96 research outputs found
Measured and modelled effect of land-use change from temperate grassland to Miscanthus on soil carbon stocks after 12 years
Soil organic carbon (SOC) is an important carbon pool susceptible to land‐use change (LUC). There are concerns that converting grasslands into the C4 bioenergy crop Miscanthus (to meet demands for renewable energy) could negatively impact SOC, resulting in reductions of greenhouse gas mitigation benefits gained from using Miscanthus as a fuel. This work addresses these concerns by sampling soils (0–30 cm) from a site 12 years (T12) after conversion from marginal agricultural grassland into Miscanthus x giganteus and four other novel Miscanthus hybrids. Soil samples were analysed for changes in below‐ground biomass, SOC and Miscanthus contribution to SOC (using a 13C natural abundance approach). Findings are compared to ECOSSE soil carbon model results (run for a LUC from grassland to Miscanthus scenario and continued grassland counterfactual), and wider implications are considered in the context of life cycle assessments based on the heating value of the dry matter (DM) feedstock. The mean T12 SOC stock at the site was 8 (±1 standard error) Mg C/ha lower than baseline time zero stocks (T0), with assessment of the five individual hybrids showing that while all had lower SOC stock than at T0 the difference was only significant for a single hybrid. Over the longer term, new Miscanthus C4 carbon replaces pre‐existing C3 carbon, though not at a high enough rate to completely offset losses by the end of year 12. At the end of simulated crop lifetime (15 years), the difference in SOC stocks between the two scenarios was 4 Mg C/ha (5 g CO2‐eq/MJ). Including modelled LUC‐induced SOC loss, along with carbon costs relating to soil nitrous oxide emissions, doubled the greenhouse gas intensity of Miscanthus to give a total global warming potential of 10 g CO2‐eq/MJ (180 kg CO2‐eq/Mg DM)
Gas exchange at whole plant level shows that a less conservative water use is linked to a higher performance in three ecologically distinct pine species
Increasing temperatures and decreasing precipitation in large areas of the planet as a consequence of
global warming will affect plant growth and survival. However, the impact of climatic conditions will
differ across species depending on their stomatal response to increasing aridity, as this will ultimately
affect the balance between carbon assimilation and water loss. In this study, we monitored gas
exchange, growth and survival in saplings of three widely distributed European pine species (Pinus
halepensis, P. nigra and P. sylvestris) with contrasting distribution and ecological requirements in
order to ascertain the relationship between stomatal control and plant performance. The experiment
was conducted in a common garden environment resembling rainfall and temperature conditions
that two of the three species are expected to encounter in the near future. In addition, gas exchange
was monitored both at the leaf and at the whole-plant level using a transient-state closed chamber,
which allowed us to model the response of the whole plant to increased air evaporative demand
(AED). P. sylvestris was the species with lowest survival and performance. By contrast, P. halepensis
showed no mortality, much higher growth (two orders of magnitude), carbon assimilation (ca. 14
fold higher) and stomatal conductance and water transpiration (ca. 4 fold higher) than the other two
species. As a consequence, P. halepensis exhibited higher values of water-use efficiency than the rest of
the species even at the highest values of AED. Overall, the results strongly support that the weaker
stomatal control of P. halepensis, which is linked to lower stem water potential, enabled this species to
maximize carbon uptake under drought stress and ultimately outperform the more water
conservative P. nigra and P. sylvestris. These results suggest that under a hotter drought scenario
P. nigra and P. sylvestris would very likely suffer increased mortality, whereas P. halepensis could
maintain gas exchange and avoid water-induced growth limitation. This might ultimately foster an
expansion of P. halepensis to higher latitudes and elevations.This work was supported by the projects ECOLPIN
(AGL2011–24296) and Remedinal 3 (S2013/ MAE-
2719) of the Madrid Government, by a FPU fellowship
from the Spanish Ministry of Education, Culture
and Sport (FPU13/03410) to DS and by EU Marie
Curie (FP7–2013-IOF-625988) fellowship to EPSC
No-till systems on the Chequen Farm in Chile: A success story in bringing practice and science together
No-till cropping systems provide an opportunity to protect the soil from erosion, while contemporaneously maintaining high yields and contributing to global food security. The historical aspects and the remarkable development of no-till systems on the Chequen Farm in Chile are reviewed. The adoption of no-till over the last 40 years has been a major turning point in reducing the devastating effects of soil erosion and a model for the evolution of sustainable crop production in highly erodible terrain in other parts of the world. The process of adoption of no-till systems in severely eroded foothills of Chile is described, as well as the environmental benefits and the sustainability of the system. The practical aspects of these developments are supported by scientific literature where appropriate, illustrating the value and coincident knowledge gained when combining analogue observations and information with scientific principles
Challenging Balance Between Productivity and Environmental Quality: Tillage Impacts
The increasing pressure to provide food security, enhance environmental quality, and address societal problems creates challenges for agriculture and requires we consider how to change our current systems to become more sustainable. Wiebe (2003) stated, “Not only is the contemporary food system inherently unsustainable, increasingly it is damaging the environment.” There have been adverse eff ects in all parts of the world on soils, water, and biodiversity. Poor management of our agricultural systems has contributed to human-induced climate change, and, in turn, human-induced climate change threatens agricultural productivity. In many developed countries, access to quality food is taken for granted, and farmers and farm workers are poorly rewarded for acting as stewards of the Earth’s land area used for agricultural production. There is litt le emphasis on the conservation ethic. More troubling, the environmental degradation caused by intensive agriculture will likely worsen as the global population grows to eight or ten billion in the next three decades.
Modern agriculture is no longer approached as a single issue and is a business that includes far more than just production of food. We have to learn how to pay farmers to not only produce food, animal feed, fiber, and biofuel, but to value the environmental services they impact during crop production. We must consider the environmental issues of biodiversity and water, the economic issues of marketing and trade, and the social concerns of gender and culture. All of this must be done in an economically, environmentally, and socially sustainable manner. We need a fundamental reevaluation of agricultural knowledge, science, and technology transfer to achieve a sustainable global food system. Challenges include giving farmers better access to knowledge, technology, and credit and bringing the necessary information and infrastructure to rural areas
Diurnal Fluctuation of Leaf‐water Potential of Corn as Influenced by Soil Matric Potential and Microclimate 1
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