NEWS
about and managed . The three are categorised as conservative , progressive , and ultimate in terms of the level to which these changes have been implemented .
The four scenarios have been laid out in Table 1 below . Factors which were kept constant were the size of the farm ( 452.5 ha ), the size of the cattle ( 450 kg cows in milk ), butterfat ( 4.4 %), protein ( 3.6 %) and the type of inputs used . Everything else was subject to the changes brought about by applying the various levers .
Fundamental change in thinking
Table 1 : Four different farm scenarios , showing the impact of changes in management practices
The two most important changes in these models were the absolute minimisation of concentrates , and the reduction in nitrogen fertiliser . Most farmers will probably look at the concentrate and nitrogen figures and say that these milk productions and pasture growths are not possible under these scenarios . And I get why you would say that – these figures have never been achieved . But they are theoretically possible .
The feed provided in these scenarios is sufficient to support the milk productions mentioned . The caveat is that the pasture quality needs to be at the specified levels . To achieve that we need high quality , multispecies pastures .
We also know that these levels of pasture growth are possible with such low fertiliser inputs ( Growing pasture with minimal nitrogen fertiliser ). The caveat here is that we need healthy soils to achieve this . Practices which improve soil health should be prioritised .
Table 2 : Changes in factors between the conservative scenario and the progressive and ultimate scenarios
cludes the weather , the milk price , and the prices of concentrates , fertiliser , fuel , and electricity . Although these are things farmers need to be aware of , it is pointless agonising over them . A farmer ’ s energy is better served focussing on things which they can control .
These include the principles which I mentioned above . You could think of various management practices on a farm as levers . When these levers are applied according to the principles , production is optimised . For example , by implementing no-till practices , multispecies pastures , smart fertilisation strategy and ideal grazing management , soil health and pasture quality can be improved . Another example is that by improving herd management that leads to healthier animals , therefore greater longevity , and by obtaining higher fertility rates , lower heifer mortality and better heifer rearing the number of heifers needed each year can be reduced .
The impact of applying these levers
I would like to use a theoretical farm in the Tsitsikamma as an example of the impact that applying the levels in the correct way can have on the sustainability of a farm . I have created a model farm based on averages of data from 23 farms on the Trace & Save database . These are all mixed irrigation and dryland farms .
I have used four different scenarios , where the levers discussed have been applied to different extents . The first scenario is a relatively normal , productive farm under current circumstances . The other three scenarios show the effects of some big changes to the way pasture-based dairy farms are thought
The challenge is then to take advantage of improved soil health . This is where I think many farmers still have a mental block . To achieve this level of progress , we need to change the way we think about fertiliser and the way we manage pastures . It is a huge mental shift .
To achieve these levels of production using such low concentrates it is also imperative that we calculate stocking rates intending to maximise pasture intake . Conventional wisdom says that a cow can take in 1.2 % of their body weight in NDF each day . We have found this factor to be closer to 1.5 %, especially in smaller cattle . For this exercise I used 1.4 % and stocked the farm so that cattle would eat the maximum amount of grass ( and silage ) every day . By improving pasture quality , therefore reducing the NDF and increasing the energy , cows can eat more pasture and produce more milk from pasture .
The changes mentioned above were the basis for the change between the normal and other three scenarios .
Grassroots Vol 20 No 4 December 2020 32