Media Clipping — January/February 2003 Rural Delivery

More kinds of crops, more kinds of critters

GPI agriculture reports put a high value on diversity, both domestic and natural

By David Lindsay

Nova Scotia needs greater integration of ruminant livestock production with row crop farming. That's the common thread linking two reports released this September by the non-profit research group GPI Atlantic.

These new publications, "Soil Quality and Productivity," and "The Value of Agricultural Biodiversity," are the first two instalments in the 5-part "Resource Capacity and Use" component of GPI's "Agriculture Accounts."

Jennifer Scott, the author of the reports, says she was surprised that the livestock issue kept coming up in her research on both topics. She recommends introducing more grazing animals in regions where row cropping is most intensive-both to increase the use of manure for boosting soil fertility and organic matter, and to create more local demand for soil-building forage crops that could be incorporated into rotations.

That kind of diversified farm system makes it possible to take fuller advantage of the agricultural "services" provided by natural ecosystems, she says, because there tends to be higher populations of earthworms and other beneficial organisms where perennial sod crops are grown, and where manure is spread on the land. Scott identifies diversity both wild and domestic as a positive indicator of farm sustainability.

"You look at pasture and you might not see much," she says. "But there's so much going on there."

Scott provides a new perspective on Nova Scotia's farmland, asserting that the abundance of pasture in the province represents a wealth of biodiversity. This area of research is relatively new in North America, so she had to seek out European sources. She says many Europeans would envy Nova Scotia's large and diverse agricultural landbase.

"They're experiencing trouble with the level of intensity of farming there," she says. "They're paying farmers to increase biodiversity."

We take it for granted, and too often think of grazing as a marginal land use, says Scott. That's why these reports are important. "Biodiversity and soils are two hidden resources. They're not visible like forests."

In the reports, Scott follows the GPI principle of assigning economic value to resources not recognized in conventional accounting systems. For example, the natural pest-control effects of ladybugs are deemed to be worth $13.8 million yearly in Nova Scotia. Using such figures, she calculates losses resulting from missed opportunities or wasteful practices. Thus erosion and declining soil quality are estimated to cost farmers in the province more than $11.5 million annually.

"GPI is like a watchdog," says Scott. "We're watching the trends."

Though some of the trends associated with more intensive agriculture are troubling, many indicators put Nova Scotia in a better position than Canada as a whole. The farms in this province are relatively diverse, manuring is a common practice, and some soil conservation measures are gaining popularity. Furthermore, many Nova Scotia farmers have a clear understanding of how they could improve their practices, and sincerely wish to do so. The report says the necessary changes are economically difficult in the short term, so there is a need for support from the public and the government.

SOIL

The report on soils, which Scott co-authored with Julia Cooper, defines soil as "the natural capital asset upon which our agricultural system is based." The economic terminology is used deliberately to emphasize the value of this resource, in accordance with the GPI theory that what is not accounted for in those terms tends to be wastefully depleted or degraded.

The report says soil degradation results in compaction and reduced fertility. Compacted soil causes poor rooting, reduced fertilizer efficiency, and higher power demands for tillage. To compensate in the short term, farmers often fertilize more heavily and plow more aggressively. The authors suggest this is a vicious cycle in more ways than one.

"Ironically, these additional fuel and fertilizer inputs are counted in our conventional measures as contributions to economic growth and 'prosperity', even though they may potentially represent a decline in ecological productivity, and additional costs to the farmer and society.

Scott and Cooper say soil conservation is a challenge in Nova Scotia because of high precipitation in the spring and fall, sloping topography, shallow soils, and narrow economic margins in the agriculture industry. In 1996, average soil loss on cultivated land in the province was estimated at 6.3 tonnes per hectare, but the report says erosion rates may be as high as 30 tonnes per hectare annually in some areas where row crops are grown intensively.

The authors use "bare soil days" as one indicator of progress in soil conservation, because fields left exposed to the elements are vulnerable to erosion, especially through the winter. Nova Scotia gets good grades on this one: between 1981 and 1996, the average number of days in a year that cultivated land was left exposed declined by 31 percent, from 50 days/ha to 34 days/ha. Newfoundland is the only province that does better. Of course, farmers can't avoid leaving soil exposed some of the time. The report says covering bare fields with bay mulch, at a cost of $105-135/ha, may reduce soil loss by 40 times.

Other measures recommended for reducing erosion include conservation tillage methods, contour farming, establishing windbreaks, and planting cover crops. The list also includes those two touchstones of diversified agriculture: manuring, and incorporating forage crops into rotations. Both have the effect of increasing organic matter in soil.

Soil organic matter, or organic carbon, is used in the report as one indicator of soil quality and productivity. A minimum of 3.8 percent organic matter is recommended for "moderate structural stability," to provide good aeration, suitable drainage, and resistance to erosion. Organic matter also prevents leaching, making nutrients (especially nitrogen, phosphorous, and sulphur) available slowly through the process of decomposition.

Manure is shown to be valuable not only for increasing organic matter, but also for improving "soil foodweb health," a relatively new indicator of soil quality, based on the mix of bacteria, fungi, protozoa, nematodes, and microarthropods that control nutrient cycling in soil. Promoting healthy microbial populations may not be exactly what Nova Scotia farmers have in mind when they haul out the spreader, but they're doing it on a relatively large scale. In 2000, 33 percent of the province's farmland received manure, compared to 7.5 percent nationally.

On the other hand, the soil report says the beneficial functions of those tiny organisms can be disrupted by synthetic fertilizers, pesticides, and intensive cropping year after year. Synthetic fertilizer was used on 62 percent of Nova Scotia farmland in 2000 - close to the 66 percent figure for Canada as a whole. And the report cites Kings County as an area of the province where practices associated with intensive farming are more common.

In Kings County, 51 percent of the land in rotation is in the soil-building phase (perennial forage) and 30 percent is in potentially soil-degrading row crops. In Colchester County, where much of the province's dairy industry is concentrated, 83 percent of rotation land is in soil-building crops. (Dairy farms also get a "thumbs up" in the report because they are most likely to spread manure; with cows kept indoors, there tends to be more manure to spread.)

Crops with fibrous root systems build organic matter by contributing root residues every year. In this respect, ryegrass, hay, and pasture crops are considered highly beneficial. Cereal crops are said to have a neutral effect on organic matter, so long as the plant residue (straw) is left on the field. But the report says row crops tend to have modest root systems, and generally do not contribute enough organic matter to replace what is lost from the open ground between rows.

NO EASY SOLUTION

The authors acknowledge there is no easy solution to the problems of erosion and declining organic matter. "The decline of livestock farming in the areas most suited to potentially soil-degrading crops is a major stumbling block," they say.

Based on minimum rates of manure application needed to produce forage yields similar to what is possible with synthetic fertilizer, they calculate that Nova Scotia farmland needs a livestock population averaging at least 1.7 "manure animal units" (MAU) per hectare. (One MAU is equivalent to one dairy or beef cow, based on 1,195 kg of dry manure per cow per year.)

Currently Digby County has the province's highest livestock density, at 2.5 MAU/ha, but this is due to the concentration of mink production in the region, and the lack of crop farming. Limited arable land also accounts for the fact that Shelburne and Yarmouth Counties are next highest, at 1.5 and 1.8 MAU/ha respectively.

The report points out that even if surplus manure were available for free from regions with higher livestock concentrations, transporting it just 10 km would add $8.50/ha to the spreading cost, so manuring is only a viable option where there is local integration of livestock farming.

Nova Scotia's average livestock density dropped in the 1970s, largely due to a reduction of the provincial cattle herd. The gradual recovery in livestock numbers since 1976 mainly reflects Increases in the number of pigs (78 percent) and poultry (16 percent). Those sectors exist is Kings County, where the report says manure is badly needed, but manure from hogs and poultry is deemed too high in nutrients to be used straight. Cattle manure is lower in nutrients, and has the added benefit of being higher in organic matter.

The average livestock density for all Nova Scotia farmland is now .87 MAU/ha. Scott and Cooper state, "This analysis shows that promotion of a healthy soil foodweb through manure additions alone may not be a realistic goal unless overall livestock numbers are increased and distribution is improved."

In response to a question about the practical aspects of integrating livestock into crop farming areas, Scott says subsidies are not necessarily the solution, though government support for community manure composting facilities could help a lot.

"The whole housing thing is a big factor in the (Annapolis) Valley," she says, observing that burgeoning residential development in the region has brought a degree of intolerance to the smell of manure. "People should realize that raising livestock is part of farming."

Residential sprawl has also inflated land values in the Valley; and Scott says this puts farmers under economic pressure to produce high-value row crops by intensive methods. She suggests livestock producers in that situation need all the support they can get, and consumers can do their part by buying meat directly from local farmers.

The soil report includes excerpts from interviews with Nova Scotia farmers conducted in 1994 and 2000, to give some sense of the "thought, caring, and innovation that actually occurs daily at the farm level." In their conclusion, the authors say all citizens need to demonstrate a similar level of commitment:

"If the conservation of our natural wealth, the health and economic viability of the agriculture sector, and the food security of future generations become prominent social priorities, then Nova Scotians will be more likely to support local farming and food production, and farmers, in turn, will more likely have the resources they need to care for the land and adopt stewardship practices that conserve and enhance the quality of the province's soil wealth."

BIODIVERSITY

In her GPI report on biodiversity, Scott sets down the following premise: "Agricultural production depends on a healthy, fully-functioning ecosystem." She states emphatically that farms cannot exist apart from nature, because they need numerous "services" provided by the interaction of natural organisms, including pest control, nutrient management, pollination, waste decomposition, and soil formation.

Scott says diminished biodiversity increases the financial and ecological costs of food production. She allows that short-term yields and predictability can be increased by replacing natural services with purchased inputs such as energy, buildings, synthetic fertilizers, pesticides, irrigation systems, and pharmaceuticals. But she says these things tend to reduce biodiversity. "This can create a spiral of increasing needs for inputs... and ultimately reduce long-term productivity and farm viability."

Because it would be impossible to identify and count all the organisms that play a role on farms in Nova Scotia, the report uses habitat as an indicator of biodiversity. Scott argues that agriculture is not necessarily an infringement on wild, natural spaces. She says farms can be "reservoirs of habitat potential," with numerous organisms living in fields, ponds, streams, and woodlands. Obviously, diversified farms provide habitat for a greater diversity of wild organisms.

Beneficial organisms, such as predators of farm pests, are more prevalent in perennial crops than in annuals, the report says. On cultivated land, crop rotation and conservation tillage methods are considered good for soil organisms. But Scott cites research indicating that pesticide use and high synthetic fertilization have the effect of reducing habitat quality, species diversity, and ecosystem services.

Adding fertility and raising pH can be beneficial for habitat up to an optimum level, beyond which it is detrimental. Generally, the habitat value of pasture is reduced by herbicide use, high nitrogen fertilization, artificial drainage, and heavy grazing.

The report says habitat is richest on farmland that is neither cropped nor grazed: hedgerows, forests, wetlands, and riparian zones (areas along watercourses). Leaving some land in a wild state can have other benefits. Scott points out that hedgerows, on top of being excellent bird and insect habitat, can provide shade and shelter for livestock. And by slowing wind speed, hedgerows can reduce soil erosion, maintain snow cover to protect perennial crops, reduce temperature fluctuations, and reduce plant desiccation. Once removed, hedgerows can be replanted, but it's hard to restore all of their original functions, because biodiversity develops naturally over a span of decades.

In Nova Scotia, 11 percent of farmland is in annual crops - a proportion that has been stable for the past 50 years. In Canada as a whole, the proportion of farmland in annual crops has risen from 32 percent to more than 40 percent in that period. Scott says this means Nova Scotia is doing a relatively good job of preserving biodiversity. It's also good that the proportion of the province's farmland in tame hay or pasture has increased to nearly a quarter. The large areas of woodland on Nova Scotia farms represent another potentially valuable habitat resource, but Scott points out this is hard to measure without knowing the quality of those forests.

The report says Kings is the most intensively farmed county in Nova Scotia, with more annual cropping, pesticide use, and synthetic fertilization. In the province as a whole there is a trend toward more intensive management, but the trend is stronger at the national level, and Prince Edward Island is cited as having a considerably more intensive agriculture industry. Scott concludes that Nova Scotia is in a relatively good position, though the province may gradually be losing beneficial ecosystem services.

The value of those ecosystem services is another indicator used in the biodiversity report. Scott says an estimated 100,000 different organisms live in soils, and since only a few of them may harm crops in any given year, it's best to have the whole range. "Diverse populations of soil organisms maintain a system of checks and balances that can keep disease organisms or parasites from becoming major plant problems." This is an instance where diversity itself is credited with providing a service to agriculture.

Similarly, the genetic diversity of crop varieties and livestock breeds is deemed highly valuable for maintaining the resilience and adaptability of agriculture. Scott says narrowing the genetic base "can heighten the risks associated with changes in environmental conditions and susceptibility to pests and disease." From the GPI perspective, this trend toward "genetic erosion" in farming represents the depletion of a precious resource.

The report also focuses on some specific wild organisms that benefit agriculture. For example, figures are given for the value of bird and wasp predation on insect pests. The Green lacewing is an insect that gets special attention, because in its larval stage it preys on aphids voraciously, and it is also known to control Two-spotted spider mites, Mealy bugs, leafhoppers, small caterpillars, and thrips.

Scott recommends more research into pest/predator interactions and biodiversity management on farms, and she says, "farmer innovation in this area should be rewarded." She stresses that taking full advantage of biodiversity is "knowledge-intensive," not input-intensive. She does not suggest a sudden shift to organic agriculture.

There is much to be learned, she says, about using appropriate and realistic combinations of purchased inputs and natural services. "Nova Scotia farms could provide leadership in finding that ecological balance, and in identifying thresholds that should not be crossed to avoid irreversibly damaging the capacity of the ecosystem to provide free services."

VALUES

Some of the figures given in the biodiversity report may raise eyebrows. Based on the price of purchased compost, the soil processing function of earthworms in Nova Scotia is valued at $3.6 billion/year far more than the value of the province's annual agricultural production.

Scott acknowledges in the report that "preliminary and rather crude estimates" are used to show what it would cost, hypothetically, to replace the work done by beneficial organisms on farms. "These numbers may have no practical economic reality," she says, "but rather demonstrate that certain ecological services are, in effect, irreplaceable or invaluable."

In her introduction, Scott says while this is "admittedly a very utilitarian approach," it is a way of "catalysing more immediate action to conserve biodiversity resources."

When questioned about this activist approach to research, Scott says it's entirely in keeping with GPI Atlantic's full-cost accounting system, which assesses social, economic, and environmental factors in equal measure. Yes, these publications represent a certain set of values. "We try to be very explicit about that," Scott says, adding that many organizations produce scientific reports with an unstated bias.

If the biodiversity report seems to have more of an ideological bent than the soils report, she says that's partly due to the scarcity of scientific data. The reports are meant to be "reviews of the literature," and Scott sees a need for more research on agricultural biodiversity in Nova Scotia.

Assigning dollar values to resources that cannot actually be bought or sold is the best way "to get people thinking about these things in relative terms," she says. "Unless you have monetary values attached to things, people tend not to pay attention."

Scott says she uses this research tool reluctantly, because she recognizes the limitations of economic data. "It's completely anti-intuitive for someone who loves the environment or someone who loves farming."

Copyright © 2001 Rural Delivery