19912015
  • Authors:
    • Shirtliffe, S. J.
    • Banniza, S.
    • Syrovy, L. D.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Field pea ( Pisum sativum L.) is an important organic crop due to its contribution to soil fertility and other rotational benefits. Leafed (wild-type) pea cultivars tend to be more weed suppressive, but their poor standing ability limits yield compared with semi-leafless cultivars. Growing mixtures of leafed and semi-leafless cultivars may improve weed suppression and yield compared with monocultures of the same cultivars by altering canopy morphology. To test this hypothesis, replicated field experiments were conducted under weedy, organic conditions in Saskatchewan, Canada, in 2011 and 2012. Mixtures of a leafed and semi-leafless cultivar, CDC Sonata and CDC Dakota, were sown in ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 leafed to semi-leafless pea, at target seeding rates of 88 and 132 plants m -2. Mixtures that included 50% or more semi-leafless pea had similar lodging resistance and weed biomass suppression to the agronomically superior semi-leafless cultivar grown alone. The strong competitive ability of the semi-leafless cultivar was unexpected based on previous accounts. The combined yield of the two cultivars grown in a 75% semi-leafless mixture exceeded the seed and biomass yield of either single cultivar by at least 18 and 12%, respectively. Yield enhancement was attributed to the leafed cultivar, whose seed yield increased by more than two and a half times in this mixture relative to its monoculture. Results suggest that breeding of leafed cultivars specifically for mixture with semi-leafless pea may be a future source of yield gains in organic and low-input systems.
  • Authors:
    • Congreves, K. A.
    • Eerd, L. L.
  • Source: Journal Article
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Vegetables are important horticultural commodities with high farm gate values and nutritional quality. For many vegetables, growers apply large amounts of N fertilizer (>200 kg N ha-1) to increase yield and profits, but such high N fertilizer applications can pose a significant threat for N loss and environmental contamination via denitrification, volatilization, leaching, runoff, and erosion. Nitrogen losses can reduce air and water quality by contributing to greenhouse gas emissions, ground-level ozone and particulate matter production, ground and surface water contamination, and eutrophication. The processes governing N loss include a complex of biological, physical, and chemical factors, which are impacted by management practices, climatic conditions and soil properties. Therefore, we reviewed and evaluated various management practices for minimizing N loss in N-intensive vegetable production within a temperate climate. Most soil nutrient management practices have focused on reducing N loss throughout the growing season, but the risk for N loss is very high after harvesting vegetables with low N harvest indices, low C:N ratios, and high quantities of N in crop residues, such as most Brassicaoleracea L. crops. Amending soil with organic C material may present a novel strategy for reducing N losses after harvest by 37 %, compared to the typical practice of incorporating N-rich vegetable crop residues. Research must focus on testing new and innovative methods of minimizing post-harvest N loss in intensive horticulture. © 2015 Springer Science+Business Media Dordrecht
  • Authors:
    • Margenot,A. J.
    • Calderón,F. J.
    • Bowles,T. M.
    • Parikh,S. J.
    • Jackson,L. E.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 3
  • Year: 2015
  • Summary: The objectives of this study were to examine soil organic matter (SOM) functional group composition and its relationship to labile SOM fractions with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). We analyzed soils from 13 organically managed tomato (Solatium lycopersicum) fields in northern California for labile organic C, N, and P fractions and by DRIFTS for bands representing organic functional groups, including aliphatic C-H (2924, 2850, 1470, 1405, 1390 cm-1), aromatic C=C (1650 cm-1) and C-H (920, 840 cm-1), polysaccharide and phenol C-O (1270, 1110, 1080 cm-1), and amine and amide N-H (3400, 1575 cm-1). Significant differences in relative band intensities occurred among the 13 organic tomato fields, in particular a relative increase in absorbance of bands representing aliphatic C-H positively associated with soil organic carbon (SOC), as well as permanganate-oxidizable carbon (POXC), extractable organic carbon (EOC) and nitrogen (EON), and potentially mineralizable N (PMN). In comparison, organic P fractions like sodium bicarbonate extractable (NaHCO3-P0) and sodium hydroxide extractable organic P (NaOH-P0) were poorly associated with SOC and functional groups represented by bands, including aliphatic C-H. This could reflect limitations of DRIFTS, but is consistent with hypotheses of greater decoupling of C and P vs. C and N in soils. This study implicates relative differences in organic functional groups with differences in SOC and labile SOM fractions, and in agreement with previous studies, identifies absorbance of infrared bands representing aliphatic C-H functional groups in these systems as a potential indicator of SOM transformations related to changes in its labile fractions. © Soil Science Society of America, 5585 Guilford Rd., Madison Wl 53711 USA.
  • Authors:
    • Miglierina,A. M.
    • Iglesias,J. O.
    • Laurent,G. C.
    • Rodriguez,R. A.
    • Ayastuy,M. E.
    • Lobartini,J. C.
  • Source: Acta Horticulturae
  • Volume: 1076
  • Issue: 1076
  • Year: 2015
  • Summary: The application of composted organic wastes to soil can be used for conserving soil organic matter, reclaiming degraded soils and supplying plants with nutrients. Two greenhouse experiments were carried out to evaluate the addition of compost on chemical and physical properties of soils. Four different texture soils were used: Sandy soil (S1), Silty loam soil (S2), Clay loam soil (S3) (33.2 O.C. g.kg -1) and Clay loam soil (S4) (14.8 O.C. g.kg -1) cultivated with lettuce ( Lactuca sativa L.) in the Bahia Blanca region, Argentina. The application of compost had a significant effect on lettuce productivity and nutrient uptake by the crop in three of the four soil types; showing a positive effect on the dry weight, number, length and width of the leaves. The applied dose (40 Mg ha -1) modified the chemical composition of the plants: those grown in soil with added compost showed higher concentrations of nutrients than those grown in control soils. In clay loam soil (S3) no difference were found in plant productivity between treatments with and without application of compost. With respect to soil properties changes, the application of compost affected the soil pH in variable way; increased organic carbon, total nitrogen and available phosphorus. The addition of compost lowered bulk density in soils S2 and S4; increased the percentage of macropores and mesopores in S2; diminished content of mesopores and increased content of micropores at S3 and S4. The variations on chemical and physical soil properties demonstrate the benefits of compost addition, even in a short period of time.
  • Authors:
    • Montemurro,Francesco
    • Tittarelli,Fabio
    • Lopedota,Ornella
    • Verrastro,Vincenzo
    • Diacono,Mariangela
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 2
  • Year: 2015
  • Summary: In organic farming, soil application of processed agro-industrial by-products could sustain soil fertility for vegetables, which have short cropping cycles. Therefore, the objectives of this 2-year research on organic spinach crop were to assess the productive performance of different experimental fertilizers, the effects on soil fertility, and investigate the dynamics of some soil properties and the N balance. Two types of olive pomace mixtures, with a different initial C/N ratio, were composted and both stopped at the active phase (A1 and B1) and processed until maturation (A2 and B2). Also an anaerobic digestate (DA), and the B2 applied as amendment (B2A) were studied. The four composts, DA, and B2A were compared with a commercial organic fertilizer (Org), and a control (N0). The Org resulted as not sustainable in maintaining soil fertility in the long-term, mainly due to reduction in the soil of total organic carbon by 32 %, compared to the average of the other treatments. Conversely, choosing stage of maturity and adequate C/N of starting mixtures was among the best practices for compost use in spinach crop. The great content of nutrients (N and K higher by 102 and 86 % than Org, respectively), and N surplus (1431 kg ha(-1)) in the B2A plots would suggest that they could accumulate after subsequent soil applications, with the risk of losses in the environment. The DA appeared to be the most suitable fertilizer to get a favorable trade-off among yield, quality and N-use efficiency, when applied according to best agronomic practices.
  • Authors:
    • Sanchez-Monedero,M. A.
    • Cayuela,M. L.
    • Roig,A.
  • Source: Acta Horticulturae
  • Volume: 1076
  • Issue: 1076
  • Year: 2015
  • Summary: The agricultural recycling of olive mill and winery wastes through composting and land application is reviewed in this manuscript in terms of the impact on greenhouse gas (GHG) emissions and the potential for soil C sequestration. The rich lignocellulosic composition and the low N availability of olive mill wastes have been revealed as the driving factors of the low degradation rate of these wastes during composting and after soil application. These peculiar characteristics minimise the emission of CH 4 and N 2O during composting and lead to an efficient and long-term C stabilisation when applied to the soil. These findings confirm the interest of the use of olive mill wastes in agriculture as a strategy to tackle the increasing CO 2 concentrations in the atmosphere, which is further supported by the well-known favourable agronomical properties of these wastes. The suitability of this strategy is also examined for winery wastes, which share some similar physicochemical characteristics with olive mill wastes. The agricultural use of these organic wastes could have important environmental benefits in Mediterranean agroecosystems.
  • Authors:
    • Cayambe,J.
    • Iglesias,A.
    • de Jalón,S. G.
    • Chuquillanqui,C.
    • Riga,P.
  • Source: ITEA
  • Volume: 111
  • Issue: 2
  • Year: 2015
  • Summary: The temperature rise of the planet associated with anthropogenic greenhouse gas emissions promotes interest for strategies to mitigate them. Since agriculture is a sector responsible for nearly a fifth of global emissions, it is necessary to identify measures to be applied, what is their mitigation potential and the estimated cost of implementing each measure. Our study addresses these questions by comparing the production of potato in two distinct production systems and with actual field data. In a first step, this paper calculates in a modern agricultural system the carbon footprint of mechanization and energy use for irrigation (located in Spain) and in less productive systems that integrate less technologies (located in Peru) . The results show that in the case studies in both countries the nitrogen cycle represents the primary source of greenhouse gas emissions, followed by energy fuel for irrigation and mechanization. Subsequently this study evaluates economically the mitigation actions through Marginal Abatement Cost Curves. These results demonstrate that the management of nitrogen fertilizer is the best alternative to reduce the carbon footprint because of their greater potential to reduce greenhouse gas emissions and their lower equivalent mitigation costs. Finally, the study provides a methodological framework that can be easily applied to other crops. © 2015, Asociacion Interprofesional para el Desarrollo Agrario. All rights reserved.
  • Authors:
    • Kibue,Grace Wanjiru
    • Pan,Genxing
    • Zheng,Jufeng
    • Li Zhengdong
    • Mao,Li
  • Source: Environment, Development and Sustainability
  • Volume: 17
  • Issue: 3
  • Year: 2015
  • Summary: Agricultural production is a complex interaction between human and natural environment, making agriculture both significantly responsible and vulnerable to climate change. China, whose socioeconomy is fundamentally dependent on agriculture, is already experiencing climate-change-related issues that threaten food security and sustainable development. Climate change mitigation and adaptation are of great concern to ensure food security for the growing population and improve the livelihoods of poor smallholder producers. A questionnaire survey was conducted in Henan Province, China to assess agronomic practices of smallholder farmers, adaptation strategies and how climate change awareness and perceptions influence the farmers' choice of agronomic practices. The results showed that the vast majority of farmers owned < 10 Chinese Mu (0.7 ha) and nearly all farmers' relied on intensive use of chemical fertilizers and pesticides to increase yield at the detriment of environment. However, farmers who were aware of climate change had adopted agronomic practices that reduce impacts of climate change. Information about climate change, lack of incentives, lack of credit facilities and small farm sizes were major hindrance to adaptation and adoption of farming practices that can reduce impacts of climate change. This study recommends that research findings should be disseminated to farmers in timely and appropriate ways. The central government should formulate policies to include subsidies and incentives for farmers to motivate adoption of eco-friendly agronomic practices.
  • Authors:
    • Michalsky,M.
    • Hooda,P. S.
  • Source: Environmental Science and Policy
  • Volume: 48
  • Year: 2015
  • Summary: Today considerable efforts are being made in identifying means of further energy efficiencies within the UK food system. Current air importation of fruit and vegetables (FVs) generates large amounts of greenhouse gas (GHG) emissions part of which could be avoided. Local food production has been recognized as an environmentally feasible alternative production option and could help reduce GHG emissions, as required under the legally binding emissions targets stipulated by the UK Climate Change Act 2008. Climate change impacts of FVs importation were determined for a selection of five indigenous FV commodities, namely: apples, cherries, strawberries, garlic and peas. Carbon dioxide equivalents (CO 2e) emissions associated with the production and transport stages were calculated using the sample of selected fruit and vegetables (SFVs). The latter stage includes three diverse geographic locations/regions for emissions comparison, namely the UK, Europe and non-European (NE) countries. On average (across the five SFVs), NE commodities, all in fresh/chilled state, were found to contain embedded (arising from production, air freighting and distribution within the UK) GHG emissions of 10.16 kg CO 2e/kg. This is 9.66 kg more CO 2e emissions compared to a kilogram of these commodities produced and supplied locally. A scenario-based approach determined the level of emissions savings that could be achieved by local FVs production in the UK. The least dramatic change of SCENARIO-1 (25% reduction in NE SFVs imports by increasing their local production by the same amount) could save 28.9 kt CO 2e/year, while SCENARIO-2 (50% reduction in NE SFVs imports) and SCENARIO-3 (75% reduction in NE SFVs imports) could result in saving of 57.8 kt and 86.7 kt, respectively.
  • Authors:
    • Oluwole,O. S. A.
  • Source: Climatic Change
  • Volume: 131
  • Issue: 2
  • Year: 2015
  • Summary: Konzo epidemics occur during droughts in East, Central, and Southern Africa, where the population depends almost exclusively on poorly processed cassava. Warm phases of El Nino-Southern Oscillation (ENSO) and Pacific decadal Oscillation (PDO) are associated with droughts in these areas of Africa, but with increase rainfall in South America. To further understanding of the relationship of droughts, cassava production, and konzo epidemics, this study was done to determine if there is coherence of spectra of ENSO, PDO and cassava production. Annual time series of cassava production in Tanzania and Brazil, multivariate ENSO index (MEI), and the Pacific Decadal Oscillation index (PDO) from 1961-2013 were compared. Wavelet and cross wavelet analyses of cassava production, ENSO, and PDO were performed. Warm phases of ENSO and PDO were associated with high cassava production in Tanzania, but with low cassava production in Brazil. Spectrogram of cassava showed significantly high production at periodicities of 3-9 years in Tanzania, but with significantly low production at periodicities of 2-6 years in Brazil. Cross wavelet spectrograms showed coherence of cassava production, ENSO and PDO in Tanzania and Brazil. Time-varying cyclical cassava production in Tanzania and Brazil are coupled to ENSO and PDO modes. Occurrence of droughts, high cassava production, and konzo epidemics in Tanzania are attributable to the impact of climate variability, which should be the focus of public health policies to control konzo epidemics.