Planting for Sustainability & Nutrition

Nitrogen-fixing Plants High in Protein

PermaCycle, Cleveland, OH — Getting a grower's understanding of the agricultural and economic value of nitrogen-fixing plants is a key to good soil management and vegetarian diets. Haricot beans, cowpeas, soya beans and peanuts all belong to this group of leguminous plants which can harness nitrogen present in the atmosphere thanks to bacteria living in their root nodules. Increasing their cultivation can help boost vegetable production on poor soils and contribute to the regeneration of degraded environments. A further plus is the high nutritional content of nitrogen-fixing plants, which are very rich in protein.

Notes on Plant Derived Pesticides

PermaCycle, Cleveland, OH — Plant pesticides are an ever-growing segment of the pest control market. Plant derived pesticides (PDPs) are compounds that are obtained from plants and used to control pests that damage crops. They have the attraction of being both low-cost and harmless to both crops and the environment. However, not all PDPs are equal. Simply because a product is labeled organic does not mean it is good for your garden. Arsenic is organic, but it is also deadly.

Research from the South Pacific shows that pesticides obtained from derris, chillies, and neem can all offer the same degree of pest control as commercially available insecticides. Trials at Lowlands Agricultural Experiment Station (LAES), the largest research station of the National Agricultural Research Institute (NARI), located in Papua, New Guinea have demonstrated the effectiveness of the plant derived pesticides.

A native plant found from India to Indonesia, Derris has been found in Hawaii. Products made from extracts of derris roots have been used as commercial pesticides for many years. Derris is an aggressive vine that smothers vegetation as it spreads, and is mainly cultivated in the tropics for its roots, a source of the insecticide Rotenone. Extracts from crushed leaves to stun or kill fish and shrimp have been prohibited in many areas.

Two plants are noted here: Derris elliptica and Derris trifoliata or "Common Derris." While it is said that Common Derris does not "strangle" its host, it can form deep "choke" marks on a host tree and, eventually, though the host trees usually prevail, breaking the vines, the battle scars remain. Although some "organic" garden stores are selling products derived from derris, we do not advise its use. Only in extreme cases should derris be considered as a deterrent outside of its native environment, as it not only kills destructive pests, but also earthworms and other helpful soil animals. The planting or spreading the native plant is absolutely advised against.

The second PDP comes from the fruit of the chilli plant, which is safe and suitable for gardens. Lastly, but certainly not least, the PDP obtained from the seeds of the neem tree has a long history, and has been the subject of biopiracy or biological imperialism in recent years. Neem is a plant with pest repellant properties that originated in India where it has been used for centuries, but which grows well almost anywhere within the South Pacific. Neem needs to be grown in areas with a dry season if it is to produce seeds.

USDA Sustainable Weed Control Research Results

In 1993, weed ecologist John Teasdale and his colleagues at the Beltsville (MD)Agricultural Research Center set up the Sustainable Agriculture Demonstration Project (SADP), a long-term study focusing on reduced tillage. Because of the site's topography — a two to 15 percent slope, running in both directions across the field — the researchers sought to prioritize soil conservation as well as crop yields and net returns in their experimental design. They settled on four different management systems, all applied to a two-year rotation of corn/winter wheat/soybean:

The SADP is now being brought to a close, Teasdale explains, "because the general outcome was clear." Although the crown vetch system performed well in years with adequate rainfall, it did poorly compared to the conventional no-till in dry years. The cover crop and organic/manure systems did the best job of returning nutrients and organic matter to the soil, but the organic system suffered from heavy weed pressure. This led to lower average yields for the organic system, although reduced inputs resulted in only slightly lower net returns—even without the inclusion of an organic premium. (Detailed results from the SADP can be found in the American Journal of Alternative Agriculture, 15,2:79-87, 2000.)

-- Abstracted from "Banking on BARC" by Laura Sayre, NewFarm.org, July 15, 2005. See complete article here.