• Francis Thicke
• A New Vision for Iowa Food and Agriculture, Food, Energy, and Agriculture Commentary
• September 21, 2010

A Grass-Based Dairy Designed to Mimic Nature’s Ecology

by Francis Thicke

[The following is an excerpt taken from my book, 'A New Vision for Iowa Food and Agriculture'.]

Chapter 13. A Grass-Based Dairy Designed to Mimic Nature’s Ecology

On the dairy farm that my wife, Susan, and I own and operate in southeastern Iowa, we base our farm’s design and management on the principles of ecology. We moved our dairy from several miles away to its current location in 1996. The land we moved the dairy to had been under continuous corn and soybean cropping for many years previously, and the farm had no buildings we could use for the dairy. We had to design and build the dairy from the ground up.

The farmland had been cash rented from an absentee landlord before we bought it, and conservation had been neglected. The land on the farm is rolling and steep in places – with some hills exceeding 15 percent slope. Most of the field’s grass waterways were gullied, with the deepest gully nearly four feet deep. Because the configuration of the landscape did not lend itself well to contour farming, convenience had dictated that row crops had been planted up and down some of the hillsides. In some areas of those hillsides, all of the topsoil was gone; that is, the surface soil – what soil scientists call the A horizon – had been lost to erosion.

We repaired the gullies and planted the cropland on the farm to a mixture of grazing forages, consisting of grasses and forbs, including legumes. Since all the buildings of the original farmstead had disappeared, (except an old wooden corn crib) we built new facilities, including a milking parlor, cattle barn, on-farm dairy processing plant and a house.

We divided about 120 acres of the new pasture into 60 small pastures – called paddocks – using simple, low-cost electric fencing materials. This paddock system allows us flexibility to manage where cows graze at all times, so we can optimize the productivity and nutritional value of the pasture forages. We manage the cows to mimic the ecological effects of bison herds roaming the prairie.

We milk about 80 cows twice a day on our farm. During the growing season, we turn the herd out to a new section of pasture after each milking. Normally, we give the milking herd half of a paddock – about one acre – to graze after each milking, twice every day. We can quickly and easily subdivide paddocks into any size increment using portable fencing materials.

Besides the milking herd, we have two other groups of grazing dairy cattle, each rotating through paddocks in separate areas of the farm. One other group consists of cows that are in the dry phase of their production cycle (each cow calves annually and for two months before calving is dried off – not milked) and pregnant heifers (heifers are young female cows). In the third group are the yearling heifers that are not yet old enough to be bred.

After a paddock has been grazed, we move the cows on to the next paddock, and the grazed forage in the paddock the cows had been in is allowed to rest and regrow as the cows rotate through other paddocks. In spring and early summer the grass grows fast, so we rotate the cows back to each paddock in about 20 or 30 days. As the summer gets hotter and drier, the forage growth rate slows, so we slow the rotation down to 40 days or more of recovery time before re-grazing a paddock. That allows the forage plants adequate time to recover and regrow from the previous grazing episode.

If they were not given adequate recovery time, the forage plants would become less productive over time, and eventually some plants would die from the stress of overgrazing. Good management promotes greater pasture productivity, higher nutritional value of pasture forages and greater diversity of forages – and ultimately more milk production per acre of land. Good pasture management also improves soil quality and fertility, helps protect water quality, and contributes to wildlife habitat. In short, we are rebuilding our farm’s ecological capital, and improving the long-term productivity of the land.

We normally begin grazing the first week of April, just as the grass begins to grow vigorously. We start grazing early – even though the forage is then short – so that when we complete the first rotation cycle around the farm’s paddocks, the forage in the paddocks that were grazed first has regrown to a prime stage for grazing again. That also sets the paddocks around the farm in a sequence of regrowth stages suitable to the timing of the paddock rotation cycle.

In early summer the pasture forage grows faster than the cows can graze it, so we harvest some of the paddocks as hay for winter feed. As the summer progresses and it gets hotter and drier, the forage growth slows, so we slow down the paddock rotation to allow more time for regrowth. Then, we bring those paddocks that had earlier been harvested for hay into the grazing rotation so it takes longer to move the cows through the full rotation of paddocks.

We are also able to continue grazing after the growing season ends in fall. To do that, we defer grazing some pasture areas in August and allow the forage there to grow and “stockpile” until the growing season ends in October. We then graze those areas throughout November and even into December, until the grass becomes covered by snow. By starting grazing as early as possible in the spring and stockpiling forage for grazing past the end of the growing season, we are able to lengthen the time the cows are able to graze each year to about eight months, and we reduce the amount of hay we need to harvest mechanically and store for winter feeding.

The grazing system that we use on our dairy farm mimics the prairiegrass/bison ecology that contributed to building the Midwest’s deep, fertile prairie soils. However, unlike the roaming bison herds, we manage where our cows graze at all times, which allows us to optimize forage productivity and utilization and to maximize the rebuilding of soil “ecological capital.”

Management is important. If paddocks are allowed too much recovery time, the plants will become overly mature and will lose nutritional value. With too little recovery time, some plant species will not recover fully and will die, reducing pasture productivity and diversity. Under good management, plant diversity is maintained or increased and soil fertility is continuously regenerated.

Over time, we have learned many simple management techniques that increase productivity and reduce energy needs. For example, we try to maintain our pasture forage mix at about half grass and half clover. Clover is an important component of the pasture forage mix because clover is a legume that fixes nitrogen from the air into a form the plant can use to make protein. Nitrogen fixation by legumes is done through a symbiotic relationship between legume plants and rhizobia bacteria that inhabit the plants’ roots. The symbiotic relationship allows the rhizobia to feed off plant roots for their energy needs while they convert inert nitrogen gas from the atmosphere into organic forms that the plants can use to make proteins. With adequate clover in our pastures, we do not need to add any nitrogen fertilizer. For that matter, we do not add any fertilizers to our pastures beyond what is recycled back to the soil in the manure – which has been enough to not only replenish but to rebuild the soil fertility in the pastures.

Sometimes paddocks will become sod-bound as grasses begin to predominate and clovers fade from the pasture. To reverse that trend, we allow the cows to graze the sod-bound pastures during rainy times. That will allow the cows’ hooves to cut through and open up the sod, allowing more spaces for clover plants to take root and grow. If clover plants begin to dominate over grass in some paddocks, we can allow those paddocks more rest time between grazing episodes, which will help strengthen the grass plants and increase grass presence in the paddock.

The design of a grass-based system is key to making it efficient to manage. We built rock-surfaced lanes throughout the pasture areas to allow the cows to walk from the milking parlor to all paddocks without making mud or causing soil erosion, and we have water tanks in all pastures so cows have access to water at all times. We use a solar-powered watering system for watering the cows in the pastures.

The solar-powered watering system is set up with an array of solar photovoltaic panels on the edge of a farm pond. The solar panels power a pump in the pond which pumps water to a 4,000-gallon tank located on top of the highest hill on the farm. The water then gravity flows from the large tank through an underground pipe system to all 60 paddocks on the farm, where there are small tanks for the cows to drink from. This water system saves us about $150 per month in costs we had previously paid for water from the rural water system (farmers in southern Iowa get most of their water from rural water systems because southern Iowa lacks abundant groundwater).

We are working on other renewable energy systems for our farm. In 2010, we installed solar hot water panels on the roof of our dairy processing plant to heat water for our processing plant and milking parlor. We are now making plans to install a wind turbine to produce electricity for the farm.

In 2010, we were able to purchase an additional 220 acres of land immediately adjacent to our dairy. Now, with about 450 total acres on the farm, we are looking to make our dairy as self-sufficient as possible for our approximately 160 head of dairy animals. We will be able to expand our operation incrementally as our market grows. We do feed some grain, currently about five to six pounds of grain per milking cow during the summer months when the cows are on pasture and 10 to 12 pounds of grain during the winter when the cows are on stored feed.

[Stay tuned to this blog: I will be posting all the chapters from my book, 'A New Vision For Iowa Food And Agriculture' to this blog during the final weeks before the election on November 2nd. I look forward to any comments or questions you have.]

Tags: Agriculture Dairy cattle Dairy farming Farm Livestock Sustainable Agriculture