• 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:
    • Ashworth,A. J.
    • West,C. P.
    • Allen,F. L.
    • Keyser,P. D.
    • Weiss,S. A.
    • Tyler,D. D.
    • Taylor,A. M.
    • Warwick,K. L.
    • Beamer,K. P.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Biological N 2 fixation (BNF) via legume intercrops can provide an alternative to inorganic N fertilizer and thereby minimize the economic and environmental costs of bioenergy feedstock and forage production. The objectives of this study were to (i) verify switchgrass ( Panicum virgatum L.) as a non-N 2-fixing reference plant for distinguishing between soil- and atmosphere-derived N; (ii) determine BNF levels via the 15N enrichment method for one cool-season legume (red clover [ Trifolium pratense L.]) and three warm-season legumes ([partridge pea] [ Chamaecrista fasciculate Michx.], sunn hemp [ Crotalaria juncea L.], and pigeonpea [ Cajanus cajan (L.) Millsp.]) when intercropped into switchgrass and a near relative, guineagrass ( Panicum maximum L.); and (iii) evaluate the validity of the N-difference method by comparing it against the 15N enrichment technique in humid temperate and semiarid tropical climates. The results revealed little difference in the N assimilation rates of legume and non-N 2-fixing reference plants, suggesting that switchgrass is an appropriate reference species. Annual fixation for red clover was greatest, followed by partridge pea, and lastly sunn hemp in temperate systems (87, 84, and 35 kg ha -1, respectively), all of which tended to supply greater amounts of N in subsequent seasons. Considerably greater BNF occurred in tropical intercrop systems (exceeding 240 kg ha -1). Consequently, the BNF of selected legumes approximates or exceeds recommended N fertilizer rates (67 kg N ha -1) in both humid temperate and semiarid tropical pasture and feedstock systems. The N-difference method did not provide estimates for BNF that were comparable to 15N-enrichment-derived values ( P>0.05).
  • Authors:
    • Deichman, C. L.
    • Kremer, R. J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: The solar corridor crop system (SCCS) is designed for improved crop productivity based on highly efficient use of solar radiation by integrating row crops with drilled or solid-seeded crops in broad strips (corridors) that also facilitate establishment of cover crops for year-round soil cover. The SCCS is an agroecosystem with diverse system structure that should inherently provide many features to build soil quality. Management strategies include reduced tillage, intercropping, and soil conservation through crop residue retention, which are associated with improved soil quality attributes of enhanced C and N content, effective nutrient cycling, and high microbial activity. Our objective was to evaluate the effect of SCCS in 76- and 152-cm (corridor) row widths on selected soil quality indicators as an assessment of soil quality during establishment of SCCS. Microbial activity, measured as soil glucosidase activity, was highest in rhizosphere soils planted to corn ( Zea mays L.) hybrids at 74,000 plants ha -1 regardless of row width. However, soil glucosidase activity was strongly correlated ( r2=0.72) with active carbon (AC), and showed trends for increased contents in rows bordering the corridor. This suggested that increased carbon fixation by plants at the wide row spacing due to greater exposure to solar radiation also increased carbon substrates released into the rhizosphere for microbial metabolism. The limited soil quality assessment conducted in this study demonstrated that an integrated cropping system represented by the SCCS offers an effective management system for maintaining crop production while promoting soil quality and soil conservation.
  • Authors:
    • Jeuffroy, M. H.
    • Hombert, N.
    • Pelzer, E.
    • Makowski, D.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: Numerous studies have been performed to study the effect of N fertilization on cereal-legume intercrops, and their results are sometimes conflicting. Our objective was to do a meta-analysis on cereal-legume intercrops testing the effects of N fertilization on land equivalent ration (LER; partial and total LER), yield ratio, and proportion of legume in the mixture of crop grains. This analysis was based on 17 published studies reporting the results of experiments performed in 15 countries on six species of cereals and 10 species of legumes. Experiments were generally based on replacement (50-50, i.e., in the intercrop, each species is sown at half the sowing rate used for the sole crop) or full substitutive (100-100, i.e., the sowing rate for each crop in the intercrop is identical to that for sole crops) designs. Nitrogen fertilization rates ranged from 0 to 180 kg N ha -1. The effect of N fertilization and its inter-study variability were analyzed with mixed-effect statistical models, including study as a random effect. Results showed that N fertilization had non-significant effects on average LER and average yield ratio but that the inter-study variability of these effects was large. Nitrogen fertilization was found to significantly decrease the grain proportion of the legume in the mixture and the partial LER of the legume in studies based on C 3 cereal intercrops. The database used for the meta-analysis is freely available (http://www6.versailles-grignon.inra.fr/agronomie/Meta-analysis-in-agron omy/Datasets/Dataset-Intercrop).
  • Authors:
    • Mary, B.
    • Jeuffroy, M. H.
    • Amosse, C.
    • David, C.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: Nitrogen (N) management is a key issue in livestock-free organic grain systems. Relay intercropping with a legume cover crop can be a useful technique for improving N availability when two cash crops are grown successively. We evaluated the benefits of four relay intercropped legumes (Medicago lupulina, Medicago sativa, Trifolium pratense and Trifolium repens) on N dynamics and their contribution to the associated and subsequent cash crops in six fields of organic farms located in South-East France. None of the relay intercropped legumes affected the N uptake of the associated winter wheat but all significantly increased the N uptake of the succeeding spring crop, either maize or spring wheat. The improvement of the N nutrition of the subsequent maize crop induced a 30 % increase in grain yield. All relay intercropped legumes enriched the soil-plant system in N through symbiotic fixation. From 71 to 96 % of the N contained in the shoots of the legumes in late autumn was derived from the atmosphere (Ndfa) and varied between 38 and 67 kg Ndfa ha(-1). Even if the cover crop is expected to limit N leaching during wintertime, the presence of relay intercropped legumes had no significant effect on N leaching during winter compared to the control.
  • Authors:
    • Porqueddu, C.
    • Pulina, P.
    • Nieddu, G.
    • Mercenaro, L.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 192
  • Year: 2014
  • Summary: In the Mediterranean area, the use of cover crops in vineyards is still debated and the results of the few scientific experiments considering the influence of cover crop on grapevine are often conflicting. This work aims at providing useful indications on sustainable management for irrigated vineyards growing in a hot and dry region. A five year study was carried out in NW Sardinia, Italy, in a 8 year old vineyard cv. Carignano. To evaluate interactions between grapevine and cover crop as well as the economic impact of intercropping, soil tillage (T1) was compared with 4 inter-row treatments: natural covering (T2), complex commercial grass-legume mixture (T3), simple experimental grass-legume mixture (T4) and perennial grass Dactilys glomerata cv Currie (T5). During the five years of the experiment, the mixtures have ensured a higher level of soil covering compared to the other treatments. Moreover, the covering and the contribution to the dry matter yield for every component of the mixtures changed drastically with an increased presence of D. glomerata. Compared to the soil tillage, the cover crops reduce the vigor but does not affect yield. Regarding fruit quality, only the perennial grass influenced positively the amount of total anthocyanins. The cost analysis has not evidenced strong differences among treatments or limiting factors for growers related to the use of cover crop in vineyards.
  • Authors:
    • Sanclemente Reyes, O. E.
    • Sanchez de Prager, M.
    • Sosa Rodrigues, B. A.
  • Source: Acta Agronomica, Universidad Nacional de Colombia
  • Volume: 63
  • Issue: 4
  • Year: 2014
  • Summary: This study provided knowledge about the agro-ecosystem N dynamics mediated by the use of agroecological practices such as GM. GM is established as legume its symbiotic action with soil rhizobia and arbuscular mycorrhiza formation, allows the cycling of nitrogen and phosphorus, among others. This study aimed at evaluating the influence of GM in the nitrogen dynamics of a Typic Haplustert located in the municipality of Candelaria (Colombia). In completely randomized blocks design with six replications, the GM coming from the intercropping Mucuna pruriens var utilis - Zea mays L. var. ICA 305 was established as T1 treatment and the native arvense Rottboellia cochinchinensis L. as T2, during the second half of year 2011. During the stage of preflowering of M. pruriens the content of organic C (OC) was evaluated as well as total N (TN), nitrate, ammonium, number of copies of amoA gene of ammonia-oxidizing bacteria, total porosity filled with water (TPW), temperature, flow of greenhouse gases: methane (CH 4), carbon dioxide (CO 2) and nitrous oxide (N 2O), as well as the dry matter (DM) and the contents of C, N and P in plant tissues. Significantly higher concentrations (p<0.05) of CO, NT, ammonium and nitrate, were recorded in T2. The number of oxidizing bacteria of ammonium was significantly higher in T1 which coincided with the higher TPW and the lower soil temperature. The emission of atmospheric CO 2 was significantly lower in T1, in contrast to the CH 4 and N 2O which scored the highest values. At the end of the trial, the GM in T1 provided about 4 t MS/ha, 1668.3 kg C/ha, 78.7 kg N/ha and 11.0 kg P/ha, with social economic benefit of 9.2 t corn/ha.
  • Authors:
    • Allen, F. L.
    • Reed, D. L.
    • Taylor, A. M.
    • Ashworth, A. J.
    • Keyser, P. D.
    • Tyler, D. D.
  • Source: JOURNAL OF CLEANER PRODUCTION
  • Volume: 87
  • Year: 2014
  • Summary: As the use of second-generation biofuel crops increases, so do questions about sustainability, particularly their potential to affect fossil energy consumption and greenhouse gas emissions. This study used a life-cycle approach to compare environmental impacts associated with three switchgrass (Panicum virgatum L.) production scenarios: i) regional production from a pool of Tennessee farmers based on in-field inputs and biomass yield; ii) varying nitrogen (N)-input levels from a replicated field study for 8-yrs i.e., a 100% and 9% decrease, and an 81% and 172% increase from 'baseline levels' of N inputs used under objective i; and, iii) a legume-intercrop system compared to baseline levels in order to determine effects of displacing synthetic-N with legumes. When compared across all agricultural inputs, nitrogen fertilizer production and breakdown resulted in the greatest environmental impacts. Although fertilization increased lignocellulosic yields, a 100% reduction in N-inputs from baseline levels reduced the formation of carbon, methane, and nitrous oxides per unit of production, (or dry tonne of biomass over 10-yrs) compared to a 172% increase. Switchgrass yield response indicated a 'less is more' scenario, as inputs beyond the current recommended input level (67 kg N ha-1) are not environmentally remunerating. During switchgrass biomass production, inputs with lesser impacts included phosphorus, herbicides, pesticides, and diesel fuel. Legume-intercropping reduced greenhouse gas emissions and groundwater acidification (5% and 27% reduction in global warming potential and formation of acidifying species, respectively) compared with the 67 kg N ha-1rate. Although N-fertilizers impact environmental sustainability of regional switchgrass feedstock production, environmental consequences can be reduced under proper N-management i.e., =67 kg N ha-1 or legume intercropping. However, given that the aim of second-generation feedstocks is to reduce the current reliance on fossil fuels, their production still requires fossil energy-based inputs. Consequently, greenhouse gas reductions and the extent of cleaner feedstock production during the agricultural biofuel supply chain is contingent upon input management and optimizing synthetic fertilizer usage.
  • Authors:
    • Jair Andrade, H.
    • Alvarado, J.
    • Segura, M.
  • Source: Revista Colombia Forestal
  • Volume: 16
  • Issue: 1
  • Year: 2013
  • Summary: The increase in greenhouse gas emissions from anthropogenic sources has resulted in climate change, which affects all living beings. Coffee (Coffea arabica L.) plantations, in monoculture or together with timber species such as salmwood (Cordia alliodora), mitigate climate change due to fixation of atmospheric CO 2 that is deposited in biomass and soils. This study was carried out in the municipality of Libano, Tolima, Colombia with the objective of defining which of the following coffee production systems store more soil organic carbon (SOC): (1) monoculture, (2) agroforestry systems (AFS) with salmwood, and (3) AFS with plantain. Farms with those systems that are the most dominant in the study zone were selected. From each system, five repetitions were identified to be analyzed with a completely randomized design. In each plot or repetition, five samples for bulk density (BD) using the cylinder method and a composite sample for concentration of SOC were taken and analyzed using the Walkley and Black approach. The systems of production did not significantly (p >0.05) affect either the BD or the concentration of SOC. However, AFS with plantain tended to have less BD than monoculture and AFS with salmwood (0.830.03 vs 0.880.03 vs 0.920.04 g.cm -3, respectively). These systems of production stored between 50 and 54 t.ha -1 of SOC in the top 30 cm, which indicates their capacity for climate change mitigation.
  • Authors:
    • Jolejole, M. C.
    • McCarthy, N.
    • Lipper, L.
    • Branca, G.
  • Source: Agronomy for Sustainable Development
  • Volume: 33
  • Issue: 4
  • Year: 2013
  • Summary: Agriculture production in developing countries must be increased to meet food demand for a growing population. Earlier literature suggests that sustainable land management could increase food production without degrading soil and water resources. Improved agronomic practices include organic fertilization, minimum soil disturbance, and incorporation of residues, terraces, water harvesting and conservation, and agroforestry. These practices can also deliver co-benefits in the form of reduced greenhouse gas emissions and enhanced carbon storage in soils and biomass. Here, we review 160 studies reporting original field data on the yield effects of sustainable land management practices sequestering soil carbon. The major points are: (1) sustainable land management generally leads to increased yields, although the magnitude and variability of results varies by specific practice and agro-climatic conditions. For instance, yield effects are in some cases negative for improved fallows, terraces, minimum tillage, and live fences. Whereas, positive yield effects are observed consistently for cover crops, organic fertilizer, mulching, and water harvesting. Yields are also generally higher in areas of low and variable rainfall. (2) Isolating the yield effects of individual practices is complicated by the adoption of combinations or "packages" of sustainable land management options. (3) Sustainable land management generally increases soil carbon sequestration. Agroforestry increases aboveground C sequestration and organic fertilization reduces CO2 emissions. (4) Rainfall distribution is a key determinant of the mitigation effects of adopting specific sustainable land management practices. Mitigation effects of adopting sustainable land management are higher in higher rainfall areas, with the exception of water management.