Fertilisers are vital
There has been much media interest recently around regenerative agriculture as a paradigm move away from ‘‘conventional’’ agriculture.
Agriculture is not static, it’s always evolving. What is alternative today may be the new conventional tomorrow. But climate change and market returns are increasing the pressure.
Higher temperatures and less rain at critical times mean the amount of water available for shallow rooting species such as ryegrass and clover reduces, and summer droughts become longer and more frequent.
Scientists such as Professor Derrick Moot of Lincoln University have challenged us to consider whether 21st-century dryland grazing systems can continue to be based on the old clover/ryegrass paradigm and whether moving to deeperrooted and/or mixed forage systems based on legumes like lucerne, need to be in the mix.
However, the main concern for the public, and the science community, has been increased agricultural intensification where ‘‘pushing the envelope’’ has led to noticeably reduced water quality.
If regenerative farming offers an alternative, it may be that it doesn’t try to push itself to the maximum all the time, stuck on a commodity treadmill of having to produce more and more to stay still.
For example, Lincoln University’s commercial dairy farm has shown that feeding a smaller number of cows more and better was more profitable for farmers than just having more cows.
With new environmental regulations biting, many are realising that we need to produce a smarter, and more diverse, range of products rather than just more milk powder.
As agricultural scientists, we conduct research to make grazing and forage systems more sustainable and profitable, but we often underestimate the time taken for these advances to filter down.
The study of such systems includes regenerative agriculture practices and where advantages can be backed up by research, then these too will be advocated in tomorrow’s farms. But many aspects are already in place, albeit unacknowledged.
However, there are misconceptions around soil health and regenerative agriculture – namely that fertiliser is counterproductive to both. This just isn’t true.
Most NZ soils, for example, are naturally poor in phosphorus. High-value plant species, such as legumes, fix nitrogen and pass some of that nitrogen to other pasture species, but they need some added phosphorus to do so.
With nutrients being steadily lost from farmland every year through stock leaving, redistribution and natural weathering processes, these need to be replaced.
If you run a system where you’re not replacing these losses, you are effectively mining the built-up fertility from previous fertiliser applications. While soil organic matter or humus is fundamental to soil health, it is productive only though decomposition and the release of nutrients, such as nitrogen and phosphorus, back to plants.
In fact, studies have shown that judicious fertiliser application increases pasture production and builds quality soil organic matter, not destroys it, through the return of residues and excreta back to the soil.
Even regenerative agriculture needs these mechanisms to be productive, or at least at a level that is profitable.
In summary, there are undoubtedly many soil conservation and regenerative agricultural practices that are, and could be, undertaken by farmers but NZ soils are not generally in decline and demonising fertiliser use ignores its importance.