CCoonnsseerrvvaattiioonn TTiillllaaggee oonn OOrrggaanniicc FFaarrmmss

by Keith R. Baldwin

Such damage to farm soils is an all-too- wo-hundred years of tillage have common occurrence in many production taken their toll on America’s farm regions, including the agrarian South. For TTsoils. The moldboard plow, extensive two centuries we have extensively cleared tillage, and other soil management land for row-crop production of tobacco, practices have promoted wind and water cotton, corn, and soybeans. The resulting erosion, costly nutrient losses from farm fields due to runoff and leaching, and a serious depletion of soil organic matter. Figure 1. A farmer cultivates soybeans grown on ridges. (Photo courtesy of USDA—NCRS) For too long, American farmers simply had to write these losses off as the necessary downside of crop production. If you farmed, it was a given that you used a moldboard or chisel plow to turn the sod bottomside-up, leaving no plant material on the surface. Then, in secondary tillage operations to create a seedbed and grow the crop, you crossed the field several times more with a disc, harrow, and cultivator. The opened soil was vulnerable to wind and water erosion.

Contents How Conservation Tillage Works—Page 2 CT Equipment for Vegetable Production —Page 12 Conservation Tillage and Management Practices on Acknowledgements—Page 13 Organic Farms—Page 5 Recommended Reading—Page 13

minimum 30 percent coverage—is retained loss of topsoil and organic matter has as mulch on the soil surface. This residue degraded soil quality. Many farm fields provides a number of benefits. During the have decreased fertility, aggregation, and growing season, the residue suppresses water-holding capacity as a result. weeds, retains soil moisture, and reduces erosion. As organic matter increases over A growing number of American farmers, time, soil fertility improves and biological however, are attempting to stem the diversity increases. degradation to our soils by adopting a cropping system known as conservation tillage (CT). In this publication, we will CT Systems: No-Till, Ridge-Till, and describe conservation tillage and discuss Strip-Till how it affects management practices on These are the three main systems of organic farms. We will focus on these conservation tillage: topics: No-till is a method of planting crops that requires no seedbed preparation other than • How conservation tillage works, opening the soil so that the seed can be including the obstacles and benefits it placed at the intended depth. In its simplest presents for organic farmers. form, no-till planting is a one-pass operation • Conservation tillage and accomplished with a multi-component management practices on organic implement that slices through surface residue farms, including the practices that and the top 3 or 4 inches of soil, drops seeds affect organic matter, soil fertility, cover into the slot, and squeezes the slot back crops, pests, and compaction. together over and around the seed, leaving • CT equipment for vegetable little or no visible evidence that the crop has production. been planted. This system produces the least soil disturbance of the three systems. Conservation Tillage Is on the Rise Ridge-till is a method of preparing the A growing number of U.S. farmers are seedbed and planting on a pre-formed ridge switching to conservation tillage. From 1990 remaining from the previous year’s crop. The to 2000, the number of U.S. cropland acres soil is left undisturbed until this single planted without tillage more than tripled to operation takes place. Ridge tillage differs 51 million acres. In the Southeast, farmers from no-till planting in that some cultivation is during the 2000 to 2001 cropping year used required during the current growing season to no-till systems in planting 39 percent of the form the ridge for next year’s crop. This corn, 20 percent of the cotton, and 58 system produces some soil disturbance, but percent of the soybeans grown in the region. not as much as the strip-till system. Strip-till is a method of preparing a seedbed HOW CONSERVATION TILLAGE on a strip 2 to 12 inches wide and 2 to 8 WORKS inches deep. Soil remaining between strips is left undisturbed. Often strip tillage equipment In CT systems, farmers disturb the soil as will include a 12-inch subsoil shank to break little as possible by using special any tillage pans that may be present. A equipment, such as disk-chisels, no-till conventional planter may be used in this planting drills, and subsoilers. A protective system. Of the three systems, this one cover of residue from the previous crop—a produces the most soil disturbance.

Organic Production—Conservation Tillage on Organic Farms 2 In an effective CT system, each field understand the consequences of excessive eventually begins to resemble a beneficial tillage. They simply strive for soil quality ecosystem in the way it conserves soil, improvements in different ways. Organic water, and energy, and in the way it growers seek improvements in soil fertility, recycles nutrients. Leaving a field primarily biological activity, and physical properties intact can reduce soil erosion by 10 to 90 through a management system that percent. Nonpoint-source pollution from emphasizes the integration of component farm fields is also reduced because the land farm processes into a whole farm system. In is better able to retain water, applied their soil building efforts, they make use of fertilizers, and chemical applications. such practices as crop rotations, green

manuring, and biological pest control. Conventional versus Conservation Tillage When possible, they also try to reduce the Conventional tillage is a system that number of tillage operations on a crop. It combines primary and secondary tillage would be advantageous to organic farmers operations to prepare a seedbed. These —and consequently America’s soils—if we operations include moldboard or chisel can find ways to adopt conservation tillage plowing, disking, harrowing, and cultivating. practices, where possible, in organic opera- Essentially no residue is left on the surface tions. after conventional tillage is completed. Conservation tillage is a system that retains It bears repeating that under a wide range of protective amounts of crop residue as mulch soil, crop and environmental conditions, on the soil surface. After planting, at least 30 conservation tillage can reduce soil loss by 10 percent of the soil surface remains covered by to 90 percent over conventional tillage. residue.

Benefits Obstacles Organic Matter Increases. Switching For organic producers, however, conser- from conventional tillage to a CT system vation tillage can present some obstacles. will generally bring about an increase in While conservation tillage practices and organic matter, most noticeably at the organic practices are both undertaken to surface and within the top 2 inches of the enhance soil quality, conservation tillage soil. In conventional tillage, plant residues, often relies on herbicides for weed control. fertilizers, and other amendments become Herbicides, of course, are prohibited on homogenized and diluted as they are mixed organic farms. Consequently, most organic deeply into the soil. But with conservation farmers continue to use intensive tillage as tillage, the residues and amendments reside a means to control weeds. Four to eight in a layer near the soil surface, and plant cultivations in a single season on an roots tend to proliferate in the top 2 inches organic farm are not uncommon. of soil where the nutrients are located. Ironically, this kind of intensive tillage contributes to poor soil quality and thwarts Biological Activity Increases. As the goals of organic farming. organic matter, in particular soil organic carbon, increases in CT systems, soil This isn’t to say that organic farmers are biological activity increases. This enhances not concerned with soil quality or don’t the diversity of organisms and the

Organic Production—Conservation Tillage on Organic Farms 3 ecosystem functions they perform. Chief Carbon and Nitrogen in CT Systems among these functions is nutrient cycling. Some intriguing things happen with carbon and Soil microbes decompose organic matter. In nitrogen in the soil when CT is used: doing so, they derive energy for themselves • by breaking the long chains of carbon CT cultivations, even without additional molecules that compose organic matter. As organic amendments, produce an increase in levels of soil organic carbon, total nitrogen they do this, many plant nutrients attached content, and soil microbial biomass carbon and to these chains are released. These nutrients nitrogen. This is in stark contrast to long-term are absorbed by the organisms themselves conventional tillage, which usually brings about or cycled to plants. When the plants or a decrease in these parameters. In many cases, microbes die, nutrients can be recycled soil organic carbon concentrations can be more once again. Thus, adding organic matter than 50 percent greater with CT operations than adds energy to this system and promotes with conventional. For instance, on one nutrient cycling. The soil microbial biomass Kentucky farm with silt loam soils where serves as both a source and a sink for nutri- conservation tillage had been used in some ents. This biomass includes other organisms fields and conventional tillage had been used in that perform additional functions, such as others, the concentration of soil organic carbon improving soil aggregation and inducing in the surface-to-6-inch layer of soil in a no-till resistance to plant diseases field was 70 percent more than in a plowed field after 10 and 20 years of using each system. • The soil biological community in CT sys- Farmers have found that seasonal changes, as tems differs from that found in conven- well as the availability of crop residue, can affect tional tillage systems. In conventional the abundance and dynamics of organic carbon and nitrogen in the soil. For example, a mid- tillage, plowing and other tillage operations summer drought can kill populations of soil bury plant residues deeply into the soil, microbes, the small organisms that keep soil where they decompose rather quickly, “alive.” As the dead microbial biomass decom- primarily because bacteria are the decom- poses, carbon and nitrogen are mineralized, and posers. But in conservation tillage, when both may be subject to leaching with subse- the soil is left undisturbed and plant quent rainfall. Understanding how seasonal residues remain at the surface, the primary changes can alter active carbon and nitrogen decomposers are fungi. Decomposition is pools can help farmers minimize losses of much slower. Slower decomposition results inorganic soil nitrogen. in an increased accumulation of organic • Some scientists believe that CT systems play materials and a rise in populations of an important role in reducing global warming assorted secondary decomposer organisms, by increasing and sustaining organic carbon such as nematodes and arthropods (insects sequestered in the soil. Concerns about the and spiders). Earthworms and other effects of atmospheric greenhouse gases on tunneling invertebrates, such as the larvae global warming have led to this conservation of some beetles, proliferate in this soil strategy, rather than promoting organic carbon conversion to carbon dioxide gas (CO through environment. This community of decom- 2) wide-spread and frequent tillage. Fewer tillage poser organisms helps to maintain soil operations also save tractor fuel, reducing CO structure and improves infiltration and 2 emissions.

aeration within the soil. Plant root growth proliferates in the tunnels and channels these organisms provide.

Organic Production—Conservation Tillage on Organic Farms 4 water and nutrient retention capacity and Soil Structure Improves. A primary promotes strong root growth. benefit of soil biological activity is that it builds soil structure, which produces good It’s clearly in the best short-term interest of crop growth and yield. Organic compounds beginning organic farmers to regularly produced during decomposition and other incorporate organic matter into the soil. As microbial processes act as glues to bind soil health improves, a rotational CT individual soil particles together into system can replace annual tillage practices. aggregates. Soil aggregates are important for In a rotational system, farmers incorporate maintaining soil tilth (tillability) and organic matter and conventionally till soils friability (looseness). The stability of these only at selected times within a long-term aggregates is also important. That is, soil rotation. Other organic matter additions should maintain its structure while (manure, composts, cover crops, and the allowing water and nutrients to flow freely. like) are left on the surface of the soil in no- Tillage destroys aggregate stability and till years. promotes compaction and crusting. CT systems help to build and preserve the Under such a plan, the full-tillage years give aggregate stability of soils. farmers an opportunity to incorporate lime and other amendments and to address the Conservation tillage, in particular no-till, nutrient stratification that can result from increases water-holding capacity and continued application of organic nutrients reduces runoff. Surface residues keep the to the soil surface. Tillage provides an ideal soil temperature cooler and reduce water opportunity to break up any nutrients that evaporation. Plant residues on the soil may have formed in deeper soil horizons surface decrease runoff during heavy storms and to disrupt pest and pathogen cycles. by increasing the infiltration of water into soil. Residues also protect the soil surface In other years, growers can practice no-till from any crusting caused by raindrop or strip-till, with green manures or other impact. organic matter amendments applied to the soil surface but not incorporated. Organic CONSERVATION TILLAGE AND matter additions will continue to contri- MANAGEMENT PRACTICES ON bute to improved soil quality, but benefits ORGANIC FARMS will primarily accrue at the soil surface.

Organic Matter Solving a Chronic Seasonal Problem Many organic farmers typically manage In North Carolina, farmers are finding that a weeds by tillage and, therefore, cannot system of minimum soil disturbance and focus on building soil structure in the same maximum soil cover is helping them avoid a way as CT practitioners. Instead, they use chronic seasonal problem—tilled, bare soil innovative practices to improve the soil that erodes in heavy rains from April through structure and conserve soil organic carbon. July. Principal CT crops in North Carolina are Organic farmers attempt to improve soil currently corn, cotton, and soybeans, but tilth and friability with frequent additions there is a growing interest in CT production of organic matter, which is either applied or systems for vegetable crops. grown in place. Organic matter improves

Organic Production—Conservation Tillage on Organic Farms 5 Soil Fertility the risk of denitrification by delaying the application of most, if not all, of the Taking soil samples in fields where nitrogen fertilizer until later in the season conservation tillage is practiced is a little when soils are drier and warmer. Placing different than in conventional-till fields. the fertilizer below the surface mulch can Instead of the usual 6-to-8-inch soil core decrease immobilization of nitrogen and sample, the sample in a CT field is taken in volatilization losses, but this may require the top 2 to 4 inches of soil. Sampling at additional labor or specialized equipment. this depth will ensure that soil pH (acidity) is accurately measured. If the soil surface has not been significantly disturbed (by Nutrients Near the Surface Enhance plowing, disking, chiseling, or bedding) for Production three years or more, a sample of the soil Do conservation tillage systems and from the top 2 inches should be collected infrequent plowing mean that nutrients won’t along with a typical soil sample (6-to-8- be adequately incorporated and distributed inch core). If the 0-to-2-inch sample calls throughout the root zone? Studies have for lime while the 0-to-8-inch sample does shown that under most circumstances, the not, one-half the suggested rate should be concentration of nutrients and soil organic

applied. matter near the soil surface may actually enhance the nutrient uptake process. Nitrogen Application. Farmers Research also shows that plant roots intending to broadcast organic nitrogen on proliferate in the upper 2 inches of soil in CT CT fields may be concerned that nutrients systems. That is because the soil near the will remain on the surface, especially where surface is moist and rich in nutrients and there is heavy residue from the previous organic matter, making it highly conducive to crop or a cover crop. For that reason, it may plant root growth. be necessary to apply slightly higher amounts of nitrogen. Nitrogen losses at the Phosphorus Application. Because surface will be due to immobilization phosphorus is so important to seedling (uptake by soil microorganisms), dentrifica- growth, farmers should band phosphorus tion (losses of N gases in saturated condi- 2 near seeds or transplants at planting. The tions), and volatilization (conversion to most effective phosphorus fertilizer place- ammonia gas). In spite of these potential ment is a band 2 inches to the side of the losses, yields for many crops are often row and 2 inches below the seeds. This may higher under conservation tillage than be easier said than done because many conventional tillage. These higher yields are organic farmers may not have the special- probably the result of greater soil water ized equipment required. In addition, retention on CT fields. Other factors, such organic phosphorus starter fertilizers that as the rotation effect, may be involved as can be banded are costly and not widely well. This may result in a considerable available. advantage for CT at equivalent nitrogen rates. Many organic fields receiving annual applications of raw and composted manure Organic farmers have several options to have high to very high soil test levels of consider for improving nitrogen use phosphorus. It is unlikely that additional efficiency in CT systems. They can lower

Organic Production—Conservation Tillage on Organic Farms 6 phosphorus will increase crop yield in these the soil surface before the full crop canopy fields, although starter applications may has been established. still be recommended. In locations where soil test results indicate a need for "The truth is that no one has ever advanced a phosphorus, amendments can be broadcast scientific reason for plowing. The entire body and incorporated when the rotation of reasoning about the management of the permits. soil has been based upon the axiomatic assumption of the correctness of plowing.” In the short term, conservation tillage —Edward Faulkner, 1943 reduces phosphorous availability. In the In his book Plowman’s Folly, Faulkner boldly long term, however, concentrations of challenged the validity and wisdom of using the available phosphorus are higher in CT moldboard plow. He was considered a fanatic by systems compared to conventional tillage the academic community of his time. Today, systems. Increased organic matter in the however, there is wide acceptance of top 2 inches of soil provides sites for conservation tillage systems throughout the increased storage of plant-available forms of world. phosphorous. Plant roots have ready access to this soil zone. Choosing a Cover Crop. In vegetable

systems, the cash crop will often determine the appropriate cover crop. Grasses offer Fertilizer Layering? good protection against soil erosion and Try Row Placement provide ample, early-season residue for Stratification (layering) of nutrients with plantings of potatoes, lettuce, and cole conservation tillage can be offset simply by crops (such as broccoli, collards, and row placement of fertilizers. Placing required cabbage). Legumes can provide a significant nutrients close to the developing plant proportion of the nitrogen requirement, as appears to be the best insurance when well as residue for warm-season vegetables, growers are concerned about the effectiveness such as tomatoes, sweet corn, snapbeans, of surface-applied fertilizer. and squash.

Cover Crops Timing. Farmers should be aware that rapidly growing cover crops may deplete Cover crops are very beneficial in CT the soil moisture needed for germination systems for a variety of reasons. They are and emergence of the following cash crop, the main sources of surface residue, which and poor, uneven stands may result. reduces soil erosion during dry and windy Therefore, the timing of cover crop kill is or rainy weather in the winter and early critically important. Although some spring. Residues also help to build soil nitrogen production by legumes will be organic matter. Cover crops are also used to sacrificed, in dry years the best strategy is to scavenge the nitrogen leftover from a kill cover crops approximately two weeks previous crop. And, as they develop, they before planting. In most years, sufficient provide nutrients to the following crop. rainfall will occur either two weeks before Cover crop residues help conserve soil planting time or immediately after moisture during the summer growing planting. If weather patterns or reports season by reducing water evaporation from suggest that adequate rainfall, soil moisture, or both will be present throughout the

Organic Production—Conservation Tillage on Organic Farms 7 planting window, farmers can let cover Other equipment. Many types of crops grow later in the spring. mowers are available that will kill cover

crops, such as bush hog, flail, and sickle bar CT Seedbeds: Points to Remember mowers. Ideally, the equipment used While CT planter performance has improved should leave the cover crop biomass as considerably over the years, the seedbed intact as possible — the smaller the pieces environment in a CT system dictates these of residue, the more quickly they will guidelines: decompose. Sickle-bar mowers serve this end best, but they are relatively ineffective • Seeding rates should be 10 to 15 percent in hairy vetch stands. Bush hog mowers greater than those for conventional tillage. place residue in a windrow in the field, • Lower soil temperatures under a cover crop leaving some soil exposed. Flail mowers residue make it imperative to select a represent the best mowing alternative cultivar that demonstrates excellent because they drop the residue right in germination and seedling vigor under cool, place, covering the entire soil surface. wet conditions. Some summer cover crops may regrow after Killing Cover Crops. In many conserva- mowing. Cowpeas and other viney legumes tion tillage systems, cover crops are com- are particularly troublesome, and monly desiccated (killed) with herbicides. undercutting is a more effective means of Organic farmers, however, must mechan- killing them. If regrowth occurs after ically kill the cover crop before planting a undercutting, tillage may be required. subsequent crop. Or, alternatively, they can plant into a living mulch. If the cover crop Other methods. One alternative will be left on the surface as mulch, organic method is to strip-till the cover crop, plant growers generally undercut, mow, or roll the cash crop in the tilled strips, and then the cover crop to kill it. let the cover crop die in its own time. Several growers are experimenting with Using an undercutter. An undercutter strip-tilled, perennial cover crops. These consists of a sharp steel bar and a roller. systems offer exciting potential, but organic The sharp steel bar slides approximately 2 farmers should be very cautious of them inches deep under the bedded cover crop, because perennial plant roots will compete severing the crop’s roots from its tops. The with crop plant roots for nutrients and roller follows to lay the residue parallel to water. Another innovative planting system the bed. This system leaves cover crop that has shown promise in the Southeast is biomass intact and on the surface. There- allowing a winter crimson-clover cover crop fore, decomposition is much slower and to reseed itself naturally between tillage residue remains in place much longer than strips. if it were chopped or otherwise cut into smaller pieces. The mulch enhances weed suppression longer into the cropping season. Slower decomposition also de- creases the rate of mineralization, meaning that less nitrogen from legume residues will be available in the early stages of crop growth.

Organic Production—Conservation Tillage on Organic Farms 8

Studying Cover-Crops in No-Till Vegetable increase the competitiveness of the cash Systems crop over weeds. Heavy residues from cover crops also aid in weed control. For example, Many researchers are studying the best uses cereal rye residues suppress the germination of cover crops in no-till vegetable systems. of some large-seeded broadleaf weeds. Michelle Infante, an agricultural agent at Rutgers Cooperative Extension, and co- Perennial weeds are often difficult to researcher R.D. Morse transplanted broccoli control in organic systems. So conventional into desiccated cover crop plots in 1996. tillage may be required for a number of Cover crop residues were either left on the soil years before CT (especially no-till) systems surface as mulch (in no-till plots) or incorpor- are practical. Before any transition is made ated to leave a clean surface (conventional-till to organic production, eradication of plots). perennial weeds—such as Johnsongrass (Sorghum halepense), bermudagrass (Cynodon They found that weed suppression and dactylon), nutsedge (Cyperus rotundus)—and marketable broccoli yield with no-till were other noxious species in heavily infested equal to or higher than with conventional-till. fields should be a priority goal. The reliance Overseeded clover living mulches did not on tillage as a primary tool in a comprehen- affect broccoli yield compared to the control sive and effective organic weed control plots, and they suppressed weeds as well as program is an obvious reason for including herbicide treatments. These results supported it at some point in a rotation. those of Hoyt et al. (1994), Morse (1995), and Morse et al. (1993), who found that establish- Diseases and Insects. Integration of ment of transplanted vegetables in no-till disease control measures, such as planting systems resulted in greater yield stability and resistant varieties, using integrated pest often achieved yields equal to or greater than management (IPM), and employing crop those achieved with conventional tillage. rotations, is perhaps more important in CT systems than conventional tillage. Destruc- tion of vegetable debris in the fall with a CT Pests practice, seeding a small grain cover crop, and implementing a rotation that provides Weeds. Certified organic growers should a host-free period will help minimize employ every weapon in their arsenal to disease carryover problems. control weeds in CT systems. These include crop residues, cover crops, appropriate crop Destruction of crop debris after harvest can rotations, and some tillage with CT cultiva- be very important in minimizing disease tors. Growers can also select competitive and insect problems in organic systems, crops that shade weeds and inhibit the especially when the same crop or a related emergence of weed seedlings. Special care one is continuously grown in the same field should be given to planting rates and year after year. Unfortunately, leaving resi- depths because stand establishment is more due on the surface in conservation tillage difficult in CT planting, and skips (missing can slow degradation of pathogen-infected plants) will result in greater weed problems. residue. Plant pathogens overwintering on Later plantings can be made in narrower residue can move to the lower foliage of row spacings to provide quick shading. subsequent crop plants via splashing. For Using transplants when possible will also example, pathogens of early blight can

Organic Production—Conservation Tillage on Organic Farms 9 splash on tomatoes, and phytophthora diseases may be better adapted to a more blight can splash on peppers. stable, no-till environment. Long-term use of CT farming practices may provide the Tillage may sometimes be necessary to soil stability necessary for establishing reduce insect pressure in succeeding crops. beneficial communities of organisms that Fields are usually tilled in the fall or early will suppress pathogen populations. spring when many kinds of insects are in Promoting crop health and growth by the overwintering stage within the soil or consistently striving for improvements in in crop residues. Direct destruction of the soil physical, chemical and microbiological insect or its overwintering chamber, properties is integral to insect and disease removal of protective cover, elimination of management. Vigorous, healthy plants are food plants, and disruption of the insect life less susceptible (and possibly less attractive) cycle generally kills many of the insects to insects and diseases. through direct contact, starvation, or exposure to predators and weather. Compaction

Accumulated plant litter at the soil surface Theoretically, conservation tillage reduces provides food and cover for certain soil compaction. This is partly because invertebrate animals, primarily insects, fewer trips are made across the field. With spiders, mites, and earthworms. It also less tillage, there is less disruption of the modifies the effects of temperature and natural soil structure, resulting in more moisture on these creatures. Because there durable aggregates with load-bearing is no physical breaking and mixing of soil capacity. Moldboard plows are not used, to temporarily remove food hosts, elimin- minimizing plow-pan formation. With ate cover, or destroy and disrupt inverte- several years of conservation tillage, the brate animals and their tunnels, significant organic matter content near the soil surface beneficial ecological changes occur in fields increases, resulting in improved soil where tillage is greatly restricted (House structure. and Brust, 1989). For example, increases in decomposer organisms resulting from the Unfortunately, traffic patterns in CT presence of more surface litter attract systems often are not controlled carefully. predacious arthropods. Research at North If much of the field's surface is traversed Carolina State University indicates that over time, the surfaces of CT soils can biological control of cutworm larvae, corn become excessively compacted. Because earworm pupae, and corn rootworm eggs farmers recognize that the bearing capacity and larvae by predatory mites and beetles of untilled soils is greater than that of tilled occurs more often under CT systems (Van soils, they tend to drive over untilled soils Duyn and House, 1989). when they are too wet, aggravating the problem. The soil ecosystem is dynamic. All of its components—both abiotic (lifeless) and Thus, prolonged conservation tillage can biotic (alive)—work together to achieve sometimes lead to compaction in some some degree of ecological stability. soils. This soil compaction can lead to Generally, that stability is greater in increased runoff, resistance to root pene- untilled than in tilled soil. Beneficial tration, and poor aeration. Compaction organisms capable of suppressing plant also reduces the total pore space in the soil,

Organic Production—Conservation Tillage on Organic Farms 10 particularly the proportion of large pores. To enhance stand and reduce seedling Large pores drain quickly after soil diseases, farmers may want to consider slot saturation and provide most of the oxygen planters and furrow openers that prevent or supply for roots during wet periods. There reduce the contact of seeds or transplants are several ways to reduce or eliminate with residues. compaction from wheel tracks in CT systems: CT transplanters are available for planting vegetable crops into both crop residues and • Establish and use controlled traffic cover crops. Equipment used for trans- patterns year after year—for example, planting vegetables like tomatoes, peppers, by establishing permanent beds. and the cole crops by conventional • Use a rotation system (chisel plow–plant methods are suitable for planting these or chisel plow–disk–plant) every few same crops in strip-tillage culture. years to break up the compacted soil. • Employ a rotation system that allows Large-seeded vegetables, such as sweet corn, full tillage at some point of production snap beans and squash, may be planted in to reduce compaction. undisturbed cover crops or residues using • Use deep-rooted crops (such as mustard) existing no-till field corn and soybean in rotations, if subsoils aren’t too acidic planters. No-till planters with seed plates for root growth, to alleviate can be used for some vegetables by carefully compaction. matching plates to seed size. Plateless, no- The lower soil temperatures that CT till planters can accommodate a wider systems often produce can affect seed range of vegetable crops. CT planters for germination, shoot emergence, and root small-seeded vegetables that must be direct- growth. In general, wet soils and those with ly seeded (such as carrots and radishes) are more surface crop residue (like CT soils) not widely available. The strip-tillage remain cooler in the spring. Low soil approach may be most appropriate for temperatures may slow early-season growth these vegetables (and perhaps others) of some summer vegetable crops (such as because seeds can be planted in the tomatoes and melons), possibly resulting in prepared seedbed strip using conventional delayed maturity and lower market prices planters. later in the season. In some cases, lower soil temperatures may favor plant pathogens (for example, the pathogens that cause ACKNOWLEDGEMENTS damping off of vegetables). Much of the material provided in this CT EQUIPMENT FOR VEGETABLE publication is taken from Cooperative PRODUCTION Extension publication AG-407, Conservation Tillage for Crop Production in North Carolina, With at least 30 percent of the soil surface M.G. Cook and W.M. Lewis (Eds.), 1989, covered by residues in CT systems, special NC State University. Raleigh, NC. implements are needed for land preparation and planting of vegetable crops. The implements most often used include heavy disk harrows, chisel plows, disk-chisels, field cultivators, subsoilers, and paraplows.

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continuous non-tilled and conventionally RECOMMENDED READING tilled corn. Soil and Tillage Research. 3:135-136. References Cited Dick, R.P. 1992. A review: long-term effects of agricultural systems on soil biochemical House, G.J. and G.E. Brust. 1989. Ecology of and microbial parameters. Agriculture, low-input, no-tillage agroecosystems. Ecosystems and Environment. 40:25-36. Agriculture, Ecosystems and Franzluebbers, A.J., F.M. Hons, and D.A. Environment. 27:331-345. Zuberer. 1995. Tillage and crop effects on Hoyt, G.D., D.W. Monks, and T.J. Monaco. seasonal soil carbon and nitrogen 1994. Conservation tillage for vegetable dynamics. Soil Science Society of America production. HortTechnology. 4:129-135. Journal. 59:1618-1624. Infante, M.L. and R.D. Morse. 1996. Frye, W.W., R.L. Blevins, L.W. Murdock, and Integration of no-tillage and overseeded K.L. Wells. 1981. Energy conservation in legume living mulches for transplanted no-tillage production of corn. In “Crop broccoli production. HortScience 31:376- Production with Conservation in the 380. ‘80s.” Proceedings of ASAE Conference on Morse, R.D. 1995. No-till, no-herbicide Crop Production with Conservation in the systems for production of transplanted ‘80s. pp. 7-81. ASAE Publishing. St. broccoli. In K.J. Bradford and R. K. Hartz Joseph, MI. (Eds.) Conservation farming-A focus on Gerhardt, R.A. 1997. A comparative analysis water quality. Proceedings Southern Region of the effects of organic and conventional Conservation Tillage for Sustainable farming systems on soil structure. Agriculture. pp. 113-116. Jackson, MS. 26- Biological Agriculture and Horticulture. 28 June, 1995. 14:139-157. Morse, R.D., D.H. Vaughan, and L.W. Belcher. Ismail, I., R.L. Blevins, and W.W. Frye. 1994. 1993. Evolution of conservation tillage Long-term no-tillage effects on soil systems for transplanted crops; Potential properties and continuous corn yields. role of the subsurface tiller transplanter Soil Science Society of America Journal. (SST-T), In P.K. Billich (Ed.) Proceedings 58: 193-198. Southern Region Conservation Tillage for Kern, J.S. and M.G. Johnson. 1993. Sustainable Agriculture. pp. 145-151. Conservation tillage impacts on national Monroe, LA. 15-17 June, 1993. soil and atmospheric carbon levels. Soil Van Duyn, J.W., and G.J. House. 1989. Insect Science Society of America Journal. management. In M.G. Cook and W.M. 57:200-210. Lewis (Eds.) Conservation Tillage for Crop Post, W.M., T.H. Peng, W.R. Emaniel, A.W. Production in North Carolina. Publication King, W.H. Dale, and D.L. DeAngelis. no. AG 407. Cooperative Extension 1990. The global carbon cycle. American Service, NC State University. Raleigh, NC. Science. 78: 310-326. Punja, Z.K. and S.F. Jenkins. 1984. Influence Additional Reading of temperature, moisture, modified gaseous atmosphere and depth in soil on Blevins, R.L. and W.W. Frye.1993. eruptive sclerotial germination of Conservation Tillage: An ecological Sclerotium rolfsii. Phytopathology. approach to Soil Management. Advances 74:749-754. in Agronomy; 51:33-78. Rasmussen, P.E. and H.P. Collins. 1991. Long- Blevins, R.L., G.W. Thomas, M.S. Smith, term impacts of tillage, fertilizer, and crop W.W. Frye, and P.L. Cornelius. 1983. residue on soil organic matter in Changes in soil properties after 10 years of

Organic Production—Conservation Tillage on Organic Farms 12 temperate semiarid regions. Advances in Agronomy. 45:94-134. Sumner, D.R., S.C. Phatak, J.D. Gay, R.B. Chalfant, K.E. Brunson, and R.L. Bugg. 1995. Soilborne pathogens in a vegetable double-crop with CT following winter cover crops. Crop Protection. 14:445-450. Sumner, D.R. 1987. Root diseases in crops following legumes in CT systems. In Proceedings National Conference On the Role of Legumes in CT Systems. Athens, GA, April 27-29. pp. 74-75. Soil Conservation Society of America, Ankeny, IA. Sumner, D.R., D.A. Smittle, E.D. Threadgill, A.W. Johnson, and R.B. Chalfant. 1986. Interactions of tillage and soil fertility with root diseases in snap bean and lima bean in irrigated multiple-cropping systems. Plant Disease. 70:730-735. Tyler, D.D., M.G. Wagger, D.V. McCracken, W.L. Hargrove, and M.R. Carter. 1994. Role of CT in sustainable agriculture in the southern United States. CT in Temperate Agroecosystems. pp. 209-229. Lewis Publishers Inc. Boca Raton, FL.

Organic Production—Conservation Tillage on Organic Farms 13

The Organic Production publication series was developed by the Center for Environmental Farming Systems,

a cooperative effort between North Carolina State University, North Carolina A&T State University, and the North Carolina Department of Agriculture and Consumer Services.

The USDA Southern Region Sustainable Agriculture Research and Education Program and the USDA Initiative for Future Agriculture and Food Systems Program provided funding in support of the Organic Production publication series. David Zodrow and Karen Van Epen of ATTRA contributed to the technical writing, editing, and formatting of these publications.

Prepared by

Keith R. Baldwin, Program Leader, ANR/CRD Extension Specialist—Horticulture North Carolina A&T State University

Published by NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

AG-659W-02 07/2006—BS E06-45788

Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, disability, or veteran status. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.