• Authors:
    • Zheng, J. F.
    • Pan, G. X.
    • Li, L. Q.
    • Zhang, X. H.
    • Zhang, A F.
    • Liu, Y. M.
    • Kibue, G. W.
    • Ye, Y. X.
    • Liu, X. Y.
    • Zheng, J. W.
  • Source: Agricultural Systems
  • Volume: 129
  • Year: 2014
  • Summary: Biochar's effects on improving soil fertility, enhancing crop productivity and reducing greenhouse gases (GHGs) emission from croplands had been well addressed in numerous short-term experiments with biochar soil amendment (BSA) mostly in a single crop season/cropping year. However, the persistence of these effects, after a single biochar application, has not yet been well known due to limited long-term field studies so far. Large scale BSA in agriculture is often commented on the high cost due to large amount of biochar in a single application. Here, we try to show the persistence of biochar effects on soil fertility and crop productivity improvement as well as GHGs emission reduction, using data from a field experiment with BSA for 5-crop seasons in central North China. A single amendment of biochar was performed at rates of 0 (C0), 20 (C20) and 40 t ha -1 (C40) before sowing of the first crop season. Emissions of CO 2, CH 4 and N 2O were monitored with static closed chamber method throughout the crop growing season for the 1st, 2nd and 5th cropping. Crop yield was measured and topsoil samples were collected at harvest of each crop season. BSA altered most of the soil physico-chemical properties with a significant increase over control in soil organic carbon (SOC) and available potassium (K) content. The increase in SOC and available K was consistent over the 5-crop seasons after BSA. Despite a significant yield increase in the first maize season, enhancement of crop yield was not consistent over crop seasons without corresponding to the changes in soil nutrient availability. BSA did not change seasonal total CO 2 efflux but greatly reduced N 2O emissions throughout the five seasons. This supported a stable nature of biochar carbon in soil, which played a consistent role in reducing N 2O emission, which showed inter-annual variation with changes in temperature and soil moisture conditions. The biochar effect was much more consistent under C40 than under C20 and with GHGs emission than with soil property and crop yield. Thus, our study suggested that biochar amended in dry land could sustain a low carbon production both of maize and wheat in terms of its efficient carbon sequestration, lower GHGs emission intensity and soil improvement over 5-crop seasons after a single amendment.
  • Authors:
    • Li, S.
    • You, D. H.
    • Lu, X. C.
    • Liu, T.
    • Tian, X. H.
    • Wang, S. J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Soil water, organic C, and N management practices exert strong influences on winter wheat ( Triticum aestivum L.) yield and soil properties under dryland farming conditions. Here, a 9-yr field experiment was conducted in northwestern China using treatments that included nine factorial combinations of three cultivation practices, conventional cultivation (CC), straw mulching (SM), and supplementary irrigation (SI), and three N application rates (0, 120, and 240 kg N ha -1). Relative yield gradually declined under CC and SM with N, yet remained steady under SI. Without N, yield decreased by 50 to 60%. Soil organic carbon (SOC), labile organic carbon (LOC), total nitrogen (TN), and available potassium (AK) in the 0 to 20 cm (upper) soil layer were significantly increased by SM but were unaffected by SI treatments. After wheat harvest, N application increased SOC, LOC, and TN in the upper soil layer by an average of 4.81, 20.70, and 7.61%, respectively, and decreased AK by 6.12%. The cultivation practice and N fertilizer effects on soil properties were more pronounced in upper than deeper layer (20-40 cm). At soil depths of 0 to 100 cm, nitrate accumulation under N 240 exceeded 69.27% of the critical environmental risk value. Thus, SI+N 120 achieved a high and stable wheat yield, and SM+N 120 increased soil fertility. However, the two combinations applied over 9 yr did not meet both high soil fertility and high productivity needs. Additionally, cultivation practices with high N fertilizer are not sustainable soil management techniques in dryland regions.
  • Authors:
    • Simmons, A.
    • Muir, S.
    • Brock, P.
  • Source: Conference Paper
  • Volume: 3
  • Year: 2014
  • Summary: Australian agricultural industries contribute approximately 14.6% of net annual national greenhouse gas (GHG) emissions, with N 2O emissions from agricultural soils the second greatest source of these emissions. Given that 25 M ha of land in Australia is cropped, the technical potential for GHG emissions reduction in Australian grain production systems is substantial. The New South Wales Department of Primary Industries (NSW DPI) has developed research capacity in Life Cycle Assessment (LCA) to assess this mitigation potential. In this paper we provide insights into the regionally-specific approach that we are taking, not only to provide credible management options at a grain grower level and ensure that detailed data are available for analysis by participants in the downstream supply chain, but also to provide data which, in an aggregated form, will underpin market access and inform national policy development. We report on initial NSW DPI studies and discuss a new project, funded by the Grains Research and Development Corporation (GRDC), to determine emissions reduction opportunities for each of Australia's agro-ecological zones. Initial studies show total emissions from wheat production in the order of 200 kg CO 2-e per tonne, with values ranging down to 140 kg CO 2-e per tonne. In one study, replacing synthetic nitrogenous fertiliser with biologically fixed N reduced emissions to 33% of prior values. The new project is particularly concerned with developing accurate foreground data by triangulating several sources of published literature (including official statistics) and conducting 'groundtruthing' through panels of regionally-based advisors to increase data specificity. The LCAs and associated mitigation strategies will be underpinned by a median and relevant distribution of values for inputs, practices and yields, with system assumptions clearly documented.
  • Authors:
    • Walter, C.
    • Viaud, V.
    • Michot, D.
    • McBratney, A.
    • Minasny, B.
    • Lacoste, M.
  • Source: Research Article
  • Volume: 213
  • Year: 2014
  • Summary: Soil organic carbon (SOC) is a key element of agroecosystems functioning and has a crucial impact on global carbon storage. At the landscape scale, SOC spatial variability is strongly affected by natural and anthropogenic processes and linear anthropogenic elements (such hedges or ditches). This study aims at mapping SOC stocks distribution in the A-horizons for a depth up to 105 cm, at a high spatial resolution, for an area of 10 km(2) in a heterogeneous agricultural landscape (North-Western France). We used a data mining tool, Cubist, to build rule-based predictive models and predict SOC content and soil bulk density (BD) from a calibration dataset at 8 standard layers (0 to 7.5 cm, 7.5 to 15 cm, 15 to 30 cm, 30 to 45 cm, 45 to 60 cm, 60 to 75 cm, 75 to 90 cm and 90 to 105 cm). For the models calibration, 70 sampling locations were selected within the whole study area using the conditioned Latin hypercube sampling method. Two independent validation datasets were used to assess the performance of the predictive models: (i) at landscape scale, 49 sampling locations were selected using stratified random sampling based on a 300-m square grid; (ii) at hedge vicinity, 112 sampling locations were selected along transects perpendicular to 14 purposively chosen hedges. Undisturbed samples were collected at fixed depths and analysed for BD and SOC content at each sampling location and continuous soil profiles were reconstructed using equal-area splines. Predictive environmental data consisted in attributes derived from a light detection and ranging digital elevation model (LiDAR DEM), geological variables, land use data and a predictive map of A-horizon thickness. Considering the two validation datasets (at landscape scale and hedge vicinity), root mean square errors (RMSE) of the predictions, computed for all the standard soil layers (up to a depth of 105 cm), were respectively 7.74 and 5.02 g kg(-1) for SOC content, and 0.15 and 021 g cm(-3) for BD. Best predictions were obtained for layers between 15 and 60 cm of depth. The SOC stocks were calculated over a depth of 105 cm by combining the prediction of SOC content and BD. The final maps show that the carbon stocks in the soil below 30 cm accounted for 33% of the total SOC stocks on average. The whole method produced consistent results between the two predicted soil properties. The final SOC stocks maps provide continuous data along soil profile up to 105 cm, which may be critical information for supporting carbon policy and management decisions. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Alvaro-Fuentes,J.
    • Plaza-Bonilla,D.
    • Arrue,J. L.
    • Lampurlanes,J.
    • Cantero-Martinez,C.
  • Source: Plant and Soil
  • Volume: 376
  • Issue: 1-2
  • Year: 2014
  • Summary: The duration of soil organic carbon (SOC) sequestration in agricultural soils varies according to soil management, land-use history and soil and climate conditions. Despite several experiments have reported SOC sequestration with the adoption of no-tillage (NT) in Mediterranean dryland agroecosystems scarce information exists about the duration and magnitude of the sequestration process. For this reason, 20 years ago we established in northeast Spain a NT chronosequence experiment to evaluate SOC sequestration duration under Mediterranean dryland conditions. In July 2010 we sampled five chronosequence phases with different years under NT (i.e., 1, 4, 11, and 20 years) and a continuous conventional tillage (CT) field, in which management prevailed unchanged during decades. Soil samples were taken at four depths: 0-5, 5-10, 10-20 and 20-30 cm. The SOC stocks were calculated from the SOC concentration and soil bulk density. Furthermore, we applied the Century ecosystem model to the different stages of the chronosequence to better understand the factors controlling SOC sequestration with NT adoption. Differences in SOC stocks were only found in the upper 5 cm soil layer in which 4, 11 and 20 years under NT showed greater SOC stocks compared with 1 year under NT and the CT phase. Despite no significant differences were found in the total SOC stock (0-30 cm soil layer) there was a noteworthy difference of 5.7 Mg ha(-1) between the phase with the longest NT duration and the phase under conventional tillage. The maximum annual SOC sequestration occurred after 5 years of NT adoption with almost 50% change in the annual rate of SOC sequestration. NT sequestered SOC over the 20 years following the change in management. However, more than 75% of the total SOC sequestered was gained during the first 11 years after NT adoption. The Century model predicted reasonably well SOC stocks over the NT chronosequence. In Mediterranean agroecosystems, despite the continuous use of NT has limited capacity for SOC sequestration, other environmental and agronomic benefits associated to this technique may justify the maintenance of NT over the long-term.
  • Authors:
    • Miller, P. R.
    • O'Dea, J. K.
    • Jones, C. A.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 68
  • Issue: 4
  • Year: 2013
  • Summary: Replacing summer fallow practices with annual legumes as green manures (LGMs) may increase the sustainability of northern Great Plains wheat (Triticum aestivum L.) systems. Viability hinges on soil water use management and realizing biologically fixed nitrogen (N) benefits. Plot-scale research has shown that managing LGMs with first-flower stage termination and no-till practices conserves soil water and that rotational N benefits can increase wheat grain quality Nonetheless, farmer adoption of LGMs has been negligible. To better understand this practice and its regional adoption potential, we conducted a participatory on-farm assessment of no-till LGM versus summer fallow wheat rotations in north-central Montana. Soil water and nitrate (NO3) levels to 0.9 m (3 ft), potentially mineralizable N (PMN) to 0.3 m (1 ft), wheat yields, conservation potential, and producer adoption challenges were assessed at five farmer-managed, field-scale sites. Compared to fallow, LGM treatment diminished mean wheat yield by 6% (0.24 Mg ha(-1) [3.7 bu ac(-1)]), diminished grain protein by 9 g kg(-1) when wheat was fertilized with N (p = 0.01), and increased grain protein by 5 g kg(-1) when wheat was unfertilized (p = 0.08). Small soil water depletions in LGM treatments below fallow at wheat seeding (17%; 30 mm [1.2 in]) and near-record high rainfall during the wheat growing season (280 to 380 mm [11 to 14 in]) suggest that LGMs likely did not limit soil water available to wheat in this study. Soil NO3 levels following LGMs were 29% to 56% less than summer fallow at wheat seeding, and conversely, greater PMN was detected in LGM treatments at 3 of 5 sites. We theorize that N mineralization from LGMs was insubstantial by wheat seeding due to dry soil conditions and low LGM biomass N contributions, consequently affecting wheat yield potential due to limited early season soil N availability. LGMs increased average use efficiency of available N by 24% during the wheat year and increased total residue carbon (C) and N returned to soils by 260 and 26 kg ha(-1) (232 and 23 lb ac(-1)), respectively, after two years. Our results illustrated that farmers viably managed LGM soil water use with early termination and no-till practices but that LGM adoption may be hindered by a lack of immediate wheat yield or protein benefits from legume-N and seed costs for LGMs. Appropriate incentives, management strategies, and yield benefit expectations (short versus long term) should be fostered to increase the adoption potential of this N-economizing soil and water conservation strategy.
  • Authors:
    • Berns, A. E.
    • Knicker, H.
    • Panettieri, M.
    • Murillo, J. M.
    • Madejon, E.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 177
  • Year: 2013
  • Summary: The impact on soil aggregates status of two tillage practices (moldboard plowing, TT, and chisel plowing, RT) applied to a farm previously cultivated under no-tillage (NT) was studied. The experiment was carried out on a Leptic Typic Xerorthent soil at the "Las Navas" dryland experimental farm located in Jerez de la Frontera (Cadiz, SW Spain). Several organic C pools such as total organic carbon (TOC), water soluble carbon (WSC), permanganate oxidizable carbon (POxC), and microbial biomass carbon (MBC) were analyzed, together with two enzymatic activities related to soil organic matter (SOM) oxidization metabolism: dehydrogenase activity (DH) and beta-glucosidase activity (beta-Glu). 13C cross polarization magic angle spinning nuclear magnetic resonance ( 13C CPMAS NMR) spectroscopy was used to characterize the composition of the SOM and its degradation status. Two years after the implementation of the new management practices, analysis of the aggregate distribution of the topsoil (0-10 cm) showed that, even after a short term, TT enhanced aggregate disruption. The apparent reduction in soil quality of TT plots was evident from the lower contents of total organic carbon (TOC), permanganate oxidizable carbon (POxC) and microbial biomass carbon (MBC) if compared with RT and NT. Moreover, TT soil showed also a lower beta-glucosidase activity. As confirmed by 13C CPMAS NMR, the SOM of the TT fractions revealed higher alkyl C to O-alkyl ratios than their RT and NT counterparts. Also signals commonly referred to lignin structures were absent in the spectra of the TT fractions, but were still present in those of the larger fractions of the NT treatment. After a short term evaluation, RT samples did not show the same declining trend as observed for the TT treatment. For this reason, chisel plowing seems to offer a viable occasional management option when required during long-term NT.
  • Authors:
    • Ruzibaev, E.
    • Akramkhanov, A.
    • Lamers, J. P. A.
    • McDonald, A.
    • Mirzabaev, A.
    • Ibragimov, N.
    • Kienzler, K. M.
    • Egamberdiev, O.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: Rainfed and irrigated agricultural systems have supported livelihoods in the five Central Asian countries (CAC) for millennia, but concerns for sustainability and efficient use of land and water resources are long-standing. During the last 50 years, resource conserving technologies were introduced in large parts of the rainfed areas while the irrigated areas were expanded largely without considering resource conservation. In more recent years, the use of conservation agriculture (CA) practices has been reported for the different agricultural production (AP) zones in CAC, albeit centering on a single AP zone or on single factors such as crop yield, implements or selected soil properties. Moreover, conflicting information exists regarding whether the current practices that are referred to as 'CA' can indeed be defined as such. Overall information on an application of CA-based crop management in Central Asia is incomplete. This discussion paper evaluates experimental evidence on the performance of CA and other resource conserving technologies in the three main AP zones of CAC, provides an overview of farmer adoption of production practices related to CA, and outlines technical and non-technical challenges and opportunities for the future dissemination of CA practices in each zone. Agronomic (e.g. implements, crop yields, duration. and crop residues), institutional (e.g. land tenure) and economic (e.g. short vs. long-term profitability) perspectives are considered. At present, adoption of CA-based agronomic practices in the rainfed production zone is limited to partial crop residue retention on the soil surface or sporadically zero tillage for one crop out of the rotation, and hence the use of single CA components but not the full set of CA practices. In the irrigated AP zones, CA is not commonly practiced and many of the pre-conditions that typically encourage the rapid spread of CA practices appear to be absent or limiting. Further, our analysis suggests that given the diversity of institutional, socio-economic and agro-ecological contexts, a geographically differentiated approach to CA dissemination is required in the CAC. Immediate priorities should include a shift in research paradigms (e.g. towards more participatory approaches with farmers), development of commercially available reduced and no-till seeders suitable for smaller-scale farm enterprises, and advocacy so that decision makers understand how different policies may encourage or discourage innovations that lead towards more sustainable agricultural intensification in the CAC.
  • Authors:
    • Ahuja, L. R.
    • Saseendran, S. A.
    • Green, T. R.
    • Ma, L. W.
    • Nielsen, D. C.
    • Walthall, C. L.
    • Ko, J. H.
  • Source: Climatic Change
  • Volume: 111
  • Issue: 2
  • Year: 2012
  • Summary: Agricultural systems models are essential tools to assess potential climate change (CC) impacts on crop production and help guide policy decisions. In this study, impacts of projected CC on dryland crop rotations of wheat-fallow (WF), wheat-corn-fallow (WCF), and wheat-corn-millet (WCM) in the U.S. Central Great Plains (Akron, Colorado) were simulated using the CERES V4.0 crop modules in RZWQM2. The CC scenarios for CO 2, temperature and precipitation were based on a synthesis of Intergovernmental Panel on Climate Change (IPCC 2007) projections for Colorado. The CC for years 2025, 2050, 2075, and 2100 (CC projection years) were super-imposed on measured baseline climate data for 15-17 years collected during the long-term WF and WCF (1992-2008), and WCM (1994-2008) experiments at the location to provide inter-annual variability. For all the CC projection years, a decline in simulated wheat yield and an increase in actual transpiration were observed, but compared to the baseline these changes were not significant ( p>0.05) in all cases but one. However, corn and proso millet yields in all rotations and projection years declined significantly ( p<0.05), which resulted in decreased transpiration. Overall, the projected negative effects of rising temperatures on crop production dominated over any positive impacts of atmospheric CO 2 increases in these dryland cropping systems. Simulated adaptation via changes in planting dates did not mitigate the yield losses of the crops significantly. However, the no-tillage maintained higher wheat yields than the conventional tillage in the WF rotation to year 2075. Possible effects of historical CO 2 increases during the past century (from 300 to 380 ppm) on crop yields were also simulated using 96 years of measured climate data (1912-2008) at the location. On average the CO 2 increase enhanced wheat yields by about 30%, and millet yields by about 17%, with no significant changes in corn yields.
  • Authors:
    • Martiniello, P.
  • Source: Agricultural Sciences
  • Volume: 3
  • Issue: 1
  • Year: 2012
  • Summary: Agricultural systems based on crop rotations favour sustainability of cultivation and productivity of the crops. Wheat-forage crops rotations (annual winter binary mixture and perennial alfalfa meadow) combined with irrigation are the agronomical techniques able to better exploit the weather resources in Mediterranean environments. The experiment aimed to study the effect of 18 years of combined effect of irrigation and continuous durum wheat and wheat-forage rotations on productivities of crops and organic matter of topsoil. The experiments were established through 1991-2008 under rainfed and irrigated treatments and emphasized on the effect of irrigation and continuous wheat and wheat-forage crop rotations on water use efficiency and sustainability of organic matter. The effect of irrigation increased 49.1% and 66.9% the dry matter of mixture and meadow, respectively. Continuous wheat rotation reduced seed yield, stability of production, crude protein characteristics of kernel and soil organic matter. The yearly gain in wheat after forage crops was 0.04 t (ha yr) 1 under rainfed and 0.07 t (ha yr) -1 under irrigation treatments. The crude protein and soil organic matter of wheat rotations, compared to those of continuous wheat under rainfed and irrigated was increase in term of point percentage by 0.8 and 0.5 in crude protein and 5.1 and 4.4 in organic matter, respectively. The rotations of mixture and meadow under both irrigated treatments increased the point of percentage of organic matter over continuous wheat (9.3.and 8.5 in mixture and 12.5 and 9.5 meadow under rainfed and irrigation, respectively). Irrigation reduce the impact of weather on crop growing reducing water use efficiency (mean over rotations) for dry matter production (15.5 in meadow and 17.5 in mixture [L water (kg dry matter) -1]) and wheat seed yield. The effect of agronomic advantages achieved by forage crops in topsoil expire its effect after three years of continuous wheat rotation.