- Authors:
- Mishra, U.
- Lal, R.
- Christopher, S. F.
- Source: Soil Science Society of America Journal
- Volume: 73
- Issue: 4
- Year: 2009
- Authors:
- Mishra, U.
- Lal, R.
- Christopher, S. F.
- Source: Soil Science Society of America Journal
- Volume: 73
- Issue: 1
- Year: 2009
- Summary: No-till (NT) agriculture has been promoted as one of the optimal management practices that preserves soil and water, and increases soil organic C (SOC) compared with conventional tillage (CT) practices. Information on SOC sequestration in NT systems, however, has been based on measurements from the surface soil (<30 cm) and little is known about the extent of SOC sequestration in NT across the entire 0- to 60-cm soil profile. We conducted a regional study of NT farming to assess the extent of SOC sequestration in the whole soil profile across 12 contrasting but representative soils in the Midwestern United States, each within a Major Land Resource Area (MLRA: 98, 111C, 114B, 122 in Indiana; 111A, 111B, 111D, 124, and 126 in Ohio; and 127 and 147 in Pennsylvania). Soils on gentle terrain were sampled in paired NT and CT fields as well as in an adjacent woodlot in each MLRA. The SOC and N concentrations were greater in the surface 0- to 5-cm soil in NT than CT in MLRA 124. The SOC concentration in CT soil was greater than in NT soil at 10 to 30 cm in MLRAs 98 and 126. The total SOC pool for the whole soil profile did not differ between NT and CT in eight of the 12 MLRAs and the total profile SOC was actually greater under CT in MLRAs 98, 127, and 126, resulting in negative C sequestration rates on conversion from CT to NT in these three MLRAs. This regional study suggests that the entire soil profile must be examined and ecosystem C budget assessed when elucidating SOC sequestration in NT vs. CT fields.
- Authors:
- Source: ClimateCHECK
- Year: 2009
- Summary: From exec summary: This Consultation Report describes the development to date of the Nitrous Oxide Emissions Reduction Protocol ("NERP"), designed on the framework provided by the Right Product @ Right Rate, Right Time, Right Place™ stewardship model of the Canadian Fertilizer Institute. The process for development includes a Technical Background Document, a Science Discussion document, and a Consultation Workshop. Following the decisions of the Consultation Workshop, the main elements of the NERP are determined. The eligibility requirements of the NERP are designed according to the criteria of the Alberta Offsets System and Canada's Offset System. The GHG emissions for the baseline scenario and project condition are calculated using the country-specific methodology used in Canada's National Inventory Report. The scope of the NERP is limited to (1) on-farm reductions of (2) emissions associated with quantification categories fertilizer, manure, residues, and irrigation. The baseline is determined according to three years of farm-level data. The essential component for participation in the NERP is defined as the implementation of a 4R N stewardship plan, as assured by (1) general guidance in the NERP confirmed by third party verification, (2) detailed design instructions in the NERP, (3) conformity with a recommended predictive model, or (4) retaining services of an approved consulting professional. The fertilizer management practices comprising the Basic, Intermediate, and Advanced levels of the NERP are listed. And, the reduction modifiers associated with the levels of the NERP are proposed.
- Authors:
- Del Grosso, S. J.
- Halvorson, A. D.
- Alluvione, F.
- Source: Journal of Environmental Quality
- Volume: 38
- Issue: 5
- Year: 2009
- Summary: Long-term effects of tillage intensity, N fertilization, and crop rotation on carbon dioxide (CO2) and methane (CH4) flux. from semiarid irrigated soils are poorly understood. We evaluated effects of. (i) tillage intensity [no-till (NT) and conventional moldboard plow tillage (CT)] in a Continuous corn rotation; (ii) N fertilization levels [0-246 kg N ha(-1) for corn (Zea mays L.); 0 and 56 kg N ha(-1) for dry bean (Phaseolus vulgaris W; 0 and 112 kg N ha(-1) for barley (Hordeum distichon L.)]; and (iii) crop rotation Under NT soil management [corn-barley (NTCB); continuous corn (NT-CC); corn-dry bean (NI-CDb)] on CO2 and CH4 flux from a clay loam soil. Carbon dioxide and CH4 fluxes were monitored one to three times per week using vented nonsready state closed chambers. No-till reduced (14%) growing season (154 d) cumulative CO2 emissions relative to CT (NT 2.08 Mg CO2-C ha(-1); CT 2.41 Mg CO2-C ha(-1)), while N fertilization had no effect. Significantly lower (18%) growing season CO2 fluxes were found in NT-CDb than NT-CC and NT-CB (11.4, 13.2 and 13.9 kg CO2-C ha(-1)d(-1) respectively). Growing season CH4 emissions were higher in NT (20.2 g CH4 ha(-1)) than in CT (1.2 g CH4 ha(-1)). Nitrogen fertilization and cropping rotation did not affect CH4 flux. Implementation of NT for 7 yr with no N fertilization was not adequate for restoring the CH4 oxidation capacity Of this clay learn soil relative to CT plowed and fertilized soil.
- Authors:
- Smith, D. L.
- Ma, B.-L.
- Rochette, P.
- Madramootoo,C.
- Zhou, X.
- Mabood, F.
- Almaraz, J. J.
- Source: Soil Science Society of America Journal
- Volume: 73
- Issue: 1
- Year: 2009
- Summary: Agriculture has an important potential role in mitigating greenhouse gas emissions (GHG). However, practices that reduce CO2 emissions from soils and increase the soil organic C level may stimulate N2O emissions. This is particularly critical in Quebec where heavy soils and a humid climate may limit the adoption of agricultural practices designed to mitigate GHG. The objective of this work was to study the effects of two tillage and N fertilization regimes on CO2 and N2O fluxes and the seasonal variability in emissions of these gases, associated with corn (Zea mays L.) grown in southwestern Quebec. Different seasonal emission patterns of CO2 and N2O were observed. Higher N2O fluxes occurred during the spring and were associated with precipitation events, while higher CO2 fluxes occurred in mid-season and were related to temperature. Conventional tillage (CT) had greater peaks of CO2 emissions than no-till (NT) only after disking in the spring. Once corn was established, differences between tillage systems were small. Peaks of N2O emission occurred in both systems (NT and CT) following N application. Plots receiving 180 kg N ha-1 in both tillage systems had large peak of N2O emission rates during the wettest parts of the season. The CT and NT systems generally had similar cumulative CO2 emissions but NT had higher cumulative N2O emissions than CT. Our findings suggests that changing from CT to NT under the heavy soil conditions of Quebec may increase GHG, mainly as result of the increase in N2O emission. This negative effect of NT could be reduced by avoiding fertilizing when precipitation is more intense.
- Authors:
- Source: Soil Science Society of America Journal
- Volume: 73
- Issue: 2
- Year: 2009
- Summary: Franzluebbers (2009) is right about the need for a more intensive soil sampling, "repeated sampling with time,"and "stratified sampling" as well as for the use of multiple fields and collection of larger number of pseudoreplicates to overcome the high field variability in soil organic carbon (SOC) pools within each Major Land Resource Area (MLRA). The selected fields were representative of each MLRA in terms of soil type, slope, and management, but it is correct that a single soil would not capture all the variability in soil and management for the whole MLRA. This study was not intended to relate the data from the single soil to the whole MLRA but rather to emphasize the differences in SOC sequestration rates among the three management systems within each soil.
- Authors:
- Urquiaga, S.
- Alves, B. J. R.
- Jantalia, C. P.
- Boddey, R. M.
- Source: Soil Science Society of America Journal
- Volume: 73
- Issue: 2
- Year: 2009
- Summary: Blanco-Canqui and Lal (2008) present data on soil organic carbon (SOC) concentrations from soils managed under no-tillage (NT) or plow-tillage (PT) from samples taken from studies of paired fields at 11 (MLRA) sites in three states of the USA. The results seem to show extremely large annual changes in soil organic C stocks between NT and PT to a depth of 60 cm, ranging from +3.75 to -6.65 Mg ha-1 yr-1 (Table 2). However, these values are far greater, and not compatible with, the data displayed in Fig. 2, nor the total stocks of soil N and the C/ N ratio displayed in Tables 3 and 4, respectively. However, the data displayed taken from seven studies in the literature (a total of 16 comparisons) are correctly reported as annual changes. Table 2 should thus be corrected as shown here (Table 1).
- Authors:
- Ma, B.
- Strachan, I.
- Zhou, X.
- Mabood, F.
- Almaraz, J.
- Smith, D.
- Source: Journal of Agronomy and Crop Science
- Volume: 195
- Issue: 5
- Year: 2009
- Summary: Climate change will alter temperature and rainfall patterns over North American agricultural regions and there will be a need to adapt crop production systems to the altered conditions. A set of field experiments were conducted in south-western Quebec, Canada, with soybean ( Glycine max L.), corn ( Zea mays L.), sorghum ( Sorghum bicolor L.) * sudangrass ( Sorghum sudanense Piper) hybrid and switchgrass ( Panicum virgatum L.) under two tillage and three nitrogen fertility regimes, to study their performance in three successive growing seasons (2001-2003), two of them with unusually warm and dry conditions. The annual crops were established in two tillage systems: conventional and no-till (NT). All crops except soybean were fertilized with three levels of nitrogen: corn - 0, 90 and 180 kg N ha -1, sorghum-sudangrass - 0, 75 and 150 kg N ha -1, switchgrass - 0, 30 and 60 kg N ha -1. The 2001 and 2002 seasons were hotter and drier than the 2003 season, which was the most favourable for crop growth. The capacity of the crops to yield in dry seasons was as follow: switchgrass > sorghum-sudangrass > corn > soybean. The corn and sorghum-sudangrass responses to nitrogen fertilizer were low in 2001 due to the combined effect of dry growing season and coarse soil texture. Soybean did not perform well under NT. Corn yielded better at the highest nitrogen fertilizer rate under NT when the early season was warmer than the normal. Our results show that switchgrass and sorghum-sudangrass could be an option in south-western Quebec if the frequency of hot and dry seasons increase in the future, because of climate change.
- Authors:
- Vyn, T.
- McIntyre, L.
- Brewer, J.
- West, T.
- Santini, J.
- Boomsma, C.
- Source: Soil & Tillage Research
- Volume: 106
- Issue: 2
- Year: 2009
- Summary: Research emphasizing slower plant growth and delayed maturity in continuous maize ( Zea mays L.), no-till (MM-NT) systems has often led to the conclusion that lower grain yields in this environment are associated with reduced plant heights. Yet prior research has shown that early-season and mature plants are not always shorter in MM-NT systems, suggesting that overall plant height may not be an accurate morphometric indicator of decreased yield in MM-NT environments. Given that plant-to-plant morpho-physiological uniformity is strongly associated with higher yield in maize, we hypothesized that greater plant height variability would provide a better agronomic explanation for yield loss in MM-NT environments than overall plant height reductions. This 14-year study primarily examined the effects of crop rotation {maize-soybean [ Glycine max (L.) Merr.] and continuous maize} and tillage system (no-till and moldboard plow) on the yield, 4-week plant population, and 4- and 8-week plant height and plant height variability of a single maize cultivar. Due to sizeable year-to-year variation, actual crop response means for the MM-NT; maize-soybean, no-till (MB-NT); and continuous maize, moldboard plow (MM-PL) treatment combinations were expressed relative to the accompanying means for the maize-soybean, moldboard plow (MB-PL) treatment. In numerous years, the MM-NT system exhibited reduced actual and relative yields and lower 4- and 8-week plant heights compared to the other treatment combinations. Both actual and relative 4- and 8-week plant height variability were rarely greatest for the MM-NT treatment, and in only a few years were actual and/or relative plant density lowest for this system. However, single-factor regression analyses between relative yield and the aforementioned relative agronomic measures revealed that a decline in relative MM-NT yield was most strongly associated with an increase in relative 4-week plant height variability. Multi-factor regression analyses between relative yield, relative 4-week plant height variability, and various weather parameters suggested that this strong inverse relationship was potentially a manifestation of (i) non-uniform germination, emergence, and early seedling growth and (ii) later-season intra-specific competition. Regression analyses between relative 4-week plant height variability and various weather parameters suggested that phenomenon (i) was potentially promoted by cool and moist or warm and dry pre-plant weather conditions while phenomenon (ii) was possibly encouraged by low precipitation and/or high temperatures during rapid stem elongation. While MM-NT systems should be managed to limit plant density reductions and minimize growth and developmental delays, increased focus should be placed on minimizing the occurrence of plant-to-plant variability in these environments.
- Authors:
- Azevedo, W.
- Pereira, H.
- Reis, E.
- Souza, E.
- Carneiro, M.
- Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
- Volume: 33
- Issue: 1
- Year: 2009
- Summary: This study investigated the effects of tillage systems and soil use on the physical, chemical and biological properties of a clayey dystrophic Red Latosol (Oxisol) and a sandy Neosol (Entisol). The treatments for the Oxisol consisted of: native savanna, pasture, conventional tillage, no-tillage with turnip and with forage sorghum as cover crop. For the Entisol: native savanna, native pasture, integrated crop-livestock, cultivated pasture, no-tillage with soyabean and maize in the summer. Soil samples were collected from a depth of 0-10 cm, in a clayey dystrophic Oxisol and a sandy Entisol in a savanna ecosystem, near the Parque Nacional das Emas in Goias, Brazil. Treatments were arranged in a completely randomized design, in 5 plots of 150 m 2, where 10 sub-samples were collected randomly. Chemical, physical and biological analyses were carried out at a soil laboratory. In the Entisol, tillage influenced the soil density, total pore volume, macroporosity and penetration resistance. In the Oxisol, tillage induced variations in soil bulk density, macroporosity and penetration resistance. Small variations in chemical properties were observed in both soils, with higher potential acidity and lower exchangeable cation and phosphorus concentrations. The soil biological properties were influenced by tillage, and were most affected in systems with more anthropic action. In the canonical data analysis the greater weighting coefficient of the physical properties in the canonic variables demonstrated that these were the least important. The contribution of the separate soil properties to evaluate soil quality was minor, but the most sustainable management systems could be defined by multivariate analysis.
