The response of coarse root biomass to long‐term CO 2 enrichment and nitrogen application in a maturing Pinus taeda stand with a large broadleaved component

While northern temperate grasslands are important for supporting beef production, it remains unclear how grassland above- and belowground biomass responds to long-term cattle grazing. Here, we use a comprehensive dataset from 73 grasslands distributed across a broad agro-climatic gradient to quantify grassland shoot, litter, and shallow (top 30 cm) root biomass in areas with and without grazing. Additionally, we relate biomass to soil carbon (C) concentrations. Forb biomass was greater (p < 0.05) in grazed areas, particularly those receiving more rainfall. In contrast, grass and total aboveground herbage biomass did not differ with grazing (total: 2320 kg ha−1 for grazed vs. 2210 kg ha−1 for non-grazed; p > 0.05). Forb crude protein concentrations were lower (p < 0.05) in grazed communities compared with those that were non-grazed. Grasslands subjected to grazing had 56% less litter mass. Root biomass down to 30 cm remained similar between areas with (9090 kg ha−1) and without (7130 kg ha−1) grazing (p > 0.05). Surface mineral soil C concentrations were positively related to peak grassland biomass, particularly total (above + belowground) biomass, and with increasing forb biomass in grazed areas. Finally, total aboveground shoot biomass and soil C concentrations in the top 15 cm of soil were both positively related to the proportion of introduced plant diversity in grazed and non-grazed grasslands. Overall, cattle grazing at moderate stocking rates had minimal impact on peak grassland biomass, including above- and belowground, and a positive contribution exists from introduced plant species to maintaining herbage productivity and soil C.

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How Does Nitrogen Application Ameliorate Negative Effects of Long-Term Drought in Two Maize Cultivars in Relation to Plant Growth, Water Status, and Nitrogen Metabolism?

Communications in Soil Science and Plant Analysis ◽

10.1080/00103624.2012.681735 ◽

2012 ◽

Vol 43 (12) ◽

pp. 1632-1646 ◽

Cited By ~ 1

Author(s):

L. X. Zhang ◽

S. Q. Li ◽

S. X. Li ◽

Z. S. Liang

Keyword(s):

Plant Growth ◽

Nitrogen Metabolism ◽

Water Status ◽

Nitrogen Application ◽

Negative Effects ◽

Maize Cultivars

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The soil organic carbon stabilization potential of old and new wheat cultivars: a <sup>13</sup>CO<sub>2</sub>-labeling study

Biogeosciences ◽

10.5194/bg-17-2971-2020 ◽

2020 ◽

Vol 17 (11) ◽

pp. 2971-2986

Author(s):

Marijn Van de Broek ◽

Shiva Ghiasi ◽

Charlotte Decock ◽

Andreas Hund ◽

Samuel Abiven ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Root Biomass ◽

Selection Process ◽

Wheat Breeding ◽

Wheat Cultivars ◽

Cultivar Selection ◽

Long Term Effect ◽

Soc Stocks

Abstract. Over the past decades, average global wheat yields have increased by about 250 %, mainly due to the cultivation of high-yielding wheat cultivars. This selection process not only affected aboveground parts of plants, but in some cases also reduced root biomass, with potentially large consequences for the amount of organic carbon (OC) transferred to the soil. To study the effect of wheat breeding for high-yielding cultivars on subsoil OC dynamics, two old and two new wheat cultivars from the Swiss wheat breeding program were grown for one growing season in 1.5 m deep lysimeters and pulse labeled with 13CO2 to quantify the amount of assimilated carbon that was transferred belowground and can potentially be stabilized in the soil. The results show that although the old wheat cultivars with higher root biomass transferred more assimilated carbon belowground compared to more recent cultivars, no significant differences in net rhizodeposition were found between the different cultivars. As a consequence, the long-term effect of wheat cultivar selection on soil organic carbon (SOC) stocks will depend on the amount of root biomass that is stabilized in the soil. Our results suggest that the process of wheat selection for high-yielding cultivars resulted in lower amounts of belowground carbon translocation, with potentially important effects on SOC stocks. Further research is necessary to quantify the long-term importance of this effect.

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Coarse root biomass allometric equations for Abies balsamea, Picea mariana, Pinus banksiana, and Populus tremuloides in the boreal forest of Ontario, Canada

Biomass and Bioenergy ◽

10.1016/j.biombioe.2011.06.045 ◽

2011 ◽

Vol 35 (10) ◽

pp. 4189-4196 ◽

Cited By ~ 33

Author(s):

Brian W. Brassard ◽

Han Y.H. Chen ◽

Yves Bergeron ◽

David Paré

Keyword(s):

Boreal Forest ◽

Populus Tremuloides ◽

Picea Mariana ◽

Root Biomass ◽

Pinus Banksiana ◽

Abies Balsamea ◽

Allometric Equations ◽

Coarse Root

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Root biomass in timothy and red clover leys estimated by soil coring and mesh bags

The Journal of Agricultural Science ◽

10.1017/s0021859600086822 ◽

1989 ◽

Vol 113 (2) ◽

pp. 241-247 ◽

Cited By ~ 6

Author(s):

E. Steen

Keyword(s):

Root Biomass ◽

Red Clover ◽

Phleum Pratense ◽

Root Decomposition ◽

Soil Core ◽

Soil Cores ◽

Medium Term ◽

Short Term ◽

Mesh Bags

SUMMARYRoot biomass of timothy grass (Phleum pratense L.), at low and high N fertilization rates, and of red clover (Trifolium pratense L.) were estimated with soil cores and in mesh bags in a field trial on a sandy loam in central Sweden. First and second full-harvest year leys were sampled three times each year from May to October. Mesh bags were inserted in the soil in autumn shortly after sowing (longterm bags); in spring and autumn of the first year and in spring of the second year (medium-term bags); and every third month during both years (short-term bags). Mesh bags of each type were sampled when the soil cores were taken.Root biomass in the long-term bags was generally about the same as that in the soil cores, but taproot biomass in the clover crop was underestimated in the bags. In the grass plots, differences between soil cores and mesh bags were probably caused by ingrowth of weed roots in bags and by larger root biomass in plant rows than between rows. If soil cores and long-term mesh bags are sampled in exactly the same way identical estimates of biomass should be obtained.Root biomass in short-term and medium-term bags was about the same as that in the soil cores and long-term bags on many of the sampling occasions. Thus a stable level of biomass was reached in a rather short time, i.e. after 3 months or less. Then root production, root mortality and root decomposition occurred simultaneously at a fairly constant level.The bags did not contain residues from earlier crops, which reduced the amount of separation work necessary. The absence of crop residues in the bags did not seem to affect root biomass.The mesh bag method is a useful alternative to soil core sampling for studying root biomass and root dynamics in perennial and annual crops. However, the bags must be inserted into the soil just after sowing and they must be placed in, as well as between, plant rows.

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