With permission of the authors
16 April 1993, Volume 260, pp. 344-349
Soil Quality and Financial Performance of
Biodynamic and Conventional Farms in New Zealand
John P. Reganold,* Alan S. Palmer, James C. Lockhart, and A. Neil Macgregor
Copyright © 1993 by the American Association for the Advancement of Science
Soil Quality and Financial Performance of
Biodynamic and Conventional Farms in New Zealand
John P. Reganold,* Alan S. Palmer, James C. Lockhart,
A. Neil Macgregor
Biodynamic farming practices and systems show promise in mitigating some of the detrimental effects of chemical-dependent, conventional agriculture on the environment. The physical, biological, and chemical soil properties and economic profitability of adjacent, commercial biodynamic and conventional farms (16 total) in New Zealand were compared. The biodynamic farms in the study had better soil quality than the neighboring conventional farms and were just as financially viable on a per hectare basis.
Concerns about environmental, economic, and social impacts of chemical or conventional agriculture have led many farmers and consumers to seek alternative practices that will make agriculture more sustainable. Both organic and biodynamic farmers use no synthetic chemical fertilizers or pesticides, use compost additions and manures to improve soil quality, control pests naturally, rotate crops, and diversify crops and livestock. Unlike organic farmers, biodynamic farmers add eight specific preparations, made from cow manure, silica, and various plants, to enhance soil quality and plant life (1).
We examined soil properties and financial performance on pairs or sets of biodynamic and conventional systems over a 4-year period (1987 to 1991) on the North Island of New Zealand (Table 1). We also made financial comparisons between these farms and representative conventional farms in each study region on the basis of models used by the New Zealand Ministry of Agriculture and Fisheries (MAF) (2). A farm pair consisted of two side-by-side farms, one biodynamic and one conventional; a farm set consisted of three adjacent farms, one biodynamic and two conventional. The choice of five farm pairs and two farm sets (totaling 16 farms) was made on the basis of surveys, interviews, and on-farm soil examinations of more than 60 farms to ensure that all soil-forming factors, except management (3), were the same in each farm pair or set.
The biodynamic farms had been managed biodynamically for at least 8 years, with the oldest for 18 years, to provide time for the biodynamic farming practices to influence soil properties. The farm pairs or sets included a range of representative farming enterprises in New Zealand: market garden (vegetables), pip fruit (apples and pears), citrus, grain, livestock (sheep and beef), and dairy. Farms in each pair or set had the same crop and livestock enterprise. Paddocks (fields) chosen for study in each farm pair or set had soils in a single soil profile class and were located at the juncture of adjoining farms. The soil of each paddock was sampled at numerous locations (4). In total, 130 soil samples from 22 paddocks were taken and analyzed (5).
J. P. Reganold, Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164.
A. S. Palmer and A. N. Macgregor, Department of Soil Science, Massey University, Palmerston North, New Zealand.
J. C. Lockhart, Department of Agricultural and Horticultural Systems Management, Massey University, Palmerston North, New Zealand.
*To whom correspondence should be addressed.
In six of the seven farm sets (Table 2), the biodynamically farmed soils had better structure and broke down more readily to a good seedbed than did the conventionally farmed soils. The crumb and nut structures found predominantly on the biodynamic farms provide better aeration and drainage for crop or grass growth compared with the blocky and clod structures found mostly on the conventional farms (6). Soil was more friable, which makes it more easily tilled by farm machinery, on four of the seven biodynamic farms compared with that of their conventional neighbors.
The surface soil bulk density was significantly less on four of the biodynamic farms than on their conventional counterparts (Table 2); when all data were aggregated, bulk density was significantly lower on the biodynamic farms (Table 3). Bulk density is related to mechanical impedance and soil structure, both of which affect root growth. Penetration or cone resistance is another indicator of mechanical impedance. Two of the three biodynamic farms in pasture had significantly lower penetration resistances in the upper 20 cm than their conventional counterparts had. The results were variable for the horticultural and mixed farms (Table 2). Overall (Table 3), the biodynamic farms had a significantly lower penetration resistance in the upper 20 cm; there was no difference between farming systems in soil 20 to 40 cm below the surface.
Organic matter content, soil respiration, mineralizable nitrogen, and the ratio of mineralizable nitrogen to organic carbon were significantly higher on almost all the biodynamically farmed soils than on the conventionally farmed soils (Table 2). The aggregated data (Table 3) indicate significantly higher values for these four parameters on the biodynamic farms. The higher amounts of organic matter on the biodynamic farms have contributed to better soil structure and consistence and to bulk density and cone resistance that are lower than those of their conventional neighbors. Soil respiration and the ratio of mineralizable nitrogen to organic carbon give an indication of the microbial activity of the soil, which accounts for the recycling of vital nutrients such as nitrogen, phosphorus, and sulfur for plant growth (7).
Topsoil was significantly thicker on two biodynamic farms than on their conventional neighbors (Table 2). Overall, 2.2 cm more topsoil was present on the biodynamic farms (Table 3). These differences were structure and consistence and to bulk density and cone resistance that are lower than those of their conventional neighbors. Soil respiration and the ratio of mineralizable nitrogen to organic carbon give an indication of the microbial activity of the soil, which accounts for the recycling of vital nutrients such as nitrogen, phosphorus, and sulfur for plant growth (7).
Earthworms were counted on the two market gardens to give another indication of biological activity. From 30 soil cores (15 cm in diameter by 15 cm deep) taken on each paddock, we found the biodynamically farmed soil to average 175 earthworms per square meter compared with 21 earthworms per square meter on the conventionally farmed soil. By mass, the biodynamically farmed soil had 86.3 g of earthworms per square meter, whereas the conventionally farmed soil had 3.4 g of earthworms per square meter. These differences were most likely due to the use of pesticides, shown to reduce earthworm populations (8), on the conventional farm.
Topsoil was significantly thicker on two biodynamic farms than on their conventional neighbors (Table 2). Overall, 2.2 cm more topsoil was present on the biodynamic farms (Table 3). These differences were partly due to the significantly lower soil bulk densities on the biodynamic farms. Greater organic matter content and biological activity contributed to the formation of topsoil at a faster rate on the biodynamic farms. Soil erosion was not significant on any of the paddocks in this study.
Cation exchange capacity and total ni trogen were more often higher on the individual biodynamic farms, whereas total and available phosphorus, available sulfur, and soil pH were more often higher on the individual conventional farms (Table 2). This relation, except for total phosphorus, holds true when the aggregated nutrient data were compared (Table 3). Aggregated amounts of calcium, magnesium, and potassium were similar in the two systems. There were a number of statistically significant differences in the amounts of phosphorus, sulfur, potassium, calcium, and magnesium between individual farms, although few differences were of biological significance (that is, almost all soils were of adequate fertility for their respective crops) (9).
To evaluate financial viability, we examined farmers' annual accounts from 1987 to 1991. These accounts are the only common source of farm financial data in New Zealand because few New Zealand farmers keep financial records of individual farm enterprises beyond annual accounts (10). Reliable economic data from annual accounts were available for 11 of the 16 farms. We compared the financial performance of the biodynamic farms both with that of their conventional neighbors and with that of the average, representative conventional farm (2) in the region of each farm pair or set. Most of the products from the biodynamic farms were sold as certified organic or biodynamic at a premium price up to 25% higher than the market price of a similar conventional product.
Profits can be different from one farm to another because of the ownership structure or the amount of fixed costs such as debt servicing. To compensate for these differences, we excluded fixed costs from our calculations and used an analysis of enterprise gross margins as a measure of financial performance (11). Gross margin is the difference between total farm income per hectare and variable or operating expenses per hectare. Examples of variable costs include those of fertilizers, pesticides, biodynamic preparations, fuel, and labor. We only examined farming enterprises requiring similar commitments of owner-operator resources per hectare, except for dairy farm pair 2, where the biodynamic farm was selling yogurt and the conventional farm milk. Here, the additional direct costs of yogurt production were included in the gross margin analysis of the biodynamic farm.
One biodynamic farm (livestock) had greater, two biodynamic farms (mixed and dairy 2) had lower, and two biodynamic farms (market gardens and citrus) had similar gross margins compared to those of their conventional neighbors (Table 4). Compared with the representative conventional farms (2) in their regions, three biodynamic farms (citrus, livestock, and dairy 1) and three conventional farms (mixed, livestock, and dairy 2) were more prosperous, two biodynamic (mixed and dairy 2) were less prosperous, and one conventional farm (citrus) was comparable. In the majority of cases, the biodynarnic farms had less year-to-year variability in gross margin than did the conventional farms. Economic stability is one of the most significant characteristics of sustainable farming systems. Total income and variable costs were not consistently lower or higher on the biodynamic farms than on their adjacent conventional neighbors or the MAF representative (2) conventional farms.
From farmer interviews and their annual accounts, we determined that the biodynamic citrus, livestock, and dairy 1 farms have been able to secure reliable markets for their products, which is an important factor for economic stability. Gross margins for the biodynamic market garden were less than for the conventional counterpart in 1988 and 1989 but greater in 1990 and 1991. Annual returns per hectare for the biodynamic market garden have increased consistently over this 4-year period because of the development of biodynamic or organic markets and improved productivity and farm management practices. The biodynamic mixed farm (except in 1991) and the biodynarnic dairy farm 2 have not matched the annual gross margins representative of conventional farms in the same region.
Although gross margins provide a comparison of financial performance of two farms under different management approaches, total gross margins illustrate the financial return to each whole farm or to the major farm enterprise. Total gross margin is simply the gross margin times the effective enterprise area of each farm or each MAF model. The biodynamic farms had lower total gross margins than their conventional neighbors and most of the MAF conventional farms (Table 4). Much of this difference was due to the smaller size and greater enterprise diversity of the biodynamic farms.
The biodynamic farms proved in most enterprises to have soils of higher biological and physical quality: significantly greater organic matter content and microbial activity, more earthworms, better soil structure, lower bulk density, easier penetrability. and thicker topsoil. The results of the soil chemical analyses were variable. On a per hectare basis, the biodynamic farms were just as often financially viable as their neighboring conventional farms and representative conventional farms.
REFERENCES AND NOTES
1 . H. H. Koepf, The Biodynamic Farm (Anthroposophic Press. Hudson, NY, 1989), pp. 94-112.
2. Ministry of Agriculture and Fisheries, Farm Monitoring Report North Central Region (MAF, Palmerston North, New Zealand, 1987-1991); Farm Monitoring Report: North Region (MAF, Hamilton, New Zealand, 1987-1991).
3. H. Jenny, Factors of Soil Formation (McGraw-Hill, New York, 1941), pp. 12-20. Fields not adjacent to the boundary between farms may differ not only in soil characteristics but in economic performance, limiting the economic component of studies with whole farms.
4. Ten pairs of paddocks were directly adjacent to each other; 5 to 6 soil samples were taken from each paddock. Two paddocks were in hill country and had to be sampled about 300 m apart to get the same slope and aspect; here 12 soil samples were taken from each paddock. Soil samples were collected in the spring of 1990 and the summer of 1990 to 1991 from the upper 10 cm.
5. Soil samples were analyzed for the following properties: total carbon, with the use of a Leco (Saint Joseph, MI) high-frequency induction furnace; extractable potassium, calcium, and magnesium, with the use of a semimicro leaching procedure; pH in a water suspension; extractable phosphorus and cation exchange capacity as described in L. C. Blakemore, P. L. Searle, and B. K. Daly, New Zealand Soil Bureau Scientific Report 80 (Department of Scientific and Industrial Research, Lower Hutt, New Zealand, 1987)]; soil respiration, by manometric measurements of the respiratory uptake of gaseous oxygen by soil [W. W. Umbreit, R. H. Burris, J. F. Stauffer, Manometric and Biochemical Techniques (Burgess, Minneapolis, 1972)] and modified by A. N. Macgregor and L. M. Naylor [Plant Soil 65, 149 (1982)]; mineralizable soil nitrogen, by incubation [D. R. Keeney and J. M. Bremner, Soil Sci. Soc. Am. Proc. 31, 34 (1967)1; total nitrogen and phosphorus, with the use of a micro-Kjeldahl digestion of soil followed by nitrogen analysis [Technicon, Industrial Method No. 329-74 W1A (Technicon, Tarrytown, NY, 1976)] and phosphorus analysis [J. R. Twine and C. H. Williams, Commun. Soil Sci. Plant Anal. 2, 485 (1971)]; and sulfate, by the automated Johnson and Nishita technique [B. Heffernan, A Handbook of Methods of Inorganic Chemical Analysis for Forest Soils, Foliage, and Water (CSIRO Division of Forest Research, Canberra, Australia, 1985)1. Soil profiles were analyzed in the field for the following properties: soil texture, structure, and consistence as described by standard New Zealand Soil Bureau procedures [N. H. Taylor and 1. J. Poinlen, Soil Bureau Bulletin 25 (Soil Bureau, Lower Hutt, New Zealand 1962)1; bulk density with the use of thin-walied aluminum cores; and penetration resistance with the use of a Rimik (Toowoomba. Queensland, Australia) CP1 0 cone penetrometer.
6. R. G. McLaren and K. C. Cameron, Soil Science: An Introduction to the Properties and Management of New Zealand Soils (Oxford Univ. Press, Auckland, New Zealand, 1990), p. 132.
7. E. W. Russell, Russell's Soil Conditions and Plant Growth (Longman, Essex, England, 1988), pp. 472-499.
8. J. K. Syers and J. A. Springett, Plant Soil 76, 93 (1984).
9. 1. S. Comforth and A. G. Sinclair, Fertiliser Recommendations for Pastures and Crops in New Zealand (MAF, Wellington, New Zealand, 1984); C J. Clarke, G. S. Smith, M. Prasad, 1. S. Comforth, Fertilizer Recommendations for Horticultural Crops (MAF, Wellington, New Zealand, 1986).
10. A. Wright, in Integrated Systems Analysis and Climate Impacts, R. W. M. Johnson, Ed. (MAF Tech, Wellington, New Zealand, 1989), pp. 55-63.
11. M ' D. BoeNje and V. R. Eiciman, Farm Management (Wiley, New York, 1984), pp. 86-91.
12. SAS Institute Inc., JMP User's Guide (SAS Institute, Cary, NC, 1989).
13. SASISTAT User's Guide, Release 6.03 Edition (SAS Institute, Cary, NC, 1988).
14. We thank the 16 New Zealand farm families for donating the use of their farms to this study. Supported by the Fertiliser and Lime Research Centre at Massey University, a Prince and Princess of Wales Science Award by the Royal Society of New Zealand, the Massey University Research Fund, and International Program Development at Washington State University.
14 September 1992; accepted 4 March 1993
SCIENCE * VOL. 260 * 16 APRIL 1993