Soil Processes Affected by Sixteen Grassland Species Grown under Different Environmental Conditions

Abstract

Plant species, and their interactions with the environment, determine both the quantity and chemistry of organic matter inputs to soils. Indeed, countless studies have linked the quality of organic matter inputs to litter decomposition rates. However, few studies have examined how variation in the quantity and chemistry of plant inputs, caused by either interspecific differences or changing environmental conditions, influences the dynamics of soil organic matter. We studied the effects of 16 grassland species from 4 functional groups (C3 and C4 grasses, forbs, and legumes) growing under ambient and elevated CO 2 (560 ppm) and N inputs (4 g m 22 yr 21 ) on soil carbon (C) and nitrogen (N) dynamics after 4 yr in a grassland monoculture experiment in Minnesota, USA. Specifically, we related soil C and N dynamics to variation among species and their responses to the CO 2 and N treatments in plant biomass and chemistry of roots, the dominant detrital input in the system. The 16 species caused much larger variation in plant litter inputs and chemistry, as well as soil C and N dynamics, than the CO 2 and N treatment. Not surprising, variation in the quantity of plant inputs to soils contributed to up to a two-fold variation in microbial biomass and amount of respired nonlabile soil C. Root N concentration (across species and CO 2 and N treatments) was significantly negatively related to decomposition of nonlabile soil C and positively related to net N mineralization. Greater labile C inputs decreased rates of net N mineralization, likely because of greater N immobilization. Thus, of the traits examined, plant productivity, tissue N concentration, and labile C production such as from rhizodeposition were most important in causing variation in soil C and N dynamics among species and in response to altered atmospheric CO 2 and N supply.

Arbuscular mycorrhiza and soil nitrogen cycling

“…Interestingly, plant litter from C 4 grasses typically is of inferior quality (less decomposable) of that from C 3 grasses (e.g. Dijkstra et al, 2006). Litter quality is known to be a key trait that affects N-mineralization (Van der Krift and Berendse, 2001) and consequently other N-cycling processes such as nitrification (Booth et al, 2005).…”

The Influence of Management Practices on Microbial and Total Soil Nitrogen

“…It is more probable that in undisturbed, northern mixed-grass ecosystems (Coupland, 1992), there is a more equal distribution of cool-season and warm-season grass species. In a reclaimed situation, though warm-season grasses are often seeded into reclaimed sites they are often out competed by cool-season grasses, and cool-season grasses are typically more productive than warm-season grasses (Dijkstra et al, 2006). Finally, reclaimed sites typically have a greater plant density than found on undisturbed, native sites, which leads to greater productivity (G. Schuman, pers.…”

What Global and/or European Agriculture Will Need from Grasslands and Grassland Breeding over the Next 10–15 Years for a Sustainable Agriculture

“…So it remains to be seen if the net result of climate change will increase or decrease the carbon sink in grassland. Whatever the outcome will be, the room to manipulate here is quite small, although Dijkstra et al (2006) andDe Deyn et al (2011) showed that species richness (with an important role for legumes) continues to be the best guarantee for carbon sequestration.…”