BY: SANDRA TAYLOR
Preservation of soils under a hill country winter cropping regime is the focus of the Farming Fund project being run on commercial farms in both islands.
The project, led by Ballance Agri-Nutrients, is building on existing knowledge of hill country cropping with helicopters (helicropping) with a focus on soil preservation.
Ballance Agri-Nutrients’ science extension forage specialist Murray Lane, says the initial work on how to grow crops on hill country was carried out nearly 20 years ago and farmers have picked up the technology and run with it.
Lane says it is not going to appeal to perfectionists, but it enables cropping and pasture development in hill country, significant time efficiencies with 40ha of crop established in six hours and has health and safety benefits.
“You’re employing just one person (the pilot) to do the job and there is no danger of farm staff rolling tractors on hillsides.”
While the practice has opened up opportunities for increasing drymatter production on hill country, Lane says farmers recognised there was a responsibility that came with growing crops on hill country, particularly around matching soil types, slope, crop type and stock classes.
The SFF project, funded by The Ministry for Primary Industries, Ballance Agri-Nutrients, Beef + Lamb New Zealand, PGGWrightson Seeds, Agricom and Nufarm is focused on keeping soil on the land and not losing it – and associated nutrients – into waterways.
Comparing crops established using a helicopter to those established through traditional cultivation clearly showed there is no soil loss under an aerial cropping regime, whereas with cultivation soil is lost, particularly after weather events.
The risk of soil loss in aerially-established crops is during winter grazing.
“We know we can grow and graze summer crops, and have the area back in pasture for winter and lose no soil, so the focus is on winter and how we can harvest forage crops without losing soil.”
Lane says one factor that has stood out all the way through on mixed terrain, is crops will be poorer on steeper slopes because of the lack of fertility on those slopes.
“Rather than apply more fertiliser to the area and grow a higher yielding crop, let’s accept lower yields on steeper slopes.
“The question is do we really want large numbers of hooves on steep slopes to harvest a large crop? Perhaps it is better to accept a lesser crop on these slopes, meaning less hooves, less damage and concentrate on the flatter areas where there will be less soil movement.”
He says they have looked at numerous ways to establish cover crops from the air, to protect the ground after grazing.
“We were not successful sowing grass cover crops prior to grazing swedes. Not because the annual ryegrass didn’t establish, but because grazing destroyed the less-than-mature ryegrass.”
The focus now is on establishing cover crops after grazing.
While cover crop seed has been successfully broadcast onto the soil, mid-winter, after grazing swedes or kale, success depends on resident bird populations. This year the research team is evaluating the use of a bird repellent to protect the seed.
They are also evaluating “companion cropping” where plantain is sown with the brassica seed. Plantain tolerates the brassica herbicide, so grows under the swede canopy over the growing season.
Lane says plantain grows very well under rape, as it is grazed over summer, however under swedes, it fills any gaps in the crop, survives under the swede and still flowers and sets seed.
Following grazing, the plantain recovers (depending on grazing pressure) and becomes the cover crop, protecting the soil.
However, plantain survival requires a move away from intensive strip grazing to a less intensive “block grazing”. This will also minimise soil damage.
Lane says some farmers have been offering stock four days grazing in a block, using a back wire and portable trough, and moving them earlier if weather conditions deteriorate.
MODERATE GRAZING VERSUS OPTIMAL UTILISATION
“We need to change the message away from optimising the crop to minimising soil damage.”
Lane admits this does require a shift in mind-set but sacrificing a small amount of crop (perhaps growing more than required) could have long-term environmental benefits to the soil and allow the companion plants (plantain) to come away quickly to protect the soil and capture the nutrients left in the wake of winter grazing.
He says one of the benefits of helicropping is soil structure is not affected, the pest/predator balance is retained as are water infiltration rates.
“Preserving this as much as possible with moderate grazing will protect soil and water resources for the future pasture.”
Murray says the ultimate goal of helicropping is to improve the quality of the resulting new permanent pasture on a range of terrain. He cites an example of one farmer, helicropping on a large-scale, who establishes permanent pasture by broadcasting seed within a month of grazing winter forage crops.
“If the pasture isn’t dense enough in its first spring, he simply lets it seed… At least it’s covering the soil in that first spring and summer.”
While this project was initiated by farmers in the central North Island, work has been done on farms in Hunterville, the Wairarapa and Te Anau.
Murray says it is amazing what farmers are doing on their farms in terms of cropping and managing their soil and water resources.
“Our role is to observe, learn and work out how to make the systems reliable.”
