careful monitoring of soil water and nitrogen avoid waste.preview.JPG "Careful monitoring of soil water and nitrogen avoid waste.")
Well planned shelter plantings on every fenceline.preview.JPG "Well planned shelter plantings on every fenceline.")
large deciduous trees create shade and shelter and reduce evapotraanspiration.preview.JPG "Large deciduous trees create shade and shelter and reduce evapotranspiration.")
Pencarrow Farm, Ashburton, macfarlane [dot] family [at] mrbusiness_co [dot] nz
"What does sustainability mean to you?
"Using our existing resources, and building new resources, efficiently and wisely, to optimise output while leaving the property in a better state for the next generation."
Andy and Tricia converted their Ashburton farm to intensive dairying nine years ago. They run 780 cows at a stocking rate of 3.62, heading to 3.55. However Andy made the interesting comment that we should really be measuring kg liveweight/ha as his crossbred cows consume kess feed and resource than the equivalent number of large friesians.
One reason for the jersey bloodlines is that they hit heat stress only at 25 degrees, compared with freisians at 21 degrees. In a mid-Canterbury summer that matters.
Andy and Tricia were the Supreme winners of the 2003 Ballance Farm Environment Awards. Andy is president of the NZ Institute of Primary Industry Management and also runs a business as a farm adviser. His environmental checklist for irrigated farms uses his own farm as a pilot for monitoring output in relation to water, nitrogen and feed.
Nitrogen application has dropped from 257 kg/ha four years ago to 160 kg this year, as a result of careful measuring and monitoring, use of urease and nitrification inhibitors, liquid nitrogen, and multiple applications of very low rates of effluent over as much of the farm as possible through the irrigation system. Andy has not detected any nitrate build up in ground water.
Paddocks are planted in a range of different pasture species, basically mid and late-flowering ryes and clovers, but including fescue and prairie grass which tolerate a wider range of environmental conditions. Andy aims to leave 1500 kg/DM/ha after grazing to ensure quality feed for the next rotation. Silage emphasises quality rather than quantity and is wilted to 45% before making on a concrete slab to minimise leaching.
What strikes you first on visiting this farm is the vast number and diversity of trees - an unusual feature in Canterbury, and much of our conversation centred on the trade-offs this creates. There is no doubt that this is one of the most visually attractive farms that I have visited, with a third of the farm dotted with large deciduous specimen trees of many varieties including some 60 fruit trees. There are substantial and well planned shelter belts in all paddocks and along races, around the milking shed and even beautifully designed native plantings around the effluent sump.
Beautiful, but do they contribute to the farm business?
Most intensive Canterbury farms have been stripped bare of trees to make way for centre pivot irrigators. There's no doubt that these use water more efficiently than border dykes - 80% efficiency compared with 60% - but unless gravity is in your favour they also greatly increase electricity use. Converting all Canterbury border dykes to centre pivot could require another couple of power stations. A third option, but 50% higher capital cost than centre pivots, is solid set sprinklers which provide continuous coverage of the paddock despite the trees.
This seems like an expensive option, but the benefits of keeping the trees includes shade and shelter for stock, reducing feed requirements, and reduced evapo-transpiration from the pasture. This is hard to quantify and Andy admits he has no exact measurements, but he believes he saves 1mm/day. Available water from the Rangitata Diversion Race and a deep bore amounts to 5.0mm/day (peak capacity) in the irrigation season, but this can be cut by half when the river drops below its minimum flow, and total evapo-transpiration without the trees is 4.5mm/day. It looks as though the trees easily earn their keep.
This balance between water, energy, shade and shelter is one of the most complex and interesting ones in farming and Andy is keen to develop some objective measurements to back up his estimates.
Listen to a conversation between this farmer and Jeanette
