Nitrogen fixation and growth response of Alnus Rubra following fertiliztion with urea or biosolids

Abstract

Nitrogen fertilization of forests using biosolids offers a potentially environmentally friendly means to accelerate tree growth. This field study was designed to analyze the effects of nitrogen fertilization on the symbiotic, nitrogen (N)-fixing relationship between Alnus rubra Bong. (red alder) and Frankia. Anaerobically digested, class B biosolids and synthetic urea (46% N) were applied at rates of 140, 280 and 560 kg ha-1 available N to a well-drained, sandy, glacial outwash soil in the Indianola series (mixed, mesic Dystric Xeropsamments). Plots were planted with A. rubra seedlings. At the end of each of two growing seasons trees were harvested and analyzed for the rate of N fixation (as acetylene reduction activity), biomass and foliar N. At year 1, there was no N fixation for trees grown with urea amendments, but control (17 µmol C2H4 g-1 hr-1) and biosolids (26-45 µmol C2H4 g-1 hr-1) trees were fixing N. At the end of year 2, all trees in all treatments were fixing N (7 µmol C2H4 g-1 hr-1, 4-16 µmol C2H4 g-1 hr-1, and 20-29 µmol C2H4 g-1 hr-1 for control, urea and biosolids respectively). Trees grown with biosolids amendments were larger overall (year 1 shoot biomass 10 g, 5 g, and 23 g for control, urea, and biosolids respectively, year 2 shoot biomass 50 g, 51 g, and 190 g for control, urea, and biosolids respectively) with higher concentrations of foliar N for both years of the study (year 1 foliar N 26 g kg-1, 27 g kg-1, and 40 g kg-1 for control, urea, and biosolids respectively, year 2 foliar N 17 g kg-1, 19 g kg-1, and 23 g kg-1 for control, urea, and biosolids respectively). Trees grown with urea amendments appeared to use the urea N over Frankia supplied N, whereas the biosolids trees appeared to be able to use both N in biosolids and N from Frankia. The results from this study indicated that the greater growth of A. rubra may have been responsible for the observed higher N demand. Biosolids may have supplied other nutrients to the trees to support this accelerated growth.

Biochar enhances seedling growth and alters root symbioses and properties of sub-boreal forest soils

“…Contrary to other studies (Cote´et al 1989;Voisin et al 2002;Martin et al 2003), urea-N had no effect on ARA (N fixation) rates or nodule frequency and size. Gaulke et al (2006) reported that urea addition (140, 280 and 560 kg N ha (1 ) inhibited N fixation (as ARA) and had a negative impact on Alnus seedling growth at the end of the first year. The N application rates in our study (equivalent to Â200 kg N ha (1 ) were comparable with the study reported by Gaulke et al (2006).…”

“…Some plants (e.g., Alnus spp.) also form actinorhizal symbioses with soil-borne filamentous bacteria (Frankia) (Gaulke et al 2006) and receive 70Á100% of their nitrogen requirement via N fixation (Nickel et al 2001;Myrold and Huss-Danell 2003). The actinorhizal symbiosis allows alders to colonize very poor or disturbed soils, thereby accelerating soil development and supporting microbial activities through addition of both N and C in the rhizosphere (Selmants et al 2005;Roy et al 2007).…”

Effects of Large-Scale Nitrogen Fertilization on Insect–Plant Interactions in the Canopy of Tall Alder Trees with N2-Fixing Traits in a Cool Temperate Forest

“…Alder species are typically the largest natural pathway for N input in certain forest types [27,28]. Given the research focus on N-limited species, it remains unclear how the leaf traits of N 2 -fixing plants may be affected by increased N deposition, and how, in turn, plant-insect interactions may be affected, even when N fertilization promotes plant growth [29,30].…”

Soil and seedling response to dehydrated septic tank sludge versus forest floor additions at a disturbed site

“…Soriano-Disla et al 2010;Singh et al 2011;Torri et al 2014b) have reported short-term (2 to 3 years) improvements of F o r R e v i e w O n l y 4 nutrient availability in unproductive forest soils after sludge application (Hallett et al 1999;Bramryd 2002;Cavaleri et al 2004;Varela et al 2011). Carbon and N addition from sludge may benefit soil microbial biomass (Kuzyakov et al 2000;Singh and Agrawal 2008), which, in turn, increases C and N mineralization rates (Khan and Scullion 2002; Gibbs et al 2006;Kao et al 2006) and the release of other nutrients such as P, Ca and K. As a whole, sludge application has been shown to improve tree nutrition and growth from increased soil organic C and nutrient availability (Gaulke et al 2006;Selivanovskaya and Latypova 2006;Holm and Heinsoo 2013).…”