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1.
J Environ Qual ; 43(3): 777-88, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-25602807

RESUMO

Little information exists about how global warming potential (GWP) is affected by management practices in agroecosystems. We evaluated the effects of irrigation, tillage, crop rotation, and N fertilization on net GWP and greenhouse gas intensity (GHGI or GWP per unit crop yield) calculated by soil respiration (GWP and GHGI) and organic C (SOC) (GWP and GHGI) methods after accounting for CO emissions from all sources (irrigation, farm operations, N fertilization, and greenhouse gas [GHG] fluxes) and sinks (crop residue and SOC) in a Lihen sandy loam from 2008 to 2011 in western North Dakota. Treatments were two irrigation practices (irrigated vs. nonirrigated) and five cropping systems (conventional-till malt barley [ L.] with N fertilizer [CTBN], conventional-till malt barley with no N fertilizer [CTBO], no-till malt barley-pea [ L.] with N fertilizer [NTB-P], no-till malt barley with N fertilizer, and no-till malt barley with no N fertilizer [NTBO]). While CO equivalents were greater with irrigation, tillage, and N fertilization than without, NO and CH fluxes were 2 to 218 kg CO eq. ha greater in nonirrigated NTBN and irrigated CTBN than in other treatments. Previous year's crop residue and C sequestration rate were 202 to 9316 kg CO eq. ha greater in irrigated NTB-P than in other treatments. Compared with other treatments, GWP and GWP were 160 to 9052 kg CO eq. ha lower in irrigated and nonirrigated NTB-P. Similarly, GHGI and GHGI were lower in nonirrigated NTB-P than in other treatments. Regardless of irrigation practices, NTB-P may lower net GHG emissions more than other treatments in the northern Great Plains.

2.
J Environ Qual ; 41(6): 1774-86, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23128735

RESUMO

Management practices, such as irrigation, tillage, cropping system, and N fertilization, may influence soil greenhouse gas (GHG) emissions. We quantified the effects of irrigation, tillage, crop rotation, and N fertilization on soil CO, NO, and CH emissions from March to November, 2008 to 2011 in a Lihen sandy loam in western North Dakota. Treatments were two irrigation practices (irrigated and nonirrigated) and five cropping systems (conventional-tilled malt barley [ L.] with N fertilizer [CT-N], conventional-tilled malt barley with no N fertilizer [CT-C], no-tilled malt barley-pea [ L.] with N fertilizer [NT-PN], no-tilled malt barley with N fertilizer [NT-N], and no-tilled malt barley with no N fertilizer [NT-C]). The GHG fluxes varied with date of sampling and peaked immediately after precipitation, irrigation, and/or N fertilization events during increased soil temperature. Both CO and NO fluxes were greater in CT-N under the irrigated condition, but CH uptake was greater in NT-PN under the nonirrigated condition than in other treatments. Although tillage and N fertilization increased CO and NO fluxes by 8 to 30%, N fertilization and monocropping reduced CH uptake by 39 to 40%. The NT-PN, regardless of irrigation, might mitigate GHG emissions by reducing CO and NO emissions and increasing CH uptake relative to other treatments. To account for global warming potential for such a practice, information on productions associated with CO emissions along with NO and CH fluxes is needed.


Assuntos
Irrigação Agrícola , Agricultura/métodos , Gases/química , Efeito Estufa , Nitrogênio/química , Solo/química , Dióxido de Carbono/química , Conservação dos Recursos Naturais , Produtos Agrícolas , Monitoramento Ambiental , Fertilizantes/análise , Metano/química , Óxido Nitroso/química , Temperatura , Fatores de Tempo
3.
J Environ Qual ; 39(3): 935-45, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20400589

RESUMO

Management practices are needed to reduce dryland soil CO(2) emissions and to increase C sequestration. We evaluated the effects of tillage and cropping sequence combinations and N fertilization on dryland crop biomass (stems + leaves) and soil surface CO(2) flux and C content (0- to 120-cm depth) in a Williams loam from May to October, 2006 to 2008, in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L.) (NTCB), no-tilled malt barley-pea (Pisum sativum L.) (NTB-P), no-tilled malt barley-fallow (NTB-F), and conventional-tilled malt barley-fallow (CTB-F), each with 0 and 80 kg N ha(-1). Measurements were made both in Phase I (malt barley in NTCB, pea in NTB-P, and fallow in NTB-F and CTB-F) and Phase II (malt barley in all sequences) of each cropping sequence in every year. Crop biomass varied among years, was greater in the barley than in the pea phase of the NTB-P treatment, and greater in NTCB and NTB-P than in NTB-F and CTB-F in 2 out of 3 yr. Similarly, biomass was greater with 80 than with 0 kg N ha(-1) in 1 out of 3 yr. Soil CO(2) flux increased from 8 mg C m(-2) h(-1) in early May to 239 mg C m(-2) h(-1) in mid-June as temperature increased and then declined to 3 mg C m(-2) h(-1) in September-October. Fluxes peaked immediately following substantial precipitation (>10 mm), especially in NTCB and NTB-P. Cumulative CO(2) flux from May to October was greater in 2006 and 2007 than in 2008, greater in cropping than in fallow phases, and greater in NTCB than in NTB-F. Tillage did not influence crop biomass and CO(2) flux but N fertilization had a variable effect on the flux in 2008. Similarly, soil total C content was not influenced by treatments. Annual cropping increased CO(2) flux compared with crop-fallow probably by increasing crop residue returns to soils and root and rhizosphere respiration. Inclusion of peas in the rotation with malt barley in the no-till system, which have been known to reduce N fertilization rates and sustain malt barley yields, resulted in a CO(2) flux similar to that in the CTB-F sequence.


Assuntos
Agricultura/métodos , Dióxido de Carbono/química , Carbono/química , Nitrogênio/química , Solo/análise , Biomassa , Produtos Agrícolas , Fertilizantes , Temperatura , Fatores de Tempo , Água/química
4.
Springerplus ; 4: 320, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26171303

RESUMO

Information on the effect of long-term management on soil nutrients and chemical properties is scanty. We examined the 30-year effect of tillage frequency and cropping sequence combination on dryland soil Olsen-P, K, Ca, Mg, Na, SO4-S, and Zn concentrations, pH, electrical conductivity (EC), and cation exchange capacity (CEC) at the 0-120 cm depth and annualized crop yield in the northern Great Plains, USA. Treatments were no-till continuous spring wheat (Triticum aestivum L.) (NTCW), spring till continuous spring wheat (STCW), fall and spring till continuous spring wheat (FSTCW), fall and spring till spring wheat-barley (Hordeum vulgare L., 1984-1999) followed by spring wheat-pea (Pisum sativum L., 2000-2013) (FSTW-B/P), and spring till spring wheat-fallow (STW-F, traditional system). At 0-7.5 cm, P, K, Zn, Na, and CEC were 23-60% were greater, but pH, buffer pH, and Ca were 6-31% lower in NTCW, STCW, and FSTW-B/P than STW-F. At 7.5-15 cm, K was 23-52% greater, but pH, buffer pH, and Mg were 3-21% lower in NTCW, STCW, FSTCW, FSTW-B/P than STW-F. At 60-120 cm, soil chemical properties varied with treatments. Annualized crop yield was 23-30% lower in STW-F than the other treatments. Continuous N fertilization probably reduced soil pH, Ca, and Mg, but greater crop residue returned to the soil increased P, K, Na, Zn, and CEC in NTCW and STCW compared to STW-F. Reduced tillage with continuous cropping may be adopted for maintaining long-term soil fertility and crop yields compared with the traditional system.

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