• Authors:
    • Steenwerth,K. L.
    • Strong,E. B.
    • Greenhut,R. F.
    • Williams,L.
    • Kendall,A.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 20
  • Issue: 9
  • Year: 2015
  • Summary: Purpose: This study assesses life cycle greenhouse gas (GHG) emissions, energy use, and freshwater use in wine grape production across common vineyard management scenarios in two representative growing regions (Napa and Lodi) of the US state of California. California hosts 90 % of US grape growing area, and demand for GHG emissions estimates of crops has increased due to consumer interest and policies such as California’s Global Warming Solutions Act. Methods: The study’s scope includes the annual cycle for wine grape production, beginning at raw material extraction for production of vineyard inputs and ending at delivery of wine grapes to the winery gate, and excludes capital infrastructure. Two hundred forty production scenarios were modeled based on data collected from land owners, vineyard managers, and third-party vineyard management companies. Thirty additional in-person interviews with growers throughout Napa and Lodi were also conducted to identify the diversity of farming practices, site characteristics, and yields (among other factors) across 90 vineyards. These vineyards represent a cross-section of the regional variability in soil, climate, and landscape used for wine grape production. Results and discussion: Energy use and global warming potential (GWP) per metric ton (t) across all 240 production scenarios range between 1669 and 8567 MJ and 87 and 548 kg CO2e. Twelve scenarios were selected for closer inspection to facilitate comparison of the two regions and grower practices. Comparison by region shows energy use, GWP, and water use for typical practices were more than twice as great in Napa (6529 MJ/t, 456 kg CO2e/t, and 265 m3 H2O/t) than Lodi (2759 MJ/t, 203 kg CO2e/t, and 141 m3 H2O/t), but approximately 16 % greater on a per hectare basis. Hand harvest (versus mechanical harvesting) and frost protection processes in Napa contributed to higher values per hectare, and lower yields in Napa account for the even larger difference per metric ton. Hand harvesting and lower yields reflect the higher value of Napa wine grapes. Conclusions: The findings underscore the regional distinctions in wine grape production, which include different management goals, soils, and climate. When vineyards are managed for lower yields, as they are in Napa, energy, water, and GWP will likely be higher on a per mass basis. Strategies to reduce emissions in these regions cannot rely on increasing yields (a common approach), and alternative strategies are required, for example developing high-value co-products. © 2015 Springer-Verlag Berlin Heidelberg
  • Authors:
    • Veenstra,J. J.
    • Burras,C. L.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 4
  • Year: 2015
  • Summary: Despite a large body of scientific research that shows that soils change on relatively short time scales under different management regimes, classical pedological theory states that we should expect these changes to occur only in the surface few centimeters and that they are not of adequate magnitude to suggest fundamental changes in pedon character over short periods of time. In fact, rarely, do the scientists that make these comparisons report on any properties deeper than 30 to 45 cm in the soil profile. With this study, we evaluate soil transformation to a depth of 150 cm after 50 yr of intensive row-crop agricultural land use in a temperate, humid, continental climate (Iowa, United States), by resampling sites that were initially described by the United States soil survey between 1943 and 1963. We find that, through agricultural land use, humans are accelerating soil formation and transformation to a depth of 100 cm or more by accelerating erosion, sedimentation, acidification, and mineral weathering, and degrading soil structure, while deepening dark-colored, organic-matter rich surface horizons, translocating and accumulating organic matter deeper in the soil profile and lowering the water table. Some of these changes can be considered positive improvements, but many of these changes may have negative effects on the soils' future productive capacity. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All rights reserved.
  • Authors:
    • Veum,K. S.
    • Kremer,R. J.
    • Sudduth,K. A.
    • Kitchen,N. R.
    • Lerch,R. N.
    • Baffaut,C.
    • Stott,D. E.
    • Karlen,D. L.
    • Sadler,E. J.
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 4
  • Year: 2015
  • Summary: The Conservation Effects Assessment Project (CEAP). was initiated in 2002 to quantify the potential benefits of conservation management practices throughout the nation. Within the Central Claypan Region of Missouri, the Salt River Basin was selected as a benchmark watershed for soil and water quality assessments. This study focuses on two objectives: (1) assessing soil quality for 15 different annual cropping and perennial vegetation systems typically employed in this region, and (2) evaluating relationships among multiple measured soil quality indicators (SQIs). Management practices included annual versus perennial vegetation, and varying grass species composition (cool-season versus warm-season), tillage intensity (no-till versus mulch-till), biomass removal, rotation phase, crop rotation (corn [Zea mays L.]-soybean [Glycine max L. Merr] versus corn-soybean-wheat [Triticum aestivum L.]) and incorporation of cover crops into the rotation. Soil samples were obtained in 2008 from 0 to 5 cm (0 to 2 in) and 5 to 15 cm (2 to 6 in) depth layers. Ten biological, physical, chemical, and nutrient SQIs were measured and scored using the Soil Management Assessment Framework (SMAF). Across SQIs, biological and physical indicators were the most sensitive to management effects, reflecting significant differences in organic carbon (C), mineralizable nitrogen (N), beta-glucosidase, and bulk density. In the 0 to 5 cm layer, perennial systems demonstrated the greatest SMAF scores, ranging from 93% to 97% of the soil's inherent potential. Scores for annual cropping systems ranged from 78% to 92%: diversified no-till, corn soybean wheat rotation with cover crops (92%) > no-till, corn-soybean rotation without cover crops (88%) > mulch-till corn-soybean rotation without cover crops (84%). Conversely, in the 5 to 15 cm layer, no-till cropping systems scored lower for overall soil function (58% to 61%) than mulch-till systems (65% to 66%). In the 0 to 5 cm layer, biological soil quality under the diversified no-till system with cover crops was 11% greater than under no-till without cover crops, and 20% greater than under mulch-till without cover crops. The effect of rotation phase was primarily reflected in 64% lower mineralizable N following corn relative to soybean. Additionally, soil nutrient function was significantly affected by biomass removal. The results of this study demonstrate that the benefits of conservation management practices extend beyond soil erosion reduction and improved water quality by highlighting the potential for enhanced soil quality, especially biological soil function. In particular, implementing conservation management practices on marginal and degraded soils in the claypan region can enhance long-term sustainability in annual cropping systems and working grasslands through improved soil quality.
  • Authors:
    • Wegner,B. R.
    • Kumar,S.
    • Osborne,S. L.
    • Schumacher,T. E.
    • Vahyala,I. E.
    • Eynard,A.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 4
  • Year: 2015
  • Summary: Excessive removal of crop residue has been shown to degrade soil organic carbon (SOC), and hence soil quality. Our objective was to assess the impacts of corn (Zea mays L.) residue removal and cover crops on various soil quality indicators. The experiment was conducted on a silty clay loam soil with and without a cover crop following three residue removal treatments. The low residue removal (LRR) treatment consisted of harvesting corn grain, leaving all other plant materials on the soil surface. Medium residue removal (MRR) consisted of harvesting grain, then chopping, windrowing and baling the remaining residue. The high residue removal (HRR) consisted of cutting the stalks 0.15 m from the ground and removing essentially all above-ground biomass. Crop residue removal significantly impacted measured soil properties including SOC, but cover cropping had minimal effects. The LRR treatment resulted in higher SOC concentrations and increased aggregate stability compared with other treatments. Residue removal significantly impacted the microbial activity as measured by hydrolysis of fluorescein diacetate (FDA). This study confirmed that HRR rates lead to SOC decomposition and adversely affect soil properties and soil quality. Soil conservation and emerging uses for crop residues must be balanced. Therefore, before making any decision to harvest crop residues, it is essential to have accumulated more C in the residue and supplemental cover crops than is needed to maintain equilibrium SOC levels. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All rights reserved.
  • Authors:
    • Woli,K. P.
    • Ruiz-Diaz,D. A.
    • Kaiser,D. E.
    • Mallarino,A. P.
    • Sawyer,J. E.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: An on-farm study was conducted in Iowa from 2004 to 2006 at 18 sites to evaluate corn ( Zea mays L.) grain yield (GY) and soil- and plant-test responses to poultry manure (PM) nutrient application at the field scale. A control and two target PM rates based on total N (PM-N) were applied in randomized field-length strips with three replications. Corn GY responded positively to PM applications. While N, P, and K plant and soil tests were related to PM nutrient rates, there was considerable variation, and relationships were probably influenced by the multiple applied nutrients. Soil-test P and soil-test K across sites increased linearly with increasing PM total P and K rates and with large increases from the high rates. This confirms high P and K crop availability. Grain yield responses to PM decreased linearly with increasing leaf chlorophyll meter (CM) and late spring soil NO 3-N test (LSNT) values but were not related to end-of-season lower corn stalk NO 3-N test values. No N test had a plateau relationship with GY, suggesting no excess N supply despite large PM-N rates. This confirms low first-year PM-N availability. The relationship between CM and LSNT indicated a critical LSNT value at 24 mg kg -1, similar to that from previous small-plot research. This field-scale study showed that PM is a valuable nutrient resource. However, due to PM multinutrient content and differences in availability, the nutrient causing GY and plant- or soil-test results often cannot be clearly identified and results need careful interpretation for reliable use.
  • Authors:
    • Xie YaPing
    • Gan YanTai
    • Li Yang
    • Niu JunYi
    • Gao YuHong
    • An HuiHui
    • Li AiRong
  • Source: Plant and Soil
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Oilseed flax ( Linum usitatissimum L.) yields are primarily fertilizer-limited, especially by N supply in the semiarid regions of North China. This study was conducted to determine whether N accumulation, translocation and N use efficiency (NUE) could be manipulated through N. The effects of N on N translocation, oilseed flax yield, oil content and NUE were studied at Zhangjiakou, China. Plants were grown at 0, 45, 90, and 135 kg N ha -1 (designated as the control, low N, moderate N, and high N, respectively), in 2011 and 2012. We found that N accumulation in leaves and capsule pericarps reached the maximum at anthesis and kernel developmental stage, respectively, then decreased rapidly before maturity. Averaged over 2 yr, N translocation from leaves to the seeds increased by 43, 150, and 150% under low N, moderate N, and high N, respectively, compared to the control; similarly, N translocation in capsule pericarps increased by 43, 243, and 190%, respectively. We discovered that leaves contributed the largest proportion of the seed N (averaging 80% in both years), and secondarily by the capsule pericarp N, which contributed 12% (in 2011) and 9% (in 2012) of the seed N. The highest seed yields were 2270 kg ha -1 (in 2011) and 1903 kg ha -1 (in 2012) which were obtained with the moderate N. Oil content was not affected by N. Nitrogen use efficiency decreased with progressively higher rates of N. The results suggest the moderate-N supply was adequate for promoting N translocation, and increasing N harvest index, NUE, and the productivity of oilseed flax.
  • Authors:
    • Proietti,P.
    • Federici,E.
    • Fidati,L.
    • Scargetta,S.
    • Massaccesi,L.
    • Nasini,L.
    • Regni,L.
    • Ricci,A.
    • Cenci,G.
    • Gigliotti,G.
  • Source: Web Of Knowledge
  • Volume: 207
  • Year: 2015
  • Summary: A new type of solid oil mill waste (SOMW), produced by latest-generation decanter, and its derived compost were spread on land for three consecutive years in an olive grove to evaluate the soil chemical characteristics, bacterial abundance and community structure, plant growth and production and oil quality. After the third year of the experiment in both treatments, there was no increase in total organic C (TOC) in the upper layer, while a reduction of TOC concentration in the deeper layer was detected. Moreover, in the upper soil layer, the available P increased in both treated soils compared to control while exchangeable K increased only in SOMW treated soil. In both the treated soils, viable counts of different bacteria showed little or no differences compared with the control. Further, PCR-DGGE analysis of the soil bacterial community indicated the presence of a very high biodiversity that was not affected by the long-term treatment with either SOMW and composted-SOMW. The treated soils with both matrices showed an increase in the vegetative activity and olive yield such as a positive effect on oil quality by increasing phenol content. The overall results indicate that both SOMW and its derived-compost can be positively used as soil amendment, thus, contributing to the reduction in the use of chemical fertilizers.
  • Authors:
    • Tribouillois,H.
    • Cruz,P.
    • Cohan,J. P.
    • Justes,E.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 207
  • Year: 2015
  • Summary: Cover crops are used during fallow periods to produce ecosystem services, especially those related to N management such as (i) capturing mineral-N from soil to reduce nitrate leaching, and (ii) improving N availability for the next main crop (green manuring). Bispecific mixtures consisting of legume and non-legume species could simultaneously produce these two services of nitrate saving and green manuring. The magnitude of these services can be estimated from indicators of agroecosystem functions such as crop growth rate, crop N acquisition rate and the C:N ratio of the cover crop. We developed a conceptual model for each indicator which was described using general linear models. A three-step procedure was used: (1) represent the behavior of each species based on a sub-model and calibrate each species in bispecific mixtures; (2) validate the complete-mixture models, corresponding to the sum of the two species sub-models, and the proportion of each species in the whole cover, and (3) validate the generality of sub-models and complete-mixture models to predict the agroecosystem function indicators of species in mixture not used for calibration. The combined use of (i) potential agroecosystem functions measured in sole crop in non-limiting conditions, (ii) difference in leaf functional traits, as indicators of plant strategies and (iii) environmental factors, was efficient in fitting and predicting the level of agroecosystem functions provided by a cover crop species in mixture in actual conditions. The models fitted for bispecific mixtures were efficient to represent the behavior of each species in mixture and to estimate the legume proportion which expressed the species dominance. The models were evaluated as satisfactory for crop growth rate and C:N ratio for their generality in predicting the agroecosystem functions provided in mixtures by other species not used in the model calibration step, which illustrates the relevance and robustness of the approach.
  • Authors:
    • Xu,X.
  • Source: Acta Scientiae Circumstantiae
  • Volume: 35
  • Issue: 8
  • Year: 2015
  • Summary: Farmland releases greenhouse gases, therefore is of great importance to climate change. Carbon footprint is an ideal method to evaluate comprehensive greenhouse gas emissions of crops through the entire life cycle. This study took Jinzhong City, Shanxi Province, a typical winter wheat planting area as an example. Carbon footprint of wheat production was calculated using life cycle assessment. Furthermore, carbon footprint was optimized based on nonlinear programming aiming at reducing carbon emission as well as increasing crop unit yield. Results showed that, after energy-based allocating, carbon footprint for 1000 kg wheat production was 1357.28 kg CO2 equivalent under traditional farm management. Two major phrases of carbon footprint generation were N2O emission from farmland and urea manufacture. Through altering the fertilizer amount and adjusting the ratio of urea and mature, carbon footprint of 1000 kg wheat production could be reduced to 469.99 kg CO2 equivalent, with 9.13% increase in unit yield. Carbon footprint of wheat production in Jinzhong City showed great difference with results from previous studies in China, which was most likely due to various fertilizer amounts and N2O emission coefficients in different studies. This study provides important information in integrated greenhouse gas emissions of wheat production and quantitative methods to decrease carbon emission and increase crop yield. ©, 2015, Science Press. All right reserved.
  • Authors:
    • Jarchow, M.
    • Horton, R.
    • Pederson, C. H.
    • Helmers, M. J.
    • Zhou, X. B.
    • Daigh, A. L. M.
    • Liebman, M.
  • Source: Journal of Environmental Quality
  • Volume: 44
  • Issue: 5
  • Year: 2015
  • Summary: We compare subsurface-drainage NO 3-N and total reactive phosphorus (TRP) concentrations and yields of select bioenergy cropping systems and their rotational phases. Cropping systems evaluated were grain-harvested corn-soybean rotations, grain- and stover-harvested continuous corn systems with and without a cover crop, and annually harvested reconstructed prairies with and without the addition of N fertilizer in an Iowa field. Drainage was monitored when soils were unfrozen during 2010 through 2013. The corn-soybean rotations without residue removal and continuous corn with residue removal produced similar mean annual flow-weighted NO 3-N concentrations, ranging from 6 to 18.5 mg N L -1 during the 4-yr study. In contrast, continuous corn with residue removal and with a cover crop had significantly lower NO 3-N concentrations of 5.6 mg N L -1 when mean annual flow-weighted values were averaged across the 4 yr. Prairies systems with or without N fertilization produced significantly lower concentrations below <1 mg NO 3-N L -1 than all the row crop systems throughout the study. Mean annual flow-weighted TRP concentrations and annual yields were generally low, with values <0.04 mg TRP L -1 and <0.14 kg TRP ha -1, and were not significantly affected by any cropping systems or their rotational phases. Bioenergy-based prairies with or without N fertilization and continuous corn with stover removal and a cover crop have the potential to supply bioenergy feedstocks while minimizing NO 3-N losses to drainage waters. However, subsurface drainage TRP concentrations and yields in bioenergy systems will need further evaluation in areas prone to higher levels of P losses.