Conventional Horticulture Research Articles

Reduced fertigation input sustains yield and physiological performance for improved economic returns and cleaner production of greenhouse eggplant

Greenhouse horticulture, a sustainable alternative to conventional horticulture, maximises resource use and return for vegetable production. This study evaluated the impact of varying nutrient solution electrical conductivity (EC) levels (EC 1.8, 2.8, and 3.8) on eggplant cultivars (Solanum melongena L. cv. Lydia, and Tracey) performance and economic viability in high-tech glasshouses. We found that morphological traits such as plant height and leaf number were consistent across EC levels, while fruit weight, length, and width are significantly higher at the lowest EC (1.8). Photosynthetic rates increased significantly with rising EC levels, while other gas exchange parameters such as stomatal conductance, intrinsic water use efficiency, and vapour pressure deficit were similar for all EC levels tested. Yield analysis revealed a negative correlation between eggplant yield and increasing EC levels, with optimal yields in both eggplant varieties (0.81 and 1.14 kg m−2 week−1 in Lydia and Tracey, respectively) achieved at the lowest EC. Economic analysis highlighted that lower EC levels lead to lower operational costs and higher net profit values (NPV). Sensitivity analysis underscored the importance of wholesale price and crop yield in determining NPV, with lower EC levels offering a shorter payback period of approximately 6 years in Australia and China and higher economic returns. The study highlights the significance of optimizing EC levels for achieving more resource-sustainable and profitable eggplant production in greenhouses.

The Analysis of Willingness to Accept and Willingness to Pay of Farmers and Consumers on Organic Horticultural Commodities Through Android Application-Based Digital Marketplace

Purpose: This study aims to analyze farmers' and consumers' willingness to accept and willingness to pay for organic horticultural commodities through an Android application-based digital marketplace. Theoretical Framework: Parameters in the economic assessment of natural resources and the environment involve how much individuals are willing to pay (WTP) and receive (WTA) Economic valuation methods for natural resources and the environment can be grouped into two types, namely the revealed preference approach and the stated preference approach The implied preference approach includes several techniques, such as the Travel Cost Method, Hedonic Pricing Method, and Averting Cost. On the other hand, the techniques included in the expressed preference approach involve the Contingent Valuation Method (CVM) and Conjoint Analysis. Method: This study was conducted in Semarang and Magelang Regencies, Central Java Province. The number of samples interviewed was 110 respondents spread across the two districts. The number of samples in each district was 55 respondents of producer farmers who are accustomed to growing organic horticulture and at the same time as consumers of organic horticulture. The analysis of users’ WTP and WTA of organic horticulture offered to the respondents. Results: The estimated Result of WTP Parameters of the characteristics of the product offered is one of the factors which can affect consumer willingness to pay (WTP). Consumer backgrounds such as income, number of family members, and education can also affect consumers' WTP of a product. In general, the determining factor for consumers’ WTP to be willing to pay more for organic horticulture through a digital marketplace compared to conventional horticulture is better quality. Conclusions: Consumer preference for organic horticulture is positive because the quality and taste are better than horticulture that has been planted before. Organic horticulture has the opportunity to create a market due to the positive response of producers and consumers as indicated by the WTA and WTP.

A comparative analysis of organic and conventional horticultural farming in the Getasan District, Semarang Indonesia

The organic horticultural farming system is a horticultural farming technique that relies on natural materials in its production and is a sustainable agriculture, in contrast to the conventional horticultural farming system which still relies on chemicals in its production process. The purpose of this research was to compare organic and conventional horticultural farming systems in Getasan district, Semarang. This study is a cross-sectional descriptive-analytical study that employed survey methodologies. This study was conducted from July to December 2019 using a sample of 314 respondents, 90 organic horticulture farmers and 224 conventional horticulture farmers as research subjects. Research results showed that the average total additional cost of restoring soil nutrients in 100 m2 / year for organic horticulture farming was IDR. 69,958.33 less than the cost for conventional farming systems, which was IDR. 79,550.00 per 100 m2 per year, with a p-value of 0.032*. The cost of purchasing fertilizer in year / 100m2 on a conventional horticultural farm was IDR. 90,575.78, greater than the cost of organic horticulture farming which was only IDR. 73,170.38 with a p-value< 0,001*. The average yield of organic horticulture farms was somewhat higher than that of conventional farms during each growing season. The average annual income from yields in 100 m2/year for organic horticulture production was IDR 2,449,246.32, while conventional IDR. 2,369,641.10 with p-value of 0.441 although not statistically significant. The average profit per 100 m2 / year for an organic horticultural farming system was IRD. 1,549,303.42, which is greater than the profit value for a conventional horticultural farming system, which was IDR. 1,450,109.82, 959,289.06, although statistically not significant, with p-value = 0.228. The total annual production cost for the organic horticulture farming system was less than the conventional system, which was IDR 901,346.78 for the organic horticulture farming system and IDR. 921,084.17 for conventional, for every 100 m2 / year with p-value = 0.383, even though not statistically significant. Statistically, there was no significant difference in labor costs between the two agricultural systems, p-value 0.702, but descriptive analysis shows that the average labor cost per 100 m2/year for organic horticulture farming was IDR. 588,859.57, which is less than IDR. 591,760.50 for conventional horticulture farming. Based on the parameters analyzed, the outcome of this study demonstrates that the organic horticulture farming system is superior to the conventional horticultural farming system. Key words: Environmental value Fertilization costs, Cultivation profits, Labor expenses, Production costs

Shifts from conventional horticulture to agroecology impacts soil fungal diversity in Central Argentina

Shifts from conventional horticulture to agroecology impacts soil fungal diversity in Central Argentina

Nemo’s Garden- the world’s first-and onlysubterranean greenhouse (A review article)

The determinant factor of agricultural productivity is the Climate and any changes will affect and become challenging for agriculture. And the predominant causal factor for climate change is the emission of greenhouse gases into the atmosphere, mainly due to anthropological activities such as deforestation for conventional cultivation. As a result, it has become clearer by the day that there is a need to reform our food system from a conventional to a sustainable one. The Nemo’s Garden, off the coast of Noli, Italy is a unique and futuristic underwater hydroponic farm for the cultivation of terrestrial crops which may provide an alternative eco-friendly and sustainable system to conventional horticulture, contribute to sustainable food production, with a positive effect on the surrounding environment. By harnessing the ocean’s environmental benefits-temperature stability, evaporative water generation, CO2 absorption, abundant oxygen, and pest protection—they aim to prove the viability of cultivating herbs, fruit, and vegetables underwater. The culinary herb basilwas initially taken as a model plant and is well adapted in the biosphere environment, but now other crops like strawberries, tomatoes, courgettes, beans, mushrooms, lettuce, stevia, aloe vera, orchids, etc are being successfully grown in the biospheres. The project is under research and pharmaceutical companies are willing to explore this alternative solution for growing plants and to reveal interesting discoveries for the future.

An assessment of urban horticultural soil quality in the United Kingdom and its contribution to carbon storage.

As participation in urban horticulture grows, understanding the quality of urban horticultural soils is of increasing importance. Until now, case studies of individual cities or gardens have limited the potential of such studies to draw generalised conclusions. Here, we present the first national scale assessment of soil quality in allotments, a dominant form of urban horticulture in the United Kingdom. We sampled soils in 200 allotments in 10 urban areas across Great Britain. We assessed a range of soil quality indicators (carbon and nitrogen concentration, C:N ratio, bulk density, carbon density, pH) comparing them to the quality of soils in rural arable and horticultural land. We present the first estimate of nationwide carbon storage on allotments. We found that allotment gardeners consistently employ management practices conducive to high soil quality. Allotment soil quality differed significantly between soil types but in general soils were of a high quality: low bulk density (0.92gcm-3) and high soil organic carbon concentration and density (58.2mgg-1 and 58.1mgcm-3 respectively). Allotment soil organic carbon concentration was 250% higher than in the surrounding arable and horticultural land. Covering only 0.0006% of Great Britain, allotments contribute a disproportionate 0.05-0.14% of nationwide total organic carbon stocks. This national-scale study provides compelling evidence that small-scale urban horticultural production, unlike conventional horticulture, does not degrade soil quality. Indeed, allotments hold a small but previously unaccounted for carbon stock nationally. Urban horticultural land is a vital part of the urban landscape with effectively functioning soils that should be protected. As public demand for urban horticultural land rises and policy-makers from local to trans-national levels of governance advocate for urban food production, our findings demonstrate that urban horticulture can protect or enhance the ecosystem services provided by soils in cities and towns where the majority of people live.

Diversity and plant growth-promoting functions of diazotrophic/N-scavenging bacteria isolated from the soils and rhizospheres of two species of Solanum

Studies of the interactions between plants and their microbiome have been conducted worldwide in the search for growth-promoting representative strains for use as biological inputs for agriculture, aiming to achieve more sustainable agriculture practices. With a focus on the isolation of plant growth-promoting (PGP) bacteria with ability to alleviate N stress, representative strains that were found at population densities greater than 104 cells g-1 and that could grow in N-free semisolid media were isolated from soils under different management conditions and from the roots of tomato (Solanum lycopersicum) and lulo (Solanum quitoense) plants that were grown in those soils. A total of 101 bacterial strains were obtained, after which they were phylogenetically categorized and characterized for their basic PGP mechanisms. All strains belonged to the Proteobacteria phylum in the classes Alphaproteobacteria (61% of isolates), Betaproteobacteria (19% of isolates) and Gammaproteobacteria (20% of isolates), with distribution encompassing nine genera, with the predominant genus being Rhizobium (58.4% of isolates). Strains isolated from conventional horticulture (CH) soil composed three bacterial genera, suggesting a lower diversity for the diazotrophs/N scavenger bacterial community than that observed for soils under organic management (ORG) or secondary forest coverture (SF). Conversely, diazotrophs/N scavenger strains from tomato plants grown in CH soil comprised a higher number of bacterial genera than did strains isolated from tomato plants grown in ORG or SF soils. Furthermore, strains isolated from tomato were phylogenetically more diverse than those from lulo. BOX-PCR fingerprinting of all strains revealed a high genetic diversity for several clonal representatives (four Rhizobium species and one Pseudomonas species). Considering the potential PGP mechanisms, 49 strains (48.5% of the total) produced IAA (2.96-193.97 μg IAA mg protein-1), 72 strains (71.3%) solubilized FePO4 (0.40-56.00 mg l-1), 44 strains (43.5%) solubilized AlPO4 (0.62-17.05 mg l-1), and 44 strains produced siderophores (1.06-3.23). Further, 91 isolates (90.1% of total) showed at least one PGP trait, and 68 isolates (67.3%) showed multiple PGP traits. Greenhouse trials using the bacterial collection to inoculate tomato or lulo plants revealed increases in plant biomass (roots, shoots or both plant tissues) elicited by 65 strains (54.5% of the bacterial collection), of which 36 were obtained from the tomato rhizosphere, 15 were obtained from the lulo rhizosphere, and 14 originated from samples of soil that lacked plants. In addition, 18 strains showed positive inoculation effects on both Solanum species, of which 12 were classified as Rhizobium spp. by partial 16S rRNA gene sequencing. Overall, the strategy adopted allowed us to identify the variability in the composition of culturable diazotroph/N-scavenger representatives from soils under different management conditions by using two Solanum species as trap plants. The present results suggest the ability of tomato and lulo plants to enrich their belowground microbiomes with rhizobia representatives and the potential of selected rhizobial strains to promote the growth of Solanum crops under limiting N supply.

Effects of Permaculture Practices on Soil Physicochemical Properties and Organic Matter Distribution in Aggregates: A Case Study of the Bec-Hellouin Farm (France)

The limitations of conventional agriculture have accelerated the need for a transition to an environmentally and economically sustainable agricultural model. In this regard, the role played by soil organic matter (SOM) is key. Here, we aimed to study the impact of permaculture and biointensive micro-gardening practices, characterized by intensive cultivation, the use of large and localized organic inputs and the non-use of mineral fertilizers and pesticides, on soil physico-chemical properties and SOM distribution in aggregate-size fractions. The physico-chemical properties of soils in permaculture farming implemented for seven years were compared with a soil under pasture. A soil experiencing conventional agriculture practices in similar geopedoclimatic conditions was simultaneously studied. Soils were separated into four aggregate-size fractions, into which organic carbon (OC) concentrations have been measured. The major soil physico-chemical properties were measured on the bulk soils. The concentrations of total OC and nitrogen (N) in bulk soils were higher under permaculture practices, due to significant inputs of manure and compost, resulting in higher concentrations of the bioavailable nutrients Ca, Mg, K and P. The permaculture practices sustained a level of macroaggregation similar to that of the pasture, and well above that of conventional practices. OC concentrations increased in the 250-2000 µm, 50-250 µm and occluded 50-250 µm fractions, but not in the <50 µm fraction compared to pasture. This can be explained by the too short duration of permaculture practices for allowing the decomposition of coarse particulate organic matter (POM) into fine sized SOM that is more associated with mineral particles in free clay and silt size fraction. The higher OC stocks in permaculture are therefore mainly governed by the coarse POM fraction. Our results show that permaculture/biointensive micro-gardening practices enhance SOM storage and modify the distribution of SOM in aggregate size fractions, while substantially improving nutrient bioavailability and suggests that permaculture practices strongly affect soil properties. The effects of permaculture practices on soil properties would certainly vary depending on geopedoclimatic context, justifying the need to implement the approach for other soil types. Finally, we recommend to compare biogeochemical budget and nutrients use efficiency of permaculture gardening with conventional horticulture gardening.

Predictors for interest to change from conventional to organic horticultural production

This study addressed factors influencing farmers’ decisions to switch from conventional to organic farming with special focus on outdoor horticulture production. A total of 343 horticulture producers responded to a survey conducted in 2014. The results indicate 12.1% of the farmers with conventional horticulture production were interested in converting to organic. Small farm size, horticulture being only a minor part of the enterprise, intermediate estimated yields, greater intent to grow new crops, hiring labor, having other income sources in addition to agriculture and participating in training courses emerged as significant predictors for the intention to switch to organic production in multivariable regression modeling. These results suggest potential to increase organic production could be found particularly among smaller part-time enterprises actively seeking new crops and knowledge.

Environmental and resource use analysis of plant factories with energy technology options: A case study in Japan

Abstract A comprehensive analysis of multiple aspects of food production is needed to address related concerns, such as the use of nitrogen, phosphorus, and potassium fertilizers, the consumption of water, the occupation or transformation of land, and greenhouse gas emissions. We examine the environmental properties of plant factories with sunlight and plant factories with artificial light, comparing them with conventional Japanese horticulture systems. Process conditions and inventory data were extracted from demonstration factories in Chiba, Japan. We found that these plant factories reduced the use of irreplaceable resources for food production, i.e., phosphorus, water, and land area, at the expense of additional energy consumption compared with conventional Japanese horticulture systems. By employing emerging energy technology options, energy consumption can be reduced sufficiently to be competitive with that of conventional horticulture systems. The results indicate that plant factories could become a viable or competitive production technology, changing the slope factors in the nexus of food, energy, and water systems.

Lower average yields but similar yield variability in organic versus conventional horticulture. A meta-analysis

Organic agriculture prohibits the use of almost all synthetic inputs and it is expected to have lower impacts on natural resources than conventional agriculture. However, previous meta-analyses have shown that yields in organic systems are in average 8 to 25% lower compared with conventional systems. Here, we focus on horticulture (fruits and vegetables) and we refine our knowledge by characterising the distributions of organic and conventional yields both in terms of average yield loss and in terms of variability across experiments and across years. We built a new dataset including 636 ratios of organic versus conventional yields covering 37 horticultural species and 17 countries and estimated (i) mean yield ratios, (ii) yield ratio probability distribution across experiments and (iii) interannual yield variances in organic and conventional systems. Our results show that yields in organic horticulture are indeed on average 10 to 32% lower than those in conventional horticulture but they exhibit large variation across experiments. An analysis of yield ratio probability distribution shows that yield loss in organic horticulture has about 10% chances to exceed 50% compared to conventional systems. The analysis gives also around 20% chances to get higher yields in organic horticulture compared to conventional systems. None of the tested covariates (e.g. crop type, climate zone) was able to explain a significant part of the yield ratio variability. We find no evidence of a larger interannual variability (i.e. lower yield stability) in organic versus conventional horticulture. Longer-term trials could nonetheless help substantiate this result. Our results support also the needs to conduct new experiments in countries from the Southern Hemisphere and to collect standard data on crop management and environmental characteristics.

Conservation Horticulture in Mango Orchards: Comparative Effects of Conventional and Conservation Management Practices on Soil Properties of an Alfisol under Seasonally Dry Tropical Savanna Climate

&lt;p&gt;Conservation horticulture is a new concept in management of soil health under perennial horticultural cropping systems. Experiments conducted reasonably over a long period on such soil management systems provide valuable information about sustainability of production systems. This paper reports the results of comprehensive investigations on soil chemical, physical, biochemical and biological properties of soils under conventional and conservation horticulture practices over a long period in drylnd mango orchards on Alfisols. Effects of conservation tillage, inter cropping and cover cropping on soil carbon fractions was measured by determination of loss on ignition, organic carbon (OC) and active carbon (AC). Soil biochemical properties were evaluated by measuring glomalin and extracellular enzymatic activities viz., dehydrogenase, urease, phosphomonoestrase and arylsulphatase and measurement of soil microbial biomass carbon (MBC) and carbon mineralization. Biological status was evaluated by estimating bacterial, actinobacterial and fungal populations, earthworms, micro arthropods and centipedes. Soil physical status was assessed by measuring bulk density, soil moisture status and infiltration rates.&lt;/p&gt;&lt;p&gt;Conservation horticultural practices improved the quality of soil, especially near the surface, by lowering the bulk density and enhancing infiltration rate. The soil aggregate formation and water stability have enhanced in plots with conservation practices because of higher production of glomalin compared with vegetable and orchard plots where conventional practices were followed. Relationship between measured infiltration and soil properties showed high average IRs in conservation plots due to high organic matter content, low bulk density values and enhanced exchangeable basic cations. Vegetable plots and conventional mango plots showed complete decline in earthworm and centipede population while plots with conservation practices showed a build-up of their population. Microbial and biochemical properties significantly improved in plots with conservation horticultural practices over orchard plots with conventional practices. Legumes as inter and cover crops were found to be superior in improving soil quality than sweet potato.&lt;/p&gt;

Economic and Environmental Performances of Organic Farming System Compared to Conventional Farming System: A Case Farm Model to Simulate the Horticultural Sector of the Niayes Region in Senegal

Horticultural production is an increasingly important activity in Senegal that is mainly located in the Niayes region between Dakar and St Louis. However, the increasing use of pesticides and inorganic fertilizers has many implications for the environment. The recognition that conventional horticulture might have a negative impact on farmers and consumers health, and on the atmosphere through the emission of GHGs, has increased in recent years, leading some NGO’s to promote organic farming. Therefore, the rising level of environmental hazards from conventional farming system made it attractive to farmers in the Niayes to adopt sustainable agriculture practices based on organic farming. A whole farm model is used to compare the economic and environmental performances of the organic and conventional horticultural farming systems in the Niayes region in Senegal. The gross margin is regarded as the economic indicator, while carbon emissions are regarded as environmental indicators. The results indicate that the conventional farming system is still more attractive than the organic farming because the sale price is the same for both systems. There is no market for organic food in the region. Simulation results also reveal that there exists a “win-win” situation for conventional farmers when they partially adopt organic farmingsystem. However, environmental results in terms of carbon emissions reduction suggest that the organic system is more effective in mitigating climate change. Our study suggests that, through appropriate investment in agro-ecological research to improve organic management and the establishment of a local market for organic crops, organic farming can become a competitive alternative to conventional farming, when it comes to healthy food production with less environmental impact in the horticultural sector. However, further studies are needed on components of sustainable intensification to see which system of production is more profitable for farmers of the Niayes region, but also beneficial for the environment, and at regional and even national levels.

Organic and conventional horticulture: are there significant ergonomic differences?

The objective of this research study was to explore possible differences, in terms of ergonomics, between conventional and organic horticulture, from the analysis of real work situations. The Ergonomic Work Analysis method was applied to four horticultural farms in Brazil, from which two of them were devoted to organic production, while the other two were associated to conventional products. The main results showed that the work systems were practically the same, differing in tasks fulfillment frequency and intensity. The workers associated to the organic horticulture experience a sense of job security which impacts favorably in the global balance of work activities. Conventional horticulture is more standardized; exhibiting more stabilized tasks, whereas the organic production was noted to be in constant experimentation. The work was found to be more complex in organic farms, needing more frequent monitoring and control; also, communication and information exchange were noted to be more intense, requiring continuous learning. Despite the fact that the physical workload was similar, there are important differences between the work in organic and conventional horticulture practices related to the fields of cognition and emotional interaction with the work.

Comparison of Management Styles in Organic and Conventional Farming with Respect to Disruptive External Influences. The Case of Organic Dairy Farming and Conventional Horticulture in the Netherlands

Conventional Dutch farming systems are constantly improving their technology to withstand disruptive external influences, while organic farming tends to focus on methods that stress conservation of natural and nonrenewable resources. We hypothesize that management styles to withstand disruptive external influences clearly differ in both systems. Conventional farming aims to protect crops and livestock with hands-on solutions, whereas organic farming aims at reducing the consequences of disruptions. To study these two extremes, we compared a conventional horticultural system with an organic dairy system and interviewed the entrepreneurs about their decision-making strategies, dilemmas, and tradeoffs when dealing with undesirable events. To our surprise, all entrepreneurs used a similar set of interventions aimed at maximizing income and minimizing costs. We also discovered that all entrepreneurs tended to aim at both homogeneity and heterogeneity dependent on the level: all aimed for a uniform output of their whole system, while utilizing the genetically defined diversity between individual plants or animals. Based on previous experiences, farmers rely on natural compensation for losses within their system: heterogeneity within their system provides flexibility to accept uncertainty within a certain range. Therefore, we conclude that the societal discrimination between management styles does not represent well-defined differences between conventional and organic farming.

Assessment of soil microbial diversity measurements as indicators of soil functioning in organic and conventional horticulture systems

Soil quality assessment is necessary to detect changes on soil properties among different management practices. Some microbial properties could be useful to predict changes in soil providing an integrated and relevant vision of soil functioning. The aim of this work was to evaluate and compare different methods to assess microbial diversity, such as methyl ester fatty acids (PLFA) and catabolic response profiles (CRP) to act as indicators of soil functioning. The study was carried out in an intensive horticulture production system. Undisturbed soil, 5 years plots, and more than 20 years plots under organic and conventional production were studied. Principal component analysis followed by multivariate discriminate analysis showed that d-glucose, d-glucosamine, α-ketobutyric, α-ketoglutaric and uric acids were the substrates with the highest sensitivity to separate situations. The same analysis was performed for PLFA, showing that C18:1w9, C13:0, C16:1w9, C14:0, i15:0 and cy19:0 methyl ester fatty acids were the most sensitive. Multivariate analysis of variance of selected substrates and fatty acids showed that CRP and PLFA techniques were both capable to characterize the studied systems. Saturated/monounsaturated (S/M), iso/anteiso (i/a) and cyclopropyl/precursors (cy/pre) microbial stress indicators were higher in plots under conventional management, presenting also these situations the lowest microbial biomass and fungi/bacteria ratio (F/B), especially in plots under conventional management for more than 20 years. Microbial functional diversity, calculated as evenness ( E) from CRP was capable to distinguish between all situations and management systems showing the potential of this measurement to act as an integrative indicator of soil functioning.

O processo de conversão de sistemas de produção de hortaliças convencionais para orgânicos

Este artigo analisa o processo de conversão para a olericultura orgânica por meio de estudos de caso junto a agricultores com comercialização em supermercados ou feiras específicas, constatando que o Estado sempre esteve à margem do processo de difusão da agricultura orgânica, determinando o estabelecimento de uma cultura de "independência" por parte desse setor produtivo. Pelo fato de a produção de hortaliças exigir um contato constante com o mercado e o processo de inovação tecnológica, há uma baixa demanda de apoio por parte pelos agricultores, independentemente do estrato socioeconômico. O artigo mostra também que ações públicas destinadas a promover a conversão para sistemas orgânicos têm maior receptividade junto a produtores familiares, em função da maior exigência por mão-de-obra na agricultura orgânica em relação à convencional, resultando em maiores custos monetários para os que recorrem à mão-de-obra contratada.

Undersowing Legume Crops for Green Manuring of Lettuce

ABSTRACT The objective of this experiment was to investigate the potential of several species of undersown legume crops to deplete soil nitrate and to accumulate nitrogen (N). A further objective was to measure the effects of the legume crops as a green manure for a succeeding early lettuce crop. In two years, different undersown legume crops were compared with a control treatment where no crop was undersown. In November, at the end of their growing season, the legume crops reduced the content of mineral nitrogen in the top 1 m of the soil to one third of what was available when no crop was undersown. The N uptake in shoots and roots was in the range of 100–160 kg ha−1. The legume crops were incorporated at the beginning of April the succeeding year. In May, the content of soil mineral nitrogen was 3–4 fold the content in November. The main increase was seen in the top 0.25 m profile of the soils in which the legume crops had been grown. In July, the N mineralized from the incorporated legume crops and from other soil organic matter was estimated to be 36 and 38 kg ha−1, respectively. The yield of lettuce was increased by 20–45% when grown after legume green manure crops compared with the control treatment. The yield level was comparable to that obtained in conventional horticulture.

An Examination of the Economics of Sustainable and Conventional Horticulture

Since World War II, U.S. agriculture has reduced production costs by substituting petrochemicals for labor. Adverse impacts from chemical intensive agriculture include increased pest levels, groundwater and surface water contamination, soil erosion, and concerns about harmful levels of pesticide residues. Sustainable farming programs such as integrated crop management (ICM) and organic farming encourage farmers to use systems that reduce the adverse impacts of chemical agriculture. However, before farmers adopt an alternative system, they must determine that economic benefits from the alternative farming activities exceed the costs incurred. Unfortunately, relatively few studies have compared the cost of organic crop production with conventional production systems. Results of these studies are mixed. In some studies, organic systems are more profitable than conventional systems with organic price premiums, but are not economically viable without price premiums. In one long-term study, the organic system was more profitable than a conventional one if the cost of family labor was ignored, but less profitable if it was included. In some studies, net returns were higher for ICM than for conventional or organic systems, but in others, they were higher. Results also vary on a crop by crop basis.

AN INTRODUCTION TO MARINE HORTICULTURE

We can think of marine horticulture as the production of specialty crops just as in conventional horticulture. Certain marine algae provide foods and have been cultivated for centuries. Ornamental marine plants find their way into the recreational and display aquarium market. Some are now used for landscaping. There is a large market in the U.S. for marine plants needed for environmental technologies. Marine botanists use a number of horticultural and biotechnological methods to provide steady supplies of these plants. Marine plant germplasm may also find future use in U.S. agronomy and horticulture. This paper will review these current uses and possible future applications of marine plants in horticulture.