Tools & Practices (continued)

Green Manures & Cover Crops

Green manuring consists of incorporating into the soil a crop grown for the purposes of soil improvement. It is a practice with a long history of use. Green manuring has been ignored in recent years as a serious option for soil improvement because the traditional practice entailed planting a full-season cover crop. This removed the field from commercial production for a whole season. Interest has returned, however, since green manuring strategies have been combined with cover cropping schemes.

Cover cropping is the growing of a crop for the purpose of soil and nutrient conservation. It appears to be a more contemporary concept than green manuring, in crop agriculture. The two concepts—cover cropping and green manuring—go well together, as most cover crops are easily used as green manures prior to the planting of a commercial crop. The combined benefits become economically feasible when the cover is grown during the off-season or inter-seeded with the main crop. It is made even more desirable when the cover crop includes nitrogen-fixing legumes.

Manuring & Composting

Livestock manures are the most traditional and widely recognized organic fertilizers. Under ideal circumstances, livestock enterprises are integrated into the whole farm operation, and manuring becomes part of a closed system of nutrient recycling. This is still strongly encouraged in organic operations. In reality, however, crops and livestock production are often divorced from each other and manures must be imported.

This has created some concerns in the organic community, as much manure is now generated by large, industrial agriculture feeding operations called CAFOs (Confined Animal Feeding Operations). Not only are there concerns about contaminants (heavy metals, antibiotics, pesticides, hormones), but many in the organic community object to any “partnering” with this segment of conventional agriculture which is considered at odds with the environmental and social values represented by organic farming.

Another issue that has grown up around manure use in organic farming relates to food safety. At a time when concerns about microbial contamination are high, questions have been raised about the risks associated with manure use on food crops. A focus piece on the February 2000 television news program 20/20 was especially controversial. The segment suggested that organic foods were more dangerous than other food products in the marketplace due to manure fertilization (22). The reporter ignored the fact that conventional farms also use manures. Were all the manure generated annually in the U.S. (about 1.4 billion tons) applied only to organic farm acreage (estimated at roughly 1.5 million acres in 1997), each acre would receive about 933 tons (23)!! Furthermore, certified organic producers have strict guidelines to follow in handling and applying manures. Most certifiers require from 90 to 120 days between the application of non-composted manures and the harvest of a food crop.

One of the most heartily recommended means of handling manures is composting. Composting stabilizes the nutrients in manure, builds populations of beneficial organisms, and has a highly beneficial effect on soils and crops. Compost can be produced on-farm by a number of means. Additional products from composts, such as compost teas, have special applications in organic agriculture.

Human manures are expressly forbidden in certified organic production. This includes composted sewage sludge (also called biosolids). The organic community made it opinion on this quite clear when the USDA’s first draft of the national rule (December, 1997) proposed allowing the use of sludge in certified production. It was counted as one of the “big three” targets of protest, along with food irradiation and genetic engineering. The prohibition of biosolids would have been disconcerting to Albert Howard, who decried the failure of cities to return their organic wastes to the countryside. Such recycling was, in his mind, a key aspect of sustainability (7).

What Howard had not taken into account is the almost universal contamination of urban wastes with heavy metals and chemicals that are not eliminated by composting and may even be concentrated. Perhaps this was not yet a serious problem in his time; it is, however, in ours. Organic farmers and consumers concerned about contamination of soil and crops with agricultural pesticides and synthetic fertilizers would be remiss to ignore the contamination hazards of even well-composted sewage.

Fred Kirschenmann, a farmer and former NOSB member, has written eloquently about the progress of the National Organic Program. In a critique of the March 2000 draft of the proposed rule (24), he pointed to another reason why the use of biosolids ought to be prohibited in organic production.

Because of the manner in which biosolids are generated, they are easily hauled and land-applied on an industrial-scale to industrial scale organic farms. Furthermore, since biosolids can essentially supplant animal manures as a source of organic matter and nutrients, their use would allow some very large farms to circumvent the traditional practices that promote biodiversity and enterprise diversity and integration. What Kirschenmann fears from biosolid use is technology that would nudge organic agriculture down the same road of industrialization taken by conventional ag.

Among the thorniest of issues swirling around the edges of organic agriculture is the role of livestock. The disagreements arise because of the diversity of people and philosophies in the organic community. Organic agriculture can usually count vegetarians and animal welfare proponents among its more vocal supporters. Many of these people feel strongly that animals should not be exploited. Their rationale often goes beyond emotional and religious beliefs; convincing human health concerns, social issues, and environmental reasons are commonly cited. On the other side of this argument are those who feel that an organic farm cannot achieve its full potential or ecological balance without livestock manure; that it is essential to nutrient cycling and to the finer aspects of soil building.

Excellent soil fertility can be built in the absence of farm livestock and livestock manures by using vegetation-based composts (25) and by harnessing the livestock in the soil—earthworms and other soil organisms. However, it is clearly easier to design a contemporary, low-input organic farm when traditional livestock are integrated. The biological and enterprise diversity that livestock can bring contributes enormously to stability and sustainability. A good example is provided by Rivendell Gardens in Arkansas, which began integrating livestock enterprises after several years as a solely horticultural operation.

The owners of Rivendell, Gordon and Susan Watkins, now rotate their strawberry and vegetable crops with grass-fed, direct-marketed beef and pastured poultry. Ideally, poultry follows beef on pasture to reduce cattle parasites. The seasons in mixed legume/grass pasture leave the soil quite mellow and well-manured for subsequent high-dollar horticultural crops (26).

The Rivendell operation demonstrates the sort of organic management where a large number of organic farmers and many animal welfare proponents find common ground. The Watkins’ animals are all raised with minimal confinement and generous access to sunshine, fresh air, and free-choice foodstuffs. While domesticated and destined for slaughter, they lead low-stress lives in conditions much closer to natural than the conventional alternatives. This is the antithesis of industrialized factory farming systems, which are increasingly becoming the norm in livestock production.

Many in both the organic and animal welfare communities are working to prohibit factory farming of livestock in organic systems. Many of the difficulties revolve around the fine interpretations of language in various organic standards. Wording such as “access to fresh air and sunlight,” for example, can be construed to mean nothing more than opening the door on one end of a large confinement poultry house for a couple hours a day.