A simple model for quantifying change in soil organic C as influenced by tillage and crop rotations on the Canadian prairies

Non-Peer ReviewedSimulation models are required for quantifying the impact of crop rotations and tillage on soil organic C dynamics, and for aggregating C sequestration over a relatively large area. However, most current models of soil organic C have been built based on kinetically defined discrete pools with different turnover times. Those pools of soil organic C only exist conceptually. They have not been determined experimentally, thus validation of kinetic models describing soil organic C turnover is usually difficult or not independent from actual measurements. Thus, there is a need to develop a simulation model that can be easily validated and used for estimating future projection of C sequestration under specified management practices. A simple model has been developed to quantify the impact of crop rotations and tillage on soil organic C and validated using long-term field experiments conducted on the Canadian prairies. This simple model required a few input parameters and accurately predicted the change of soil organic C with a relative error of 5% or better. Crop rotation in cereal-dominant cropping systems, affected the amount of soil organic C due to differences in the amount of crop residue inputs. Clay content of soil played a vital role in determining the soil organic C sequestered under conservation tillage compared to tilled systems. This study also showed that the rate constant of soil organic C turnover was about the same for all systems in the drier region of the Canadian prairies, regardless of soil texture and the cropping system

Long-term tillage and crop rotation effect on soil aggregation

Non-Peer ReviewedTillage and cropping sequences play a key role in controlling soil aggregation. We measured water-stable aggregate (WSA), wind erodible fraction (WEF), and geometric mean diameter (GMD) for six mid to longterm (8 to 25 years) experiments comparing tillage and cropping sequences in the Brown, Dark Brown, and Black Chernozemic soils of Saskatchewan. In the coarse-textured soil, no-tillage (NT) had a higher value of WSA by 49% more than in the wheat-phase of fallow-wheat (F-W), and had a lower value of WEF by 27% less than in the fallow-phase of F-W compared with minimum tillage (MT). In the medium-textured soils, NT had a higher WAS, ranged from 17 to 38%, and a lower WEF, ranged from 37 to 64% compared with conventional tillage (CT), depending on crop rotation systems. The reduced WEF under NT in the medium-textured soils was due mainly to increased GMD. In the fine-textured soils, NT had a higher WSA, ranged from 10 to 19% compared with MT or CT, and a lower WEF by 47% compared with MT only in the heavy clay soil. Change in GMD was not detectable in the light- and fine-textured soils. Continuous cropping compared with rotations containing fallow improved soil physical properties by increasing WSA, reducing WEF in the medium and fine-textured soils, and increasing GMD only in the medium-textured soils. Of the three soil physical properties determined in this study, WSA was the most sensitive to changes in tillage and crop rotations, then WEF and the least GMD

Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF

The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at the Fermilab Long-Baseline Neutrino Facility (LBNF) is described

Tillage impact on carbon sequestration on rolling landscapes of farm fields in Saskatchewan

Non-Peer ReviewedLong term (10 to 25 years) rotation studies on the Canadian prairies have shown that conservation tillage and reduced fallow have, depending upon clay content and soil moisture deficits, sequestered from 0.3 to 0.7 Mg C ha-1yr-1 soil organic C (Liang et al., 1999a,b). However, since these studies were conducted on replicated and relative level research plots, it is questionable whether they reflect the reality of actual farm fields where landscapes and management practices often differ markedly from that on research plots. Therefore, the objective of this study was to quantify carbon sequestration as a function of conservation tillage on a range of typical soil-landscapes throughout Saskatchewan by comparing neighboring farmer’s fields with and without conservation tillage

Quantifying C changes in crop rotations in southwestern Saskatchewan

Non-Peer Reviewe

Crop rotation and tillage impact on carbon sequestration in Saskatchewan soils

Non-Peer ReviewedSix field experiments from the Brown to Black soil zones and from light- to heavy-textured soils in Saskatchewan were conducted to quantify C sequestration under different tillage and crop rotations. Continuous cropping compared with crop rotations containing various frequency of fallow sequestered soil C ranging from 0.5 to 6.7 Mg C ha-1, depending on the duration of experiments, frequency of fallow and soil texture. This increase in soil organic C under continuous cropping varied from 36 to 453 kg C ha-1yr-1. The potential for sequestering soil C with continuous cropping was greater in the Dark Brown and Black soil zones than in the Brown soil zone even through the frequency of fallow was greater in the Brown soil zone. No-tillage compared with conventional tillage also sequestered soil C ranging from 0.6 to 13.2 Mg C ha-1. This increase in soil organic C under notill varied from 50 to 528 kg C ha-1yr-1. With elimination of both tillage and fallow, the soil organic C increase was approximately 200 kg C ha-1yr-1 in the Brown soil zone regardless of soil texture, and from 600 to 800 kg C ha-1yr-1 in the Dark Brown and Black soil zones. Relative annual increase in soil organic C under no-till was approximately a linear function of clay content. This study also indicated that potential gains of soil organic C under no-till were not necessarily related to the level of soil organic C prior to adoption of no-till. Heavy-textured soils would have a greater potential for gains in soil organic C under no-till in the prairie soils

Total and labile soil organic N as influenced by crop rotations and tillage in Saskatchewan soils

Non-Peer ReviewedCrop rotations and tillage practices affect quantity and quality of soil organic N (SON). Six field experiments varying from 8 to 25 years across various soil zones in Saskatchewan were conducted to evaluate the impact of crop rotations and tillage practices on SON and mineralizable N. In the Brown soil zone, continuous wheat over the fallow-wheat increased SON from 6 to 17 kg N ha-1yr-1. In the Dark Brown soil zone, continuous cropping increased SON by 30.7 kg N ha-1yr-1, compared with cropping systems containing a fallow once every three years in the Elstow clay loam, and in the Black soil zone by 24 kg N ha-1 yr-1, compared with cropping systems containing a fallow once every four years in the Indian Head clay. Increases in SON under continuous cropping over fallow-containing cropping systems were greater in Dark Brown and Black soil zones than in the Brown soil zone even though the frequency of fallow was less in the Dark Brown and Black soil zones. Increases in SON with continuous cropping also accompanied by a greater increase in the labile fraction of SON in the Brown soil zone, but not in the Dark Brown and Black soil zones. Notillage compared with conventional tillage increased SON by 4.5 kg N ha-1yr-1 for the Hatton fine sandy loam, 3.6 kg N ha-1yr-1 for the Swinton silt loam, 14.6 kg N ha-1yr-1 for the Sceptre clay, 30.5 kg N ha-1yr-1 for the Elstow clay loam, 43.6 kg N ha-1yr-1 for the Melfort silty clay loam, and 34 kg N ha-1yr-1 for the Indian Head clay. Increases in SON under no-till followed by a greater increase in the mineralizable N in the 0-7.5-cm soil for the Hatton fine sandy loam, Melfort silty clay loam and Indian Head clay, indicating that this increased SON under no-till is more labile or mineralizable than the native SON. However, the increased SON under no-till in the Swinton silty loam, Sceptre clay and Elstow clay loam did not translate to any increase in the soil mineralizable N, indicating that this increased SON was more resistant to decomposition than the native SON. Therefore, increases in SON under improved management practices such as conservation tillage and extended crop rotations may not necessarily increase soil N availability