Many natural systems benefit from complexity. When natural processes are mimicked within a cropping system and are allowed to adapt and grow in concert with present and introduced species, efficiency among species are often a resulting benefit.
Take the experience of farmer Daniel Unruh, who specializes in the production of walnuts. His orchard floors can be identified quite easily even by someone speeding by in a car—very few other orchard floors in the area have mustard blooming in significant numbers in the spring. Several years ago, Daniel started planting a five-species mix of radish and mustard in the walnut alleys, which was recommended to decrease nematode numbers. In a soil test done prior to planting the cover crop, his nematode counts were around 5,000/sample. Daniel continued planting this five-species mix until last year, when he expanded this mix to include a row of vetch and mustard, a row of four mustards, a row of six different small grains, and a row of bell beans and Austrian peas—14 species in all! He repeats this sequence of rows three times in his alleys. This mix provides many services to his farm and bottom line: soil cover, good drainage, excellent tilth, beneficial habitat, feeding soil microbes, providing nitrogen, and reducing nematodes. Daniel is investing in his soils.
In addition to added the fertility and soil structure benefits of using cover crops, they can also help create an environment for beneficial soil microbes. Farmers who don’t invest in their soils oftentimes find that there is an increased need for chemical management of pest species due in part to the lack of natural predators. When we think of pest species that have an effect on plant root/beneficial microbe relationships there are few more damaging than the nematode. Daniel has found a dramatic positive impact on soil biology, particularly when it comes to nematode activity in his soils. His first soil test revealed a 5,000 nematodes per sample. In subsequent years, this number has decreased dramatically, with recent soil tests showing an average of 115/sample! This dramatic drop in pest species has occurred naturally, due in part to the habitat that has been created on the farm under his feet by investing in his soil—perhaps the most important piece of capital equipment on the farm.
Pictured at right is the Dikon tillage radish
species Daniel has elected to
plant in his fields. In addition to
the benefits discussed above,
the radish also provides ground
cover, mines nutrients, breaks up
compacted soil, and out-competes
many weed species, for a multi-use
multi-benefit cover crop.