Effects of several stale seedbed procedures on weed density and biomass were evaluated on a silt loam soil in central New York. After an initial rotary tillage, weeds were allowed to emerge and either single or multiple applications of glyphosate, propane flame, spring tine weeder, springtooth harrow, or rotary tiller were used to kill the weeds over a 4-week period. The last (or only) application occurred immediately prior to simulated seeding of a crop performed by passing an empty seeder through the plots. These stale seedbed treatments were compared with a control consisting of a single rotary tillage just before simulated planting. Flaming or glyphosate stale seedbed techniques significantly reduced density and biomass of the principal broadleaf species, common purslane (Portulaca oleracea L.) and common chickweed [Stellaria media (L.) Cyrillo], in most cases. A single delayed flame or glyphosate stale seedbed treatment was usually as effective as multiple treatments. None of the stale seedbed techniques was effective against yellow nutsedge (Cyperus esculentus L.). A flexible tine weeder was not effective as a stale seedbed weed-killing treatment in this study because of poor penetration of crusted soil. Penetration was better with a springtooth harrow, but this failed to reduce weed density. None of the stale seedbed treatments fully controlled weeds. However, glyphosate or flaming a stale seedbed could be incorporated into integrated weed management programs to improve control and reduce the need for herbicides. Broadleaf weed density within 3.8 cm of the center of the seeder wheel track was greater than elsewhere in the plot. Chemical name used: N-(phosphonomethyl)glycine (glyphosate).

e transition period to organic grain production presents an economic obstacle for farmers, and early management may a ect subsequent crop performance. Using a corn-soybean-winter spelt/red clover [Zea mays L.-Glycine max (L.) Merr.-Triticum spelta L./Trifolium pratense L.] rotation in central New York, we compared yields and economics in four organic cropping systems during and a er transition. ese were high fertility (HF), low fertility (LF), enhanced weed management (EWM), and reduced tillage (RT). Corn and soybean yields in HF, LF, and EWM were similar among systems throughout the experiment and averaged 65 and 91%, respectively, of those in surrounding Cayuga County (CC) during transition. In the rst year a er transition, HF, LF, and EWM corn yields averaged 63% of CC, but a er that 98 to 114% of CC. Soybean yield trends relative to CC remained the same a er transition. Transitional spelt yields tended to be higher in HF and EWM than in LF. Spelt yields a er transition were variable. Starting in 2006, RT yields were lower than other organic systems in all crops due to equipment problems. Weeds generally increased in all systems over 6 yr, and reached the highest biomass levels in RT and HF. Under our soil and climate conditions, higher fertility amendments in HF compared with LF increased weed biomass but not corn or soybean yield. Economic budgets revealed lower relative net returns (RNR) during transition for the HF, LF, and EWM systems compared with values calculated from CC yields and practices, but higher RNR therea er.Supplemental material available online. B. Caldwell,

In many respects the long standing and vigorous debates over alternative agriculture and organic farming are becoming less strident and less polarized. However, despite the mounting evidence that key elements of both the conventional and alternative agricultural communities are beginning to "build bridges" to each other, and to establish formal institutional programs and arrangements for improved communication and program development, important differences continue to separate the proponents and opponents of alternative agriculture. In part, these lingering differences result from the lack of adequate and reliable data, misinformation, and faulty data analyses. In order to clarify those issues which continue to divide the critics and advocates of alternative agriculture, this reappraisal of the debate begins with a methodological critique of comparison studies of conventional and organic farms. Also included is an assessment of fertilizer and pesticide use in American agriculture, the environmental impacts of conventional and reduced-input systems, the relationship between alternative agriculture and efforts to save the family farmer, and the prospects for increased public sector research on reduced-input farming systems.

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Weed management is a major constraint in organic cropping systems. In 2004, the Cornell Organic Vegetable Cropping Systems Experiment was established in central New York state using a split-plot randomized complete block design with two crop rotation entry points (split-plot factor). Four organic vegetable cropping systems that varied in cropping intensity and tillage (main plot factor) were compared: (1) intensive, (2) intermediate, (3) bio-extensive, and (4) ridge tillage. The basic crop rotation was cabbage, lettuce, potato, and winter squash, with additional short-season crops in the intensive system and with cover crops and fallow substituted for cabbage and potato in the bio-extensive system. In 2014, two uniformity trials were conducted in which oat and then a mixture of sorghum-sudangrass plus Japanese millet were grown uniformly over the entire experiment. Prior to sowing oat, soil samples were collected from each plot and an emergence bioassay was conducted to assess the soil weed seedbank. Crop biomass, weed density, and weed biomass were sampled in the uniformity crops. Soil weed seedbank density was three to four times greater in the intensive, intermediate, and ridge-tillage systems than in the bio-extensive system. The bio-extensive system also had lower weed density and weed biomass in the oat uniformity trial compared with the other three systems. Oat biomass did not differ between the cropping systems. Weed density and biomass in oat were also affected by the crop rotation entry point. Cropping system legacy effects on weed abundance and community composition were greater in the oat than in the sorghum-sudangrass plus Japanese millet uniformity trial. Our results illustrate the effects of different organic vegetable production practices on weed community structure and highlight the value of tilled fallow periods, cover crops, and prevention of weed seed rain for reducing weed populations.

Most previous research on changes in weed abundance and community composition in cropping systems has focused on field crops. The study presented here examined changes in the weed seedbank and aboveground biomass in four organic vegetable cropping systems over a 10-yr period. The systems included an Intensive system with six crops per 4-yr rotation, an Intermediate system with one cash crop per year, a Bio-extensive system with alternating cash crop and tilled fallow years plus prevention of seed rain, and a Ridge-tillage system with one cash crop per year. Systems also differed in the types and number of cover crops between cash crops. During the course of the experiment, the weed community shifted from one dominated by summer annual broadleaf species that reproduce at the end of their lives to a community dominated by summer and winter annuals that mature rapidly. This shift in community composition can be attributed to the change in land use from conventionally managed corn (Zea maysL.) and alfalfa (Medicago sativaL.) to organic vegetable production. In particular, crop rotations with diverse preplantings and postharvest tillage dates interrupted the life cycle of common lambsquarters (Chenopodium albumL.) and pigweed species (Amaranthusspp.: mostly Powell amaranth [Amaranthus powelliiS. Watson], with small numbers of redroot pigweed [Amaranthus retroflexusL.] and smooth pigweed [Amaranthus hybridusL.]), while favoring a diverse assemblage of quickly maturing species. The study thus demonstrates that an appropriate crop rotation can control the seedbank of weeds likeC. albumthat potentially persist well in the soil. The Ridge-tillage system greatly reduced the frequency and depth of tillage relative to other systems while effectively suppressing perennial weeds. The early-reproducing annuals, however, became more abundant in the Ridge-tillage system than in the other systems, primarily due to escapes along the edge of the scraped ridges. The tilled fallow periods coupled with prevention of seed rain in the Bio-extensive system substantially reduced weed abundance through time and relative to the other systems.

Management constraints in reduced tillage organic vegetable production may be alleviated by combining strip tillage (ST) with overwintering cereal-legume cover crop mixtures. Field studies in Michigan and New York over 6 site-years evaluated the effects of preceding cover crops, including cereal rye (R; Secale cereale L.), hairy vetch (V; Vicia villosa Roth) and crimson clover (CC; Trifolium incarnatum), on N availability, weed management, and yields in ST organic cabbage (Brassica oleracea L. var. capitata). Cover crop treatments included R-legume mixtures (RV and RCC) planted under two spatial arrangements, standard full-width mixed [-M] vs. segregated strips [-S] (legumes planted in-row and R between-row), and R and V monocultures. Cover crop aboveground biomass (5-10 Mg ha -1 ) and N content (>90 kg N ha -1 ) were not different among RV and RCC but the C/N of RCC was 58% greater than RV. Cabbage yields after RCC-M were lower than RV-M in five of six cases with yield reductions ranging from 22 to 41%. Spatial arrangement had no effect on cabbage yield after RV but improved yields after RCC from 23 to 39% in one, relatively dry, site-year. Without N fertilizer, yields after RV and V were equivalent to or greater than R-S with 134 kg N ha -1 in seven of nine and four of four cases, respectively. Legume species and spatial arrangement had little or no impact on the efficacy of in-row mechanical cultivation, hand-weeding time or weed biomass.Overall, N supplied from V and RV mixtures was an important driver of ST organic cabbage yields across different soil types and weather conditions.