• Authors:
    • Zhang, X. X.
    • Hu, X. B.
    • Zhang, G. S.
    • Li, J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 145
  • Year: 2015
  • Summary: Plastic mulch is widely used for vegetable cropping in the mid-Yunnan plateau, southwestern China. However, the effects of plastic mulch on soil physical properties are poorly understood. A field experiment was conducted to evaluate the effects of different plastic mulch patterns (narrow and wide plastic mulch) and rotations (broccoli-zucchini-winter wheat and broccoli-zucchini-fallow) on soil physical properties and soil organic carbon content in a vegetable production system at a research station in the region. The experiment comprised four treatments and laid out in the field using randomized complete block design replicated nine times. The soil (0-20cm) under wide plastic mulch retained more water than the soil narrow plastic mulch under the vegetable growing season over 3 consecutive severe drought years. Significant decline (11%) of surface soil (0-5cm) organic carbon was observed in 2012 compared with in 2010, but soil organic carbon and physical properties did not differ significantly between the two different plastic mulch patterns. The higher macro-porosity, aggregate stability, Ksat and lower bulk density in the plastic mulched ridges imply that the conversion from narrow-plastic-mulch to wide-plastic-mulch increases mulched area thereby conserving larger area soil structure in the croplands. Although increased catch crop stubble retention in the furrows apparently improved surface soil macro-porosity and saturated hydraulic conductivity, the autumn rotary cultivation in broccoli-zucchini-winter wheat rotation system has significantly decreased (5%) surface soil organic carbon. The results suggested that continued use of vegetable-cereal crop rotation system, even with stubble retention, may result in loss soil organic carbon. Further research that covers wetter years should be taken to assess effects of vegetable-cereal crop rotation pattern on soil physical properties in this region.
  • Authors:
    • Verger, E. O.
    • Martin, A.
    • Rehm, C. D.
    • Drewnowski, A.
    • Voinnesson, M.
    • Imbert, P.
  • Source: AMERICAN JOURNAL OF CLINICAL NUTRITION
  • Volume: 101
  • Issue: 1
  • Year: 2015
  • Summary: Background: A carbon footprint is the sum of greenhouse gas emissions (GHGEs) associated with food production, processing, transporting, and retailing. Objective: We examined the relation between the energy and nutrient content of foods and associated GHGEs as expressed as g CO 2 equivalents. Design: GHGE values, which were calculated and provided by a French supermarket chain, were merged with the Composition Nutritionnelle des Aliments (French food-composition table) nutrient-composition data for 483 foods and beverages from the French Agency for Food, Environmental and Occupational Health and Safety. Foods were aggregated into 34 food categories and 5 major food groups as follows: meat and meat products, milk and dairy products, frozen and processed fruit and vegetables, grains, and sweets. Energy density was expressed as kcal/100 g. Nutrient density was determined by using 2 alternative nutrient-density scores, each based on the sum of the percentage of daily values for 6 or 15 nutrients, respectively. The energy and nutrient densities of foods were linked to log-transformed GHGE values expressed per 100 g or 100 kcal. Results: Grains and sweets had lowest GHGEs (per 100 g and 100 kcal) but had high energy density and a low nutrient content. The more-nutrient-dense animal products, including meat and dairy, had higher GHGE values per 100 g but much lower values per 100 kcal. In general, a higher nutrient density of foods was associated with higher GHGEs per 100 kcal, although the slopes of fitted lines varied for meat and dairy compared with fats and sweets. Conclusions: Considerations of the environmental impact of foods need to be linked to concerns about nutrient density and health. The point at which the higher carbon footprint of some nutrient-dense foods is offset by their higher nutritional value is a priority area for additional research.
  • Authors:
    • Fan, M.
    • Zhang, F.
    • Yan, Y.
    • Six, J.
    • Lee, J.
    • Cao, J.
  • Source: European Journal of Soil Biology
  • Volume: 68
  • Year: 2015
  • Summary: In China, considerable cropland previously under grain production has been rapidly converted to greenhouse vegetable production by farmers since 1980s. Vegetable crops generally require higher nitrogen (N) inputs from manure amendments and more frequent tillage and irrigation operations compared to grain crops. Here, we compared potential denitrification-derived N2O emissions across the soil profile (0-90cm depth) between grain and greenhouse vegetable fields. Denitrification enzyme activity (DEA) was assessed in the top 0-15cm soil layer. Soil samples from five wheat (Triticum aestivum L.) - maize (Zea mays L.) fields, paired with adjacent vegetable greenhouse fields, were collected across typical vegetable production regions. Conversion from the grain fields to the greenhouse vegetable fields led to greater potential denitrification-derived N2O emissions in the 0-15 and 15-30cm depths, respectively, with 4 and 3 times higher cumulative emissions over the 10-day incubation. Continuous manure amendments and chemical N input increased water extractable organic carbon and nitrate concentrations, which significantly enhanced potential denitrification-derived N2O production in the 0-30cm soil depth of vegetable crop fields. The differences in microbial community for the two cropping systems did not seem to affect the surface N2O production potential since denitrification enzyme activity were not significantly different between the two production systems. There was a small to negligible potential N2O flux in 30-90cm soil depths for both production systems because of limited carbon availability and microbial activity. Managing surface labile carbon and mineral N pool may be critical in reducing regional N2O emissions in China's greenhouse vegetable production systems.
  • Authors:
    • Sorensen, P.
    • Petersen, S. O.
    • Li, X. X.
    • Olesen, J. E.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: Legume-based catch crops (LBCCs) may act as an important source of nitrogen (N) in organic crop rotations because of biological N fixation. However, the potential risk of high nitrous oxide (N 2O) emissions needs to be taken into account when including LBCCs in crop rotations. Here, we report the results from a one-year field experiment, which investigated N availability and N 2O emissions as affected by three LBCCs, i.e., red clover (CL), red clover-ryegrass mixture (GC) and winter vetch (WV), two non-LBCCs, i.e., perennial ryegrass (GR) and fodder radish (FR), and a control (CO) without catch crops. The effect of two catch crop management strategies was also tested: autumn harvest of the catch crop versus incorporation of whole-crop residues by spring ploughing. LBCCs accumulated 59-67 kg N ha -1 in their tops, significantly more than those of the non-LBCC, 32-40 kg N ha -1. Macro-roots accounted for >33% of total N in the catch crops. In accordance with this, LBCCs enhanced the performance of the succeeding unfertilised spring barley, thus obtaining a grain yield of 3.3-4.5 Mg ha -1 compared to 2.6-3.3 Mg ha -1 grain yield from non-LBCC and the fallow control treatments. Autumn harvest of catch crops, especially LBCCs, tended to reduce crop yield. The annual N 2O emissions were comparable across treatments except for fodder radish, which had the highest N 2O emission, and also the highest average yield-scaled N 2O emission, at 499 g N 2O-N Mg -1 grain. Although the sampling strategy employed in this study introduces uncertainty about the spatial and temporal variability, differences in seasonal emission patterns among catch crops were captured and harvest of catch crops in late autumn induced significantly higher emissions during winter, but lower emissions after residue incorporation in spring. In comparison with non-LBCC, LBCCs have the potential to partly replace the effect of manure application in organic cropping systems with greater crop production and less environmental footprint with respect to N 2O emissions. However, harvest of the catch crops may reduce crop yield unless the harvested N is recycled as fertiliser to the crops in the rotation.
  • Authors:
    • Tenhunen, J.
    • Huwe, B.
    • Kwon, H. J.
    • Arnhold, S.
    • Xue, W.
    • Lee, B.
    • Otieno, D.
    • Lindner, S.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: The Asian agricultural landscape, which accounts for approximately 12.6% of the world's agricultural land, is highly heterogeneous due to the multicultural cropping system. Information regarding CO 2 exchange and carbon (C) balance of these agro-ecosystems is scarce, even though they are likely to immensely contribute to the global C budget. Net Ecosystem CO 2 Exchange (NEE) and Ecosystem respiration ( Reco) were measured between 2009 and 2010 on 5 dominant crops (potato, rice, radish, cabbage and bean) in the Haean catchment of South Korea, using a closed chamber system to quantify CO 2 fluxes in this agricultural landscape characteristic of the Asian cropping system. Parallel measurements were conducted on leaf area index (LAI), plant biomass and climatic variables, mainly photosynthetic active radiation (PAR), air temperature, soil temperature and soil moisture. Biomass and LAI development differed among the crops likely as a result of differences in light use efficiencies (alpha) and carbon allocation patterns. The peak total biomass for radish, cabbage, potato, rice and bean were 0.530.07, 0.550.12, 1.850.51, 2.540.35 and 1.010.26 kg m -2, respectively, while the respective maximum LAI were 2.8, 3.7, 6.4, 6.3 and 6.7 m 2 m -2. Variations in seasonal patterns, magnitudes and the timing of maximum NEE and gross primary production (GPP) among the crops were likely the result of differences in LAI and alpha. The lowest peak Reco rate was 3.80.5 mol m -2 s -1, measured on rice paddies while the highest was 34.44.3 mol m -2 s -1 measured on the cabbage fields. The maximum NEE rates were -29.40.4 and -38.76.6 mol m -2 s -1, measured in potato and cabbage fields, respectively. Peak GPP rates in potato and cabbage fields were 39.50.6 and 63.07.2 mol m -2 s -1, respectively. PAR explained more than 90% of the diurnal variations in GPP, while LAI and α determined the seasonal trends of maximum GPP. The timing of maximum CO 2 assimilation (GPP Max) differed among the crops, thus, even though maximum CO 2 uptake in the respective crops only lasted a couple of weeks, the effect of the staggered peak GPP resulted in extended period of high CO 2 uptake. These differences among crops were significant, hence, modeling approaches need to consider the heterogeneity in ecosystem CO 2 exchange associated with these multicultural agriculture landscapes.
  • Authors:
    • Li, Y. F.
    • Wang, Y.
    • Zheng, C. Y.
    • Zhang, G.
    • Xin, Y.
  • Source: ACTA AGRICULTURAE SCANDINAVICA SECTION B-SOIL AND PLANT SCIENCE
  • Volume: 65
  • Issue: 4
  • Year: 2015
  • Summary: Soil organic carbon plays an important role in soil fertility and carbon sequestration. In the North China Plain, soil nutrients and organic carbon are still lacking in salt-affected soil after a successfully reclamation in the 1980 s. Our objectives were to investigate the effects of land use types under different soil management practices on soil fertility, organic carbon pools, and the microbial community at this site. Three land use types were investigated: original land without farming, farmland with residue return, and a vegetable greenhouse with farmyard manure amendment. The carbon stocks were calculated according to the equivalent soil mass method, and microbial community structure was determined by phospholipid fatty acid analysis. Over 30 years, the current concentrations of alkali-hydrolysis nitrogen, available potassium (AK), and available phosphorus increased in the three land use types, except for the AK concentration in farmland, which decreased due to the lack of potassium fertilizer input. The nutrients in the greenhouse were significantly higher than those in the original land and farmland. The carbon stocks in the original land, farmland, and greenhouse were increased by 103%, 179%, and 660%, respectively. Both land use types and seasons influenced particulate organic carbon, chemical-labile organic carbon, and microbial biomass carbon. The microbial community structures were distinctly different between the three land use types. Overall, the soil available nutrients and carbon stocks increased compared to their 1980 levels in the three land use types, and labile carbon pools and microbial community structure exhibited different responses in the three land use types. Compared to spontaneous development, mineral fertilization and organic amendment are more effective for recovering soil fertility in reclaimed soils.
  • Authors:
    • Sheaffer, C. C.
    • Fernandez, A. L.
    • Wyse, D. L.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Field pea ( Pisum sativum L.) and lentil ( Lens culinaris Medik.) have potential as grain-producing legumes in organic rotations, but their yield is limited by weed competition. Intercropping can control weeds and increase total grain productivity per land area compared to sole cropping. A field experiment was conducted to investigate the effect of intercropping on field pea and lentil yields. Intercrop treatments were spring wheat ( Triticum aestivum L.), oat ( Avena sativa L.), and radish ( Raphanus sativus L.), which were harvested for grain; and winter rye ( Secale cereale L.) and rapid-cycling brassica ( Brassica campestris L.), which were not harvested. Intercropped lentil yields and total (lentil plus intercrop) yields were lower than or equal to weeded and unweeded sole cropped lentils in 5 of 6 site-years. Intercropped pea yields and total (pea plus intercrop) yields were lower than or equal to weeded and unweeded sole cropped pea in all site-years. Unharvested intercrops showed variable effectiveness at suppressing weeds. In lentil, winter rye intercropping reduced weed biomass compared to the unweeded control in 4 site-years, and rapid-cycling brassica reduced weed biomass in 2 site-years. In pea, winter rye, and rapid-cycling brassica treatments reduced weed biomass in all site-years. However, reductions in weed biomass were not associated with increases in grain yield. Estimated net returns to intercropping were variable, but generally similar for sole crops and intercrops on average. We did not observe consistent agronomic or economic advantages to the use of intercrops with field pea and lentil in the Minnesota environments studied.
  • Authors:
    • Franco,J. G.
    • King,S. R.
    • Masabni,J. G.
    • Volder,A.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 203
  • Year: 2015
  • Summary: In natural ecosystems, plant communities composed of functionally diverse species produce more biomass overall than less diverse communities. This increased biomass production is thought to occur due to complementary use of resources such as nutrients and water, and facilitation during sub-optimal environmental conditions. Using the same concept in a crop setting may lead to increased yield (overyielding) in diverse cropping systems when compared to monocultures. Different combinations of peanut, watermelon, okra, cowpea, and pepper planted alone or in various intercropping combinations were investigated over two growing seasons in a low-input system in the peak of summer heat in Texas. Each species was selected to perform a specific function within the system. Results from land equivalent ratio (LER) indicate that the within-row combination with peanut, watermelon and okra ( Wpwo) and peanut, watermelon, okra and cowpea ( Wpwoc) consistently overyielded in 2011 and 2012. LER values were 1.17 each for Wpwo and Wpwoc in 2011 and 1.17 and 1.20 in 2012, respectively. In 2011, watermelon was the dominant crop and was up-regulated in all intercropping combinations while all other component crops were down-regulated. Watermelon per plant production was significantly higher in the combination containing all species ( Wall) when compared to its monoculture, 5.50 and 2.09 kg fruit plant -1, respectively. In 2012, okra was the dominant crop and was up-regulated in all intercropping combinations while watermelon, cowpea, and pepper were down-regulated. Okra per plant production was significantly higher in Wpwoc and Wall than in monoculture, 2.28, 2.46, and 1.13 kg fruit plant -1, respectively. These findings suggest that three and four species intercropping combinations, whereby each crop is selected to perform a specific function within the system, may provide small-scale sustainably-minded producers a model system that can be utilized in suboptimal conditions and allow them to reduce inputs while increasing overall yields.
  • Authors:
    • Rezaei Rashti,M.
    • Wang,W.
    • Moody,P.
    • Chen,C.
    • Ghadiri,H.
  • Source: Atmospheric Environment
  • Volume: 112
  • Year: 2015
  • Summary: The emission of nitrous oxide (N2O) from vegetable fields contributes to the global greenhouse gases budget. However, reliable estimation of N2O emissions from vegetable production in the word has been lack. Vegetable cropping systems are characterised with high N application rates, irrigation, intensive production and multiple planting-harvest cycles during the year. Improved understanding of the key factors controlling N2O production is critical for developing effective mitigation strategies for vegetable cropping systems under different climate, soil type and management practices. Based on a comprehensive literature review and data analysis, we estimated the global N2O emission from vegetable production using seasonal fertiliser-induced emission factors (EFs) and examined the relationship of the seasonal emissions and EFs to possible controlling factors. The global average seasonal EF for vegetable fields is around 0.94% of applied N fertiliser, which is very similar to the Intergovernmental Panel on Climate Change (IPCC) annual emission factor of 1.0% for all cropping systems. The total N2O emission from global vegetable production is estimated to be 9.5×107kgN2O-N yr-1, accounting for 9.0% of the total N2O emissions from synthetic fertilisers. Stepwise multiple regression analysis on the relationships of soil properties, climatic factors and N application rates to seasonal N2O emissions and N2O EFs showed that N fertiliser application rate is the main regulator of seasonal N2O emission from vegetable fields but the seasonal EFs are negatively related to soil organic carbon (SOC) content. In fields receiving =250kgha-1N fertiliser, 67% (n=23, P=0.01) of the variation in seasonal emissions can be explained by the combined effects of N application rate, mean water-filled pore space (WFPS) and air temperature, while 59% (n=23, P=0.01) of the variation in seasonal EFs relates to temperature, mean WFPS and soil pH. The result also shows that in vegetable fields with mean seasonal air temperature higher than 14°C, increases in SOC decrease the seasonal EF and total N2O emissions from fertiliser N. © 2015 Elsevier Ltd.
  • Authors:
    • Weber-Blaschke, G.
    • Lampert, P.
    • Soode, E.
    • Richter, K.
  • Source: Agriculture Article
  • Volume: 87
  • Year: 2015
  • Summary: Global climate change problem can be linked to production efficiency and everyday consumption patterns by calculating the greenhouse gas emissions resulting from each product. This is usually referred to as product carbon footprint (PCF). Only limited information is available about the PCF of German horticultural products. We measured the cradle-to-grave PCF of German strawberries, asparagus, roses and orchids in different production systems and compared it to the PCF of the same products grown in other countries. For the production and customer stage we collected primary data, for the comparison with products in other countries we used literature data. The results showed that the average consumer stage constitutes 3-71% of the PCF, the best case consumer scenario 1-39% and the worst case 60-99%. The consumer shopping trip was a hotspot in all analysed systems where a private car was used. Electricity for production, fuel use for soil management, and cooking and washing dishes were also among the most often identified hotspots. German open field strawberries perform better, German open field roses and asparagus are on the similar level with the same products produced abroad. However, asparagus transported by plane, and strawberries and roses grown in greenhouses have several times higher PCF regardless of the producing country. Consumers as well as producers are responsible for reducing the climate impact of horticultural products. Shopping trip on foot or by bike and using renewable energy can reduce the PCF significantly. We recommend extending the analysis to the life cycle assessment or product environmental footprint to consider more indicators to identify which products are less harmful to the environment.