Alan P. Moulin

Organic matter quality and structural stability of a Black Chernozemic soil under different manure and tillage practices

Abstract No-tillage (NT) and addition of organic matter can improve soil aggregation and affect soil organic matter (SOM) levels. The effects of short-term (3 years, 1993–1996) conventional tillage (CT), NT, and cattle manure applications on SOM quality and water-stable aggregates (WSA) were investigated on a Melfort silty clay loam (Orthic Black Chernozem) at Melfort (Saskatchewan, Canada). Four methods for managing manure (dry weight basis) within CT and NT were established: fresh manure (FM) was applied at the beginning of the experiment at 23.0 Mg ha−1 and annually at 4.5 Mg ha−1, whereas stockpiled manure (SM) with equal N concentration to FM was applied at the beginning of the study at 23.0 Mg ha−1 and annually at 4.5 Mg ha−1. The control treatment consisted in annual application of 81.0 kg N ha−1 as ammonium nitrate and 9.3 kg P ha−1 as monoammonium phosphate, according to soil test recommendations. Soil samples (0–15 cm) were collected at the end of the 3-year period and lipids were extracted with diethyl ether (DEE) and chloroform (CHCl3) to assess SOM quality. Water-stable aggregates were measured with and without ethanol pretreatment and before and after extraction of unbound lipids. The amounts of C and N was not affected by the treatments. Between NT and CT, the changes in SOM were expressed by an increase of 21% of the amounts of total extractable lipids (TEL) in the CT soils, whereas in the NT soils, the DEE/CHCl3 ratio used to assess the degree of biodegradability of OM increased by 40%. Following the application of FM, the stability of soil aggregates against the dissolution and dispersive actions of water decreased by 13 and 16% in CT and NT soils, respectively; however, this effect was compensated by an equivalent increase in resistance to slaking forces. In contrast, the incorporation of SM did not affect the stability of soil aggregates against the dissolution and dispersive actions of water, but increased by 7% the resistance of aggregates to slaking forces.

Pattern of greenhouse gas emission from a Prairie Pothole agricultural landscape in Manitoba, Canada

To obtain accurate N2O and CH4 emission estimates from the Prairie Pothole Region of North America, knowledge of landscape pattern and soil factors is important. A field study was conducted investigating the temporal and spatial variation in N2O and CH4 emissions from spring to fall 2005 and spring-thaw to post-fertilizer application period 2006 using static-vented chambers located at upper, middle and lower landscape elements planted to spring wheat in 2005 and flax in 2006 and riparian areas in an undulating terrain in southern Manitoba. N2O was emitted during spring-thaw and post-fertilizer application periods for cropped positions and CH4 was emitted about 7 wk after soil thaw for lower and riparian elements. While there was no statististical difference in N2O emission from upper, middle and lower landscape elements, there was greater occurrence of N2O emission hotspots at the lower element, associated with its comparatively higher soil moisture and carbon availability. A location of intense CH4 emiss...

Effect of Rotation on Crop Yield and Quality in an Irrigated Potato System

The productivity of potato (Solanum tuberosum L.) systems may be strongly influenced by rotation. A field study consisting of six rotations (potato with canola (PC), wheat (PW), canola-wheat (PCW), oat-wheat (POW), wheat-canola-wheat (PWCW), and canola underseeded to alfalfa-alfalfa-alfalfa (PCAA)) arranged as an RCBD was established on a clay loam in Manitoba, Canada in 1998 and monitored for twelve years to determine effects on potato yield and quality. Higher yields for canola-containing rotations were evident in three years (P < 0.10), but not beyond 2005. From 2007 onward, 2-year rotations produced a markedly lower yield than other rotations. Yields of 3- and 4-year rotations were similar, although PCW and PCAA were most frequently among the higher-yielding rotations. Overall, PC had a lower specific gravity than other rotations. Results suggest 3- and 4-year rotations, particularly PCW and PCAA, helped maintain productivity. Two-year rotations of PC and PW were not sustainable due to declining yields.ResumenLa productividad de los sistemas de papa (Solanum tuberosum L.) pueden estar fuertemente influenciados por la rotación. Se estableció un estudio de campo consistente en seis rotaciones; papa con canola (PC), con trigo (PW), con canola-trigo (PCW), con avena trigo (POW), con trigo, canola, trigo (PWCW), y con canola mezclada con alfalfa-alfalfa-alfalfa (PCAA), arreglado en un diseño experimental de bloques completos al azar, en un suelo franco-arcilloso en Manitoba, Canadá, en 1998, y monitoreado por doce años, para determinar los efectos en rendimiento y calidad de la papa. Se hicieron evidentes más altos rendimientos en las rotaciones que incluían a la canola en tres años (P < 0.10), pero no más allá de 2005. A partir de 2007, las rotaciones de dos años produjeron un rendimiento más bajo bien marcado que en otras rotaciones. Los rendimientos de rotaciones de 3 y 4 años fueron similares, aunque PCW y PCAA estuvieron entre las más frecuentes de las rotaciones de mayores rendimientos. En general, PC tuvieron gravedad específica más baja que otras rotaciones. Los resultados sugieren que rotaciones de 3 a 4 años, particularmente PCW y PCAA, ayudaron a mantener la productividad. Rotaciones de dos años de PC y PW no fueron sostenibles debido a la disminución en rendimientos.

Alternative transformations of nitrous oxide soil flux data to normal distributions

Moulin, A. P., Glenn, A., Tenuta, M., Lobb, D. A., Dunmola, A. S. and Yapa, P. 2014. Alternative transformations of nitrous oxide soil flux data to normal distributions. Can. J. Soil Sci. 94: 105-108. Non-normal distributions of soil N2O fluxes are commonly log transformed prior to statistical analysis. These data are transformed to ensure that analysis of variance and regression based on least squares, meet the assumptions of normality for the distribution of data and equality of variances. Analysis of micrometeorological and static chamber-based fluxes of N2O in Manitoba show that continuous functions such as the Johnson Su and Sl, Generalized Log or normal quantile may be useful as alternatives to the lognormal, which was relatively less effective in transforming data, though each transformation should be evaluated on a case-by-case basis.

Climate change, agricultural inputs, cropping diversity, and environmental covariates in multivariate analysis of future wheat, barley, and canola yields in Canadian Prairies: a case study

Abstract: Canada’s grain and oilseed production in the Canadian Prairies may be affected by climate change, but the impact of input and diversity has not been assessed relative to projected variability in precipitation and temperature. This study assessed wheat, canola, and barley yields simulated with the environmental policy integrated climate model for historical weather and future climate scenarios in the context of agricultural inputs and cropping diversity at Scott, SK, Canada. Variation of future yield was explored with recursive partitioning in multivariate analyses of inputs, cropping diversity, future growing season precipitation (GSP), and growing degree days (GDD). Agricultural inputs significantly affected wheat yield but not barley or canola. Wheat yield was highest under the reduced input level and lowest under the organic input level. The combination of input and diversity accounted for about one-third of variation in future wheat yield and approximately 10% for barley yield. Most of the variability in yield was correlated with GSP in May–July and GDD in April–June and August–September. Future growing season maximum and minimum temperatures increased by 1.06 and 2.03 °C, respectively, and 11% in future GSP. This study showed how input management and reduced tillage maintained or improved yield, in the context of increased temperature due to climate change.

Probability distribution functions for short-term daily nitrous oxide fluxes in a prairie pothole agricultural landscape in western Canada

Moulin, A., Tenuta, M., Lobb, D., Dunmola, A. and Yapa, P. 2011. Probability distribution functions for short-term daily nitrous oxide fluxes in a prairie pothole agricultural landscape in western Canada. Can. J. Soil Sci. 91: 303-307. Probability distributions of N2O fluxes are often non-normal due to large temporal and spatial variability of environmental factors. The most common approaches to statistical analyses of these fluxes in the scientific literature are to transform data with a log function, or conduct non-parametric tests. Analysis of N2O flux data for 128 sites within a 16-ha field, taken on 20 dates in 2005 and 2006 near Brandon, Manitoba, show that the Johnson Su and generalized log probability distributions provided the best fit for the majority of sample dates. The results of this research indicate that statistical analysis of N2O fluxes with the Johnson Su probability function should be considered as an alternative to the lognormal function.

Economic and Risk Effects of Rotation Based on a 14-Year Irrigated Potato Production Study in Manitoba

Crop rotations can be used to optimize economic return by preserving or enhancing soil quality and reducing pest pressure. A field experiment consisting of six rotations of potato with canola (P-C), wheat (P-W), canola-wheat (P-C-W), oat-wheat (P-O-W), wheat-canola-wheat (P-W-C-W), and canola underseeded to alfalfa-alfalfa-alfalfa (P-C(A)-A-A) organized in a Randomized Complete Block Design was established on a clay loam soil in Manitoba, Canada and monitored for fourteen years to assess the relative economic performance of potato in each rotation. A stochastic budget based on returns and risk of returns trade-offs was used to determine each rotation’s profitability. While differences in average annual net income of all crops between rotations were not significant, the P-C-W rotation was the most stable. Despite the economic advantage of P-C in the first two cycles, longer P-C-W or P-C(A)-A-A rotations are recommended, as two-year rotations increase plant disease and decrease economic viability in the long run.ResumenLas rotaciones de cultivos pueden usarse para optimizar la recuperación económica mediante la preservación o aumento de la calidad del suelo y en la reducción de presión de plagas. Se estableció un experimento de campo consistente en seis rotaciones de papa con canola (P-C), trigo (P-W), canola-trigo (P-C-W), avena trigo (P-O-W), trigo-canola-trigo (P-W-C-W), y canola mezclada con alfalfa-alfalfa-alfalfa (P-C(A)-A-A) organizado en un diseño de bloques completos al azar, en un suelo arcillo-limoso en Manitoba, Canadá, y monitoreado por 14 años para evaluar el comportamiento relativo económico de papa en cada rotación. Se usó un presupuesto estocástico basado en recuperaciones y en el riesgo de compensaciones de recuperaciones para determinar la redituabilidad de cada rotación. Mientras que las diferencias en el promedio anual de ingresos netos de todos los cultivos entre rotaciones no fueron significativas, la rotación P-C-W fue la más estable. A pesar de la ventaja económica de P-C en los primeros dos ciclos, se recomiendan las rotaciones más largas P-C-W o P-C(A)-A-A, ya que las rotaciones de dos años aumentan enfermedad de la planta y a la larga disminuyen la viabilidad económica.