Worry over spray and pray
Horizons Regional Council is unsure how much of Manawatu/whanganui is covered by ‘‘spray and pray’’ heli-cropping for putting in winter crops on hill country.
Hill country farmers contract helicopter pilots to spray land so the grass dies and can be over sown with crop seed without cultivation.
The pray part of the equation is the hope that rain will come to help the seed germinate and grow.
Horizon’s environmental manager of land, Grant Cooper, said the regional council had received some feedback on the practice.
‘‘We do know there is not a lot of it going on throughout the region. Middle Rangitikei is the main area. We don’t see it around the Ruapehu area, or on the East Coast where it is dry.’’
He said the big concern in Rangitikei would be if it was done on the side of a hill, which could mean soil was eroded and ended up in waterways.
‘‘But although there is one phrase, spray and pray, it can mean many things. Such as when pasture is sprayed, when a crop is planted, it might be replaced by more pasture. We just don’t know.’’
He said Horizons had known it was happening in some areas, but not how many hectares were covered by the process.
‘‘The good thing is technology is improving. The spray goes on in the right places, and the seed is going on better too.’’
Massey University’s Professor Peter Kemp said the spray and pray practice had been around for years.
‘‘Spray and pray is an old term that summarises the optimism of broadcasting seed onto uncultivated land. It has been reprised to describe the practice of spraying herbicide on the pasture on hillsides and broadcasting seed from the air to establish winter feed crops.’’
He said farmers risked economic loss if crop establishment was poor because of unpredictable weather and there was another risk of environmental damage through soil erosion.
Kemp said it was a risky process and something that was not yet proven economically or environmentally sustainable. Helicopter spraying technology had advanced , but students at Massey University were taught that the method was risky because of unpredictable rainfall, particularly on steep slopes.
‘‘If spray and pray catches on it will cause sediment build-up in the rivers. As soon as you strip vegetation from a slope, you are prone to erosion, and if you have nutrients in the soil, they will get into the waterway.’’
Feilding-based Hodder and Taylor business manager Duncan Thomas was the key advisor for most farmers in Rangitikei using the practice called heli-cropping by farmers.
Thomas said most hill country farmers had limited or no flat land on which to put crops for winter feed so they put crops on hill country.
‘‘But we suggest anything above 23 degrees - steeper land with sheep tracks should not use the practice. If it is done right it is great, but you have to get it right.
‘‘It can go horribly wrong if farmers do it, without talking to the right people – there can be insufficient spray, it can be done on the wrong contour and there are plenty of examples of people who do it wrong.’’
Thomas said it was done to sow winter feed of brassicas, such as kale, rape and swedes.
He said the main aim was to get a paddock into new pasture.
Thomas said if it was well done, there were no soil losses.
One farmer using the method, Mark Grace said it had improved his land, and was safer than using a tractor on hill country.
He said there was no cultivation and no sediment loss.
Federated Farmers Manawatu/ Rangitikei president Richard Morrison said heli-cropping could work if it was done well and the risks could be mitigated.
‘‘It is done to provide better quality forage options for stock, thus improving animal performance and production. It is a way of improving the grass species and clover content of the pasture at the end of the helicropping program.’’