With fundamental changes now taking place in the way in which soil fertility is viewed there is an increasing demand for nutrient programmes that deliver at least as much pasture production without the need for regular applications of fertiliser nitrogen.
These programmes already exist and are practised widely throughout New Zealand. They are based on information and experience gathered over decades of work here and overseas.
Increased efficiency of applied nutrient, as well as soil moisture are keys to the success of these programmes and mycorrhizal fungi play a central role in achieving outstanding results.
As early as 1978 MAF trial work showed that introduced mycorrhizal fungi on an eroded Kaikoura soil in Canterbury resulted in large and very highly significant growth responses in Marku lotus.
Between 1978 and 1981 several field trials were undertaken at Invermay’s Wairoa farm that showed the introduced mycorrhizal species Glomus mosseae gave significant increases in plant growth at all levels of applied phosphorus.
Phosphorus is a major cost in conventional fertiliser programmes and a reduction in required inputs can provide real cost savings.
The products CalciZest and DoloZest made by Eco-Logic Soil Improvement contain a wide range of selected soil friendly fungi and bacteria that include mycorrhizal fungi. Mycorrhizal fungi grow out from plant roots increasing the area from which plant requirements, particularly phosphorus and moisture, can be harvested.
Recently science backed trial work on two properties has been initiated. One property has a nutrient programme based around CalciZest /DoloZest that has been in place for a number of years, the other a neighbouring property implementing a fertiliser nitrogen driven programme.
One of the initial observations from this research has been the marked difference in the fungal growth extending from plant roots.
Mycorrhizal fungi, rhizobia bacteria, legumes, and nonlegume plants can all interact in a four-way mutually beneficial relationship. Due to the link provided by mycorrhizae, nitrogen fixed by clovers can be taken up by nonlegume plants and phosphorus provided to the less efficient P harvesting clover plants.
Obviously a great deal more research is required to know with certainty the effect that different nutrient programmes have on this process, however soils that are physically well structured and biologically active are capable of providing more total pasture growth over a twelve month period.
Animal feet provide a great deal of downward pressure and the only way of ensuring soils do not become increasingly compacted is by providing an environment that favours both earthworms and other beneficial soil dwellers.
Both dolomite and lime have a marked effect on the physical structures and biological activity of pastoral soils. Calcium provided by lime increases moisture holding capacity as well as earthworm activity. Dolomite is frequently used where magnesium is also a requirement.
When calcium is applied in the form of CalciZest or DoloZest further improvements in pasture and animal performance can be expected. The benefits of more total clover relatively unaffected by clover flea or weevil is being welcomed by an increasing number of farmers using these programmes.
Regulations limiting the quantity of nitrogen used by pastoral farmers are getting closer, however the most intense pressure for change is likely to come from within the farming community as increasing numbers of farmers implement programmes that deliver more, in all respects, as a result of enhancing and stimulating natural soil processes.