Organic Cropping Systems Research Articles

Effect of living mulches and conventional methods of weed control on weed occurrence and nutrient uptake in potato

The aim of the study was to determine the biomass, abundance and species composition ofweeds, as well as macroelement uptake in potato weeded using mechanical, mechanical–chemical and mechanical control combined with the sowing of living mulches of white mustard,common vetch, Persian clover and tansy phacelia. Abundance and biomass of the weeds was themost effectively limited by the mechanical treatments. The effectiveness of mechanicaltreatments in weed biomass reduction was 2.5–fold lower. The mechanical treatments moreeffectively limited the number of monocotyledonous than dicotyledonous weeds. Livingmulches increased the efficiency of mechanical weeding by affecting both weed biomassdevelopment and weeds abundance. The living mulch that most effectively limited the growthof weed biomass was white mustard, while vetch was effective to reduce of the number ofmonocotyledonous weed and Persian clover for dicotyledonous weeds. The most frequentlyoccurring weed species were Galinsoga parviflora, Chenopodium album and Echinochloacrus-galli. The share of N accumulated in the biomass of neighboring plants constituted from5% to 34%, P from 6% to 38%, K from 5% to 36%, Ca from 27% to 190% and Mg from 12% to55% of the amount of these nutrients absorbed by potato plants. Mechanical treatments plusliving mulches, especially Persian clover, may be useful in organic cropping systems due totheir effectiveness at reducing weed abundance and biomass and relatively low nutrient uptakecompared with weeds.

Reduced inter-row distance improves yield and competition against weeds in a semi-dwarf durum wheat variety

Weed and nutrient management in cropping systems of semi-arid areas is a major constraint to cereal yield. Where the use of herbicides is banned or discouraged, the competitive ability of a crop is crucial to reduce weed growth and diffusion. Genotypic differences in the competitive abilities of crops are an important trait to reduce weeds, especially for plant height. However, there is contrasting information about the interactions of other management practices and genotypic traits on wheat yield and competitive ability against weeds and weed growth. The present study investigated yield and quality of durum wheat (Triticum durum Desf.) and weed growth and composition for two wheat cultivars with contrasting competitive abilities against weeds. Wheat was grown under three spatial arrangements (5-cm, 15-cm, 25-cm inter-row distance) and three sowing densities, and broadleaf weeds were either removed or not. The sowing rate did not affect the yield of these wheat cultivars or the weed growth. Reduced inter-row distance dramatically reduced weed biomass for both wheat cultivars, and increased wheat yield and nitrogen uptake in the low-competitive, high-yielding, semi-dwarf cv. ‘PR22D89’, when both weed free and with weeds. These results have direct implications for weed and nutrient management in low-input and organic cropping systems.

A two-stage DEA approach for quantifying and analysing the inefficiency of conventional and organic rain-fed cereals in Spain

This paper assesses the efficiency of rain-fed cereals crops grown in Southern Spain. The proposed approach uses a two-stage Data Envelopment Analysis (DEA) plus regression approach. In the first stage a Slacks-based Inefficiency (SBI) DEA model is used to project conventional and organic cropping systems onto the efficient frontier. The results of the efficiency analysis show that conventional production is more inefficient than organic production and that the main sources of inefficiency in the case of conventional production correspond to excessive input consumption and GHG emissions. In the case of organic production, the inefficiency comes from output shortfalls. It is shown that reducing inefficiency would reduce the amount of GHG emitted per unit of fresh matter yielded. This potential gain is more pronounced in the case of conventional production but also occurs for organic production. In the second stage, the crops efficiency scores are regressed against some exogenous variables using a fractional regression model. The regression results confirm that organic production significantly decreases inefficiency and they also indicate that the larger the farm, the larger the inefficiency and that growing barley is more inefficient than wheat.

Balancing multiple objectives in organic feed and forage cropping systems

Balancing weed suppression, beneficial insect conservation, soil quality and profitability is challenging in organic cropping systems due to reliance on soil disturbance for weed control. We hypothesized that the benefits of tillage can be retained while mitigating adverse impacts on soil quality by alternating tillage with practices that can build soil organic matter. We conducted a four-year experiment in central Pennsylvania, USA, to compare four organic feed and forage cropping systems, each differing in tillage, manure management, and cropping strategies. Each system was designed to address baseline soil quality and weed pressure conditions arising from practices implemented during the previous three-year transition period. To assess cumulative system effects, we established a soybean (Glycine max) uniformity trial across all systems in year four. Systems that were in perennial forage for 2 years outperformed annual crop-based systems in weed control and beneficial insect conservation, while maintaining overall profitability over the four-year study period. Soybean yields during the uniformity trial were more than 30% greater in systems that had included perennial forages than in systems with only annual crops. Labile soil carbon pools, an indicator of soil quality, were maintained over time in all systems. Our results indicate that soil quality, weed management, beneficial insect conservation, and profitability can be maintained in organic systems when periodic tillage is coupled with perennial forage crops in rotation.

English

A research was carried out to study phytosociology and to determine the periods of weed interference in the okra crop in organic cropping system. The experiment was laid out in a randomized complete block design with 20 treatments and four replications. The treatments were 10 periods of weed coexistence with the crop during 0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56, 0-63 and 0-74 days after crop emergence (DAE) and 10 periods weed free during 0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56, 0-63 and 0-74 DAE. The weeds were evaluated by the number of individuals and accumulated dry biomass of each population in the treatments. The relative frequency, relative density, relative dominance and importance value index of each species were used to determine the effect the weeds. The most important weeds based on the Importance value index were Commelina benghalensis L., Cynodon dactylon (L.) Pers., Eleusine indica L., Phyllanthus niruri L. and Alternanthera tenella Colla. The period prior to interference and the total period of interference prevention were respectively of 12 and 36 days after emergence. The weed community caused yield losses of around 51%. In okra organic cropping system, weed control should be done early to boost okra plant growth in order to provide shade on the weeds to reduce the need for long control period.   Key words: Abelmoschus esculentus (L.) Moench, competition, weed community.

Field-scale experiments reveal persistent yield gaps in low-input and organic cropping systems

Knowledge of production-system performance is largely based on observations at the experimental plot scale. Although yield gaps between plot-scale and field-scale research are widely acknowledged, their extent and persistence have not been experimentally examined in a systematic manner. At a site in southwest Michigan, we conducted a 6-y experiment to test the accuracy with which plot-scale crop-yield results can inform field-scale conclusions. We compared conventional versus alternative, that is, reduced-input and biologically based-organic, management practices for a corn-soybean-wheat rotation in a randomized complete block-design experiment, using 27 commercial-size agricultural fields. Nearby plot-scale experiments (0.02-ha to 1.0-ha plots) provided a comparison of plot versus field performance. We found that plot-scale yields well matched field-scale yields for conventional management but not for alternative systems. For all three crops, at the plot scale, reduced-input and conventional managements produced similar yields; at the field scale, reduced-input yields were lower than conventional. For soybeans at the plot scale, biological and conventional managements produced similar yields; at the field scale, biological yielded less than conventional. For corn, biological management produced lower yields than conventional in both plot- and field-scale experiments. Wheat yields appeared to be less affected by the experimental scale than corn and soybean. Conventional management was more resilient to field-scale challenges than alternative practices, which were more dependent on timely management interventions; in particular, mechanical weed control. Results underscore the need for much wider adoption of field-scale experimentation when assessing new technologies and production-system performance, especially as related to closing yield gaps in organic farming and in low-resourced systems typical of much of the developing world.

Adaptation to climate change impacts on crop water requirements in Kikafu catchment, Tanzania

Agricultural activities are the main livelihood for about 70% of Tanzania's population, with women being the main players. Crops need water (crop water requirements, CWRs) for their growth and production, which can either be rain-fed or irrigation sourced. However, climate change has affected the hydrological cycle, particularly water available for agricultural crops. Since impacts and consequently adaptation are site-specific, an assessment of the effects of climate change on maize water requirements in Kikafu sub-catchment was conducted using a crop simulation model, CROPWAT. Accordingly, climate scenarios were obtained from A2 emission scenario using three general circulation models (GCMs). These scenarios were downscaled at two site locations using the Long Ashton Research Station Weather Generator (LARS-WG) model. The baseline period for the change analysis was 1971–2000. The CWRs are projected to increase by 3.8% in the 2020s and 7.1% in the 2050s at the Moshi Airport and 19.9 and 22.4% at Lyamungu station, respectively. More impact is projected to be during 70–80 days of the development stage and the entire mid-season (81–140 days) whereby the temperature will be high but with low precipitation. With the increasing CWRs, better adaptation measures are increase crop diversification, restore soil organic matter and change cropping systems as established through the multi-criteria analysis.

Hubungan Antar Sifat Jagung Manis yang Dibudidayakan Secara Organik

Capability of growing well under organic conditions is prerequisite for a sweet corn variety to provide high yield under organic cropping management. Therefore, development of high yielding sweet corn varieties for organic cropping system would require sufficient information on the association among the growth traits to facilitate the determination of criteria in the selection program. Objective of this study was to estimate the degree of association among plant growth and developmental traits, in terms of phenotypic and genotypic correlations, in 64 genotypes generated from a complete diallel cross of 8 inbred lines under organic cropping system. Study was conducted from January-March 2016 on Ultisol of Medan Baru, Kandang Limun, sub-district of Muara Bangkahulu, City of Bengkulu at 10 m above sea level. A randomized complete block design with three replications to allocate the genotypes on double row plots with 4 length and 20 cm planting space. No agrochemical inputs was applied in cultural practices. Data were collected for plant height,stem diameter, leaf area, leaf number, tasseling date, and silking date. Analysis of variance was performed to determine the significant variation among the genotype. The degree of association among trait was estimated by both phenotypic and genotypic correlations analysis. Analysis of variance showed significant variation for all observed traits. High phenotypic and genotypic correlations were revealed between the growth traits (plant height, stem diameter, leaf area, and leaf number) and between the developmental traits (tasseling date, and silking date). However, the growth traits showed low correlation to the developmental traits.

Irrigation and Fertilization Management Effect on Chinese Cabbage Chemical Composition

ABSTRACTChinese cabbage is a leafy green with great economic potential, mostly in those areas where it has not yet been widely cultivated, but its demand is increasing, due to its high nutritional and therapeutic value. The experimental factors involved three cultivars of Chinese cabbage, different irrigation, and fertilization treatments. The main aims of the present research were to establish the influence of water and fertilization management on Chinese cabbage chemical composition in an organic cropping system and to determine relations between the organic fertilizers and cabbage leaf macroelements, essential microelements, and heavy metal concentrations. The results showed that sheep manure was richer in almost all the studied elements, including heavy metals; plants fertilized with this manure have higher levels of heavy metals; irrigation had a secondary effect on the decreasing heavy metal concentration in plants; and plants fertilized with biofertilizers showed high amounts of potassium (K), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn).

Does organic farming accumulate carbon in deeper soil profiles in the long term?

Organic farming systems provide the opportunity to deliver more soil ecosystem services than conventional practices. One such service could be soil organic C (SOC) accumulation, but recent debates suggest that this is unclear. Furthermore, organic farming potential to accumulate SOC for the entire soil profile is not well known. We quantified the cumulative SOC stocks, aggregate-associated SOC, and particulate organic matter (POM) concentrations for the 0–100cm depth of the soil profile in a comparative crop rotation experiment in eastern Nebraska after >20yr of management. We studied: 1) conventional farming, 2) conventional farming with diversified rotation, 3) organic rotation with alfalfa (Medicago sativa L.) as green manure, and 4) organic rotation receiving 37Mgha−1yr−1 cattle manure. All the treatments had been managed for 40yr except the organic rotation with green manure, which had been in place for 20yr. Organic farming increased SOC stock, aggregate-associated SOC, and POM concentrations but only in the 0–15cm soil depth. The SOC stock under organic cattle manure system was 19% greater than under conventional farming (33.1Mgha−1) and 13% greater than under conventional farming with diversified rotation (34.8Mgha−1). The SOC stock under organic rotation with green manure (36.6Mgha−1) was 10% greater than in conventional farming. Results suggest that organic cropping systems accumulated SOC at 0.16MgCha−1yr−1 with cattle manure and 0.18MgCha−1yr−1 with green manure. Growing alfalfa for only two years in the 4-yr organic rotation probably limited its potential to increase SOC for the whole soil profile. Overall, in the long term, organic farming increases SOC stock but only in the upper 15cm of the soil profile.

Soil organic matter, greenhouse gases and net global warming potential of irrigated conventional, reduced-tillage and organic cropping systems

Reducing tillage intensity and diversifying crop rotations may improve the sustainability of irrigated cropping systems in semi-arid regions. The objective of this study was to compare the greenhouse gas (GHG) emissions, soil organic matter, and net global warming potential (net GWP) of a sugar beet (Beta vulgaris L.)-corn (Zea mays L,) rotation under conventional (CT) and reduced-tillage (RT) and a corn-dry bean (Phaseolus vulgaris L.) rotation under organic (OR) management during the third and fourth years of 4-year crop rotations. The gas and soil samples were collected during April 2011–March 2013, and were analyzed for carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions, water-filled pore space (WFPS), soil nitrate (NO3 −–N) and ammonium (NH4 +–N) concentrations, soil organic carbon (SOC) and total nitrogen (TN), and net global warming potential (net GWP). Soils under RT had 26% lower CO2 emissions compared to 10.2 kg C ha−1 day−1 and 43% lower N2O emissions compared to 17.5 g N ha−1 day−1 in CT during cropping season 2011, and no difference in CO2 and N2O emissions during cropping season 2012. The OR emitted 31% less N2O, but 74% more CO2 than CT during crop season 2011. The RT had 34% higher SOC content than CT (17.9 Mg ha−1) while OR was comparable with CT. Net GWP was negative for RT and OR and positive for CT. The RT and OR can increase SOC sequestration, mitigate GWP and thereby support in the development of sustainable cropping systems in semiarid agroecosystems.

بررسی توانایی چند گیاه دارویی در کنترل قارچ های عامل پوسیدگی انباری Rhizopus nigricans) و Alternaria alternate) در گوجه فرنگی های تولید شده در سامانه های کشاورزی رایج و زیستی

بیماری پوسیدگی ریزوپوسی و نقطه سیاه از مهم ترین بیماری های انباری در گوجه فرنگی می باشند. به منظور بررسی توانایی چند گیاه دارویی بر ماندگاری و کنترل قارچ های عامل پوسیدگی انباری Rhizopus nigricans) و Alternaria alternate) در گوجه فرنگی های تولید شده در سامانه های کشاورزی رایج و زیستی، آزمایشی به صورت فاکتوریل در قالب طرح کاملا تصادفی با 14 تیمار و سه تکرار در دانشگاه فردوسی مشهد در سال 1389 اجرا شد. دو سامانه تولید شامل گوجه فرنگی رایج و زیستی (ارگانیک) و شش گونه گیاهی (آویشن (Thymus vulgaris L.)، پونه (Mentha pulegium L.)، نعناع فلفلی (Mentha piperita L.)، اکالیپتوس (Eucalyptus globules L.)، کرچک (Ricinus communis L.) و گوجه فرنگی (Lycopersicom esculentum Mill.)) به همراه تیمار شاهد به ترتیب عامل اول و دوم در این آزمایش بودند. بر اساس نتایج آزمون غیر پارامتری کروسکال– والیس، تفاوت معنی داری بین سامانه های تولید گوجه فرنگی های ارگانیک با نوع غیرارگانیک آن از نظر سرعت پوسیدگی انباری ناشی از رشد قارچ های بیماری زا مشاهده شد. به طوری که در گوجه فرنگی های ارگانیک، سرعت پوسیدگی (47/1 عدد میوه در هفته) تا حدود 20 درصد کمتر از نوع غیرارگانیک آن بود. نتایج حاصل از آنالیز غیرپارامتری گونه های گیاهی نیز حاکی از وجود تفاوت بین این گونه ها از نظر تأثیر بر سرعت پوسیدگی انباری در گوجه فرنگی بود؛ به طوری که به جز کرچک و گوجه فرنگی، سایر گیاهان دارویی منجر به کاهش معنی دار سرعت رشد و توسعه قارچ های بیماری زا در انبار شدند.

Impact of Cropping Systems, Soil Inoculum, and Plant Species Identity on Soil Bacterial Community Structure.

Farming practices affect the soil microbial community, which in turn impacts crop growth and crop-weed interactions. This study assessed the modification of soil bacterial community structure by organic or conventional cropping systems, weed species identity [Amaranthus retroflexus L. (redroot pigweed) or Avena fatua L. (wild oat)], and living or sterilized inoculum. Soil from eight paired USDA-certified organic and conventional farms in north-central Montana was used as living or autoclave-sterilized inoculant into steam-pasteurized potting soil, planted with Am. retroflexus or Av. fatua and grown for two consecutive 8-week periods to condition soil nutrients and biota. Subsequently, the V3-V4 regions of the microbial 16S rRNA gene were sequenced by Illumina MiSeq. Treatments clustered significantly, with living or sterilized inoculum being the strongest delineating factor, followed by organic or conventional cropping system, then individual farm. Living inoculum-treated soil had greater species richness and was more diverse than sterile inoculum-treated soil (observed OTUs, Chao, inverse Simpson, Shannon, P < 0.001) and had more discriminant taxa delineating groups (linear discriminant analysis). Living inoculum soil contained more Chloroflexi and Acidobacteria, while the sterile inoculum soil had more Bacteroidetes, Firmicutes, Gemmatimonadetes, and Verrucomicrobia. Organically farmed inoculum-treated soil had greater species richness, more diversity (observed OTUs, Chao, Shannon, P < 0.05), and more discriminant taxa than conventionally farmed inoculum-treated soil. Cyanobacteria were higher in pots growing Am. retroflexus, regardless of inoculum type, for three of the four organic farms. Results highlight the potential of cropping systems and species identity to modify soil bacterial communities, subsequently modifying plant growth and crop-weed competition.

Use of biological indicators of soil health to estimate reactive nitrogen dynamics in long-term organic vegetable and pasture systems

Diverse crop rotations, cover crops and the possibility of integrating livestock make organic systems potentially more sustainable than other agroecosystems. Lower reactive nitrogen (N) in organic systems minimizes the potential for N losses. However, addition of organic manures and residues containing mineralizable N and carbon (C) have the potential to enhance nitrous oxide (N2O) emissions. We conducted a 39 d laboratory incubation to assess key microbiological drivers controlling nitrification and denitrification in long-term organic agroecosystems during simulated freeze-thaw cycles. Soils were collected from two annual organic vegetable systems receiving 1) mixed-compost, or 2) broiler litter and 3) an organic perennial pasture system cropped to vegetables every third year. Soil microcosms amended with 15N labelled sugar beet residue or unamended were maintained at 40, 60 and 80% of water filled pore space (WFPS). Significant N2O was emitted (4287–6138 μg kg−1soil) via denitrification from amended soil microcosms at 3 °C and 80% WFPS. Archaeal (AOA) and bacterial (AOB) nitrifier amoA gene copies were affected by temperature and reactive N species during freeze-thaws. Long-term organic vegetable cropping systems receiving mixed-compost additions had the potential to accumulate C and immobilize excess reactive soil N (particularly nitrates) thereby improving soil health and reducing N2O emissions.

Soil microbial diversity and activity linked to crop yield and quality in a dryland organic wheat production system

One of the primary goals of organic agriculture is increasing soil quality through the enhancement of soil biological diversity and activity. Greater soil microbial activity and diversity increase soil organic matter turnover and contribute to soil fertility, one of the main challenges associated with organic management. The objectives of this study were to 1) compare soil microbial abundance and activity between organic and conventional cropping systems, and 2) explore connections between soil microbial community indicators and crop productivity in organic and conventional winter wheat (Triticum aestivum)/spring wheat/winter pea (Pisum sativum) rotations. Soil and plant tissue was sampled following six years of organic and conventional management, and soil was analyzed for microbial abundance and activity. Fungal and bacterial abundance, soil enzyme activity, and soil organic carbon (C) were greater in the organic system than in the conventional system, and all four measures were positively correlated. Community-level physiological profiling (CLPP) indicated that C substrate utilization was greater in the organic than in the conventional system, though bacterial T-RFLP data did not demonstrate different community structure between systems, suggesting that management type affected bacterial community function, but not structure. Fungal T-RFLP results indicated that fungal community structure was different between the organic and conventional systems. Hay yield and tissue nitrogen (N) were greater in the organic system, and were positively correlated with fungal and bacterial abundance, but grain yield and protein were greater in the conventional system. The results of this study indicate that management type (organic vs. conventional) has implications for microbial abundance and microbial community function, and that differences in soil microbial abundance and activity likely impact crop yields and N uptake.

Long-term weed dynamics and crop yields under diverse crop rotations in organic and conventional cropping systems in the Canadian prairies

Alternative cropping systems are gaining attention throughout the world in order to increase the sustainability of agro-ecosystems. On the Canadian prairies, the tillage-based crop-fallow system has been replaced by no-till reduced input systems or tillage-based organic systems with more diversity in crop rotations but with no external inputs. However, the long-term effects of these alternative systems on weed and yield parameters have not been assessed. A study to examine weed and crop yield dynamics under diverse cropping systems was conducted within a 18-year cropping systems study near Scott, Saskatchewan. The trial was laid out in a split-split-plot design with four replicates. The main plots were three levels of inputs; a high input system (HIGH) that used tillage and inputs to maximize yield, a reduced system (RED) that used no-till practices and minimal inputs, and a tillage-based organic system (ORG) with no external inputs. The subplots were cropping diversity (rotations); fallow-annual grains (LOW), diversified annual grains (DAG), and diversified annuals and perennial forage (DAP). The sub-sub plots were the six phases of each rotation. There was an input by rotation interaction for weed biomass but not for weed density and crop yields. ORG systems had 7× and 4× greater weed density (107 plants m−2), 4× higher weed biomass (154kgha−1), and 32% and 35% lower yields (1052kgha−1) than RED and HIGH systems respectively. RED and HIGH input systems had similar crop yields and lower weed density than ORG. The LOW rotation had the lowest weed density. LOW and DAG rotations had similar yields, which were higher than in DAP. All systems showed an increase in weed density and biomass over time but did not impact on crop yields which was increasing over time likely influenced by a concurrent increase in rainfall. This study concludes that eliminating tillage and reducing agrochemicals is possible but eliminating agrochemicals requires better crop rotations for weed management as well as for nutrient management.

Rhizosphere interactions in an organic horticultural cropping system: effect of living mulch on artichoke mycorrhization

Rhizosphere interactions in an organic horticultural cropping system: effect of living mulch on artichoke mycorrhization

Tillage System and Cover Crop Management Impacts on Soil Quality and Vegetable Crop Performance in Organically Managed Production in Tennessee

Research is lacking on the impact of alternative reduced tillage (RT) systems on vegetable crop performance and soil quality, especially in organic production systems, where weed control cannot rely on synthetic herbicides. A 2-year field study was implemented in Aug. 2010 in Knoxville, TN, to evaluate cover crop–based systems for organic vegetable production either with or without spring tillage. Treatments, all organically managed, included 1) Till (+ACC), spring tillage of a winter cover crop with aboveground cover crop biomass (ACC) retained and soil covered by polyethylene mulch; 2) Till (−ACC), spring tillage of a winter cover crop with aboveground cover crop biomass (ACC) removed before tillage and soil covered by polyethylene mulch; and 3) RT system with no spring tillage and mechanically terminated winter cover crop residue on the soil surface. Vegetable crops of eggplant (Solanum melongena L.) and watermelon [Citrullus lanatus (Thunb.) Matsum. et Nakai] were planted in 2011 and 2012, respectively. Crop yield, cover crop biomass accumulation, soil N and C dynamics, and weed density were assessed. Marketable eggplant yield and marketable watermelon yield did not differ among treatments, but weed density was higher in the RT system. Measures of soil quality after 2 years of the study indicated that particulate organic matter-carbon (POM-C) and -nitrogen (POM-N) were highest in the RT treatment, a significant increase as compared with values at the beginning of the study. As a measure of the active fraction of soil organic matter, this indicates that the RT system may best maintain and improve soil quality in similar regional organic vegetable cropping systems. As indicated by measures of soil quality and crop yield, removal of aboveground cover crop biomass did not negatively impact the Till (−ACC) system as compared with the Till (+ACC).

Fall-sown cover crops as mulches for weed suppression in organic small-scale diversified vegetable production

AbstractCover crop-based reduced tillage (CCBRT) has achieved positive impacts in organic row crop systems, contributing to the conservation of soil resources and the facilitation of weed management. This technique, which uses cover crop residues as mulches to suppress weeds, has shown more variable success in organic vegetable production systems. This experiment examined CCBRT for small-scale organic vegetable production in the upper Midwestern USA, specifically evaluating weed suppression, labor inputs and crop yields. Cereal rye (Secale cerealeL.) and winter wheat (Triticum aestivumL.) were fall-sown in 2012 and 2013 in a strip-plot design, including control treatments with no cover crop and spring-applied oat straw mulch. Cover crop plots were strip-tilled in mid-April to establish a planting zone, with cover crops terminated in late May at anthesis with a hand-tractor mounted sickle-bar mower. Bell peppers (Capsicum annuumL. var. ‘Revolution’), snap beans (Phaseolus vulgarisL. var. ‘Tavera’), and potatoes (Solanum tuberosumL. var. ‘Red La Soda’) were hand-planted either as transplants or seed in each treatment immediately following cover crop termination. During each summer growing season, weeds were completely eliminated from each plot by hand approximately every 10–14 days, with time for manual weeding recorded for each treatment. Vegetable crop yields and quality were measured at harvest during 2013 and 2014. Cereal rye and winter wheat produced similar biomass at the time of termination. Greater weed biomass was collected in the wheat treatment as compared with the cereal rye, increasing the in-season labor required for manual weeding. Bean yields were decreased in the all CCBRT treatments compared with control treatments in both years of the study. Pepper yields did not differ in CCBRT treatments as compared with the control in both 2012 and 2013, although the CCBRT treatments did yield lower marketable peppers compared with the straw mulch plots. Potato tuber yields were not different in the CCBRT treatments as compared with the control in 2012, but were lower in 2013. These data indicate that, if CCBRT is to be more widely adopted in small-scale vegetable production, further optimization of the system must be achieved to ensure consistent and adequate weed suppression while maintaining crop yield and quality.

Production and physicochemical characteristics of strawberry cultivars produced in organic cropping system

The conventional production of strawberries has been characterized by high use of inputs resulting in chemical waste in the fruit. Strawberry produced on organic cropping system becomes important, because have more economic autonomy to family farms and reaches levels ecological, social and economic sustainability. The production and physicochemical characteristics of four short-day strawberry plants – Campinas, Chandler Dover and Vila Nova – were evaluated in order to obtain information to the development of organic system productive in the northwestern region of Rio Grande do Sul state, in Brazil. The experiment was conducted between May 1 st and November 3 rd , 2014. As regarded production characteristics, in each productive month and in total accumulated of the cycle were evaluated the mass and the quantity of accessory fruit produced by the plant. The physicochemical characteristics were determined through the soluble solid content, titratable acidity, pH and the color of the accessory fruits. Referring to the productivity, 'Campinas' stood on the other cultivars, showing bigger mass and total accessory fruit number. About the relation of soluble solid content and titratable acidity, the cultivars Chandler and Dover reached the best results, whereas the color of the 'Chandler', 'Campinas' and 'Villa Nova' accessory fruits submitted higher °Hue value.