You will look long and hard to find land more naturally suited to raising high-value specialty crops. Pinwheel’s natural resources include both pre-existing, fairly unchangeable resources like soil type and groundwater, and also resources that have been actively developed in the last 20 years during my stewardship of the land…all of the highest quality and abundance. These resources, combined with a long growing season, readily allow production of crops without the labor and expense of conventional irrigation. Heavy mulch, which provides many other benefits, takes the lead as a tool for soil moisture management, while preventing irrigation-related issues such as mineral build-up.
Extensive information about the farm’s major natural resources is publicly available. The Lawrence/Douglas County Planning Dept. has a wealth of information about the farm and its surrounding areas. Planner Mary Miller has worked extensively on issues related to Pinwheel Farm and is most knowledgable. The Northeast Sector Plan contains extensive information about the nature of the area in terms of soil, groundwater, etc. Various studies have been done regarding storm water management issues in the area. The farm remains on the rolls of the USDA Farm Service Agency, and much historical data may be available there.
Soil Type: Eudora Silt Loam (ESL) is the dominant soil type on the upland portions of the farm, with a Eudora/Kimo complex under the northern 3-4 acres. Within the “complex”, there are alternating bands of the two different types. When boring fence posts along the middle of the west side, it was remarkable how the soil could be entirely different from one hole to the next. The Kimo portion has more clay than the ESL portion.
There is also a “sand boil” area rumored to date back to the 1951 flood, which covered the farm. This area near the west part of the pasture contains extremely sandy soil which was notably unproductive and highly erodible when the farm was in row crops prior to my purchase. Prairie grasses have become well established there, with good results.
Prior to the 1951 flood, there was allegedly a pond partially on the Northeast corner of the property. Some traces remain, but the neighbors’ grading has significantly changed the waterway there, and natural succession is reclaiming the area as woodland.
The exact nature of the ESL soil is quite remarkable. Excess water drains out almost immediately, so with proper management, standing water occurs only briefly after heavy rains unless lower levels are frozen in early spring. However, once the excess storm water drains down, usually within an hour of a major storm, the soil holds a tremendous amount of water for a long time. Because there is virtually no clay component in the ESL, the soil is not the least bit sticky when wet. This means that weeds can be pulled, and the soil can be cultivated, within hours of a significant rain. In fact, it is very rare that rainfall stops all work at the farm for more than an hour or two.
The soil supports a great amount of weight when compacted, while retaining good drainage. There are only a few areas where runoff from buildings create areas that can remain impassable to vehicle traffic after a storm for more than a day. When cut at a near-verticl angle, the soil does not slide, wash, or crumble, but can retain a vertical cut almost indefinitely. 4′ vertical cuts near the edge of the neighbor’s land, between Pinwheel’s pasture and their row crops, have shown no movement towards our fence in 20 years despite no attempts to abate them. Sandier portions of the farm are, however, very prone to erosion; ruts between corn rows were as deep as the corn was tall (8″) in the sand boil area.
Some of the excellent drainage is due to the soil particle size, but it is also greatly enhanced by the prevalence of moles, worms, ants, etc. constantly tunneling under the soil. Due to the weigh bearing capacity of the soil, these tunnels are persistent. Over time, the soil will rise up around heavy fixed objects due to such underground activity. It is like leavening in bread dough. We sharply curtailed tillage when we realized that tilling this soil actually creates serious drainage and compaction problems by eliminating these underground tunnels–like punching down a loaf of bread dough right before putting it in the oven. Local folk wisdom among old-timers is that “you can’t dig enough soil out of a hole to fill it back up again” due to the porous structure that is destroyed by digging.
Left with the natural structure intact, the soil naturally wicks up water from far below if surface evaporation is curtailed. This was demonstrated by accident one year. I covered a large (20′ x 30′) area with a black tarp to kill weeds prior to mulching and planting. When I removed the cover after several week of baking sun, the soil underneath was baked as hard as concrete. I mulched the area with a thick layer of waste hay from the sheep, and awaited a significant rain. After two weeks, only 1/4″ of precipitation had been received–barely enough to soak the heavy mulch. However, when I pulled back the mulch, I found that the soil was uniformly extremely moist and perfect for transplanting. This water content can only have come from the soil/groundwater below the tillable zone.
Areas which have not received surface water in many years, such as the middle of the Green Barn (8 years since the top was replaced), continue to sprout vegetation (weeds and spilled crop seeds) every year. Wild sunflowers in the middle of the Green Barn can easily grow 13′ or more in height. This observation led to our experiments with non-irrigated crops, both out doors and inside the high tunnel.
The areas that have been gardened fairly consistently for the past 20 years have obviously more organic matter and greater tilth than the pasture areas, due to nearly two decades of mulching with organic matter such as waste hay, autumn leaves, wood chips, grass clippings, etc. Naturally, fertility is excellent as well. Few amendments have been used other than the organic mulches and compost.
When installing frost-free hydrants, we dug up to 56″ below the soil surface using only hand tools. Such a hole can be easily dug by hand in an hour, with help outside the hole to remove dirt from the edge of the excavation. Throughout this depth, there was little change in soil texture except for obvious higher levels of organic matter closer to the soil surface.
There are no rocks except those that have been carried in.
Ground water: Groundwater is generally recognized as lying about 17 feet below the soil surface in this area. When we replaced the sand point well that serves the household and farm, we found this to be accurate.
The farm lies in a bend of the Kansas River, and it’s likely that the exact ground water level is roughly contiguous with water levels in the nearby (1/2 west, 1 mile south) river. The groundwater flows within a sand layer under the covering soil, at a reasonably rapid rate.
The water is generally excellent in quality, and abundant, but does include some iron and calcium. When simply filtered, the water is fine for all farm uses including vegetable processing and livestock watering. When also softened in a conventional household system, it is fine for most domestic purposes, but does tend to stain fixtures. A common, harmless iron-loving bacteria exacerbates the visible iron content wherever water stands repeatedly, such as bathroom fixtures. We bring in bottled municipal water for drinking purposes.
Nitrate levels in Pinwheel’s water have fluctuated considerably over the years, but have always been within acceptable levels for drinking water. Levels dropped significantly after we bought the farm ground and ceased application of nitrogen fertilizers.
When the Bismarck Gardens subdivision was built, the developer offered to test groundwater from nearby wells to establish a baseline due to neighbor concerns about potential contamination due to dredging a nearby farm pond. Water was tested for many common pesticides, and Pinwheel’s water was free of any traces.
Historical industrial uses that have led to persistent groundwater contamination (arsenic from a phosphorous facility to the southeast of the farm) do not affect the farm. There could be traces of residual toxic minerals such as copper and arsenic, from vegetable crop production prior to the invention of organic chemical pesticides, but this is true of most land that was historically farmed. Sheep tend to bioaccumulate copper in the liver, and we have seen no signs of toxicity in our flock.