• Authors:
    • Shonnard, D.
    • Archer, D.
    • Beck, E.
    • Ukaew, S.
  • Source: Journal
  • Volume: 20
  • Issue: 5
  • Year: 2015
  • Summary: Rapeseed is being considered as a potential feedstock for hydrotreated renewable jet (HRJ) fuel in the USA through its cultivation in rotation with wheat. The goal of this research was to determine the impact of soil C changes, induced through replacing the fallow period with rapeseed in rotation with wheat, and the effects it would have on emission of greenhouse gases (GHG) of rapeseed HRJ. The Intergovernmental Panel on Climate Change (IPCC) (Tier 1) method was used with modifications to determine the changes in soil C of wheat-wheat-rapeseed (WWR) relative to the reference wheat-wheat-fallow (WWF) rotation for 20 years of cultivation. The 27 case scenarios were conducted to study the impacts of changes in management practices (tillage practice and residue input) on changes in soil C for WWR rotation in multiple locations in 10 US states. The CO2 emissions resulting from soil C changes were incorporated into the rapeseed HRJ pathway in order to evaluate the GHG emissions. Introducing rapeseed to replace the fallow period with wheat could either increase or decrease changes in soil C, depending on management practices. Soil C is predicted to increase with increased residue input and reduced tillage. The greatest gain of soil C was found when using high residue input for wheat and rapeseed under no tillage, resulting in the best management practice. Conversely, adding low residue input to both crops with full tillage created the highest loss of soil C, referring to as the worst management practice. Soil C changes varied across locations from -0.22 to 0.32 Mg C ha(-1) year(-1). Consequently, the GHG emissions of rapeseed HRJ ranged from 4 to 70 g CO2 eq./MJ, comparing to 46 g CO2 eq./MJ for excluding soil C change. The rapeseed HRJ exhibited the GHG savings of 65-96 % for the best practice and 20-42 % for the worst practice when compared to petroleum jet fuel. Based on results using the modified IPCC method, adoption of high residue input with no tillage for the rotation cropping of rapeseed with wheat had the potential to increase soil C. However, the method has limitations for predicting soil C changes regarding crop management practices. Biogeochemical-based models that have a potential to capture processes of C and N dynamics in soil and yield may be better suited to quantify regional variations in soil C changes for the rotation cropping of rapeseed with wheat.
  • Authors:
    • Yu, Z.
    • Zhang, Y.
    • Shi, Y.
    • Guo, Z.
    • Wang, H.
  • Source: Article
  • Volume: 153
  • Year: 2015
  • Summary: Although the effects of tillage practices on soil properties and root growth is well studied, how they affect nitrogen accumulation and translocation in wheat in dryland regions is poorly understood. Here, the impact of different tillage practices, namely, strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R), and rotary tillage after subsoiling (RS), on nitrogen accumulation and translocation, grain yield, and economic benefit in wheat and soil nitrate-nitrogen leaching in drylands was studied over three wheat growing seasons from 2009 to 2012. The results showed that compared with R, nitrogen accumulation amount under SRS increased by 36.8% from jointing to maturity in 2009-2011 and by 12.9 and 16.4% from sowing to maturity in 2009-2010 and 2010-2011, respectively. Post-anthesis nitrogen accumulation, its contribution rate to grain and nitrogen accumulation in grains at maturity under SRS were 48.3, 31.3 and 12.7% higher, respectively, compared to that under R in 2009-2010. On the other hand, nitrate-nitrogen accumulation under SRS in 0-60cm soil layers was lower in comparison to that under SR and R, which suggested that SRS promoted absorption of nitrate-nitrogen in soil layers by wheat. However, no significant difference in nitrate-nitrogen accumulation in the 60-200cm soil layers was observed between SR and R. Average grain yield, nitrogen production efficiency and economic benefit were all the highest under SRS at 598.78gm-2, 39.9kgkg-1 and 8350.8 RMB¥ha-1, respectively, over the study period. Therefore, we propose that SRS is the optimal tillage practice for wheat production in this region. © 2015 Elsevier B.V.
  • Authors:
    • YaJun, G.
    • QunHu, C.
    • PengWei, Y.
    • ChangWei, Y.
    • Zheng, W.
    • Na, Z.
    • DaBin, Z.
    • WeiDong, C.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Scant rainfall and poor soil fertility are the two major obstructions to crop production on the Loess Plateau. To improve crop productivity and to reduce N fertilizer rates, a 4-yr field experiment was conducted to investigate the effects of leguminous green manure (GM) and N fertilizer on winter wheat ( Triticum aestivum L.) growth, yield, and economics on the Loess Plateau. Following a split-plot design, the main treatments included three legume species: Huai bean ( Glycine ussuriensis Regel et Maack.), soybean [ G. max (L.) Merr.], mung bean ( Phaseolus radiatus L.), and summer fallow (as control treatment [CK]); The subtreatments included four N fertilizer rates that were applied to the wheat. Leguminous GM apparently improved wheat growth, productivity, and nutrient uptake compared to bare fallow, especially during a wet year. At least 2 yr and abundant rainfall are required for bettering the GM approaches. Incorporation of GM for 4 yrs could effectively reduce the N fertilizer rate for wheat by 33% (54 kg N ha -1), with even more potential during a wet year. High expenditures for field management and variable weather patterns led to few direct economic benefits of GM approaches. Huai bean is a more profitable legume species to be used as GM crops. The cultivation of leguminous GM during summer is a better option than bare fallow for sustaining wheat productivity, and decreasing the required N fertilizer rates not only on the Loess Plateau of China but also in the other similar dryland regions around the world.
  • Authors:
    • Ren, X.
    • Han, Q.
    • Jia, Z.
    • Wang, K.
    • Li, Y.
    • Wei, T.
    • Zhang, P.
  • Source: Article
  • Volume: 153
  • Year: 2015
  • Summary: The soil degradation caused by conventional tillage in rain-fed areas of northwest China is known to reduce crop yields because of major losses of soil organic carbon and nutrients. To evaluate the effects of straw incorporation on soil organic carbon (SOC) and total nitrogen (STN) sequestration capacity in loessial soil, we investigated the effects of straw incorporation on SOC, STN and crop yield in semiarid areas of southern Ningxia for a 4-year period (2007-2010). Four treatments were tested: (i) no straw incorporation (NA); (ii) incorporation of maize straw at a low rate of 4.5Mgha-1yr-1 (LA); (iii) incorporation of maize straw at a medium rate of 9.0Mgha-1yr-1 (MA); and (iv) incorporation of maize straw at a high rate of 13.5Mgha-1yr-1 (HA). In the final year (2010), the results showed that the mean soil bulk density in the 0-60cm depth had decreased with high, middle, and low straw incorporation rate treatment compared with no straw incorporation treatment (NA) by 3.7% (P low straw incorporation rate treatment > no straw incorporation treatment. The mean soil C:N ratio was significantly higher with straw incorporation, i.e., 6.9% higher than no straw incorporation treatment. Straw incorporation significantly (P<0.05) increased the stratification ratio of SOC, STN, and soil C:N ratio from the surface (0-10cm) to all depths compared with NA, i.e., the stratification ratio of SOC at the 0-10:20-40cm depth increased with HA, MA and LA by 11.3% (P<0.05), 10.7% (P<0.05), and 4.4%, respectively, compared with no straw incorporation treatment (NA). © 2015.
  • Authors:
    • Grosso, S. J.
    • Spatari, S.
    • Pourhashem, G.
    • Mitchell, J. G.
    • Adler, P. R.
    • Parton, W. J.
  • Source: Research Article
  • Volume: 25
  • Issue: 4
  • Year: 2015
  • Summary: Crop residues are potentially significant sources of feedstock for biofuel production in the United States. However, there are concerns with maintaining the environmental functions of these residues while also serving as a feedstock for biofuel production. Maintaining soil organic carbon (SOC) along with its functional benefits is considered a greater constraint than maintaining soil erosion losses to an acceptable level. We used the biogeochemical model DayCent to evaluate the effect of residue removal, corn stover, and wheat and barley straw in three diverse locations in the USA. We evaluated residue removal with and without N replacement, along with application of a high-lignin fermentation byproduct (HLFB), the residue by-product comprised of lignin and small quantities of nutrients from cellulosic ethanol production. SOC always decreased with residue harvest, but the decrease was greater in colder climates when expressed on a life cycle basis. The effect of residue harvest on soil N 2O emissions varied with N addition and climate. With N addition, N 2O emissions always increased, but the increase was greater in colder climates. Without N addition, N 2O emissions increased in Iowa, but decreased in Maryland and North Carolina with crop residue harvest. Although SOC was lower with residue harvest when HLFB was used for power production instead of being applied to land, the avoidance of fossil fuel emissions to the atmosphere by utilizing the cellulose and hemicellulose fractions of crop residue to produce ethanol (offsets) reduced the overall greenhouse gas (GHG) emissions because most of this residue carbon would normally be lost during microbial respiration. Losses of SOC and reduced N mineralization could both be mitigated with the application of HLFB to the land. Therefore, by returning the high-lignin fraction of crop residue to the land after production of ethanol at the biorefinery, soil carbon levels could be maintained along with the functional benefit of increased mineralized N, and more GHG emissions could be offset compared to leaving the crop residues on the land.
  • Authors:
    • Rachmilevitch, S.
    • Asensio, J. S. R.
    • Bloom, A. J.
  • Source: Research Article
  • Volume: 168
  • Issue: 1
  • Year: 2015
  • Summary: A major contributor to the global carbon cycle is plant respiration. Elevated atmospheric CO 2 concentrations may either accelerate or decelerate plant respiration for reasons that have been uncertain. We recently established that elevated CO 2 during the daytime decreases plant mitochondrial respiration in the light and protein concentration because CO 2 slows the daytime conversion of nitrate (NO 3-) into protein. This derives in part from the inhibitory effect of CO 2 on photorespiration and the dependence of shoot NO 3- assimilation on photorespiration. Elevated CO 2 also inhibits the translocation of nitrite into the chloroplast, a response that influences shoot NO 3- assimilation during both day and night. Here, we exposed Arabidopsis ( Arabidopsis thaliana) and wheat ( Triticum aestivum) plants to daytime or nighttime elevated CO 2 and supplied them with NO 3- or ammonium as a sole nitrogen (N) source. Six independent measures (plant biomass, shoot NO 3-, shoot organic N, 15N isotope fractionation, 15NO 3- assimilation, and the ratio of shoot CO 2 evolution to O 2 consumption) indicated that elevated CO 2 at night slowed NO 3- assimilation and thus decreased dark respiration in the plants reliant on NO 3-. These results provide a straightforward explanation for the diverse responses of plants to elevated CO 2 at night and suggest that soil N source will have an increasing influence on the capacity of plants to mitigate human greenhouse gas emissions.
  • Authors:
    • O'Dea,Justin K.
    • Jones,Clain A.
    • Zabinski,Catherine A.
    • Miller,Perry R.
    • Keren,Ilai N.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 2
  • Year: 2015
  • Summary: In the North American northern Great Plains (NGP), legumes are promising summer fallow replacement/cropping intensification options that may decrease dependence on nitrogen (N) fertilizer in small grain systems and mitigate effects of soil organic matter (SOM) losses from summer fallow. Benefits may not be realized immediately in semiarid conditions though, and longer-term effects of legumes and intensified cropping in this region are unclear, particularly in no-till systems. We compared effects of four no-till wheat (Triticum aestivum L.) cropping systems-summer fallow-wheat (F-W), continuous wheat (CW), legume green manure (pea, Pisum sativum L.)-wheat (LGM-W), and pea-wheat (P-W)-on select soil attributes in an 8-year-old rotation study, and N fertilizer effects on C and N mineralization on a duplicate soil set in a laboratory experiment. We analyzed potentially mineralizable carbon and nitrogen (PMC and PMN) and mineralization trends with a nonlinear model, microbial biomass carbon (MB-C), and wet aggregate stability (WAS). Legume-containing systems generally resulted in higher PMC, PMN, and MB-C, while intensified systems (CW and P-W) had higher WAS. Half-lives of PMC were shortest in intensified systems, and were longest in legume systems (LGM-W and P-W) for PMN. Nitrogen addition depressed C and N mineralization, particularly in CW, and generally shortened the half-life of mineralizable C. Legumes may increase long-term, no-till NGP agroecosystem resilience and sustainability by (1) increasing the available N-supply (similar to 26-50 %) compared to wheat-only systems, thereby reducing the need for N fertilizer for subsequent crops, and (2) by potentially mitigating negative effects of SOM loss from summer fallow.
  • Authors:
    • Scotti-Campos,P.
    • Semedo,J. N.
    • Pais,I. P.
    • Oliveira,M.
    • Passarinho,J.
    • Santos,M.
    • Almeida,A. S.
    • Costa,A. R.
    • Pinheiro,N.
    • Bagorro,C.
    • Coco,J.
    • Costa,A.
    • Coutinho,J.
    • Macas,B.
  • Source: Emirates Journal of Food and Agriculture
  • Volume: 27
  • Issue: 2
  • Year: 2015
  • Summary: Restricted water availability and yield reductions derived from climate changes have become a strong concern as regards fundamental crops, such as wheat. There is an increasing need to characterize germplasm diversity in order to highlight drought tolerant genotypes and to assist Portuguese wheat breeding programs. Bread wheat ( Triticum aestivum) varieties were selected from four different evolutive and/or breeding groups: ancient landraces, traditional varieties, modern currently used and advanced lines. The aim of this work was to identify physiological traits that contribute to drought tolerance during grain filling period. Plants were cultivated in pots, under semi-controlled greenhouse conditions. Drought was imposed by withholding irrigation after anthesis. Well irrigated and water stressed plants were compared as regards leaf gas exchanges (net photosynthetic rate, Pn; leaf stomatal conductance, gs; transpiration, E), instantaneous water use efficiency (iWUE), membrane electrolyte leakage, osmotic potential and leaf pigments. Subsequently, plants were maintained under a controlled irrigation (droughted plants: 50% of the water given to fully irrigated controls) until harvest, to quantify yield. Pn and gs were significantly reduced by drought in all varieties. As regards membrane integrity ancient and traditional varieties presented lower membrane injury, what may reflect a higher protoplasmic tolerance to drought. More evolved varieties (modern and advanced) showed higher spike weight per plant and number of grains per spike, disregard the water regime. Under water deficit 1000 kernel weight was reduced in all varieties except in traditional Pirana, which also showed an increase in the number of spikes per plant. Higher membrane stability, increased pigments and lower osmotic potential under drought may underly such improved response to drought, pointing this variety as an interesting genetic resource for breeding purposes.
  • Authors:
    • Singh,R. J.
    • Ahlawat,I. P. S.
  • Source: Environmental Monitoring and Assessment
  • Volume: 187
  • Issue: 5
  • Year: 2015
  • Summary: Two of the most pressing sustainability issues are the depletion of fossil energy resources and the emission of atmospheric green house gases like carbon dioxide to the atmosphere. The aim of this study was to assess energy budgeting and carbon footprint in transgenic cotton–wheat cropping system through peanut intercropping with using 25–50 % substitution of recommended dose of nitrogen (RDN) of cotton through farmyard manure (FYM) along with 100 % RDN through urea and control (0 N). To quantify the residual effects of previous crops and their fertility levels, a succeeding crop of wheat was grown with varying rates of nitrogen, viz. 0, 50, 100, and 150 kg ha-1. Cotton + peanut–wheat cropping system recorded 21 % higher system productivity which ultimately helped to maintain higher net energy return (22 %), energy use efficiency (12 %), human energy profitability (3 %), energy productivity (7 %), carbon outputs (20 %), carbon efficiency (17 %), and 11 % lower carbon footprint over sole cotton–wheat cropping system. Peanut addition in cotton–wheat system increased the share of renewable energy inputs from 18 to 21 %. With substitution of 25 % RDN of cotton through FYM, share of renewable energy resources increased in the range of 21 % which resulted into higher system productivity (4 %), net energy return (5 %), energy ratio (6 %), human energy profitability (74 %), energy productivity (6 %), energy profitability (5 %), and 5 % lower carbon footprint over no substitution. The highest carbon footprint (0.201) was recorded under control followed by 50 % substitution of RDN through FYM (0.189). With each successive increase in N dose up to 150 kg N ha-1 to wheat, energy productivity significantly reduced and share of renewable energy inputs decreased from 25 to 13 %. Application of 100 kg N ha-1 to wheat maintained the highest grain yield (3.71 t ha-1), net energy return (105,516 MJ ha-1), and human energy profitability (223.4) over other N doses applied to wheat. Application of 50 kg N ha-1 to wheat maintained the least carbon footprint (0.091) followed by 100 kg N ha-1 (0.100). Our study indicates that system productivity as well as energy and carbon use efficiencies of transgenic cotton–wheat production system can be enhanced by inclusion of peanut as an intercrop in cotton and substitution of 25 % RDN of cotton through FYM, as well as application of 100 kg N ha-1 to succeeding wheat crop. © 2015, Springer International Publishing Switzerland.
  • Authors:
    • Smith,E. G.
    • Janzen,H. H.
    • Larney,F. J.
  • Source: Canadian Journal of Soil Science
  • Volume: 95
  • Issue: 2
  • Year: 2015
  • Summary: Long-term cropping system studies offer insights into soil management effects on agricultural sustainability. In 1995, a 6-yr bioassay study was superimposed on a long-term crop rotation study established in 1951 at Lethbridge, Alberta, to determine the impact of past cropping systems on soil quality, crop productivity, grain quality, and the relationship of yield productivity to soil quality. All plots from 13 long-term crop rotations were seeded to wheat ( Triticum aestivum L.) in a strip plot design [control, nitrogen (N) fertilizer]. Prior to seeding, soils were sampled to determine soil chemical properties. Total wheat production for the last 4 yr of the study was used as the measure of productivity. The 1995 soil analysis indicated crop rotations with less frequent fallow and with N input had higher soil quality, as indicated by soil organic carbon (SOC) and light fraction carbon (LF-C) and N (LF-N). SOC had a positive relationship to total wheat yield, but was largely masked by the application of N in this bioassay study. Frequent fallow in the previous crop rotation lowered productivity. The concentration of LF-C had a negative relationship, whereas LF-N had a positive relationship to total wheat yield, with and without N fertilization in this bioassay study. Grain N concentration was higher with applied N and when the long-term rotation included the addition of N by fertilizer, livestock manure, annual legume green manure or legume hay. This study determined that long-term imposition of management practices have lasting effects on soil quality and crop productivity.