Final Report for LNC09-310
Anticipated soil quality and other benefits have generated interest in adoption of no-till practices on organic farms. Vegetative mulch provided by killed cover crops is relied on heavily for weed suppression in no-till organic systems. This project included one study where 12 different cover crop treatments were screened for potential use in no-till organic systems at locations in IA, MN, ND, and WI, with up to 10 different treatments evaluated at any one location. Different methods of terminating cover crops were compared with a no-till method (rolling-crimping) common to all locations. A separate field study compared performance of up to five different market crops when seeded directly into rolled-crimped cover crop mulch at three locations. Fall-seeded small-grain crops produced over 14,000 kg/ha (12,500 lb/ac) in WI and hairy vetch over 8000 kg/ha (7140 lb/ac) in ND of rolled-crimped vegetative mulch and have the greatest near-term potential as cover crops in no-till organic farming systems. Grain production was successful when soybean was seeded directly into cover crop mulch, but problems were encountered when corn and other grain crops were grown. Refinement of the rolling-crimping method for killing cover crops, screening of additional cover crop species, and modification of current no-till organic farming strategies are needed so that crops in addition to soybean can be grown using no-till organic practices in the north central region.
Most organic farmers rely on cultivation to control weeds, but tillage can destroy soil structure, reduce organic matter content, and diminish overall sustainability of cropping systems. Karlen et al. (1994) found that soil aggregate stability, total carbon, microbial activity, and earthworm populations were enhanced after eliminating tillage over a 12-year period in a continuous corn system. Those researchers concluded that soil quality could be improved by replacing tilled with no-till cropping systems. Similarly, Tanaka et al. (2002) and others (Carr et al., 2006, 2008) reported that crop performance was improved by eliminating tillage in semiarid portions of the north central region, probably because plant water-use efficiency was enhanced. Trewavas (2004) speculated that conventional no-till farming was superior to organic farming for enhancing soil health because of the deleterious effects of tillage on soils. Robertson et al. (2000) warned that organic farming and other food production systems relying on tillage contributed more in greenhouse gas emissions than conventional no-till systems. Organic farming has been suggested as promoting poor soil stewardship because of the perception that intensive tillage practices are needed for weed control and contribute to excessive erosion and overall soil degradation (Kuepper, 2001). However, recent studies indicate that soil quality can be improved by organic farming practices compared with conventional, no-till farming methods, even though tillage is used in the organic systems. Soil combustible C and N were higher after nine years in an organic system that included cover crops compared with three conventional, no-till systems, two of which included cover crops (Teasdale et al., 2007). However, weed populations reportedly were unacceptable in the organic system by the end of the study. Similarly, Miller et al. (2008) indicated that potentially mineralizable N was greater in an organic system than conventional, no-till cropping systems in a 4-year study. Winter wheat grain yields were equal or greater in the organic system compared with the conventional no-till systems. However, weeds were a serious problem in the organic system after only four years. Developing no-till, organic farming methods would eliminate the detrimental impacts of tillage on soil health. For that reason, many organic farmers want reduced- and no-till farming systems to be developed (Sooby et al., 2007). However, eliminating tillage removes a major weed control practice on many organic farms. The challenge of how to control weeds without tillage on U.S. organic farms was considered by Creamer et al. (1995) in a comparison between no-till (i.e. flail and sickle bar mowing) and reduced-till (i.e., undercutting followed by rolling) methods for terminating cover crops in Ohio. Creamer also evaluated different cover crop termination methods that relied on little if any tillage in the southeastern U.S., and published results demonstrating that cover crops could be killed mechanically without tillage (Creamer and Dabney, 2002). Creamer and Dabney (2002) concluded that rolling with a stalk chopper was not always effective in killing cover crops unless delayed until plants reached seed development growth stages. Conversely, mowing generally was effective at killing broadleaf cover crops (e.g., cowpea), even at vegetative growth stages in some instances. The scientists encouraged others to continue exploring methods to seed directly into rolled cover crops as a way to incorporate no-till methods into systems that cannot rely on synthetic herbicides (e.g., certified organic systems). Research cited by Morse (1999) demonstrated that cover crops could be killed by mowing and rolling prior to transplanting broccoli. Implements used to roll the cover crops ranged from empty grain drills to rollers with attached blades designed specifically for that purpose. Morse (1999) cautioned readers that mowing and rolling were effective termination methods only when delayed until cover crops were flowering and, in several instances, even at more advanced growth stages. Similar conclusions regarding the importance of delaying rolling until plants reached reproductive growth stages were made by Creamer and Dabney (2002). Cover crops have been killed using rollers with blunt steel blades welded onto cylindrical drums in conservation tillage systems for many years in South America (Ashford and Reeves, 2003). The blades crimp or crush but do not cut plant stems, thereby improving efficacy of the termination method while also maintaining intact plant residue on the soil surface. Winter oat, rye, and wheat cover crops were killed with a roller-crimper as effectively as with herbicides when rolling and crimping were delayed until small-grain plants reached the early milk growth stage of kernel development in a 2-year study in Alabama (Ashford and Reeves, 2003). Rolling and crimping were ineffective at killing small-grain plants during vegetative growth stages in that same study. Southern U.S. scientists have been exploring roller-crimper prototypes that improve upon older designs (Kornecki et al., 2006). Similarly, scientists at The Rodale Institute in Kutztown, Pennsylvania, developed an improved roller-crimper design in collaboration with a local farmer and manufacturer (J. Moyer, 2011). The innovative design maximizes tractor driver comfort without compromising cover crop killing efficacy when the roller-crimper is operated in the field. The roller-crimper developed by The Rodale Institute scientists has chevron-shaped blades welded onto a drum that can be filled with water for added weight. A particular innovation is the ability to mount the unit on the front of the tractor so that cover crop termination and no-till seeding of the subsequent crop can occur in a single pass. Previous SARE Projects and Other Funded Research SARE has funded numerous projects promoting reduced- and no-till farming methods. Several projects have focused specifically on conservation tillage practices in systems managed organically. Several projects included no-till treatments. These projects ranged from farmer/rancher grants (e.g., Project FS08-231), to graduate student grants (e.g., Project GS07-058) and research and education grants (e.g., Project LNE08-268). Professional development program grants promoting no-till organic farming also have been awarded (e.g., Project ES06-085). Funding no-till organic research has not been limited to SARE; the Organic Farming Research Foundation has funded several projects directed specifically at developing no-till organic systems, and virtually all of these include a cover crops component. Past research on no-till organic farming is noteworthy and has increased our knowledge base. However, the current project differed from previous efforts in several important ways. First, several past studies focused on horticultural crops (e.g., pumpkin; SARE Project LNC07-276) which are of local importance but not widely grown across the north central region. Second, some projects focused on widely grown field crops (e.g., soybean; SARE Project LNC04-240) but included only a few cover crop treatments and termination methods. Third, some projects were fairly broad in scope (SARE Project LNE06-244) but based recommendations on field activities in environments that differ markedly in climate, soils, cropping practices, and other factors from those existing in the north central region. References Ashford, D.L., and D.W. Reeves. 2003. Use of a mechanical roller-crimper as an alternative kill method for cover crops. American J. Alt. Agric. 18:37-45. Carr, P.M., R.D. Horsley, and G.B. Martin. 2008. Impact of tillage on field pea following spring wheat. Can. J. Plant Sci. (in press) Carr, P.M., Horsley, R.D. and Martin, G.B. 2006. Impact of tillage and crop rotation on grain yield of spring wheat I. Tillage effect. [Online] Available: http://www. plantmanagementnetwork.org/ pub/cm/research/2006/wheat1/ [verified 17 September 2008] Creamer, N.G., B. Plassman, M.A. Bennett, R.K. Wood, B.R. Stinner, and J. Cardina. 1995. A method for mechanically killing cover crops to optimize weed suppression. American J. Alt. Agric. 10:157-162. Creamer, N.G., and S.M. Dabney. 2002. Killing cover crops mechanically: Review of recent literature and assessment of new research results. American J. Alt. Agric. 17:32-40. Karlen, D.L., N.C. Wollenhaupt, D.C. Erbach, E.C. Berry, J.B. Swan, N.S. Eash, and J.L. Jordahl. 1994. Long-term tillage effects on soil quality. Soil and Tillage Res. 32:313-327. Kornecki, T.S., A.J. Price, and R.L. Raper. 2006. Performance of different roller designs in terminating rye cover crop and reducing vibration. Applied Eng. Agric. 22:633-641. Kuepper, G. 2001. Organic matters. Pursuing conservation tillage systems for organic crop production. National Center for Appropriate Technology, Butte MT. Available: http://attra.ncat.org/attra-pub/PDF/omconservtill.pdf [verified 09 October 2008] Miller, P.R., D.E. Buschena, C.A. Jones, and J.A. Holmes. 2008. Transition from intensive tillage to no-tillage and organic diversified annual cropping systems. Agron. J. 100:591-599. Morse, R.D. 1999. No-till vegetable production – its time is now. HortTech. 9:373-379. Moyer, J. 2011. Organic no-till farming. Advancing no-till–crops, Soils, Equipment; Acres USA: Austin, TX, USA, p. 204. Robertson, G.P., A. P. Eldor, and R.R. Harwood. 2000. Greenhouse gases in intensive agriculture: Contributions of individual gases to the radiative forcing of the atmosphere. Science 289:1922-1925. Sooby, J., J. Landeck, and M. Lipson. 2007. National Organic Research Agenda. Organic Farming Research Foundation, Santa Cruz, CA. 74 p. Tanaka, D. L., J. M. Krupinsky, M. A. Liebig, S. D. Merrill, R. E. Ries, J. R. Hendrickson, H. A. Johnson, and J. D. Hanson. 2002. Dynamic cropping systems: An adaptable approach to crop production in the Great Plains. Agron. J. 94:957-961. Teasdale, J.R., C.B. Coffman, and R.W. Mangum. 2007. Potential long-term benefits of no-tillage and organic cropping systems for grain production and soil improvement. Agron. J. 99:1297-1305. Trevewas, A. 2004. A critical assessment of organic farming-and-food assertions with particular respect to the UK and the potential environmental benefits of no-till agriculture. Crop Protection: 23-757-781.
The primary objective of this project was to develop management recommendations for killing cover crops mechanically without tillage, and using the vegetative mulch that was produced for weed suppression in no-till organic grain production systems in the north central region. Specific objectives were to: (1) identify cover crop species and species mixtures that produced large amounts of above-ground dry matter (DM); (2) determine if cover crops could be killed effectively by rolling-crimping under environmental conditions in the north central region; (3) grow field crops successfully following rolling-crimping of cover crops; and (4) stimulate adoption of organic no-till methods on at least one organic farm in IA, MN, ND, and WI.
Organic farmers were involved in the conceptualization of this project; they articulated the need for eliminating intensive tillage from cropping methods, and challenged scientist members of the team with developing no-till, organic farming methods. Those same farmers invited researchers to conduct field experiments on their farms. Farmer-scientist group members conducted preliminary, on-farm research evaluating the roller-crimper method for killing cover crops and subsequently no-till seeding into killed cover crop mulch. That research and consultation with others using cover crops in no-till, organic farming systems led to a face-to-face group meeting in summer 2007. This project was a result of subsequent interactions and discussions among a committed farmer-scientist group. It contained two separate experiments: one compared various cover crops and termination methods for adaptation across IA, MN, ND, and WI, and the other compared agronomic performance of different market crops when no-till seeded into cover crops killed mechanically.
Ten cover crop treatments along with two no-cover-crop checks (12 total treatments) were established at the NDSU Dickinson Research Extension Center, ND (DREC-ND) during two, 2-yr periods (2009-10 and 2010-11). Six treatments were established in spring to early-summer (fababean, spring rye, spring triticale, sudangrass, a mixture of field pea, mustard, oat, and radish [spring mix], and a no-cover-crop check) and six were established in late-summer to early fall (Austrian winter pea, hairy vetch, winter rye, winter triticale, a mixture of buckwheat, soybean, proso millet, and sunflower [fall mix], and a no-cover-crop check). Seeding/establishment dates of the treatments varied depending on cover crop species or species mixture and year (Table 1). A smaller group consisting of five of the six late-summer to early fall cover crop treatments were established at the ISU Neely-Kinyon Research Farm in IA (NKRF-IA), the UM Southwest Research and Outreach Center in MN (SWROC-MN), and the UW Arlington Agricultural Research Station in WI (AARS-WI), along with a rye-hairy vetch mixture at the NKRF-IA site and winter barley at the AARS-WI site. Cover crop treatments established in spring to early-summer during 2009 (2009-10 field experiment and 2010 (2010-11 field experiment) were disked, undercut, mowed, and rolled-crimped a few months later at the DREC-ND location; those same four mechanical treatments were applied in plots of late-summer to early fall seeded cover crops the following spring to early summer period in 2010 and 2011. The two no-till methods used to terminate cover crops (mowing and rolling-crimping) were compared at AARS-WI and SWROC-MN locations, while rolling-crimping and disking were compared at the NKRF-IA location. The timing of termination depended on cover crop treatment, kill method, location, and year (Table 2). Corn was seeded into plots at all locations in 2010. Timing of corn seeding depended on the location and method used to terminate cover crop treatments (Tables 2). For example, corn generally was seeded immediately after rolling-crimping cover crops and oftentimes at the same time in a one-pass system, whereas corn seeding was sometimes delayed several days after cover crops were terminated by disking. As a result, the corn seeding date ranged from 11 May to 12 July, depending on the termination method, year and location (Table 3). Corn was harvested for silage at all locations except the SWROC-MN site and at the NKRF-IA site in 2011, in part because of the late corn seeding date (Table 3). Corn grain and silage harvest dates ranged from 30 September to 24 October, depending on the location and year. Experimental Design and Data Collection Treatments were arranged in a randomized complete block in a split-plot pattern with termination method comprising whole plots and cover crop comprising subplot treatment variables. Treatments and treatment combinations were replicated four times. There were 192 plots in the field experiment at the DREC-ND site (4 termination methods and 12 cover crop species with treatment combinations replicated 4 times), and 40 to 48 plots at the satellite sites in IA, MN, and WI. Field experiments were conducted during 2009-10 and 2010-11 growing seasons at all locations for a total of eight site-years. Cover crop and weed density were determined by counting living plants in a 0.25- to 0.5-sq. m. (2.7-sq. ft.) area selected randomly in each plot two to four weeks after seeding both fall- and spring-seeded cover crop treatments, and again when growth resumed the following the spring for the fall-seeded treatments. Above-ground DM of cover crops, grass and broadleaf weeds was determined by harvesting above-ground plant parts in a 0.25- to 0.5-sq. m. area selected randomly in each plot just prior to imposing termination methods. The biomass were weighed, dried until at constant weight, and reweighed. The effectiveness of termination methods in killing cover crops was assessed 14 days after application using a visual rating method described by Ashford and Reeves (2003), and from collecting above-ground plant parts in a 0.25-sq. m. area in each subplot and determining plant moisture content. Soils from a 0- to 15-cm (0- to 6-in) depth in winter rye, hairy vetch, spring rye, and fababean cover crops that were disked and roller-crimped at the DREC-ND site were collected and composited prior to establishing cover crop treatments, and after harvesting corn. Soil samples were analyzed for extractable nitrate-N, particulate organic matter C and N, potentially mineralizable and total N, and total soil organic and inorganic C to provide an early indication of the impact that no-till organic farming has on soil quality at the surface compared with tilled organic methods. Soil samples also were collected and analyzed for soil quality parameters at the NKRF-IA location. Soil moisture content was determined in winter and spring rye plots (spring rye at the DREC-ND site only), and no-cover-crop check plots, immediately before disking (at the DREC-ND site) and roller-crimping, and 14 days after corn was seeded at 0- to 15-cm (0 to 6 inches), and 15- to -30 cm (6 to 12 inches) using a Field Scout soil moisture probe. Soil moisture also was measured at the AARS-WI location. Corn plant density was determined 21 to 28 days after seeding and plants were surveyed for cutworm feeding symptoms two to three weeks after planting at each location, depending on growing conditions. Grain yield was determined in plots at locations and in years where a sufficient number of heat units had accumulated for plants to reach physiological maturity. This did not occur in several instances because of the late corn seeding date (Table 3), which was needed so that killing effectiveness of rolling-crimping (all locations) could be maximized (Mischler et al. 2010; Mirsky et al., 2009), as well as mowing (three of four locations) and undercutting (one location). Corn silage yield was determined when it was not possible to determine grain yield. Soybean was substituted for corn at the AARS-WI location in 2011 because of the delay in planting and armyworm damage to corn in 2010. Above-ground weed biomass was determined in plots within 14 days of corn harvest. Agronomic data were analyzed using SAS software.
Five market crops (buckwheat, corn, flax, dry bean, and spring wheat) were seeded directly into rolled-crimped hairy vetch, spring rye, and winter rye cover crops in ND during 2009-10, and buckwheat, corn, and dry bean seeded directly into cover crop mulch during the 2010-11 growing season. The spring rye cover crop was seeded and roller-crimped during the first year of each 2-yr growing season; the winter wheat and hairy vetch cover crops were seeded in the first year but rolled and crimped in the second year. Market crops were seeded in the second year from early- to mid-May directly into mulch produced by spring rye cover crop that was rolled-crimped the previous year, and immediately after fall-seeded cover crops were rolled and crimped. Corn along with flax and soybean were direct seeded into hairy vetch and winter rye cover crops at both AARS-WI and SWROC-MN locations. Experimental Design and Data Collection. Cover crop and subsequent crop treatment variables were arranged as a randomized complete block in a split-plot pattern at AARS-WI and SWROC-MN locations, and in a split-block pattern at the DREC-ND location. Treatments and treatment combinations were replicated four times. A total of 60 plots was included in the field experiment in North Dakota (five grain and seed crops following three cover crops with treatment combinations replicated 4 times) during the 2009-10 growing season; flax and spring wheat subplot treatments were not included in the field experiment during the 2010-11 growing season because of the likelihood of complete crop failure, thereby reducing plot number to 36. Field experiments at the AARS-WI and SWROC-MN satellite sites included 24 plots during both growing seasons. The ease of establishing market crops into cover crop mulch after rolling and crimping was determined by counting living plants in a 0.25-sq. m. (2.7-sq. ft.; buckwheat, flax and spring wheat) to 1.5-sq. m. (16-sq. ft.; corn and dry bean) area selected randomly in each plot 2 to 4 weeks after seeding. Above-ground weed DM production when or shortly before market crops reached physiological maturity. Grain yield was determined by harvesting grain from the center of each plot from locations and market crops where a harvestable yield was produced; above-ground DM production of market crops was determined from locations and plots where grain production failed. Agronomic data were analyzed using SAS software. References Mirsky, S.B.; W.S. Curran, D.A. Mortensen, M.R. Ryan, and D.L. Shumway. 2009. Control of cereal rye with a roller/crimper as influenced by cover crop phenology. Agron. J. 101: 1589–1596. Mischler, R.; S.W. Dulker, W.S. Curran, and D. Wilson. 2010. Hairy vetch management for no-till organic corn production. Agron. J. 102: 355–362.
Two manuscripts are under review for publication consideration in scientific journals with a third in preparation for submission. A detailed presentation of results is not provided in this final report so publication of these data in the refereed literature is not jeopardized. Readers interested in learning more about results generated by the studies are encouraged to read the journal articles when they are published. AARC-WI 2009-10 Comparable amounts of DM were produced by winter rye (10,240 kg/ha [9135 lb/ac]), winter triticale (14,560 kg/ha [13,000 lb/ac]), and winter barley (11,715 kg/ha [10,450 lb/ac]) just prior to mowing and rolling-crimping. All three small-grain cover crops produced more above-ground DM than Austrian winter pea (6295 kg/ha [5615 lb/ac]) and hairy vetch (3675 kg/ha [3280 lb/ac]). However, there was no difference in weed DM across the cover crop treatments at termination, which averaged 30 kg/ha (25 lb/ac) and was significantly less than weed DM in no-cover-crop check plots (225 kg/ha [200 lb/ac]). There was significant armyworm feeding damage following corn seeding, so corn was replanted. The replanted corn plant density tended to be higher when seeded directly into hairy vetch mulch (average=7 plants/sq. m. [27,765 plants/ac]) than the mulch of other cover crops across both no-till termination methods. Corn plant density averaged 6 plants/sq. m. (19,960 plants/ac) when seeded directly into winter rye mulch and only 4 plants/sq. m. (17,785 plants/ac) when seeded directly into winter triticale mulch. Differences in weed DM existed at corn silage harvest among the previous cover crop treatments. However, weed DM production was relatively low regardless of cover crop. For example, weed DM production was in rolled-crimped winter rye plots compared with plots of other cover crop treatments but totaled only 390 kg/ha (350 lb/ac). Corn silage yield averaged 15.6 mt/ha (7 t/ac) and was similar across cover crop treatments and termination methods. 2010-11 As in the 2009-10 field experiment, cover crop DM at the time of termination generally was greater in the small-grain cover crop plots than in the hairy vetch cover crop plots. Dry matter production averaged 10,325 kg/ha (9220 lb/ac) for winter rye and winter barley compared with 4995 kg/ha (4455 lb/ac) for hairy vetch cover crops. There was no difference in DM production between hairy vetch and winter triticale (6385 kg/ha [5695 lb/ac]). The poor relative DM yield of winter triticale cover crop resulted from extensive winter injury that occurred. Austrian winter pea winterkilled and failed to produce cover crop mulch in 2011. Weed DM production was significantly less in winter rye and winter barley plots than plots of other cover crops in the 2010-11 field experiment, averaging less than 10 kg/ha (9 lb/ac) in winter barley plots and winter rye plots. However, weed DM production was minimal in all plots, averaging only 55 kg/ha (50 lb/ac) in hairy vetch plots. Weed DM production was low even in weedy control plots (225 kg/ha [200 lb/ac]). Weed DM prior to soybean harvest was virtually non-existent in rolled-crimped winter rye plots and only 420 kg/ha [375 lb/ac] in mowed winter rye plots. By comparison, weed DM production averaged 3635 kg/ha [3240 lb/ac]) in hairy vetch plots across both no-till termination methods. Weed DM production was even greater in disked no-cover-crop check plots, averaging over 8000 kg/ha (7135 lb/ac). In spite of relatively high weed DM production, soybean yield in hairy vetch plots was similar statistically to those in winter rye plots, averaging 1815 kg/ha (1620 lb/ac) in hairy vetch plots and 3150 kg/ha (2810 lb/ac) in winter rye plots across no-till termination methods. Soybean yields were highest in the control treatments (3480 kg/ha [3110 lb/ac]). However, soybean yields from both the rye and the hairy vetch treatments (3225 kg/ha and 2240 kg/ha respectively) were not significantly different from that of the control. DREC-ND 2009-10 Greater amounts of vegetative mulch were produced by rolled-crimped winter triticale (7370 kg/ha [6580 lb/ac]), hairy vetch (6935 kg/ha [6190 lb/ac]), and winter rye (6460 kg/ha [5770 lb/acre]) than other rolled-crimped cover crop treatments during the 2009-10 growing season (P < 0.05). Significantly less dry matter (DM) was produced by these same three cover crop treatments when terminated by disking, except for winter rye (5560 kg/ha [4964 lb/ac]). This reduction in DM production when disked compared with rolled-crimped reflects the difference in timing between these two field operations (Table 2). Fall-seeded cover crops were rolled-crimped more than 50 days later than they were disked, resulting in the production of additional DM. By comparison, differences were not detected between spring-seeded cover crops when rolled-crimped vs. disked since both field operations were done at the same time in late summer. Comparable amounts of DM generally were produced by cover crops when mowed or undercut compared with rolled-crimped since these three field operations were done within a 10-day period for fall-seeded treatments, and on the same date for spring-seeded treatments. Cover crops treatment ranking for weed DM production at the time of cover crop termination tended to reflect the inverse of their ranking for cover crop DM production. Less weed DM occurred in winter rye (10 kg/ha ), hairy vetch (25 kg/ha [22 lb/ac]), winter triticale (120 kg/ha [107 lb/ac]), spring rye (195 kg/ha [174 lb/ac]), and spring triticale (280 kg/ha [250 lb/ac) plots than those of other cover crop treatments across the four mechanical termination methods. By comparison, 2570 kg/ha (2295 lb/ac) of weed DM was produced in the no-cover-crop check plots. No-till methods (mowing, rolling-crimping) used to kill cover crops were less effective than mechanical methods that disturbed the soil (i.e., disking and undercutting). Disking killed cover crops effectively. By contrast, neither mowing nor rolling-crimping appeared particularly effective at killing small-grain cover crops (kill rate<90%) even though both methods were applied at advanced cereal growth stages (late watery ripe to early milk kernel growth stages). For example, rolling-crimping appeared to terminate only about 75% of growth of winter rye and winter triticale plants 14 days after application, and moisture content of crop residue averaged almost 30% across these two treatments at that time. Soil quality analyses failed to indicate any differences between the cover crop treatments that were compared, with the exception of the nitrate-N pool. Nitrate-N content was greater across hairy vetch and winter rye plots that were disked than across plots that were rolled-crimped. The transitory nature of this N pool suggests that soil quality improvements are limited during the initial year that no-till practices are integrated into organic farming systems. Corn plant density (3 plants/sq. m. [12,180 plants/ac]) was significantly less when seeded directly into rolled-crimped cover crop mulch than into disked (6 plants/sq. m. [24,355 plants/ac]) or mowed and undercut (4 plants/sq. m. [16,240 plants/ft2]) plots. Corn was seeded into an extremely dry seedbed in rolled-crimped plots; sensor probes attached to the soil moisture unit could not pushed into the soil and were bent as efforts were made to force them to depths greater than the top inch or so. There was little evidence of cutworm damage to corn plants in any plot. Weed DM production prior to corn harvest was lower when cover crops were disked (1220 kg/ac [1090 lb/ac] average across cover crop treatments) than when rolled-crimped (5490 kg/ac [4900 lb/ac]), with a few exceptions. Relatively low amounts of weed DM were produced in rolled-crimped hairy vetch (230 kg/ha [205 lb/ac]), winter rye (455 kg/ha [405 lb/ac]) and winter triticale (780 kg/ha [695 lb/ac]) plots. Greater amounts of DM were produced in plots of rolled-crimped spring rye than hairy vetch and winter rye plots. Weed DM totaled more than 6000 kg/ha (5360 lb/ac) in weedy no-cover-crop plots disked once in spring 2010 and over 10,000 kg/ha (8930 lb/acre) in weedy no-cover-crop plots disked once the previous fall. Corn failed to mature and produce harvestable grain in the 2009-10 field experiment, or even harvestable amounts of silage in plots following spring- and summer-seeded cover crops that were rolled-crimped the previous year. Among fall-seeded cover crop treatments, silage yield was low but greater in disked plots (4.6 mt/ha [2.5 t/ac]) than in mowed (0.6 mt/ha [536 lb/ac]), undercut (0.5 mt/ha [446 lb/ac]), and rolled-crimped (0.4 mt/ha [357 lb/ac]) plots. Silage yield of corn seeded directly into rolled-crimped hairy vetch (1.3 mt/ha [0.6 t/ac]) was equal or greater than corn silage yield following any other rolled-crimped cover crop treatment. 2010-11 Hairy vetch produced more DM just prior to rolling-crimping (8330 kg/ha [7440 lb/ac]) than other cover crop treatments in the 2010-11 field experiment. Interestingly, DM production by rolled-crimped hairy vetch (8945 kg/ha [7985 lb/ac]) was similar when disked hairy vetch even though disking was done 20 days earlier than rolling-crimping. The similarity in DM production probably reflects damage suffered by plants from a hailstorm that occurred at the DREC-ND site on 19 June 2011. The data suggest that DM production may have exceeded amounts that were produced if rolled-crimped plant had not been suffered the visual injury by hail several days prior to termination. Winter rye and winter triticale produced more DM (average= 5935 kg/ha [5299 lb/ac]) than other cover crop treatments when rolled crimped or disked, except for hairy vetch. By comparison, DM production of rolled-crimped spring triticale totaled 4430 kg/ha (3955 lb/ac) and rolled-crimped spring rye totaled 3830 kg/ha [3420 lb/ac]). Similar amounts of DM were produced by these four cover crop treatments when disked. Weed DM production was lower in winter rye (230 kg/ha [205 lb/ac]), winter triticale (340 kg/ha [303 lb/ac]), and spring rye (520 kg/ha [464 lb/ac]) plots than other cover crop plots at the time of cover crop termination, except for spring triticale cover crop (665 kg/ha [595 lb/ac]) across the four termination methods. By comparison, weedy check plots contined 3810 kg/ha (3401 lb/ac) of weed DM. No-till methods were not as effective as mechanical methods that disturbed the soil in killing cover crops, as also was the case in 2009-10. In the 2010-11 field experiment, moisture content of crop residue averaged around 25% across mowed and rolled-crimped cover crop treatments 14 days after termination was attempted. Weed competition was severe in plots where cover crops were seeded and killed the previous year so corn plant density was not determined. Neither cover crop treatment (P =0.51) nor termination method (P=0.72) affected corn plant density among fall-seeded cover crops. Corn plant density was low and averaged only 3 plants/sq. m. (0.3 plants/sq. ft.). Weed DM just prior to corn harvest was lower in rolled-crimped winter triticale (280 kg/ha [250 lb/ac]), winter rye (290 kg/ha [259 lb/ac]) and hairy vetch (650 kg/ha [580 lb/ac]) plots than other rolled-crimped plots, and similar to amounts where fall-seeded cover crops were disked prior to seeding corn. Corn failed to mature and produce harvestable grain in 2010-11, as had been the case in 2009-10. Excessive weed competition prevented corn from producing a harvestable silage yield in plots where cover crops were established and terminated in 2010. Average silage yield was greater across cover crops when disked (2.7 mt/ha [1.2 tons/ac]) than when rolled crimped (0.7 mt/ha (0.3 tons/ac) across fall-seeded treatments. Among rolled-crimped treatments, corn silage was greater following hairy vetch and winter triticale (1.8 mt/ha [0.8 tons/ac]) than other cover crop treatments except winter rye and the fall mixture. However, silage yield for all cover crop by termination method combinations was low. NKRF-IA 2009-10 Rolled crimped winter triticale (8290 kg/ha [7400 lb/ac]), winter rye (7910 kg/ha [7060 lb/ac]), and winter rye-hairy vetch (7280 kg/ha [6500 lb/ac]) cover crop treatments produced more DM just prior to termination than either hairy vetch (3430 kg/ha [3065 lb/ac]) or Austrian winter pea (2105 kg/ha [1880 lb/ac]) in the 2009-10 field experiment. The low relative yield of the legume cover crops resulted from poor establishment the previous fall, along with winter injury to Austrian winter pea. In spite of the relative low production of vegetative mulch, spring (27 May) weed DM production was non-measurable in hairy vetch plots prior to cover crop termination, as in plots containing small-grain cover crops. In contrast, weed DM was low but totaled 41 kg/ha in Austrian winter pea plots and over 100 kg/ha in no-cover-crop check plots. The ranking of cover crop treatments for weed DM production remained unchanged later in the season (05 August) when weed DM production was assessed. No differences in corn plant density were detected in plots where cover crops were disked and cover crops were rolled crimped; over 6 corn plants/sq. m. (26,000/ac) were counted. There was no difference in insect damage to corn plants across cover crop treatments and termination methods. However, corn silage yield was greater when cover crop treatments were disked (average=55 mt/ha [25 tons/ac]) than when rolled/crimped (average=15 mt/ha [6.7 tons/ac]). Corn silage yield was similar across cover crop treatments when rolled-crimped, and between cover crop treatments when disked. Corn plants failed to produce harvestable grain in 2008-09. 2010-11 Rolled-crimped winter triticale (3470 kg/ha [3098 lb/ac]), winter rye (4030 kg/ha [3500 lb/ac]), and rye-vetch mixture (3515 kg/ha [3140 lb/ac]) produced more DM than legume cover crops, though overall DM production was relatively low. The ranking of cover crop treatments for DM production was similar to the the ranking in the 2009-10 field experiment. Poor legume performance for cover crop DM production was attributed to problems with establishment and winter injury. The limited amount of DM produced by legume cover crops (less than 500 kg/ha) failed to suppress weed growth compared with cover crop treatments that included a small-grain component. Corn plant density was affected by cover crop treatment in the 2010-11 field experiment. In disked plots, corn plant density was heaviest following Austrian winter pea (8 plants/sq. m. [32,250 plants/ac]) and in no-cover-crop check plots (8 plants/sq. m. [31,000 plants/ac]), while in rolled-crimped plots fewest corn plants occurred in the no-cover-crop control (6 plants/sq. m. [25,230 plants/ac]). Corn plant density was higher following hairy vetch than winter rye in disked plots, while more plants occurred in winter rye plots when cover crops were rolled-crimped. Corn failed to produce harvestable grain in plots where cover crops were rolled-crimped in the 2010-11 field experiment. Corn silage yield in rolled-crimped plots averaged 29.6 mt/ha (13.2 tons/ac) with no differences in DM production detected across treatments. Grain yield in disked plots was higher where Austrian winter pea cover crop had been grown previously (7715 kg/ha [6890 bu/ac]), or hairy vetch (7400 kg/ha [6610 bu/ac]), than cover crop treatments including a small-grain crop component (average=3620 kg/ha [3250 bu/ac]). The higher yield in the legume plots partially reflected the greater plant-N availability following legume cover crops at this location. Soil test results indicated higher nitrate-N concentrations in plots where Austrian winter pea and hairy vetch cover crops were established than winter rye and triticale cover crops. Similarly, soil plant analyses development (SPAD) data indicated lower plant leaf-N levels following rye and rye-vetch cover crops than Austrian winter pea, and a non-significant trend compared with hairy vetch cover crop. There was limited corn borer damage detected among plants in the 2010-11 field experiment with no differences among cover crop treatments or termination methods. SWROC-MN 2009-10 Small-grain cover crops produced more DM than legume cover crops; DM production averaged over 10,870 kg/ha (9705 lb/ac) for winter rye and winter triticale cover crops. Cover crop species and no-till termination method (mowing, rolling-crimping) did not affect DM production. By comparison, DM production by hairy vetch across both termination methods averaged 3350 kg/ha (2990 lb/ac) while that of Austrian winter pea averaged 1135 kg/ha (1015 lb/ac). The poor relative performance of Austrian winter pea cover crop for DM production was attributed to winter kill with a 50% reduction in plant stand comparing spring 2010 to fall 2009 plant density. There was an inverse relationship between DM production by cover crops and weed DM production at cover crop termination. Weed DM production totaled 2730 kg/ha (2438 lb/ac) just prior to terminating cover crop growth in Austrian winter pea plots. Total amounts of weed DM in other cover crop plots averaged less than 400 kg/ha (360 lb/ac) at that same time. Cover crop termination method failed to affect total weed DM. No-till termination methods were not effective at killing cover crops. Visual estimates of killing effectiveness ranged from 13% (rolled-crimped hairy vetch) to 82% (mowed Austrian winter pea). Actual moisture content of cover crop mulch 14 days after imposing termination methods for these same two treatments was 73% (hairy vetch) and 27% (Austrian winter pea). Moisture content of vegetative mulch for other cover crop treatments ranged from 22% (mowed winter triticale) to 77% (rolled-crimped Austrian winter pea). Plant density of corn when seeded directly into cover crop mulch was lower following Austrian winter pea, hairy vetch and winter rye when rolled-crimped than mowed. The average reduction in plant density was 2 plants/sq. m. (8700 plants/ac). However, the reduction in plant stand did not translate into any depression in corn grain yield, which averaged 6710 kg/ha (5990 lb/ac) across cover crop treatments and termination methods. There were differences in weed DM production at corn grain harvest, with more grassy weeds in mowed Austrian winter pea and hairy vetch plots than those of other mowed or rolled-crimped cover crop plots, except for rolled-crimped Austrian winter pea plots. Broadleaf weed DM was lower in triticale cover crop plots compared with other cover crop treatments regardless of termination method. 2010-11 Small-grain cover crops produced more DM than legume cover crops, as also was the case in the 2009-10 field experiment. Dry matter production averaged 17,270 kg/ha (15,420 lb/ac) for winter rye and winter triticale cover crops in 2010-11. Small-grain cover crop species and no-till termination method did not affect DM production. Dry matter production by hairy vetch across both termination methods averaged 9350 kg/ha (8350 lb/ac) while that of Austrian winter pea averaged only 2955 kg/ha (2640 lb/ac). The poor relative performance of Austrian winter pea cover crop for DM production was attributed to winter kill, as was the case in the 2009-10 field experiment. Plant numbers declined 80% from fall to spring. Weed DM production was comparable in hairy vetch plots and small-grain cover crops just prior to terminating cover crops. In contrast, weed DM totaled over 6000 kg/ha (5360 lb/ac) in mowed Austrian winter pea plots. This amount of weed DM was greater than in weedy no-cover-crop control plots where DM production totaled 2320 kg/ha (2070 lb/ac). Weed DM production in rolled-crimped Austrian winter pea plots totaled 775 kg/ha (690 lb/ac). No-till methods for terminating cover crops (mowing, rolling-crimping) were not effective at killing cover crops, as also had been the case in the 2009-10 field experiment. Visual estimates of killing effectiveness were has high as 100% (mowed winter rye), but actual moisture content of cover crop mulch 14 days after imposing termination methods ranged from 52% (rolled-crimped hairy vetch) to 74% (rolled-crimped winter triticale). Moisture content in small-grain cover crop residue 14 days after termination ranged from 59% (mowed winter rye) to 75% (rolled-crimped triticale). Plant density of corn when seeded directly into cover crop mulch was reduced following Austrian winter pea when rolled-crimped compared with mowing. No differences were detected between cover crop termination methods for corn plant density across the other cover crop treatments. Corn grain yield was significantly greater following hairy vetch cover crop compared with other cover crop treatments, regardless of cover crop termination method. Corn yield averaged 3355 kg/ha (2990 lb/ac) across hairy vetch cover crops and was similar to grain yield in weed-free check plots (3450 kg/ha [3080 lb/ac]). There was no difference in corn grain yield following small-grain cover crop treatments (average=1300 kg/ha [1160 lb/ac]) and no-cover-crop weedy check plots (1755 kg/ha [1570/ac]). Grassy weed DM production was similar in hairy vetch and small-grain cereal cover crop plots just prior to corn harvest, but elevated in Austrian winter pea plots (4480 kg/ha [4000 lb/ac]) and no-cover-crop weedy check plots (3050 kg/ha [2725 lb/ac]). Broadleaf weed DM also was higher in Austrian winter pea plots and no-cover-crop check plots than those of other cover crops, except for hairy vetch plots when mowed.
AARC – Wisconsin 2009-10 Extensive armyworm damage forced replanting of corn plots following an initial seeding. As a result, corn failed to produce grain. Similarly, there was a complete crop failure when flax was seeded directly into rolled-crimped winter rye and hairy vetch plots. Grain yield totaled 1345 kg/ha (20 bu/ac) when soybean was seeded directly into rolled-crimped hairy vetch and 1950 kg/ha (29 bu/ac) into rolled-crimped winter rye mulch. 2010-11 There was complete winterkill of the hairy vetch cover crop seeded in fall 2010. Excessive wet conditions and heavy weed pressure limited grain harvest to soybean plots, as had been the case in the 2009-10 field experiment. DREC – North Dakota 2009-10 Plant density was much heavier across five market crops (buckwheat, corn, dry bean, flax, and spring wheat) when seeded directly into vegetative mulch produced by spring rye (78 plants/sq. m. [7 plants/sq. ft.) rolled-crimped in 2009 than in that produced by winter rye (11 plants/sq. m. [1 plant/sq. ft.]) or hairy vetch (2 plants/sq. m. [0.2 plants/sq. ft.]) that were rolled/crimped in 2010. Dry soil conditions at planting that persisted explain the poor establishment success of market crops when seeded into cover crops that were rolled-crimped in 2010. The greater availability of plant-available water coupled with the lack of persistence in cover crop mulch in 2010 resulted in weed DM production of over 2800 kg/ha (2565 lb/ac) by late-summer in spring rye plots compared with 980 kg/ha (875 lb/ac) in winter rye plots and 370 kg/ha (330 lb/ac) in hairy vetch plots. Market crops failed to produce harvestable grain when seeded directly into rolled-crimped vegetative mulch produced by the three cover crops. Above-ground DM production by market crops was greatest for buckwheat (830 kg/ha [740 lb/ac]), corn (580 kg/ha [520 lb/ac]), and dry bean (485 kg/ha [435 lb/ac]) across the three cover crop treatments. Less than 300 kg/ha [270 lb/ac]) of above-ground biomass was produced by flax and spring wheat when direct seeded into cover crop mulch. Plant density was heavier across three market crops (buckwheat, corn, and dry bean) when seeded directly into rolled-crimped spring rye vegetative mulch than rolled-crimped hairy vetch mulch, as was the case in the 2009-10 field experiment. There was no statistical difference in crop plant density between hairy vetch and winter rye plots. Weed DM production again was greater by late-summer in rolled-crimped spring rye (1945 kg/ha [1735 lb/ac]) than winter rye (475 kg/ha [425 lb/ac]) and hairy vetch (375 kg/ha [335 lb/ac]) plots. Above-ground crop DM production was greater following rolled-crimped hairy vetch (1950 kg/ha [1740 lb/ac]) than winter rye (830 kg/ha [740 lb/ac]) and spring rye (255 kg/ha [230 lb/ac]). Corn failed to produce grain in the 2010-11 field experiment, as was the case in the 2009-10 field experiment. Both buckwheat and dry bean produced grain, with average amounts across both market crops greater following rolled-crimped hairy vetch (400 kg/ha [360 lb/ac]) than winter rye (195 kg/ha [175 lb/ac]) and spring rye (35 kg/ac [30 lb/ac]), though these quantities are too low to have much commercial relevance. SWROC – Minnesota 2009-10 Plant density was unaffected by rolled-crimped cover crop treatment, though there was a non-significant trend for crop plant numbers to be elevated following rolled-crimped winter rye than hairy vetch cover crops. Grass weeds produced equal or greater amounts of DM in rolled-crimped hairy vetch than winter rye plots. No differences were detected in DM production by broadleaf weeds across cover crop treatments. Soybean produced more grain following rolled-crimped winter rye (3025 kg/ha [2700 lb/ac]) than hairy vetch (1625 kg/ha [1450 lb/ac]). Corn yield averaged 6270 kg/ha (6000 lb/ac) and was similar across both cover crop treatments. Flax failed to produce a harvestable grain yield. 2010-11 Differences in plant density were not detected for corn, flax, and soybean when seeded directly into rolled crimped hairy vetch and winter rye mulch, as was the case in the 2009-10 field experiment. Soybean produced more grain following rolled-crimped winter rye (2385 kg/ha [2130 lb/ac]) than rolled-crimped hairy vetch (1205 kg/ha [1075 lb/ac]), while there was no difference in corn yield following the two cover crop treatments (average yield= 2695 kg/ha [2405 lb/ac]). Flax failed to produce grain following rolled-crimped hairy vetch and produced only 690 kg/ha [615 lb/ac] following rolled-crimped hairy vetch.
This project demonstrated that fall-seeded cover crops can produce amounts of DM needed to suppress annual weeds when used as rolled-crimped vegetative mulch in the north central region, based on previous research in other regions (Carr et al., 2013). Small-grain cover crop species (e.g., winter rye) produced more DM than legume cover crops species in this project, except in North Dakota where hairy vetch produced equal or greater amounts of biomass than small-grain cover crop treatments. Winter injury to hairy vetch was reported at IA and WI locations, and to Austrian winter pea cover crop at all locations. Hairy vetch has potential as a fall-seeded cover crop in no-till organic systems within the north central region in areas where winter injury is not observed, while commercially available seed lots of Austrian winter pea may not be adapted to winter conditions in the region. Results of field experiments at the North Dakota location indicated that spring- and summer-seeded cover crops established and rolled-crimped the previous year fail to produce sufficient quantities of persistent vegetative mulch to suppress weeds when market crops are grown the following year. This inability resulted from the failure of spring- and summer-seeded cover crops to produce comparable amounts of above-ground DM as fall-seeded cover crops, coupled with the decomposition of vegetative mulch produced by spring- and summer-seeded cover crops that occurred prior to seeding market crops the following year. Spring wheat was grown successfully when seeded directly into vegetative mulch produced by spring pea and mixed oat-pea cover crops that were rolled-crimped the previous year at more northerly and humid locations (Vaisman et al., 2011). Rolling-crimping small-grain cover crops at advanced growth stages (75% flowering or even more advanced growth stages) had kill rates less than 85%, with moisture content of cover crop residue averaging around 25 to 30% 14 days after rolling-crimping. Likewise, rolling-crimping was not effective in killing hairy vetch or other cover crops consistently at all locations. These results conflict with the killing effectiveness of rolling-crimping cover crops reported in studies outside of the north central region (Mirsky et al. 2009; Mischler et al. 2010), suggesting that environmental factors in addition to crop growth stage determine the effectiveness of rolling-crimping in terminating cover crop stands. Grain production has been successful when corn was seeded directly into cover crop mulch that was rolled-crimped during the same growing season in the mid-Atlantic region (Mirsky et al. 2012). Similar success was not be duplicated in the north central region during this project, except in Minnesota. Even when grown for silage, corn DM production was considerably less in rolled-crimped plots than disked plots following cover crops where disking and rolling-crimping comparisons were made (IA and ND). These results suggest that success when growing corn for grain in no-till organic systems is limited within the north central region to certain environments (e.g., western Minnesota) in central and northern tier states. Similarly, other field crops showed limited potential for grain production in no-till organic systems in this project, with one exception. Soybean was grown successfully when seeded directly into rolled-crimped vegetative mulch produced by winter rye cover crop in Minnesota and Wisconsin. There may be nutrient deficiency concerns in a no-till organic production system when growing soybean (Carr et al. 2013); nevertheless, soybean seems to have the greatest near-term potential for successful grain production in no-till organic systems in the region. References Carr, P.M., G.G. Gramig, and M.A. Liebig. 2013. Impacts of organic zero tillage systems on crops, weeds, and soil quality. Online. Sustainability 5: 3172-3201 Mirsky, S.B.; W.S. Curran, D.A. Mortensen, M.R. Ryan, and D.L. Shumway. 2009. Control of cereal rye with a roller/crimper as influenced by cover crop phenology. Agron. J. 101: 1589–1596. Mirsky, S.B.; M.R. Ryan, W.S. Curran, J.R. Teasdale, J. Maul, J., J.T. Spargo, J. Moyer, A.M. Grantham, D. Weber, and T.R. Way. 2012. Cover crop-based rotational no-till grain production in the mid-Atlantic region. Renew. Agric. Food Syst. 27:31-40. Mischler, R.; S.W. Dulker, W.S. Curran, and D. Wilson. 2010. Hairy vetch management for no-till organic corn production. Agron. J. 102: 355–362. Vaisman, I., M.H. Entz, D.N. Flaten, and R.H. Gulden. 2011. Blade roller–green manure interactions on nitrogen dynamics, weeds, and organic wheat. Agron. J. 103:879-889.
This project generated growing interest in no-till organic systems in central and northern tier states in the north central region. On-farm trials of no-till organic practices occurred after organic farmers learned of this project at summer field days and farmer-directed meetings. An NCR-SARE producer grant resulted following exposure by the farmer to the no-till organic concept and this project (FNC08-702). Prior to this project, a belief existed among some proponents of no-till organic farming that seeding grain corn directly into rolled-crimped hairy vetch vegetative mulch in a single pass or a short relay system (i.e., seeding corn within a few days of rolling-crimping) would be successful in the north central region. Results of this project demonstrated that no-till organic production of corn poses challenges when attempted, whether for grain or silage. No-till organic production of corn can be successful but only in specific environments in the region, at least when following current management recommendations. Insight gained from this project suggested that winter wheat as a viable alternative to corn in no-till organic grain production systems in wheat producing areas (e.g., North Dakota). Field experiments have been established and initial results indicate that no-till organic production of winter wheat can be successful. Additional research is needed to validate these preliminary data. Successful no-till organic production of soybean was demonstrated in this project, leading to no--till organic soybean production on three commercial farms in Wisconsin. This project identified obstacles that must be overcome before widespread adoption of no-till organic farming methods can be anticipated. Many of the challenges relate to cover crop termination by rolling-crimping, both in terms of improving its effectiveness and its impact on the timely seeding of the market crops that follow. In the near-term, successful no-till organic production of market crops beyond soybean and perhaps winter wheat depends on developing strategies that ensure the consistent and timely success of terminating cover crops by rolling-crimping.
Economic analyses are provided in manuscripts currently under review for publication in refereed journals and cannot be duplicated here.
An organic farmer in North Dakota compared termination of yellow-blossom sweetclover by rolling-crimping to disking after learning about this project and no-till organic farming concepts. Problems were identified when attempting to kill sweetclover by rolling-crimping and articulated in the final report of a NCR-SARE farmer producer grant (LNC09-210). The problems encountered before and after rolling-crimping sweetclover and following with a cover crop mixture reflect those articulated in this final report when various market crops are seeded directly into the vegetative mulch produced by different cover crop species and species mixtures. Three farmers are growing soybean under no-till organic conditions currently (2013) after observing the field experiments located at the AARC-WI site included in this project. Similar interest among small groups of farmers in no-till organic farming has been generated in other northern tier states within the north central region after observing field experiments included in this project, or discussing no-till organic farming concepts with scientist team members.
Educational & Outreach Activities
Two refereed publications are under review for publication in scientific journals; one is focused on the field studies located in WI and the other on the field studies in ND. A third manuscript is being prepared for publication consideration that summarizes selected results from the field studies located in Minnesota and North Dakota. An. M.S. thesis was completed that summarizes results of the field study in Iowa (D. Cwach; Evaluation of Cover Crops in Reduced Tillage Systems for Organic Production). Summer field days were held at each location where organic farmers and others interested in no-till organic farming systems were able to observe the field experiments included in this project and interact with scientist team members. The project also was discussed at educational meetings attending by organic farmers in each state, and at the 2010 annual meeting of the American Society of Agronomy during a symposium focused on no-till organic systems research in Canada and the USA.
To view a video of this SARE project follow this link:https://youtu.be/TokouvvRcME
Areas needing additional study
Several areas of research are needed so that recommendations can be provided to organic farmers which optimize the likelihood of success if no-till organic farming practices are adopted. Screening of cover crop germplasm is needed which adds to the list of small-grain and legume species identified in this project as being adapted to no-till organic farming practices in the region. Fast-growing, early maturing species are preferred over slow-growing, late maturing species in most organic ZT farming systems being considered. Breeding is needed to develop new cultivars that are suited to the harsh winter conditions common in central and particularly northern tier states within the region. Management strategies are needed which allow early rolling and crimping of cover crops so that the seeding of subsequent market crops is timely and within the recommended seeding date window. Cultivar selection and fall-seeding dates can affect when cover crops are rolled-crimped the following spring or early summer. Strategies should be considered where a cover crop is rolled-crimped and a subsequent market crop seeded during the first year but harvested during the second year, rather than accomplishing all field activities in the same year as generally is done. This reflects a common practice of tilling under a cover crop during the first growing season and producing a market crop the next year on many organic farms in drier portions of the north central region (e.g., North Dakota). Adoption of no-till practices has resulted in significant soil quality improvements at shallow depths in conventional farming systems and is well documented in the literature. Similar improvements in soil quality are anticipated following adoption or no-till practices on organic farms, but refereed scientific literature documenting improvements in soil quality following adoption of no-till organic farming methods is extremely limited. Long-term studies on the impact of no-till compared with tilled farming practices are needed so soil quality improvements can be documented.