• Authors:
    • Rust, J.
    • Kimber, S.
    • Herridge, D.
    • Rose, T.
    • Zwieten, L. V.
    • Cowie, A.
    • Morris, S.
  • Source: Article
  • Volume: 395
  • Issue: 1/2
  • Year: 2015
  • Summary: Background and aims: Acid soils constrain legume growth and biochars have been shown to address these constraints and enhance biological N 2 fixation in glasshouse studies. A dissection of causal mechanisms from multiple crop field studies is lacking. Methods: In a sub-tropical field study, faba bean ( Vicia faba L.) was cultivated in rotation with corn ( Zea mays) following amendment of two contrasting biochars, compost and lime in a rhodic ferralsol. Key soil parameters and plant nutrient uptake were investigated alongside stable 15N isotope methodologies to elucidate the causal mechanisms for enhanced biological N 2 fixation and crop productivity. Results: Biological N 2 fixation was associated with plant Mo uptake, which was driven by reductions in soil acidity following lime and papermill (PM) biochar amendment. In contrast, crop yield was associated with plant P and B uptake, and amelioration of soil pH constraints. These were most effectively ameliorated by PM biochar as it addressed both pH constraints and low soil nutrient status. Conclusions: While liming resulted in the highest biological N 2 fixation, biochars provided greater benefits to faba bean yield by addressing P nutrition and ameliorating Al toxicity.
  • Authors:
    • Merino-de-Miguel, S.
    • Sanchez-Giron, V.
    • Litago, J.
    • Inclan, R.
    • Schmid, T.
    • Uribe, C.
    • Huesca, M.
    • Rodriguez-Rastrero, M.
    • Cicuendez, V.
    • Palacios-Orueta, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 212
  • Year: 2015
  • Summary: The assessment of soil respiration processes in agroecosystems is essential to understand the C balance and to study the effects of soil respiration on climate change. The use of spectral data through remote sensing techniques constitutes a valuable tool to study ecological processes such as the C cycle dynamics. The objective of this work was to evaluate the potential to assess total (Rs) and autotrophic (Ra) soil respiration through spectral information acquired by field spectroscopy in a row irrigated corn crop ( Zea mays L.) throughout the growing period. The relationships between Rs and Ra with leaf area index (LAI), spectral indexes and abiotic factors (soil moisture and soil temperature) were assessed by linear regression models using the adjusted coefficient of determination (Radj 2) to measure and compare the proportion of variance explained by the models. Results showed significant differences and a high variability in the relationships between Rs and Ra with spectral indexes within the corn field during the phenological stages and in measurements under the plants and between the rows. Best results were obtained when assessing Ra during vegetative stages. However, during the reproductive stages, spectral indexes were better related to Rs which could be related to the presence of rhizomicrobial respiration linked to vegetation activity. Spectral indexes contain significant functional information, beyond mere structural changes, that could be related to carbon fluxes. However, specific models should be applied for the different phenological stages and there is a need to be cautious when upscaling remote sensing models. The results obtained confirm that in irrigated crop systems remote sensing data can produce relevant information to assess both Rs and Ra through spectral indexes.
  • Authors:
    • Larsen, E.
    • Grossman, J.
    • Hoyt, G.
    • Line, D.
    • Osmond, D.
    • Edgell, J.
  • Source: Journal of Environmental Quality Abstract - Surface Water Quality
  • Volume: 44
  • Issue: 6
  • Year: 2015
  • Summary: Organic agricultural systems are often assumed to be more sustainable than conventional farming, yet there has been little work comparing surface water quality from organic and conventional production, especially under the same cropping sequence. Our objective was to compare nutrient and sediment losses, as well as sweet corn ( Zea mays L. var. saccharata) yield, from organic and conventional production with conventional and conservation tillage. The experiment was located in the Appalachian Mountains of North Carolina. Four treatments, replicated four times, had been in place for over 18 yr and consisted of conventional tillage (chisel plow and disk) with conventional production (CT/Conven), conservation no-till with conventional production (NT/Conven), conventional tillage with organic production (CT/Org), and conservation no-till with organic production (NT/Org). Water quality (surface flow volume; nitrogen, phosphorus, and sediment concentrations) and sweet corn yield data were collected in 2011 and 2012. Sediment and sediment-attached nutrient losses were influenced by tillage and cropping system in 2011, due to higher rainfall, and tillage in 2012. Soluble nutrients were affected by the nutrient source and rate, which are a function of the cropping system. Sweet corn marketable yields were greater in conventional systems due to high weed competition and reduced total nitrogen availability in organic treatments. When comparing treatment efficiency (yield kg ha -1/nutrient loss kg ha -1), the NT/Conven treatment had the greatest sweet corn yield per unit of nutrient and sediment loss. Other treatment ratios were similar to each other; thus, it appears the most sustainably productive treatment was NT/Conven.
  • Authors:
    • Robertson, G.
    • Tang, J.
    • Cui, M.
    • Gelfand, I.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 212
  • Issue: December 2015
  • Year: 2015
  • Summary: Climate change is causing the intensification of both rainfall and droughts in temperate climatic zones, which will affect soil drying and rewetting cycles and associated processes such as soil greenhouse gas (GHG) fluxes. We investigated the effect of soil rewetting following a prolonged natural drought on soil emissions of nitrous oxide (N 2O) and carbon dioxide (CO 2) in an agricultural field recently converted from 22 years in the USDA Conservation Reserve Program (CRP). We compared responses to those in a similarly managed field with no CRP history and to a CRP reference field. We additionally compared soil GHG emissions measured by static flux chambers with off-site laboratory analysis versus in situ analysis using a portable quantum cascade laser and infrared gas analyzer. Under growing season drought conditions, average soil N 2O fluxes ranged between 0.2 and 0.8 g N m -2 min -1 and were higher in former CRP soils and unaffected by nitrogen (N) fertilization. After 18 days of drought, a 50 mm rewetting event increased N 2O fluxes by 34 and 24 fold respectively in the former CRP and non-CRP soils. Average soil CO 2 emissions during drought ranged from 1.1 to 3.1 mg C m -2 min -1 for the three systems. CO 2 emissions increased ~2 fold after the rewetting and were higher from soils with higher C contents. Observations are consistent with the hypothesis that during drought soil N 2O emissions are controlled by available C and following rewetting additionally influenced by N availability, whereas soil CO 2 emissions are independent of short-term N availability. Finally, soil GHG emissions estimated by off-site and in situ methods were statistically identical.
  • Authors:
    • AKBAR, T.
    • FAEZEH, G.
    • MOHAMMAD, M. S. S. A.
    • HABIBEH, J.
    • MEHRDAD, M. G.
    • MEHDI, P.
  • Source: Journal of Field Crop Science
  • Volume: 45
  • Issue: 3
  • Year: 2014
  • Summary: Water deficit, ultraviolet radiation and carbon dioxide enrichment are the most important environmental factors in global climate change. This research was conducted in Tarbiat Modares University, Research Greenhouse and the objective of that was to study the effects of three levels of carbon dioxide (500, 900 and 1300 ppm), UV-radiation (UV-A, B and C with intensity of 18, 25 and 40 W.cm 2 respectively) and water deficit (common irrigation and 40 percent of available water remain in soil) on grain yield, some quality traits of sweet corn ( Zea mays L. var. Sacarata). The experiment was conducted as factorial arrangement in randomized complete block design with three replications in one year (2009). The results showed that interaction among UV-C radiation, elevated CO 2 and water stress had a significant effect on grain yield and Fv/Fm. The highest grain yield was obtained in water deficit and 900 (l/l) CO 2 concentration. The most content Fv/Fm was obtained under water deficit and 1300 (l/l) CO 2 concentration. Water deficit and elevated CO 2 increased proline, and decreased chlorophyll a, chlorophyll b, chlorophyll a+b, carotenoids and flavonoids. Grain protein decreased with wavelength UV reduction. Above result showed that three main environmental stresses reduced plant productivity strategy in most condition and as a result decreased the performance of corn plant.
  • Authors:
    • Bjornsson,L.
    • Prade,T.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: In an analysis of climate effects, increased soil organic carbon will have a dual effect due to both increased soil fertility and carbon sequestration. Even so, soil carbon changes are neglected in many crop production LCAs. In the present study, the introduction of grass-clover crops in cereal-dominated crop production was evaluated. The grass-clover crops were used for biogas production, and the digested residue was recycled to the farm as biofertilizer. A shift from the cereal-dominated crop rotation to integrated production of food crops and one or two years of grass-clover crops used as biogas feedstock would result in avoided emissions of 2-3 t CO 2-eq. ha -1 a -1. Integrated food and energy crop production would in this case improve soil organic carbon content at the same time as resulting in considerably decreased greenhouse gas emissions from the cultivation system.
  • Authors:
    • Fumagalli,M.
  • Source: Italian Journal of Agrometeorology
  • Volume: 20
  • Issue: 1
  • Year: 2014
  • Summary: Intensive maize production in Lombardy region (northern Italy) is widespread and requires big amounts of input, especially nitrogen (N), thus leading to potential environmental risks. Starting from farm survey data the current work aims to evaluate how alternative N management options for reducing losses can be effective in climate change mitigation. Under current management (ACT) of typical continuous maize cropping systems across the region, the greenhouse gases (GHG) emissions from the production of inorganic fertilisers and from direct and indirect N2O released after N application accounted for, on average, 67% of the total GHG emissions. The adoption of the best N management plans (FERT scenario), reduced GHG emissions and C-footprint (expressed per unit of agricultural product) by 27 and 26%, respectively. Furthermore, the double cropping system (two crops harvested in 12 months - ROT scenario) strongly increased GHG emissions in comparison with the only cultivation of a summer crop. However, the high productivity of this system, led to a C-footprint lower than the ACT one and still higher than the FERT one. The current work highlights the opportunities for carbon mitigation offered by changes on field N management, without significantly impact the yield. © 2015, Patron Editore S.r.l. All rights reserved.
  • Authors:
    • Torres,C. M.
    • Anton,A.
    • Castells,F.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector (LCA Food 2014)
  • Year: 2014
  • Summary: Certain complexities in the agricultural production differentiate this sector from the conventional industrial processes. The main feature to take into account is that the resources consumption and production is subjected to high variability in soil, rainfall and latitude. We show here an environmental tool developed in close cooperation with farmers in order to achieve applicability and comprehensibility. The procedure relies on the data retrieved from parcel management monitoring of different crops, mostly allocated in Catalonia and Ebro river watershed region (NE Spain). A set of comprehensive but also simple reports are provided, including material and energy balances, agronomic efficiencies and water and carbon footprints. The calculations also cover impacts due to infrastructure, including the estimation of materials in the use of greenhouses. Besides, a simple algorithm for reporting uncertainty using an approximation method of error propagation was added using the input uncertainties as defined by their data pedigree.
  • Authors:
    • Attavanich,Witsanu
    • McCarl,Bruce A.
  • Source: Climatic Change
  • Volume: 124
  • Issue: 4
  • Year: 2014
  • Summary: This paper analyzes the impact of climate, crop production technology, and atmospheric carbon dioxide (CO2) on current and future crop yields. The analysis of crop yields endeavors to advance the literature by estimating the effect of atmospheric CO2 on observed crop yields. This is done using an econometric model estimated over pooled historical data for 1950-2009 and data from the free air CO2 enrichment experiments. The main econometric findings are: 1) Yields of C3 crops (soybeans, cotton, and wheat) directly respond to the elevated CO2, while yields of C4 crops (corn and sorghum) do not, but they are found to indirectly benefit from elevated CO2 in times and places of drought stress; 2) The effect of technological progress on mean yields is non-linear; 3) Ignoring atmospheric CO2 in an econometric model of crop yield likely leads to overestimates of the pure effects of technological progress on crop yields of about 51, 15, 17, 9, and 1 % of observed yield gain for cotton, soybeans, wheat, corn and sorghum, respectively; 4) Average climate conditions and climate variability contribute in a statistically significant way to average crop yields and their variability; and 5) The effect of CO2 fertilization generally outweighs the effect of climate change on mean crop yields in many regions resulting in an increase of 7-22, 4-47, 5-26, 65-96, and 3-35 % for yields of corn, sorghum, soybeans, cotton, and wheat, respectively.
  • Authors:
    • Long, S. P.
    • Ort, D. R.
  • Source: Article
  • Volume: 344
  • Issue: 6183
  • Year: 2014
  • Summary: In total global production, corn (maize, <I>Zea mays</I> L.) is the most important food and feed crop. Of the 967 million metric tons produced in 2013, 36.5% were produced in the United States, mostly in the Midwest Corn Belt. The United States is by far the world's largest corn exporter, accounting for 50% of corn exports globally (<I>1</I>, <I>2</I>). Until recently, breeding and management have allowed farmers to increase the number of plants per acre without loss of yield per plant. On page 516 of this issue, Lobell <I>et al.</I> (<I>3</I>) use a detailed data set for farms across the Corn Belt, to show that increasing yields have been accompanied by rising drought sensitivity, with important implications for future crop yields.