Showing papers by "H. Henry Janzen published in 2011"

Global Prospects Rooted in Soil Science

Abstract: Th e biosphere, our fragile and exquisite home, is changing abruptly and irrevocably, largely from human interference. Most or all of the coming stresses have links to the land, so fi nding hopeful outcomes depend on wide and deep understanding of soils. In this review, we pose eight urgent issues confronting humanity in coming decades: demands for food, water, nutrients, and energy; and challenges of climate change, biodiversity, “waste” reuse, and global equity. We then suggest some steps soil scientists might take to address these questions: a refocusing of research, a broadening of vision, a renewed enticement of emerging scientists, and more lucid telling of past successes and future prospects. Th e questions posed and responses posited are incomplete and not yet fully refi ned. But the conversations they elicit may help direct soil science toward greater relevance in preserving our fragile home on this changing planet.

Impact of Sampling Depth on Differences in Soil Carbon Stocks in Long-Term Agroecosystem Experiments

Abstract: The depth of sampling has recently been highlighted as critical to making accurate measurements of changes in SOC stocks. This paper aimed to determine the effects of land management changes (LMC) on soil organic carbon (SOC) by re-sampling long-term agoecosystem experiments (LTAEs) across Canada using identical sampling and laboratory protocols. The impact of sampling depth on the monitoring of LMC-induced differences in SOC stock in LTAEs in Canada, and the implications on statistical power and sampling design, were assessed. In most cases, four cores would be suitable for detecting a significant difference in SOC stock of 5 Mg ha -1 at 95% confidence for LMCs in western Canada. The impact of eliminating fallow on SOC stocks was typically restricted to the surface 15 cm. The impact of perennial forages on the average cumulative SOC was sufficiently large to be detectable at all sampling depths (to 60 cm). In three of the six LTAEs sampled in western Canada comparing conventional tillage to no-till, there was a significantly greater SOC storage in the 0- to 30-depth than the 0- to 15-cm depth, suggesting that sampling below 15 cm could be necessary. The same comparisons in eastern Canada suggested that sampling often must exceed the 30-cm depth to account for any changes in SOC due to moldboard plow tillage. Nonetheless, there was little evidence to suggest that increasing sampling intensity or sampling deeper would improve the ability to detect a difference in SOC stocks for this LMC.

Plant lignin and nitrogen contents control carbon dioxide production and nitrogen mineralization in soils incubated with Bt and non-Bt corn residues

Abstract: Bt ( Bacillus thuringiensis ) corn is reported to produce lignin-rich residues, compared to non-Bt (NBt) corn, suggesting it is more resistant to decomposition As the Bt gene is expressed selectively in stem and leaf tissue, it could affect lignin distribution in corn, which naturally has greater lignin content in roots than in stems and leaves Our objective was to evaluate the effects of corn plant components, the Bt gene and elevated-lignin inputs on decomposition Roots, stems and leaves from Bt corn and NBt corn isolines enriched with 13 C and 15 N were finely ground and mixed separately with soil, then incubated at 20 °C for 36 weeks The effect of elevated lignin on decomposition was tested by adding a commercial lignin source (indulin lignin) to half of the samples In addition to weekly CO 2 analysis and regular measurement of N mineralization, the degree of lignin degradation was evaluated at 1 and 36 weeks from the acid to aldehyde ratio (Ad/Al) of vanillyl and syringyl lignin-derived phenols The CO 2 production and N mineralization was lower in root-amended soils than stem- and leaf-amended soils The Bt genetic modification increased CO 2 production from stem-amended soils ( P 13 C and 15 N results also showed more residue-C and -N retained in soils mixed with NBt stem residues After 36 weeks leaf- and stem-amended soils with indulin lignin had a lower Ad/Al ratio and were less degraded than soils without exogenous lignin In conclusion, plant lignin and nitrogen contents were good predictors of CO 2 production and N mineralization potential Corn roots decomposed more slowly than aboveground components emphasizing the importance of recalcitrant root residues in sustaining the organic matter content of soil

Human-Soil Relations are Changing Rapidly: Proposals from SSSA's Cross-Divisional Soil Change Working Group

Abstract: A number of scientists have named our age the Anthropocene because humanity is globally affecting Earth systems, including the soil. Global soil change raises important questions about the future of soil, the environment, and human society. Although many soil scientists strive to understand human forcings as integral to soil genesis, there remains an explicit need for a science of anthropedology to detail how humanity is a fully fledged soil-forming factor and to understand how soil change affects human well being. The development and maturation of anthropedology is critical to achieving land-use sustainability and needs to be nurtured by all soil disciplines, with inputs from allied sciences and the humanities,. The Soil Science Society of America (SSSA) has recently approved a cross-divisional Working Group on Soil Change, which aims to advance the basic and applied science of anthropedology, to facilitate networks of scientists, long-term soil field studies, and regional databases and modeling, and to engage in new modes of communications about human–soil relations. We challenge all interested parties, especially young scientists and students, to contribute to these activities and help grow soil science in the Anthropocene.

Human-Soil Relations are Changing Rapidly: Proposals from SSSA's Cross-Divisional Soil Change Working Group Soil Science Issues

Abstract: A number of scientists have named our age the Anthropocene because humanity is globally affecting Earth systems, including the soil. Global soil change raises important questions about the future of soil, the environment, and human society. Although many soil scientists strive to understand human forcings as integral to soil genesis, there remains an explicit need for a science of anthropedology to detail how humanity is a fully fledged soil-forming factor and to understand how soil change affects human well being. The development and maturation of anthropedology is critical to achieving land-use sustainability and needs to be nurtured by all soil disciplines, with inputs from allied sciences and the humanities,. The Soil Science Society of America (SSSA) has recently approved a cross-divisional Working Group on Soil Change, which aims to advance the basic and applied science of anthropedology, to facilitate networks of scientists, long-term soil field studies, and regional databases and modeling, and to engage in new modes of communications about human–soil relations. We challenge all interested parties, especially young scientists and students, to contribute to these activities and help grow soil science in the Anthropocene.

Residual effects of one-time manure, crop residue and fertilizer amendments on a desurfaced soil

Abstract: Larney, F.J., Janzen, H.H. and Olson, A.F. 2011. Residual effectsof one-time manure, crop residue and fertilizer amendments on a desurfaced soil. Can. J. Soil Sci. 91: 1029–1043. Organic amendments are often used to mitigate the effects of soil degradation caused by erosion. In spring 1992, a desurfaced soil (∼15 cm depth mechanically removed to simulate erosion) received one-time applications of amendments (20 Mg ha⁻¹ dry wt), and was subsequently seeded annually to spring wheat (Triticum aestivum L.). By 2009, six treatments (fresh and old cattle manure, hog and poultry manure, alfalfa (Medicago sativa L.) hay and straw+200 kg P ha⁻¹) had cumulative yields which were not significantly different (−6.5 to −19.5%) from the topsoil check treatment (no topsoil removed, no amendment). Most (8 of 13) amendment treatments showed significant power function relationships between cumulative grain yield (expressed as a percent of topsoil check) and time while two (hog and poultry manure) were quadratic. Soil organic carbon (SOC) accrued on all treatments over time, increasing significantly from an average of 12.2 g kg⁻¹ in 1992 to 13.2 g kg⁻¹ (0–15 cm depth) in 2003. Residual amendment effects on total nitrogen (N) and phosphorus (P) were apparent 11.5 yr after application. Results demonstrated that while drastically disturbed soils may recover productivity in the absence of organic amendments (e.g., eroded check treatment), organic amendments play a residual role in their ongoing maintenance.