Dairy One Project

July 2015

A Massey University study looking at better understanding of dairying within limits

Dairy One is a collaborative project on the No 1 Dairy Farm at Massey University that is looking at sustainable production within resource limits.

No.1 Dairy farm occupies land purchased from the Batchelar estate for the establishment of Massey Agricultural College in 1926.  A dairy herd was established there in 1929 and is the basis of the present No. 1 Dairy farm.

The purpose of Project Dairy 1 is to create an environment for collaborative research to deliver innovative solutions around issues of environmental stewardship, community connection and animal health and welfare in dairy farming.  With help from industry, the project aims to identify management systems and technologies that are cost effective and environmentally responsible.

Professor of Dairy Production Systems, Danny Donaghy is leading the research programme.  He says the idea is to collaborate with industry, with farmers, regulatory authorities and companies and see how they can work together so the whole community benefits.

He says it’s about testing to see if those ‘laboratory discoveries’ and ‘innovations from farmers’ will work in a commercial dairying operation.  No. 1 Dairy Farm provides the researchers with an ideal platform to do it.

In 2013 Massey announced major changes to No. 1 Dairy including reducing the size of the milking platform by nearly 40%, reducing cow numbers from 360 to 240 and changing to once-a-day (OAD) milking.  Some of the land taken from the original milking platform was to be planted in trees, some used as feed for cows and the rest for riparian plantings.  Other land will be used for crops such as lucerne for feeding cows.

The farm is just across the road from the main Massey campus and backs onto the Manawatu River, noted for claims that it is being polluted by dairy farms upstream and local council sewage systems in its lower reaches.  Horizons Regional Council One Plan had heightened awareness for many people in the region about the challenges of farming in a sustainable manner financially, environmentally and socially.

Many of the changes are about measuring what is happening in the farming operation.  The plans include measuring just about everything that moves on the farm.  That includes the health and production of each cow and the pasture it eats, the nutrient and water movements on the farm, the weather and the impact on people working on the farm.  Researchers will use this information to assess management systems and technologies being trialled on the farm.

Ranvir Singh is a Massey senior lecturer in environmental hydrology and soil science.  His research project is about understanding the transport of farm nutrients – how they change and where they end up.  He says that while the cycling and leaching of nitrogen in the soil profile is reasonably well understood, there is limited information about its transport and transformation in the area below the root zone.  He says that understanding how nutrients are transported and transformed is a key component to managing and mitigating their impact on water bodies.

Ranvir says that current N management efforts seem to be largely focused on identifying intensive farms that leach the largest amounts of N from the root zone – and developing management practice to reduce that leaching.  He says this approach fails to consider other factors that might reduce the flow of N in the subsurface environment.   “So a nitrogen management approach only based on nitrogen leaching from the farms is a bit limited.  It ignores the transport and transformation of nitrate-nitrogen (NO3-N) along water and nitrogen flow pathways from farms to shallow groundwater to rivers and lakes.”

In a number of studies overseas in Europe and USA, it is being observed that a significant amount of nitrate-nitrogen leached from the root zone can be reduced (attenuated) by denitrification, a biogeochemical process which converts soluble nitrate-nitrogen to gaseous forms of nitrogen, predominantly to dinitrogen in groundwater systems.  This nitrogen reduction capacity is mainly governed by the physical, chemical and biological characteristics of the subsurface environment, and importantly by the quantities of nutrient, dissolved oxygen, and oxidisable carbon in nitrogen flow pathways from farms to rivers/lakes.

Ranvir says, “In our current nitrogen management approach, little if any consideration is given to this potential reduction of nitrate-nitrogen in subsurface environment as it passes from the paddock root zone to shallow groundwater to rivers and lakes.  And the main reason this is not considered and accounted for is that relatively very little is known about this nitrogen reduction potential in our catchments, where it occurs and what factors control it.

And if we understand this better then we can be very targeted in our efforts where we need to reduce the nitrogen leaching and where it’s not so much of a problem. Further down the road once we understand this process in more detail in our local catchments, we may be able to enhance this potential nitrogen attenuation capacity in our agricultural catchments to reduce nitrogen loads to rivers and lakes.

Our team of post-graduate research students at Massey has done some preliminary analysis using long-term available river water flow and water quality observations in Manawatu River catchment which suggests that the nitrogen loads measured in the rivers are significantly smaller than the estimates of nitrogen leached from the root zone of farms in a number of river’s catchment area.

We are further conducting dedicated field surveys, monitoring and experiments to assess and understand this denitrification potential under different hydrogeologic conditions across Manawatu River Catchment “

He has established a test site at the Massey No.1 Dairy farm.   At this site, ceramic suction cups have been set up to monitor soil water at four depths.   The collected soil water and groundwater samples are being analysed for nitrate-nitrogen, ammonium, dissolved oxygen and dissolved organic carbon.  The samples are analysed in a lab for a range of hydrochemistry parameters to assess occurrence and potential of denitrification in subsurface environment below the root zone.

The collected information will be used to develop an N flow model – and help in the management of N loss from farms to rivers.

Preliminary field monitoring and experiments at a test site established on the Massey University’s No. 1 Dairy Farm indicated the potential and occurrence of denitrification in the subsurface environment.

Ranvir says that they reasonably understand the factors that interplay in determining how much nitrogen runs off and/or leaches from a farm, and there is significant variation in these factors such as the farm type and its nutrient/fertilizer input itself.  There is also variation in the amount of excess rainfall to carry some of nitrogen away from the farms.  All this knowledge has been gathered and accumulated in the models such as Overseer, which enables people to estimate nitrogen runoff or leaching from a farm, i.e. the root zone of the farm.

Ranvir goes on to say “ What we are actually missing is a model that can further consider effects of different hydrogeologic conditions on transport and potential reduction of nitrate-nitrogen from farm’s root zones to river and lakes.

Our fundamental research hypothesis is that the contribution of nitrogen leached from the root zone of different farms to nitrogen loadings in rivers/lakes is not uniform, but varies significantly from sub-catchment to sub-catchment depending on the underlying geology and nitrogen flow pathways.  We are basically hypothesizing that significantly higher cost-effective improvements in water quality can be achieved by targeting nitrogen management and mitigation measures on the basis of the nitrogen attenuation capacity in subsurface environment (below the rootzone) in NZ agricultural catchments.”

The fact that the No. 1 Dairy farm location is next to the Manawatu River makes it an ideal test site.  It also has a number of different soil types and landuses /crops which provide varied environments for understanding the behaviour of nitrate-nitrogen in the subsurface environment.

This will help identify factors affecting denitrification occurrence in different hydrogeological settings, provide inputs for integrated water and nitrogen flow modelling including denitrification process in the subsurface environment, and fill an identified and important gap in the knowledge for targeting management and mitigation of nitrogen runoff.

Ranvir predicts that farmers will be able to identify the capacity of their land to transport and transform nitrogen, and understand the soil and land use practices that will reduce the amount of nitrogen reaching waterways, while maintaining productivity.