers and the effects on disease by adding corn into the rotations. Dr Hulugalle said soil organic carbon was higher after corn than cotton in the surface of on-farm sites in the MIA and Macquarie Valley. Similar results were also seen in the Namoi valley during the previous season. He said of particularly interest was the increase in carbon in the sub-soil in the ACRI trial, at depths of 60cm or more.
“A large proportion of the root mass of the corn crop goes to depths below 60cm and there is a significant increase in the amount of organic matter in these depths.
“Another advantage of this rotation was that cotton root systems after corn went deeper and were much more extensive so were able to access extra moisture and nutrients.
“There was also a significant decrease in the black root rot numbers in corn. We suspect corn is controlling other diseases as well.”
The success of the trial has led to a number of other projects being proposed for the near future. Dr Hulugalle said they would like to look at the deep sub-soil carbon storage and also the interaction between soil fertility and soil fauna.
“Soil fauna influence litter and organic matter decomposition in soils and have an important role in ecosystem productivity.”
He said adding another crop into the rotation caused changes to the type and amount of soil fauna and could be another factor in why corn works so well in a cotton rotation.