• Authors:
    • Siebert, S.
    • Wolf, J.
    • Hoffmann, H.
    • Webber, H.
    • Gang, Z.
    • Ewert, F.
  • Source: Primary Research Article
  • Volume: 21
  • Issue: 11
  • Year: 2015
  • Summary: This study evaluates the impacts of projected climate change on irrigation requirements and yields of six crops (winter wheat, winter barley, rapeseed, grain maize, potato, and sugar beet) in Europe. Furthermore, the uncertainty deriving from consideration of irrigation, CO 2 effects on crop growth and transpiration, and different climate change scenarios in climate change impact assessments is quantified. Net irrigation requirement (NIR) and yields of the six crops were simulated for a baseline (1982-2006) and three SRES scenarios (B1, B2 and A1 B, 2040-2064) under rainfed and irrigated conditions, using a process-based crop model, SIMPLACE . We found that projected climate change decreased NIR of the three winter crops in northern Europe (up to 81 mm), but increased NIR of all the six crops in the Mediterranean regions (up to 182 mm yr -1). Climate change increased yields of the three winter crops and sugar beet in middle and northern regions (up to 36%), but decreased their yields in Mediterranean countries (up to 81%). Consideration of CO 2 effects can alter the direction of change in NIR for irrigated crops in the south and of yields for C3 crops in central and northern Europe. Constraining the model to rainfed conditions for spring crops led to a negative bias in simulating climate change impacts on yields (up to 44%), which was proportional to the irrigation ratio of the simulation unit. Impacts on NIR and yields were generally consistent across the three SRES scenarios for the majority of regions in Europe. We conclude that due to the magnitude of irrigation and CO 2 effects, they should both be considered in the simulation of climate change impacts on crop production and water availability, particularly for crops and regions with a high proportion of irrigated crop area.
  • Authors:
    • Madejon, E.
    • Murillo, J.
    • Soriano, M.
    • Griffith, D.
    • Carmona, I.
    • Gomez-Macpherson, H.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 213
  • Year: 2015
  • Summary: Conservation agriculture (CA), which is promoted worldwide to conserve soil, water and energy and to reduce production costs, has had limited success in Europe. The objectives of this study were to assess annual crop systems currently managed under CA in southern Spain, identify obstacles to CA adoption, and recommend strategies to overcome those obstacles. We employed the following methods: (i) examination of original government data used to monitor CA; (ii) survey of CA farmers to characterize their practices and perceptions; (iii) agronomic, economic and energy use comparison of minimum tillage (MT) and conventional tillage (CT); and (iv) a stakeholder focus group to identify strategies for improving CA. Farmers selectively implemented some components of CA while disregarding others as a strategy to adapt to local conditions. Although most researchers define CA as a system that combines minimum soil disturbance, maintenance of crop residues, and crop rotation, in practice most farmers and organizations equated CA with direct seeding of cereals without considering residues or crop rotation. Official national statistics did not include all of these CA components either. Examination of government data revealed that only 13% of monitored plots were not tilled consecutively. The most common CA system (50% of farms) was direct seeded wheat rotated with tilled sunflower. This system (classified as MT) and CT were not significantly different with regard to wheat yield, soil quality, net return or energy use in either crop, which was likely due to similar residues management, recurrent soil disturbance in MT, and disuse of moldboards in CT. In wheat, fertilizers represented the largest energy input (68% TEI) in both systems followed by diesel consumption (12% and 19% in MT and CT, respectively). To overcome the most important identified problems in CA, we highlight the need for collaborative research with farmers and other stakeholders to develop appropriate drill technology for spring crops, identify non-cereal crops that are better adapted to CA than sunflower, improve residues management, increase energy efficiency through better fertilizer management, and promote CA among farmer groups excluded by socioeconomic barriers. Finally, international standards to guide data collection and statistical analyses on all components of CA will enable researchers and institutions to compare information and find solutions to common problems.
  • Authors:
    • Chen, D.
    • Weng, B.
    • Zhang, J.
    • Zheng, X.
    • Hu, X.
    • Zhang, Y.
    • Li, S.
    • Ding, H.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 103
  • Issue: 3
  • Year: 2015
  • Summary: To investigate the fate of urea nitrogen (N) applied to vegetable fields, three N rates, N0 (0 kg N/ha), N1(225 or 240 kg N/ha) and N2 (450 or 480 kg N/ha) were applied to a rotation system. Nitrogen fertilizer recovery (NFR), N residue in soil, and N losses were measured in situ. Higher N application rates resulted in lower NFR, and increased N residues in soil and losses. The NFR, Chinese cabbage, and eggplant were different in the N1 and N2 groups (P < 0.01). The ratios of N fertilizer residue at 0-60 cm deep ranged from 30.2 to 41.1 % (N1), and 33.1 to 57.7 % (N2). The N loss ratios were only 6.6 % (N1) and 11.9 % (N2), because of the lower precipitation rates and temperatures characteristic of its growing season; meanwhile, N losses were 31.1 and 37.4 % in cayenne pepper, and 24.1 and 29.2 % in eggplants in the N1 and N2 treatments, respectively. The main pathways of N loss were leaching, followed by gaseous losses; these were major pathways of N loss in seasons with lower precipitation rates. NH3 volatilization was correlated with soil temperature (P < 0.01), and N2O emissions were correlated with soil moisture in the N1 treatment and with soil NH4 (+)-N concentration in the N2 treatment (P < 0.01). Denitrification rates were correlated with soil moisture in the N0 and N1 treatments, and with NO3 (-)-N content in the N2 treatment (P < 0.01). Finally, loss due to runoff was correlated with precipitation (P < 0.01).
  • Authors:
    • Howden, M.
    • Chapman, S.
    • Zheng, B.
    • Moore, A.
    • Kokic, P.
    • Ghahramani, A.
    • Crimp, S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 211
  • Issue: December 2015
  • Year: 2015
  • Summary: Wheat is one of the main grains produced across the globe and wheat yields are sensitive to changes in climate. Australia is a major exporter of wheat, and variations in its national production influence trade supplies and global markets. We evaluated the effect of climate change in 2030 compared to a baseline period (1980-1999) by upscaling from farm to the national level. Wheat yields and gross margins under current and projected climates were assessed using current technology and management practices and then compared with 'best adapted' yield achieved by adjustments to planting date, nitrogen fertilizer, and available cultivars for each region. For the baseline climate (1980-1999), there was a potential yield gap modelled as optimized adaptation gave potential up scaled yields (tonne/ha) and gross margins (AUD$/ha) of 17% and 33% above the baseline, respectively. In 2030 and at Australian wheatbelt level, climate change impact projected to decline wheat yield by 1%. For 2030, national wheat yields were simulated to decrease yields by 1% when using existing technology and practices but increase them by 18% assuming optimal adaptation. Hence, nationally at 2030 for a fully-adapted wheat system, yield increased by 1% and gross margin by 0.3% compared to the fully adapted current climate baseline. However, there was substantial regional variation with median yields and gross margins decreasing in 55% of sites. Full adaptation of farm systems under current climate is not expected, and so this will remain an on-going challenge. However, by 2030 there will be a greater opportunity to increase the overall water use and nitrogen efficiencies of the Australian wheat belt, mostly resulting from elevated atmospheric CO 2 concentrations.
  • Authors:
    • Tan, C. S.
    • Fleming, R.
    • Drury, C. F.
    • Reynolds, W. D.
    • Yang, X. M.
    • Denholm, K.
    • Yang, J. Y.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: Household food waste compost (FWC), yard waste compost (YWC) and pig manure plus wheat straw compost (PMC) were applied once in the fall of 1998 to a Brookston clay loam soil in southwestern Ontario to determine immediate and long-term effects of organic amendments on soil quality and productivity. In this report, we describe the residual effects of these single compost applications on soil organic carbon (SOC) and total soil nitrogen (TN) stocks 10 yr after compost addition (2009). FWC was applied at 75 Mg ha -1, 150 Mg ha -1 and 300 Mg ha -1, while YWC and PMC were applied at the single rate of 75 Mg ha -1. The 75 Mg ha -1 additions of YWC, PMC and FWC increased SOC in the top 30 cm relative to a control (no compost additions) by 12.3% (9.0 Mg ha -1), 16.6% (12.2 Mg ha -1) and 0%, respectively; and they increased TN relative to the control by 8.0% (0.53 Mg ha -1), 11.7% (0.77 Mg ha -1), and 0%, respectively. The 150 and 300 Mg ha -1 additions of FWC increased SOC in the top 30 cm by 13.0 and 24.7 Mg ha -1, respectively, and they increased TN by 0.93 and 1.70 Mg ha -1, respectively. These results indicate that increases in SOC and TN stocks accruing from a single compost addition can persist for at least a decade, but the degree of increase depends strongly on compost type and addition rate. It was concluded that high compost addition rates of FWC and/or addition of composts derived from recalcitrant organic materials may be a good strategy for achieving long-term carbon and nitrogen sequestration in the cool, humid fine-textured soils of southwestern Ontario.
  • Authors:
    • Shu, X.
    • Xu, X. H.
    • Zhang, J. B.
    • Chen, X. M.
    • Zhu, A. N.
    • Yang, W. L.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 99
  • Issue: 1-3
  • Year: 2014
  • Summary: The backward Lagrangian stochastic (BLS) model and open-path tunable diode laser (OPTDL) analyzer were used to monitor ammonia (NH3) emissions from urea applied to winter wheat in the North China Plain. The high-temporal resolution measurements of ammonia concentrations provided an opportunity for estimating the diel patterns of ammonia emissions, as well as valuable information about the factors that influence NH3 emissions. The results showed both large diel variability and daily variability in NH3 volatilization, with NH3 emissions highest during the daytime. The diel pattern of ammonia volatilization depended mainly on the diel variation of wind speed and soil temperature, while the overall pattern of NH3 loss was strongly affected by soil moisture content, soil NH4 (+)-N concentration, wind speed and soil temperature. At the end of the measurement period, the cumulative NH3 loss was 12.21-16.43 kg N ha(-1), calculated based on different time scale average Q (BLS). Due to sensitivity of the OPTDL analyzer, the estimated total ammonia loss was still doubtful in this study.
  • Authors:
    • De Benedetto, D.
    • Cocozza, C.
    • Marino, L.
    • Stellacci, A. M.
    • Vitti, C.
    • Castrignano, A.
    • Diacono, M.
    • Troccoli, A.
    • Rubino, P.
    • Ventrella, D.
  • Source: PRECISION AGRICULTURE
  • Volume: 15
  • Issue: 5
  • Year: 2014
  • Summary: Precision agriculture (PA) technologies allow us to assess field variability and support site-specific (SSP) application of inputs. The joint application of PA and organic farming practices might be synergetic. The objective of this 3-year study was to propose a multivariate statistical and geostatistical approach, to evaluate the effects of SSP nitrogen (N) fertilization on durum wheat in transition to organic farming. Soil parameters were measured to assess soil fertility level before the SSP fertilization on wheat, which was carried out by management zones in the third year. Radiometric measurements were performed with a hyperspectral spectroradiometer and N-uptake at anthesis and grain yield were determined. The expected values and 95 % confidence intervals of the soil parameters, N-uptake and yield data were estimated with polygon kriging for each management zone. Reflectance data were reduced through principal component analysis and the retained principal components were submitted to factorial co-kriging analysis to estimate orthogonal scale-dependent factors. Comparisons between N-uptake and yield and between the retained regionalized factors (F1) and yield were performed. The spatial pattern of F1 at shorter scales was mostly reproduced in the N-uptake map, suggesting the predictive capacity of hyperspectral data for crop N-status. Within-cluster variance for yield was reduced, quite probably as a combined effect of meteorological pattern and management. The preliminary results seem to be promising in the perspective of PA. Moreover, an inverse relationship between grain yield and crop N-status was observed.
  • Authors:
    • Ellerbrock, R.
    • Mumme, J.
    • Lanza, G.
    • Dicke, C.
    • Kern, J.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 43
  • Issue: 5
  • Year: 2014
  • Summary: The application of biochar to soil is a potential tool for the long-term sequestration of C and a possible mitigation of greenhouse gas (GHG) emissions. Among the various processes available to produce biochar, hydrothermal carbonization is one technique that is suitable for moist feedstock like digestates from biogas production. The aim of this study was to investigate the stability of C and emissions of N 2O after the addition of (i) digested wheat ( Triticum aestivum L.) straw (digestate) and (ii) hydrothermally carbonized (HTC) char of wheat straw as well as (iii) HTC char of digested wheat straw to two soil horizons that differed in C content. The HTC chars were obtained from wheat straw and digested wheat straw that were hydrothermally carbonized at 230°C for 6 h. The digestate and HTC chars were mixed with soil and incubated in 125-mL vessels. The GHG emissions of CO 2 and N 2O were measured at regular intervals. Additionally, after 108 d, N was applied in the form of NH 4NO 3 equivalent to 100 kg N ha -1. After 500 d of incubation, the digestate had lost 34% of C, while the soil mixture with the corresponding HTC char lost 12% of C in the form of CO 2 from the topsoil. The estimated bi-exponential half-life of the recalcitrant C was more than 50% longer for the carbonized material than for the untreated digestate. The N 2O emissions from both HTC chars were significantly reduced compared with untreated digestate. The reductions were up to 64% for the topsoil and 60% for the subsoil samples. These laboratory results show that HTC holds the potential to increase the C stability of fermented and carbonized biomasses and to reduce N 2O emissions.
  • Authors:
    • Zhang, H. L.
    • Lal, R.
    • Chen, Z. D.
    • Dikgwatlhe ,S. B.
    • Chen, F.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 144
  • Year: 2014
  • Summary: The importance of soil organic carbon (SOC) and nitrogen (N) sequestration in agricultural soils as climate-change-mitigating strategy has received robust attention worldwide in relation to soil management. This study was conducted to determine the temporal effects of different tillage systems and residue management on distribution, storage and stratification of SOC and N under wheat (Triticum aestivum L.) - maize (Zea mays L.) cropping systems in the North China Plain (NCP). Four tillage systems for winter wheat established in 2001 were: moldboard plow tillage with maize residues removed (PT0), moldboard plow tillage with maize residues incorporated (PT), rotary tillage with maize residues incorporated (RT), and no-till with maize residues retained on the soil surface (NT). Compared with PT0 and PT, significantly higher SOC and N concentrations were observed in the surface layer (0-10cm depth) under NT and RT. In 2004, the SOC stocks were lower (PRT>PT>PT0 in both years. Compared with other treatments, SOC and N stocks were the lowest (P<0.05) under PT0. Therefore, crop residues play an important role in SOC and N management, and improvement of soil quality. The higher SOC stratification was observed under NT and RT than under PT and PT0, whereas the C:N ratio was higher (P<0.05) under PT and PT0 than under NT and RT systems. Therefore, the notion that NT leads to higher SOC stocks than plowed systems requires cautious scrutiny. Nonetheless, some benefits associated with NT present a greater potential for its adoption in view of the long-term environmental sustainability under wheat-maize double-cropping system in the NCP. © 2014 Elsevier B.V.
  • Authors:
    • Horowitz, J.
  • Source: Climate Change Economics
  • Volume: 5
  • Issue: 2
  • Year: 2014
  • Summary: Agriculture is a source of greenhouse gas emissions that could be included as offsets in a cap-and-trade system. This paper describes offset rules that could be applied to reduced nitrogen fertilizer application on wheat, a source of nitrous oxide emissions. Unlike other papers that have examined offset rules, we do not assume that farmers' business-as-usual nitrogen emissions can be perfectly predicted. We construct a structural model of wheat production and use this, along with Agricultural Resource Management Survey data, to model or estimate participation in the offset market, offset supply conditional on participation, and business-as-usual emissions. We find that roughly two-thirds of the supplied offsets would be non-additional at an allowance price of $15/tonne CO 2-e. Under assumptions about the social damages from greenhouse gas emissions, we find that allowing nitrogen offsets would marginally pass a standard benefit-cost test.