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Its not all about ‘N’: Getting off the ‘N’ Death Cycle and on the Healthy Soil Wagon with Canaan Ahu

Its not all about ‘N’: Getting off the ‘N’ Death Cycle and on the Healthy Soil Wagon with Canaan Ahu

Canterbury is often seen to be the promised land for dairy farming as we have the ability to irrigate the land and, when combined with good sunlight hours, extend our lactation days. On the flip side this means the land has the highest production expectations often resulting in higher geared systems which results in all manner of potential issues down the farm production line.  

At Agrownomics our focus has been in helping the dairy industry as independent consultants. The need for independent advice was something we saw farmers were continually seeking.  

Many could see there was a dire need to fix systemic animal health issues and poor grass production or to find a better way than simply putting more fert on their paddocks.  

To date, in the dairy community, there has been little emphasis on the entire Nitrogen cycle yet significant emphasis has been placed on applied N resulting in increased DM growth. The atmosphere we breathe daily comprises of 78% Nitrogen; this equates to 7800kilograms above every hectare. There are many types of N fixing bacteria and microbes in the soil & on the plant leaf and significant focus needs to be on getting these microbes etc. to draw N from the atmosphere over the current preference of applying it synthetically. N fixing microbes require air, without air in the soil, they simply cannot fix atmospheric N. There are some trace elements required too but that is a discussion for another day.  

Responsible, Independent advice the key to great results

Like professionals in many industries, farmers often employ farm consultants or external help in the areas they are not skilled in. In many cases this has gone well, like outsourcing advice on farm systems, capital investment or staff management.  

What is commonly missing in our farm consultants, however, is a sound knowledge grounded in soil. The result of this lack of knowledge is a default ‘recipe type’ approach.  

Moreover, constant pushing for production goals with little understanding to the tradeoffs, a biological system or how a farms soil is functioning has led to farms becoming completely dependent on an approach that simply relies on the ‘put more on’ approach to nutrient management 

Farm consultants have had little responsibility for the advice that has been given, often distracted by incentives or commissions, aka. zero responsibility for the high use of things like significant N use/abuse.  

3 years ago in our community, it was not uncommon to hear of Canterbury dairy farmers still using 400kg/ha of N. The focus was to maximise N use in growing more DM. More DM intake would lead to a higher producing animal and thus milk.  

Indeed, this methodology grew more grass, but the consequences of this approach have been seen in the environmental impacts on water quality and more directly on farm in animal health.  

This philosophy over time has degraded the nature of what the cows are eating. A plant requires more than 26 minerals, if you simply only replace 2-4 of these then this will potentially lead to a degrading system, a system that includes soil, pasture, animal, milk production and so on. These co-factors, synergistic minerals and biological interactions all get compromised to some degree, yet dry matter production is propped up by the N input. The grass will grow until the wheels truly fall off. 

The Science of Healthy Soil 

Over applying N is one of the most detrimental cycles of death a farm can get on – impacting N leaching, collapsed soil structure, bacterial dominated soils and very low Organic Matter (OM).  

The US Department of Agriculture has researched this topic well in one of its studies showing “Per every 1kg of applied N/ha above the plants requirement burns out 100kg of carbon/ha”. Organic Matter (carbon) is not only a source of energy for microbes but it is also the anion storehouse in soils due to its particles containing both negative and positive charge. In soil a negative charged site (-) binds to a positive charged site (+), so OM plays a significant role in holding onto both ammonium (NH4+) and nitrate (NO3-) in any soil. If the OM has been compromised by the overuse of N, any anion (N, S, B, Mo) that is supplied has a very limited ability to be held by the soil due to the lack of positively charged OM to stick too. 

In farmer language, “the grass doesn’t grow until the fert truck turns up” – frankly this wasn’t the way it was designed to function.  

This may be a US study but we have observed this to hold truth here too. Healthy, functioning soil principally needs air, water, microbes and minerals. A compromise in one of these categories has the power to compromise the others and the system starts to under-perform. Without good soil structure, the soil’s ability to breathe and hold water is diminished. So, treating soil as a valuable resource will always yield itself to production and the positive wellbeing of livestock.  

Agrownomics has set up a support system to help our farmers navigate the topic of soil health, mineral use and budget. Our approach is to meet the farmer where the farmer is at. Farmers rely on trust; trust is built around expectations being met repeatedly. We do this monthly with our farmers, taking shape in the form of farm walks, digging holes, measuring plant sap, analysing herbage tests then adjusting the game plan to our findings. Soil is a dynamic living eco-system, we need to be able to read & assess what’s going on to then pull the right leavers of action. Initially this often means playing in the space the farmer is used too – basic NPKS use 

In Canterbury significant focus was placed on N and very little around the supporting mineral & biological co-factors.  

For example, Nitrogen without the co-factor sulfur cannot convert nitrate nitrogen into amino acids such as cysteine and methionine. This means the nitrate stays as “crude protein” rather than being converted into higher order compounds which are then used by the plant for growth. Potentially worse still, is crude protein has a massive energy draw on the animal to be processed by the liver and urinated out only contributing to the problematic cycle. There are many mineral and biological co-factors, the more we learn to work with them the greater the outcomes to the farmer & stock.  

Farmers blame the cow for high N excretion through urine, but no one asks who fed the cow high N grass? In the dairy world of today reducing the application of N and the methodology in how that N is applied is not only a sensible farming practice, it is also good business practice in the current economic realm. What business would not want to save money yet achieve the same results whilst potentially improving other aspects of their business along the way.  

Canaan Ahu is a Director and Consultant with Agrownomics.  Canaan established Agrownomics in 2013 a soil advisory company based in Central Canterbury.  We are passionate about soils & growing with our farmers