Organic Management Systems Research Articles

Functional Gene Differences in Soil Microbial Communities from Conventional, Low-Input, and Organic Farmlands

Various agriculture management practices may have distinct influences on soil microbial communities and their ecological functions. In this study, we utilized GeoChip, a high-throughput microarray-based technique containing approximately 28,000 probes for genes involved in nitrogen (N)/carbon (C)/sulfur (S)/phosphorus (P) cycles and other processes, to evaluate the potential functions of soil microbial communities under conventional (CT), low-input (LI), and organic (ORG) management systems at an agricultural research site in Michigan. Compared to CT, a high diversity of functional genes was observed in LI. The functional gene diversity in ORG did not differ significantly from that of either CT or LI. Abundances of genes encoding enzymes involved in C/N/P/S cycles were generally lower in CT than in LI or ORG, with the exceptions of genes in pathways for lignin degradation, methane generation/oxidation, and assimilatory N reduction, which all remained unchanged. Canonical correlation analysis showed that selected soil (bulk density, pH, cation exchange capacity, total C, C/N ratio, NO(3)(-), NH(4)(+), available phosphorus content, and available potassium content) and crop (seed and whole biomass) variables could explain 69.5% of the variation of soil microbial community composition. Also, significant correlations were observed between NO(3)(-) concentration and denitrification genes, NH(4)(+) concentration and ammonification genes, and N(2)O flux and denitrification genes, indicating a close linkage between soil N availability or process and associated functional genes.

Are there any Advantages of Genetically Diverse Material in Cereal Breeding Programmes for Organic Farming?

Employing cereal genetic variation in breeding programmes for organic farming is one of the ways to create varieties with higher stability and adaptability. The aim of the study was to compare and evaluate grain yield, quality and other traits of barley pure lines, hybrid populations, variety mixtures, as well as winter wheat hybrid populations and parental varieties, in organic and conventional farming systems. Significant evidence for advantages of using barley mixtures and populations under organic and conventional management systems was not observed. More advantages with respect to yield, adaptability to unfavourable environments and TGW were observed for breeding lines selected for suitability to organic conditions. Combination of distinctive genotypes may result in a fairly stable mixture with average yield above the components. The study confirmed that resistance of winter wheat genotypes to abiotic stress is one of the significant traits that is closely connected with limitation of the wheat productivity in both growing conditions. Yield and grain quality value of winter wheat genotypes was lower under organic conditions compared to a conventional growing system. Advantages of populations were not observed under organic conditions, but significantly higher yield, in comparison to parental varieties, was obtained for two populations in conventional conditions. In general, the yield of populations was intermediate to that of the parents.

A long‐term comparison of the influence of organic and conventional crop management practices on the content of the glycoalkaloid α‐tomatine in tomatoes

α-Tomatine, synthesized by Lycopersicon and some Solanum species, is a steroidal glycoalkaloid which functions to protect against pathogens and insects. Although glycoalkaloids are generally considered toxic, α-tomatine appears to be well tolerated in humans. α-Tomatine has numerous potential health benefits including the ability to inhibit cancer cell growth in in vitro studies. α-Tomatine is influenced by numerous agronomic factors including fertilization and nitrogen availability. Herein, the levels of α-tomatine were compared in dried tomato samples (Lycopersicon esculentum L. cv. Halley 3155) produced in organic and conventional cropping systems that had been archived over the period from 1994 to 2004 from the Long Term Research on Agricultural Systems project (LTRAS) at UC Davis. The α-tomatine levels of tomatoes in both cropping systems ranged from 4.29 to 111.85 µg g(-1) dry weight. Mean levels of α-tomatine were significantly higher in the organically grown tomatoes than conventional ones (P < 0.001). In the organic management system, α-tomatine content was also significantly (P < 0.001) different between cropping years, suggesting that other influencing factors such as environmental conditions also affect α-tomatine content in tomato. The organically produced tomatoes had higher average α-tomatine content than their conventional counterpart over the 10-year study. Significant annual variability in the α-tomatine content in tomatoes was also observed and suggests that environmental factors, external to nitrogen fertilization, influence α-tomatine content in tomatoes.

Soil Quality After Eight Years Under High Tunnels

The sustainability of soil quality under high tunnels will influence management of high tunnels currently in use and grower decisions regarding design and management of new high tunnels to be constructed. Soil quality was quantified using measures of soil pH, salinity, total carbon, and particulate organic matter (POM) carbon in a silt loam soil that had been in vegetable production under high tunnels at the research station in Olathe, KS, for eight years. Soil under high tunnels was compared with that in adjacent fields in both a conventional and an organic management system. The eight-year presence of high tunnels under the conventional management system resulted in increased soil pH and salinity but did not affect soil carbon. In the organic management system, high tunnels did not affect soil pH, increased soil salinity, and influenced soil carbon (C) pools with an increase in POM carbon. The increases in soil salinity were not enough to be detrimental to crops. These results indicate that soil quality was not adversely affected by eight years under stationary high tunnels managed with conventionally or organically produced vegetable crops.

Temporal development and relationship amongst brown rot blossom blight, fruit blight and fruit rot in integrated and organic sour cherry orchards

The aim of this 4‐year study was to characterize temporal development of brown rot blossom blight and fruit blight (caused by Monilinia spp.) and their sporulating areas in sour cherry orchards; and to determine the relationships amongst incidence and sporulating area of blossom blight, fruit blight and fruit rot. The study was performed in integrated and organic orchard blocks on two cultivars (Újfehértói fürtös and Érdi bőtermő). On both cultivars, disease progress on flowers and fruits was 2–10 times slower in the integrated than in the organic management system. The peak incidence values were 9 and 31 days after petal fall for blossom blight and fruit blight, respectively. After these dates, no new blight symptoms on flowers and/or fruits appeared and the disease was levelling off. Final blossom blight incidence ranged from 1 to 5% and from 12 to 34%, and fruit rot incidence from 2 to 6% and from 11 to 26% in the integrated and the organic orchards, respectively. The sum of fruit blight incidence ranged from 9 to 22% for the organic system, but was below 5% for the integrated system, while the final sporulating area was 5–16 mm2 and &lt;3 mm2, respectively. Among the five highest Pearson's correlation coefficients, relationships between blossom blight and early fruit blight stage (r = 0·845, P = 0·0087 integrated; r = 0·901, P = 0·0015 organic), and between sporulating area and fruit rot (r = 0791, P = 0·0199 integrated; r = 0·874, P = 0·0039 organic) were the most significant relationships from an epidemic standpoint as they indicated a connection between different brown rot symptom types.

Balancing control and flexibility in joint risk management: Lessons learned from two construction projects

Joint risk management (JRM) is an approach that highlights the importance of collaboration between the project actors in managing risk that cannot be identified at the outset of the project. Despite the recognition of the concept in the literature, the use of JRM in practice seems to be rare. Based on contingency theory, we investigate how mechanistic (control-oriented) and organic (flexibility-oriented) management systems influence the implementation of JRM in two construction projects. In the first project, the actors managed to achieve a balance between control and flexibility, which paved the way for successful JRM. The extensive use of control in the second project hampered flexibility and constrained the use of JRM. We conclude that JRM requires both control for managing risk that has been identified and flexibility for dealing with unforeseen events. When a mechanistic approach is dominant, risk management remains a formal process carried out individually rather than collaboratively.

Performance of Dry Bean Genotypes Grown under Organic and Conventional Production Systems in Michigan

The lack of data on the performance of dry bean (Phaseolus vulgaris L.) cultivars grown under organic management systems in Michigan prompted the evaluation of 32 diverse dry bean genotypes in side‐by‐side trials under organic and conventional production systems. Trial sites were located in grower fields in Gratiot County, in 2007 and 2008 and in Tuscola County in 2009 and at the Kellogg Biological Station in Kalamazoo County, in all 3 yr. The conventional plots were treated following standard acceptable management practices including application of granular fertilizer at planting and use of chemical seed treatments and foliar sprays to control pests. For the organic treatments certified organic land was used and only approved methods for organic production were followed. Rhizobium inoculant was applied to seeds in the organic treatment before planting. Yields were 20% higher in conventional systems than in the organic systems over all locations. Seed classes that yielded well in the organic system included pink‐, small red‐, and black‐seeded genotypes and these classes also had the highest accumulation of seed N (36%). Some genotypes appear better suited to organic production than others; however, those genotypes performing poorly under the organic system also performed poorly under conventional system. Overall genotypes of Andean origin performed 25% lower than genotypes of Middle American origin in either organic or conventional systems. Older cultivars, such as the heirloom navy bean Michelite, commonly believed to be better suited to organic production, did not perform as well as modern commercial cultivars.

Chemical and Microbiological Soil Characteristics under Conventional and Organic Coffee Production Systems

The objective of this study was to evaluate the effect of Conilon coffee (Coffea canephora) cultivated under conventional and organic management systems on the chemical and microbiological characteristics of the soil, as compared to an Atlantic forest. Chemical soil properties, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial activity (MA), and metabolic quotient (qCO2) were determined at depths of 0–10 cm and 10–20 cm in two seasons (summer and winter). Although microbiological attributes varied according to the season and soil depth, MBC provided 54.15% of relative contribution to distinguish the treatments, followed by MBN and MA. Results indicate that the cultivation of coffee under organic management is more sustainable than under conventional system. Carbon from microbial biomass was the most important soil microbiological attribute in the clustering of the different management methods. Atlantic forest soil followed by organic coffee cultivation soil showed the best soil-quality indices.

THE EFFECTS OF BIOTIC INTERACTION BETWEEN TOMATO AND COMPANION PLANTS ON YIELD

Tomato plants are mainly cultivated as monocrops in Brazil by intensive using of chemical products. Aiming to contribute for the reduction of the use of pesticides and enhancing biodiversity on plantation area, we conducted field experiments with tomato plants intercropped with aromatic herbs, in Sergipe state, Brazil, to evaluate the performance of tomato plants grown in monocrop and in two intercrop designs: replacement series and additive designs. The herbs used were basil (Ocimum basilicum), rue (Ruta graveolens), fennel (Foeniculum vulgare) and peppermint (Mentha piperita). Two experiments were carried out under an organic management system and they were designed in a complete randomized blocks design with four replicates. Total height, canopy area, production, yield and land equivalent ratio (LER) were determined. Herbs used different competitive strategies in interactions. Tomato plants had lower yield in intercrop with fennel than using other intercrops. A reduction was observed on tomato yield: from 20.4 t ha-1, in monocrop, to 13.1 t ha-1 in intercrop. Fennel plants had higher height and canopy area than other intercrops used and it caused shadow on tomato plants. However, it was noted that tomato plants had lower percentage of yield loss caused by tomato fruitworm (24%) in intercrop with fennel than others. The tomato relative yield was larger in intercrop with rue (13.6 t ha-1) and lower in intercrop with fennel (6.4 t ha-1). The rue plants supported a significant increase on commercial yield of tomato fruits (about 26%). The greatest losses by tomato fruitworm damage occurred in monocrop and in intercrop with peppermint. The results show the interaction between tomato and rue plants was advantageous for tomato yields. Among herbs, basil had higher yield (96.5 t ha-1) than others. LER results reveal that all intercrops studied allowed for improving use of land.

ECONOMIC PERFORMANCE OF PRE-CROPS IN A THREE-YEAR ROTATION PROGRAM FOR ORGANIC VEGETABLE PRODUCTION

A four year experiment is being carried out, at Ege University Department of Horticulture, in which three different pre-crops are tested under an organic management system as compared to fallow. The aim of the experiment is to identify the most suitable rotation program for organic vegetable production in Turkey. Vicia sativa (common vetch), Brassica oleracea var. italica (broccoli), Vicia faba ‘Sevilla’ (faba bean) and fallow are tested as preceding (winter) crops. During the experiment carried out between 2007 and 2009, the main crops were tomato (2007), zucchini (2008) and pepper (2009). Broccoli represented the farmers’ choice as a winter vegetable. Vetch (incorporated) and faba bean (partially harvested and incorporated) were selected as legumes well adapted to the regional conditions. Soil fertility was maintained by incorporation of the crop residues at the end of both cycles and addition of organic-certified commercial compost (Bioaktif) and compost tea during the main cycle. All the management, including disease and pest management, was carried out according to the organic regulations valid in Turkey and the EU. During the production seasons, all variable costs and revenue, during both the pre-crop and main crop cycles, were recorded and gross margin calculated for each treatment. Economic analysis showed that broccoli as a pre-crop required the highest variable costs followed by faba bean, vetch and fallow, in all three years. Total revenue was the highest in plots where broccoli was the pre-crop. It is followed by faba bean plots mostly because higher yields were obtained in main crop plots following faba bean. The least profitable was fallow – main crop rotation. Broccoli plants also have some extra benefits like adding a high amount of biomass to soil and suppressing weed growth due to shading and allelopathic effects.

COMPARATIVE STUDY OF NUTRIENT AVAILABILITY IN INTEGRATED AND ORGANIC APPLE ORCHARDS

Nowadays, there is an increasing interest in environmental friendly fruit growing systems. Regarding this, the most frequented environmentally-benign fruit management systems are the integrated and organic systems. Although there are several differences between these growing systems only few information is available about their nutritional aspects, mostly in eastern Europe. Our experimental site (eastern Hungary) gave excellent possibility to carry out a comparative study to investigate differences between these growing systems because the plantations are situated side by side. The aim of our two-year study was to compare the nutrient status of the soil-leaf-fruit system in integrated and organic apple management systems, and take an effort to improve nutrient supply in environmentally friendly apple orchards. For leaf and fruit analysis four cultivars were selected. A traditional Hungarian cultivar: ‘Idared’, and three resistant cultivars ‘Rewena’, ‘Reanda’ and ‘Retina’. It was found that the seasonal patterns of examined nutrients were similar in both growing systems but the availability of these nutrients was more stable in the integrated orchard than in the organic one due to the fertilization management. Results suggested that applying chemical fertilizers in integrated orchards provided higher nutrient uptake, yield and resulted better fruit quality than in organic orchards where only natural nutrient sources are allowed. Detailed soil, leaf and fruit results are discussed in the paper.

Greenhouse gas emissions in coffee grown with differing input levels under conventional and organic management

Coffee plays a key role in sustaining millions of livelihoods around the world. Understanding GHG emissions from coffee supply chains is important in evaluating options for climate change mitigation within the sector. We use data from two long-term coffee agroforestry experiments in Costa Rica and Nicaragua to calculate carbon footprints (CF) for coffee and identify emission hotspots within different management systems, levels of inputs and shade types. Management system and input level were the main cause of variation in CFs. Carbon footprints for 1kg of fresh coffee cherries were between 0.26 and 0.67 kgCO2e for conventional and 0.12 and 0.52 kgCO2e for organic management systems. The main contributor to GHG emissions for all management systems was the inputs of organic and inorganic nitrogen. Nitrous oxide emissions from pruning inputs contributed between 7% and 42% of CFs. However, these estimates were strongly influenced by the choice of emission factor used in the calculations. Research is required to develop emission factors that account for different qualities and management of nitrogen inputs to enable effective calculation of the CF from different management strategies, and especially from the pruning and organic inputs managed in agroforestry systems. As such, effective climate change mitigation strategies can only be developed from site-specific studies which utilise accurate accounting and regional-specific emission factors.

Predicting long-term organic carbon dynamics in organically amended soils using the CQESTR model

The CQESTR model is a process-based C model recently developed to simulate soil organic matter (SOM) dynamics and uses readily available or easily measurable input parameters. The current version of CQESTR (v. 2.0) has been validated successfully with a number of datasets from agricultural sites in North America but still needs to be tested in other geographic areas and soil types under diverse organic management systems. We evaluated the predictive performance of CQESTR to simulate long-term (34 years) soil organic C (SOC) changes in a SOM-depleted European soil either unamended or amended with solid manure, liquid manure, or crop residue. Measured SOC levels declined over the study period in the unamended soil, remained constant in the soil amended with crop residues, and tended to increase in the soils amended with manure, especially with solid manure. Linear regression analysis of measured SOC contents and CQESTR predictions resulted in a correlation coefficient of 0.626 (P < 0.001) and a slope and an intercept not significantly different from 1 and 0, respectively (95% confidence level). The mean squared deviation and root mean square error were relatively small. Simulated values fell within the 95% confidence interval of the measured SOC, and predicted errors were mainly associated with data scattering. The CQESTR model was shown to predict, with a reasonable degree of accuracy, the organic C dynamics in the soils examined. The CQESTR performance, however, could be improved by adding an additional parameter to differentiate between pre-decomposed organic amendments with varying degrees of stability.

Grazing sericea lespedeza for control of gastrointestinal nematodes in lambs

Alternatives to chemical dewormers are needed to counter anthelmintic resistance and improve worm control in organic management systems. The objective was to examine the effectiveness of grazing sericea lespedeza (SL) compared with grass pastures for control of gastrointestinal nematodes (GIN) in lambs. In Experiment 1, Katahdin lambs grazed bermudagrass (BG; n=14), tall fescue (TF; n=7), or SL (n=19) pastures during early summer months. In Experiment 2, lambs grazed TF (n=15) or SL (n=13) pastures during late summer. Stocking rate of pastures was based on forage availability; additional lambs grazed pastures in Experiment 2, but were not sampled. Lambs were dewormed with 0.5g COWP if FAMACHA© score was >3. In Experiment 1, FEC were reduced within 35 days in SL compared with BG lambs (forage by time, P=0.03). The PCV was more resilient to changes over time in SL compared with other groups of lambs (forage by time, P=0.001). In Experiment 2, FEC were lower (P=0.02) and PCV tended to be higher (P=0.09) in lambs grazing SL compared with TF forage. Incidence of deworming was similar among forage groups in both experiments. Grazing SL reduced FEC in lambs in early and late summer, despite reluctance by lambs to graze. Grazing forage and selective deworming using COWP was effective in lambs.

Evaluation of organic management system on the population control of Panonychus citri (Acari: Tetranychidae) in a citrus orchard in South China

ABSTRACT The citrus red mite, Panonychus citri (McGregor), is a key pest in citrus orchards of China. The effect of organic management on the natural population control of citrus red mite was evaluated in a navel orange orchard in Meizhou, South China. Index of population trend (I), interference index of population control (IIPC), and exclusive index of population control (EIPC) were used to evaluate the effect. The results showed I < 1 for the citrus red mite, and predation was still an important factor suppressing the natural population of the citrus red mite in organic management systems. These results suggest that an organic management system is helpful in achieving the ecological management of citrus red mite population in citrus orchards, and the related indices of population control are valuable tools to evaluate the control effect of mites.

Enumeration of Arthropods Density in Context to Plant Diversity and Agricultural (Organic and Conventional) Management Systems

Enumeration of Arthropods Density in Context to Plant Diversity and Agricultural (Organic and Conventional) Management Systems

Effect of production system, alternative treatments and calf rearing system on udder health in organic dairy cows

In the last decade the main goals of organic dairying have been to attain acceptable levels of milk production, increase opportunities for animals to perform species own behaviour, resulting in improved animal welfare and animal health, and minimize the use of therapeutic interventions, including the reduction of the (preventive) use of antibiotics. Maintaining animal health without the use of therapeutic interventions is a major challenge for organic dairy farmers. In particular, udder health remains a major problem in both conventional and organic farming. In the QualityLowInputFood (QLIF) project udder health status and management were assessed in different production systems and European regions. These studies suggest that good udder health can be maintained in organic or low-input farming management systems. Novel strategies to control mastitis were evaluated and the potential of using internal teat sealers for the control of environment-associated pathogens was shown. Also oral application of a herd profile based single homeopathic remedy combined with homeopathic silica had a significant effect on cows with a relative low somatic cell count before drying-off. Suckling systems in calf rearing, as an integrated management approach, did not result in better udder health. None of the studies presented identified new variables affecting udder health. QLIF studies also demonstrated the importance of comparing udder health parameters in contrasting organic, low input and conventional production systems, since clear differences in antibiotic use against mastitis could be identified not only between organic and conventional systems, but also among dairy systems used in different EU-countries. Although alternative treatments used in organic systems could not be shown to be fully effective, results suggest that the use of individual or combined alternative strategies to improve udder health on organic or low-input farms warrants further investigation. Based on the results obtained it is recommended that future research should focus on identifying the reasons for variability in udder health between organic farms that use different management protocols to identify ‘best current practice’ when carrying out this research.

Weed Seed Persistence and Microbial Abundance in Long-Term Organic and Conventional Cropping Systems

Weed seed persistence in soil can be influenced by many factors, including crop management. This research was conducted to determine whether organic management systems with higher organic amendments and soil microbial biomass could reduce weed seed persistence compared with conventional management systems. Seeds of smooth pigweed and common lambsquarters were buried in mesh bags in organic and conventional systems of two long-term experiments, the Farming Systems Project at the Beltsville Agricultural Research Center, Maryland, and the Farming Systems Trial at the Rodale Institute, Pennsylvania. Seed viability was determined after retrieval at half-year intervals for 2 yr. Total soil microbial biomass, as measured by phospholipid fatty acid (PLFA) content, was higher in organic systems than in conventional systems at both locations. Over all systems, locations, and experiments, viable seed half-life was relatively consistent with a mean of 1.3 and 1.1 yr and a standard deviation of 0.5 and 0.3 for smooth pigweed and common lambsquarters, respectively. Differences between systems were small and relatively inconsistent. Half-life of smooth pigweed seeds was shorter in the organic than in the conventional system in two of four location-experiments. Half-life of common lambsquarters was shorter in the organic than in the conventional system in one of four location-experiments, but longer in the organic than in the conventional system in two of four location-experiments. There were few correlations between PLFA biomarkers and seed half-lives in three of four location-experiments; however, there were negative correlations up to −0.64 for common lambsquarters and −0.55 for smooth pigweed in the second Rodale experiment. The lack of consistent system effects on seed persistence and the lack of consistent associations between soil microbial biomass and weed seed persistence suggest that soil microorganisms do not have a dominating role in seed mortality. More precise research targeted to identifying specific microbial functions causing seed mortality will be needed to provide a clearer picture of the role of soil microbes in weed seed persistence.

Spring wheat genotypes differentially alter soil microbial communities and wheat breadmaking quality in organic and conventional systems

Nelson, A. G., Quideau, S., Frick, B., Niziol, D., Clapperton, J. and Spaner, D. 2011. Spring wheat genotypes differentially alter soil microbial communities and wheat breadmaking quality in organic and conventional systems. Can. J. Plant Sci. 91: 485–495. Wheat (Triticum aestivum L.) cultivars may have differential effects on soil microbial communities and the breadmaking quality of harvested grain. We conducted a field study comparing five Canadian spring wheat cultivars grown under organic and conventional management systems for yield, breadmaking quality and soil phospholipid fatty acid (PLFA) profile. Organic yields (2.74 t ha−1) were roughly half of conventional yields (5.02 t ha−1), but protein levels were higher in the organic system than the conventional system (16.6 vs. 15.3%, respectively). Soil microbial diversity measures were significantly higher in the organic system compared with the conventional system, including PLFA richness (31 vs. 27 unique PLFAs per sample, respectively) and PLFA div...

Comparing conventional and organic olive groves in central Greece: plant and bird diversity and abundance

AbstractThe present study was conducted in Magnesia Prefecture, central Greece, during the period May–June 2007. It aimed at the comparison between conventional and certified organic olive groves with regard to olive and olive oil production, diversity of plants (herbaceous and woody) and diversity and abundance of avifauna. Correlations between variables within herbaceous plants (linear regression) and woody plants (Principal Component Analysis), and the role of integration time of olive groves to the organic system were investigated. Also, finding easily measurable parameters indicating high bird diversity levels within organic and conventional management systems was a main target of the study. According to our findings, neither edible olive yield nor olive oil yield showed significant differences between conventional and certified organic olive groves. There is an increasing trend for alpha and beta diversity of herbaceous plant species, woody plant beta diversity, density and cover of woody plants, and density of breeding birds in certified organic olive groves (10 years) in comparison with conventional ones. The effect of time since the adoption of organic procedures is very important and produces benefits for the biodiversity. In the total olive groves 15 insectivorous, six granivorous and three insectivorous/granivorous birds species were recorded. Nine bird species distinguished by Ward's hierarchical clustering were identified as typical (indicator value, IndVal&gt;50%) of specific farming systems. Among them, the Eurasian jay, associated with the 10-year certified organic olive groves, and the common cuckoo, Orphean warbler and Red-backed shrike, associated with the 6-year certified organic olive groves, should be regarded as characteristic species (IndVal&gt;70%). Conclusively, organic farming favors some aspects of diversity of herbaceous and woody plants of olive grove ecosystems. On the contrary, similar effects on breeding bird diversity and density were not clearly recorded. However, breeding bird density proved a good indicator of their richness.