Alley cropping in a hillside terrace system

My grant project “Alley Cropping in a Hillside Terrace System” sought to transform the steep slopes of a newly planted fruit orchard into a sustainable agriculture system incorporating earth berm terraces, no till annual agriculture, with a cut-and-carry mulch system.   Goals included creating access to and passive water harvesting for the entire landscape, obtaining an immediate yield of annual crops that could be repeated until the fruit trees matured many years later.  Also this annual system needed to build soil rather than lose it to erosion, it needed to be cultivated with minimal effort, little to no outside inputs, and minimal equipment and capital needs. 

To achieve this, I began by shaping the hillside into a series of flat cultivable terraces separated by earth retaining slopes. Placing the terraces on contour, the system was able to passively collect rainwater and any organic matter or nutrient runoff and hold it in the terrace beds.  I then planted the slopes above the terraces with nitrogen fixing and deep rooted, mineral accumulating plants that would later be cut and used to mulch the crops planted on the terraces.

By planting butternut squash into small patches of disturbed earth within the established sod of the terraces, and then carefully mowing down the sod until the squash began to sprawl outside of the planting patch, and finally cutting the slope above the terrace and raking the detritus down onto the terrace and using it to smother the weeds around the squash, I was able to obtain a significant yield of squash without any weeding, tilling, outside fertilizer or herbicide application, or significant irrigation.  With only a push mower, a scythe, shovel, and a rake I was able with minimal effort to raise a crop in a manner that is ecologically sound, cost effective, and quite possibly actually sustainable.  

The question of long term sustainability is one that I set out to discover.  I had hoped that the system would continuously enhance the nutrient profile and % organic matter of the soil in both the terrace and hillside (mulch producing) areas, but this I did not discover.  The assumption I worked under and hoped to test was that by using the right plants I could somehow violate the so called “Law of Return” of Albert Howard.  By growing and harvesting perennial nitrogen fixing plants I hoped that atmospheric nutrients like carbon and nitrogen could be fixed into the soil creating an excess of these elements on the hillside plots, plus these same elements would be accumulated in the aerial parts of the plant and when used as mulch would add “free” nitrogen and carbon to the terrace.  Growing deep rooted plants in the same area was intended to mine the soil minerals like Potassium and Phosphorus and the rest of the micronutrients from the subsoil.  Repetitive cuttings of these crops, I thought, could speed up the rate at which the roots and soil biology could mineralize these nutrients from the earth and pull them from the subsoil and upon decomposition, add them to the topsoil.  Some of this nutrient would be accumulated in the aerial parts and spread to the terrace as mulch and some would be re-dispersed in the hillside through root sloughing and winter dieback of the uncut portion.  To measure this I conducted a series of soil tests, comparing two test plots to a control, however, the results of the test showed such variability (increases in some nutrients and decreases in others) that I could draw no conclusions.

Despite the lack of scientific rigour, the project anecdotally achieved all of its objectives and demonstrated to me that a sustainable annual agriculture system is possible in hilly regions of the world and it can be achieved by anyone with access to land and a few hand tools.  

Introduction:

Conventional farming through mechanical tilling and harrowing when performed on even gently sloping terrain inevitably results in erosion and loss of topsoil during heavy rain events.  Even heavy grazing of livestock on steep hillsides can result in erosion and the creation of gullies.  Furthermore, mowing these areas can be quite hazardous to farmers as tractors can easily tip over if not used properly.  The result is that these lands are often subject to degradation through erosion or left to return to forest.  If one has plenty of flat arable land to work with, then leaving the hillsides to nature is a reasonable option, but if all the land in the region is on a slope as in SE Ohio, then a better method is necessary.  Taking a lesson from ancient agricultural societies around the world, I devised a regional adaptation of the traditional terrace system.  As labor is not as abundant, and time not as cheap as it once was, and given the typical resouce base of those in Appalachia, my project sought to quickly and cheaply create a terrace system using only the dirt from the site itself.  

To make the project fit within my particular interest of working with hand tools and onsight resources, I further designed the system to produce all of its own fertilizer, weed control, and moisture retention via a cut-and-carry mulch application. Placing the terraces on contour, or perpendicular to the flow of water, allows them to naturally catch and hold rainwater as it flows downhill.  Incorporating mulch allows this harvested rainwater to stay around longer. Growing the mulch directly above the terrace on the retaining bank, means that it only has to be raked a few feet downhill once cut.  By employing a variety of nitrogen fixing and deep rooted perennial plants in the mulch patches I hoped to create the most nutrient rich mulch possible.

All of this combined results in "Alley Cropping in a Hillside Terrace System" or a low-cost, low-input, sustainable agriculture method for hilly regions around the world.