Northland dairy farmer Allister McCahon cut palm kernel feeding by 50% last season despite a very dry summer, partly by trying diversified pastures on his light, porous soils.
Plot and field trials produced extraordinary plant growth rates for McCahon and Pouto Peninsula neighbour Roger Gillatt, who is also a lucerne advocate.
Their sandy loams went through 100 days with soil moisture levels approaching permanent wilting point from January to March.
When ryegrass and clover pastures couldn’t grow, the deep-rooted lucerne, tall fescue, cocksfoot, plantain and chicory kept going and were block grazed and/or cut for silage.
The Northland Diversified Forages Project aims to improve farm system resilience and reduce feed supply risk by identifying and exploiting forage solutions that have advantages in yield, feed quality and/or timing of growth.
It also measures the alternatives to ryegrass species in a range of different environments all over the north.
Other grasses, legumes and herbs have all been researched before and are now being tried as season gap fillers, thrivers in drought and conserved feed sources.
In the west of the province two participating sites are near Te Kopuru (Gillatt and McCahon) and a third is on the Northland Agricultural Research Farm, just north of Dargaville. All three are dairy farms.
Funding over four years has come from the Ministry for Primary Industries, Northland Regional Council, Hine Rangi Trust, FAR, Ellett Agricultural Research Trust, Agricom, Ballance, PGG Wrightson Seeds, Eurofins and Northland Seed and Supplies.
The project is managed by Gavin Ussher of Clover Consultancy, Kaitaia.
No novices with lucerne, Roger and Barbara Gillatt enjoyed daily growth rates of 67kg/ha/day DM compared with less than 10kg for new ryegrass, clover and plantain during the driest period last summer.
The first cut for silage came in late October and the next cut or feed out was in early January, after which beef steer calves were fed during the really dry period and gained 1.5kg/day compared with siblings that lost weight by 0.3kg/day on kikuyu and ryegrass.
After 15 years’ experience with the deep-rooted lucerne on light soils the Gillatts thought 10% of the effective grazing area would provide a specific solution for that farm, herd and climate.
For diversity’s sake they also sprayed out a 12-year-old lucerne paddock and last May sowed AR 37 perennial ryegrass (8kg/ha seed), red clover (5kg), two varieties of white clover (1.5kg each), plantain (2kg), Persian annual clover (4kg) and Alsike clover (3kg).
In the 10 months to the beginning of May that paddock grew 12,600kg/ha DM, of which the ryegrass contributed 54%, the plantain 16% and the Persian clover 14%.
Maximum growth was 75kg/ha/day DM in September and minimum 6kg at the end of January.
Another paddock sown with a similar seed mix totalled 13,200kg/ha over 10 months but plantain was the biggest contributor at 39% overall and over 60% in the maximum growth period in late December.
The ryegrass-plus paddocks started growing earlier than the lucerne but crashed earlier in the dry. They were estimated to have also grown 15-16,000kg/ha despite the dry period.
Lucerne tested at 11.2 MJ ME/kg DM in February and 32% of crude protein.
Over the past two seasons it grew 18,000kg/ha DM and 15-16,000kg (estimated).
Despite good plant densities it wasn’t all plain sailing with young lucerne.
Major soil pathogen problems emerged from April to June last year leading to crown rot and some root damage but the plants bounced back with growth rates of 40-70kg/ha/day DM from September to February.
On Allister and Maree McCahon’s 400ha effective, 1000-cow farm the diversified paddock-scale trials have focused on tall fescue, cocksfoot, white and annual clovers and lucerne, sown in autumn 2017.
Total production in year one was 17,500kg/ha DM and in year two 13,500kg, with a constant 7-8000kg coming from the grasses.
But clovers contributed 50% of the drymatter in the first season and only 15% in the second year while lucerne kicked in with 27% in the second year.
Ryegrass control plots were hammered with the summer dry and even in May after the autumn recovery the target species dropped to 24%.
By contrast the tall fescue and cocksfoot plots persisted with 85-100% target species after the dry and produced as much total drymatter over year two as ryegrass.
Plot samples taken in mid-January in the Far North showed cocksfoot growing at 81kg/ha/day DM, with energy of 9.8 MJ ME/kg DM and protein of 12.9%.
The figures for tall fescue were 51kg, 9.5 MJ and 13.5% respectively, compared with ryegrass at 34kg, 8.9 MJ and 17.4%.
Other treatments on the McCahon farm involved putting plantain and chicory into a standard tall fescue, cocksfoot and clover mix and comparing the results to the same seed mix without the herbs.
All treatment mixes had 12kg/ha of tall fescue, 1.5kg of cocksfoot, 3.5kg of while clover, 4kg of red clover and 3kg of Persian clover. The herbs were added at 1kg/ha each.
With plantain and chicory present total pasture growth was 15,991kg/ha/yr DM and without 13,578kg.
The herbs contributed about 50% of the drymatter and the grasses very little while in the paddocks without herbs the annual clovers supplied 40% of the total mass, red clover 26% and grasses 23%.
The cost of the extra production from adding herbs was a simple calculation, being just the cost of the seed and they gave a considerable boost in the first year and could be expected to provide feed for a longer period.
“We are looking for a more sustainable strategy and this project enables us to road-test the alternatives to re-grassing with annual ryegrass,” McCahon said.
“We have two years’ positive experience and now we need to see what happens after three or four years in these diversified pastures.
“Climate change models say that we will have more persistent C4 grasses like kikuyu.
“It has several significant limitations, including an inability to carry quality feed into winter and annual mechanical control measures.”
