• Authors:
    • Fontana,M.
    • Berner,A.
    • Mäder,P.
    • Lamy,F.
    • Boivin,P.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 5
  • Year: 2015
  • Summary: soil conservation practices are growingly used with different aims such as reducing fuel consumption and preserving soil organic carbon (soc). among others, reduced tillage (rt) often replaces conventional tillage (ct). However, the compared impact of these practices on soil quality remains a matter of controversy. Moreover, the various changes expected are rarely considered all together though they are known to interact. this study aimed at characterizing together the changes in soc, microbial activity, and a large set of physical properties when comparing rt and ct performed on a clayey soil. shrinkage analysis allowed to characterize simultaneously the soil pore systems, their volume, air and water content, the hydro-structural stability, and the swelling properties of the soil. analysis of covariance (ancoVa) was used to compare the soil properties taking in account clay content variability. we showed that clay and soc changes induced most of the variance of the other parameters. at standardized clay content soc was increased with rt in the topsoil and homogenized with smaller values in the ct layer. Many soil physical and biochemical properties were enhanced accordingly with rt which induced a more stable soil with increased porosity and improved microbial activity. sharp changes in soil quality seem to occur at the ct plow limit, while smooth changes with depth are observed with rt. independently from the soc increase with rt, changes in physical properties and microbial activity could be due to mechanical stress in ct or changes in organic matter quality in rt. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All Rights reserved.
  • Authors:
    • Meriem, S.
    • Triadiati, T.
    • Leuschner, C.
    • Kotowska, M. M.
    • Hertel, D.
  • Source: Primary Research Article
  • Volume: 21
  • Issue: 10
  • Year: 2015
  • Summary: Natural forests in South-East Asia have been extensively converted into other land-use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large-scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPP total) in above- and belowground tree biomass in land-use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above- and belowground carbon pools in tree biomass together with NPP total in natural old-growth forests, 'jungle rubber' agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land-use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha -1) was more than two times higher than in jungle rubber stands (147 Mg ha -1) and > four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha -1). NPP total was higher in the natural forest (24 Mg ha -1 yr -1) than in the rubber systems (20 and 15 Mg ha -1 yr -1), but was highest in the oil palm system (33 Mg ha -1 yr -1) due to very high fruit production (15-20 Mg ha -1 yr -1). NPP total was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha -1) but also in carbon sequestration as carbon residence time (i.e. biomass-C:NPP-C) was 3-10 times higher in the natural forest than in rubber and oil palm plantations.
  • Authors:
    • Kurganova,I.
    • Gerenyu,V. L. de
    • Kuzyakov,Y.
  • Source: Research Articles
  • Volume: 133
  • Year: 2015
  • Summary: Most land use changes (LUC) significantly affect the amount of carbon (C) sequestered in vegetation and soil, thereby, shifting the C balance in ecosystems. Disintegration of the USSR and the followed collapse of collective farming system have led to abandonment of more than 58 million ha (Mha) of former croplands in Russia and Kazakhstan that comprise together about 90% of land area in the former USSR. This was the most widespread and abrupt LUC in the 20th century in the northern hemisphere. The spontaneous withdrawal of croplands in 1990s caused several benefits for environment including substantial C sequestration in post-agrogenic ecosystems. The new estimations of net ecosystem production (NEP) and changes in soil organic carbon stocks (Delta SOC) in post-agrogenic ecosystems presented here are based on the uniform bio-climatic approach, and hereby, allow to update C balance of the former USSR. The total extra C sink in abandoned croplands in Russia (45.5 Mha) and Kazakhstan (12.9 Mha) is estimated to be 15527 Mt C yr -1 and 312 Mt C yr -1, respectively. This additional C sink could cover about 18% of the global CO 2 release due to deforestation and other land use changes or compensate annually about 36% and 49% of the current fossil fuel emissions in Russia and Kazakhstan, respectively. The extra C sink to the post-agrogenic ecosystems in Russia and Kazakhstan contributes possibly about 1/3 part to the total current C balance of the former USSR. Hence, the disintegration of the former USSR significantly affected national and global C budget over few decades after LUC.
  • Authors:
    • HongYeng, L.
    • Agamuthu, P.
  • Source: Article
  • Volume: 103
  • Issue: 2
  • Year: 2015
  • Summary: High levels of nitrogen (N) are typically used in leafy vegetable farms to maximize production. However, such practice often leads to nutrient pollution. Hence, N balance in intensive leafy vegetable farm production must be explored to improve current farm management practices and to avoid environmental pollution. This study aimed to generate partial N balance in two organic (OF1 and OF2) and two conventional (CF1 and CF2) vegetable farms by employing material flow analysis/substance flow analysis in the STAN modeling software. Results showed that 31,556, 32,798, 19,498, and 19,337 t ha(-1) y(-1) of materials entered CF1, CF2, OF1, and OF2, respectively, and contributed to the nitrogen surplus levels of 1577, 1667, 2953, and 961 kg N ha(-1) y(-1), respectively. The STAN model revealed the presence of N surplus in the organic and conventional systems used in the study.
  • Authors:
    • Lupwayi, N.
    • Blackshaw, R.
    • Li, L
    • Pearson, D.
    • Larney, F.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Dry bean ( Phaseolus vulgaris L.) production on the Canadian prairies has traditionally used wide rows, inter-row cultivation, and undercutting at harvest. Recent breeding efforts have produced cultivars with more upright growth which are better suited to solid-seeded narrow-row production systems. A 12 yr (2000-2011) study compared conservation (CONS) and conventional (CONV) management for dry bean in 3- to 6-yr rotations. The CONS rotations included reduced tillage, cover crops, feedlot manure compost, and solid-seeded narrow-row dry bean. Effects of CONS management on plant density were inconsistent with some years showing lower density when seeded into high-residue conditions. On average, there was a 3 d maturity advantage with CONS (103 d) vs. CONV (106 d) management. The CONS rotations showed significantly higher mean incidence (19%) of white mold [ Sclerotinia sclerotiorum (Lib.) de Bary] than CONV rotations (6%). Averaging across 12 yr, there was no significant rotation effect on yield ( P=0.19) showing that CONS production performed as good as CONV production. In the last 2 yr (2010-2011) of the study, in an attempt to reduce harvest losses, CONS dry bean was undercut rather than direct combined. This led to significantly higher (25%) yield with CONS (3311 kg ha -1) vs. CONV management (2651 kg ha -1). Our results provide incentive for more rapid adoption of conservation-oriented soil and crop management practices for dry bean production on the Canadian prairies, including narrow rows, reduced tillage, cover crops, and feedlot manure compost addition.
  • Authors:
    • Grehan, E.
    • Tournebize, J.
    • Billen, G.
    • Garnier, J.
    • Benoit, M.
    • Bruno, M.
  • Source: Article
  • Volume: 213
  • Year: 2015
  • Summary: Agricultural activities can lead to nitrogen losses in the environment, particularly nitrate (NO 3-) leaching and nitrous oxide (N 2O) emissions. This study aims to measure N losses from organic farming (OF) and conventional farming (CF) arable cropping systems, both adopted in a single farm, located on the same drained loamy soil in the Seine basin, in the North of France. Leaching was measured with ceramic cups and N 2O emissions with automatic and manual chambers over the 2011-2014 period. Manual chambers showed the same trend as automatic chambers but underestimated small variations and overestimated peak emissions. On average, N 2O emissions were lower in OF (0.650.64 kg N ha -1 yr -1) than in CF fields (0.950.77 kg N ha -1 yr -1). The mean amount of N leached was 13.3 kg N ha -1 yr -1 in the OF system during the 8-crops rotation (alfalfa 1, alfalfa 2, wheat, green bean, wheat, faba bean, wheat, flax) and 18.4 kg N ha -1 yr -1 in the CF system for a 3-crops CF rotation (legume, wheat, wheat), corresponding to 9 and 10% of total N inputs, respectively. Leached N and N 2O emissions expressed per unit of protein-N harvested were slightly higher in CF (0.11 kg NO 3-N kg -1 N yr -1 and 5.4 N 2O-N kg -1 N yr -1, respectively) than in OF systems (0.10 kg NO 3-N kg -1 N yr -1 and 4.7 g N 2O-N kg -1 N yr -1, respectively). These results show a relative lower environmental impact of OF practices compared to CF practices (-30% area-scaled and -12% yield-scaled for leaching and N 2O emissions), with further margins of progress in both systems, including a better management of fertilisers, legumes and catch-crops.
  • Authors:
    • Hermansen, J. E.
    • Chirinda, N.
    • Olesen, J. E.
    • Meyer-Aurich, A.
    • Knudsen, M. T.
  • Source: Journal of Cleaner Production
  • Volume: 64
  • Issue: February
  • Year: 2014
  • Summary: Many current organic arable agriculture systems are challenged by a dependency on imported livestock manure from conventional agriculture. At the same time organic agriculture aims at being climate friendly. A life cycle assessment is used in this paper to compare the carbon footprints of different organic arable crop rotations with different sources of N supply. Data from long-term field experiments at three different locations in Denmark were used to analyse three different organic cropping systems ('Slurry', 'Biogas' and 'Mulching'), one conventional cropping system ('Conventional') and a "No input" system as reference systems. The 'Slurry' and 'Conventional' rotations received slurry and mineral fertilizer, respectively, whereas the 'No input' was unfertilized. The 'Mulching' and 'Biogas' rotations had one year of grass-clover instead of a faba bean crop. The grass-clover biomass was incorporated in the soil in the 'Mulching' rotation and removed and used for biogas production in the 'Biogas' rotation (and residues from biogas production were simulated to be returned to the field). A method was suggested for allocating effects of fertility building crops in life cycle assessments. The results showed significantly lower carbon footprint of the crops from the 'Biogas' rotation (assuming that biogas replaces fossil gas) whereas the remaining crop rotations had comparable carbon footprints per kg cash crop. The study showed considerable contributions caused by the green manure crop (grass-clover) and highlights the importance of analysing the whole crop rotation and including soil carbon changes when estimating carbon footprints of organic crops especially where green manure crops are included. (C) 2013 Elsevier Ltd. All rights reserved.
  • Authors:
    • Gavito, M. E.
    • Garciarreal, A.
    • Villamil-Echeverri, L.
    • Merlin-Uribe, Y.
    • Astier, M.
    • Masera, O. R.
  • Source: Ecological Indicators
  • Volume: 43
  • Issue: August
  • Year: 2014
  • Summary: There is a worldwide growing awareness of the negative impacts of the increasing fossil fuel reliance and greenhouse gas (GHG) emissions from agriculture, in particular for intensive crop systems. We analyze the energy balances and greenhouse gas emissions from export-oriented avocado orchards in Mexico. Avocado is a very important export crop and one of the main drivers of land-use change in the country. We compared 12 avocado orchards under organic and conventional management during two production cycles (2010 and 2011) in a representative region of Central Mexico. Our analysis shows no significant differences in energy consumption and GHG emissions between organic and conventional systems with 55 and 56 GJ ha(-1), and 3.30 t CO2 equiv. ha(-1) and 3.57 t CO2 equiv. ha(-1), respectively. Organic systems show three times more use of renewable energy than their conventional counterparts. However both systems depend heavily on fossil fuel inputs, machinery and N-fertilizers (synthetic or organic). Also, there is a high heterogeneity in management practices and input application within both systems, which is reflected in a large variation of their energy-related parameters. Given that avocado production is rapidly expanding in Mexico, a move toward organic production without systematically changing toward less fossil fuel dependent agricultural practices would not be sufficient to ensure a sustainable production. (c) 2014 Elsevier Ltd. All rights reserved.
  • Authors:
    • Burmester, C. H.
    • Balkcom, K. S.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 2
  • Year: 2014
  • Summary: Alabama wheat ( Triticum aestivum L.) farmers are changing management practices, which include using higher N fertilizer rates and planting wheat with no-tillage or other conservation tillage systems to maximize yields. Experiments were conducted to (i) determine the level of tillage necessary to optimize wheat yields across different regions of Alabama and (ii) determine if N requirements change across tillage systems and regions in Alabama at four locations resulting in 9 site-year comparisons. Each experiment consisted of a split-plot design with tillage as the main plot and 12 N fertilizer treatments as subplots, replicated four times to compare Zadoks' Growth Stage (GS)-30 tiller densities, tiller N concentrations, tiller biomass, GS-31 wheat biomass, biomass N concentration, wheat yields, and grain crude protein. Nitrogen treatments consisted of different rates across fall, GS-30, and GS-31 application times. Tillage systems had no effect on tiller density, tiller N concentration, or tiller biomass, but fall N increased tiller density 15% and tiller biomass 34% across Coastal Plain locations. Non-inversion tillage increased wheat yields 13% on Coastal Plain soils compared to conventional tillage. Fall N increased wheat yields 10%, and N applied at GS-30 improved yields 18% compared to delaying application until GS-31, indicating application of fall N and applying total N by GS-30 was imperative for successful wheat production on Coastal Plain soils. Neither tillage system nor N applications affected wheat production extensively across the Limestone Valley. Non-inversion tillage or no-tillage with current recommended N practices can be successfully used in Alabama wheat production.
  • Authors:
    • Mahanta, S. K.
    • Ghosh, P. K.
  • Source: Invited Article
  • Volume: 35
  • Issue: 2
  • Year: 2014
  • Summary: Globally soils contain around twice the amount of carbon in the atmosphere and thrice in vegetation. Therefore, soil is both 'a source and a sink' for greenhouse gases and balance between the functions is very delicate. The gases move continuously from one pool to another maintaining balance in different pools of the ecosystem. Appropriate management of soil offers to the potential to provide solutions for each of the challenges related to food security and climate change. The estimated carbon sequestration potential of world soils lies between 0.4 to 1.2 Gt per year which includes 0.01-0.30 Gt per year from grasslands. Carbon sequestration can be enhanced in grasslands through grazing management, sowing favorable forage species, fertilizer application and irrigation, restoration of degraded grasslands etc. However, there are certain limitations that hinder in adopting the practices for enhancing carbon sequestration in grasslands. The limitations include continuous degradation of grasslands, changing climate, paucity of information on carbon stock of grasslands from developing countries, disagreement on systems for documenting carbon stock changes over a period of time, hindrance in policy implementations etc.