Mass loss and nitrogen dynamics during the decomposition of a 15N-labeled N2-fixing epiphytic lichen, Lobaria oregana

2003 ◽  
Vol 81 (7) ◽  
pp. 698-705 ◽  
Author(s):  
Scott M Holub ◽  
Kate Lajtha

We studied mass loss and nitrogen dynamics during fall and spring initiated decomposition of an N2-fixing epiphytic lichen, Lobaria oregana (Tuck.) Müll. Arg., using 15N. We developed a method of labeling lichens with 15N for use in a decomposition study that involved spraying lichen material with a nutrient solution containing 15N-enriched ammonium. Through the first 180 days of sampling, lichens placed in the field during the spring had a smaller decay constant (k = 1.24 year–1) than the lichens placed in the field during the fall (k = 3.1 year–1). However, both spring and fall lichen samples were decomposed beyond recognition after 1 year. Patterns in exogenous N uptake and N concentration did not differ by season. Both spring and fall lichens took up N from the surrounding environment during decay while simultaneously losing N to the environment. The N concentration in both sets of lichen additions increased during decay to a peak of around 2.8% N, equal to a C to N ratio of about 16, and then began to decrease. This indicates that early in decay, net N immobilization occurred in the remaining lichen, but this was followed by net N mineralization in later stages of decay.Key words: decomposition, nitrogen, Lobaria oregana, lichen, mineralization, immobilization.

2005 ◽  
Vol 85 (5) ◽  
pp. 579-587 ◽  
Author(s):  
Y. K. Soon ◽  
S. S. Malhi

The influence o f landscape position on the dynamics of N in the soil-plant system has not been adequately studied. Our aim with this study on a predominantly Black Chernozem soil was to evaluate the effect of slope position (upper vs. lower) and N fertilizer application (none vs. 60 kg N ha-1) on soil and wheat (Triticum aestivum L.) N through the growing season. Landscape position had a dominant effect on soil NO3− and soluble organic N (SON) concentrations, especially in the surface 15 cm. These pools of soil N and net N mineralization were greater at the lower than at the upper slope position. The landscape effect is attributed to higher organic matter content (as measured by organic C) and water availability in lower compared with upper slope positions. Nitrogen application had no measurable effect on soil NO3− and SON concentrations. Exchangeable and non-exchangeable NH4+ were little affected by slope position or N fertilization. Nitrogen application increased wheat N uptake; however, its influence was less than that of slope position, especially on N accumulation in wheat heads during grain-filling. Although N application increased wheat yields, landscape position exerted the greater influence: grain yield was less on upper than lower slope positions due to earlier onset of crop maturity. During grain filling, net N mineralization was suppressed at the upper slope position and by N application. The increase in crop yield and N uptake due to N application was not significantly different between slope positions. This study demonstrated that landscape position had a greater influence on N dynamics and availability than the application of typical amounts of fertilizer N and that the two effects were mostly independent of each other. Key words: Available N, landscape position, N uptake, net N mineralization, soluble organic N


1988 ◽  
Vol 68 (2) ◽  
pp. 337-344 ◽  
Author(s):  
C. A. CAMPBELL ◽  
R. P. ZENTNER ◽  
F. SELLES

Data from an 18-yr crop rotation study carried out on a Brown loam soil at Swift Current, Saskatchewan, were used to estimate equations that relate spring wheat straw yields, and N and P content of grain and straw to moisture use (MU). Moisture use was defined as soil moisture content in 0- to 120-cm depth at seeding, less soil moisture content at harvest, plus growing season precipitation. Grain yields were also related to straw yields and to N content of the straw. Potential net N mineralization (Nmin) in summerfallow (periods during the growing season with negative Nmin omitted) was related (r = 0.74**) to precipitation received during the spring to fall period. An attempt to relate apparent net Nmin (determined by N balance) in cropped systems to growing season precipitation or to MU was not successful. Highly significant linear regressions were obtained for straw yields, grain N and P contents vs. MU, and for grain yield vs. straw yield (r = 0.66** – 0.83**), but the other relationships were less reliable (r = 0.41** – 0.55**) though still significant. We discussed how these relationships might be used to estimate fertilizer N requirements, for examining N immobilization-mineralization, and for estimating residue sufficiency for erosion control on summerfallowed land. Key words: Straw:grain ratio, N uptake, P uptake, crop residues, N mineralization


Author(s):  
A.M. Van Dam ◽  
P.A. Leffelaar

Catch crops (winter rye [Secale cereale] and fodder radish [Raphanus sativus]) were grown on lysimeters with rhizotron facilities in Wageningen, Netherlands, from September-March (1993-94) and August-March (1994-95) in order to study root growth and water and nitrogen dynamics under different regimes of irrigation and N supply. Catch crops took up 20-30 g N/msuperscript 2, of which 37-48% was present in dead leaves in March. Rooting depth increased by 2.6 cm/day for both species at the start of the growing season. Catch cropping reduced the NO-3-N concentration in the soil considerably, initially in the top layers and then further down the soil profile. The reduction in total leached N was similar to the total crop N uptake. Nitrate-N concentrations in leached water were reduced by 49-85 mg/litre (62-99%), depending upon N availability and irrigation. Due to catch cropping the NO-3-N concentration in the percolate decreased with increasing irrigation (or precipitation), whereas the amount of N leached increased with irrigation. Evapotranspiration from a catch cropped soil was close to the potential evapotranspiration under optimal growth conditions.


2000 ◽  
Vol 30 (11) ◽  
pp. 1698-1706 ◽  
Author(s):  
K D Thomas ◽  
C E Prescott

Forest floor samples from a 25-year-old plantation of three tree species (Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), and paper birch (Betula papyrifera Marsh.)) growing on the same site were incubated (aerobically) in the laboratory for 29 days. Rates of N mineralization in the forest floors of Douglas-fir (165.1 µg/g) was significantly greater than either birch (72.9 µg/g) or lodgepole pine (51.2 µg/g). Douglas-fir forest floors also had the highest N concentration, lowest C/N ratio, and highest NH4-N concentrations, followed by paper birch and lodgepole pine. Douglas-fir forest floors also mineralized more N per unit of either N or C than the other species. There were no differences in rates of CO2-C mineralization in forest floors among the three species. Nitrogen mineralization rates were positively correlated with the N concentration of the forest floor (r2 = 0.81) and also with the C/N and NH4-N concentration of the forest floor. Nitrogen concentration, C/N, and lignin/N of foliar litter were poor predictors of N mineralization rates resulting from Douglas-fir litter having the lowest N concentrations in litter but the highest rates of net N mineralization in the forest floor. Nitrogen mineralization in the forest floor was negatively correlated (r2 = 0.67) with the lignin concentration in foliar litter. Douglas-fir litter had low lignin concentrations, which may allow more of the mineralized N to remain in inorganic forms rather than being bound in humus. Our results suggest that a component of Douglas-fir might improve N availability in coniferous forest floors.


1983 ◽  
Vol 13 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Knute J. Nadelhoffer ◽  
John D. Aber ◽  
Jerry M. Melillo

Annual net N mineralization in the 0–10 cm mineral soil zone of nine forest stands on silt–loam soils was measured using a series of insitu soil incubations from April 1980 through April 1981. Differences in soil organic matter (SOM) dynamics among sites were shown with net N mineralization ranging from 0.54 to 2.10 mg N mineralized•g SOM−1•year−1. This variation was not related to percent N in SOM. Net N mineralization varied seasonally with maximum rates in June and very low rates in winter. Nitrification rates were constant from May through September despite fluctuations in soil ammonium pools. Nitrification was greater than 50% of annual net N mineralization at all sites. N uptake by vegetation, as estimated by net N mineralization plus mineral N inputs via precipitation, with minor corrections for mineralization below the incubation depth and for mineral N losses to groundwater, ranged from 40.3 to 119.2 kg N•ha−1•year−1. Annual leaf and needle litter production ranged from 2.12 to 4.17 Mg•ha−1•year−1 and was strongly correlated with N uptake (r = 0.938, P < 0.01). N returned in leaf litter was also correlated with N uptake (r = 0.755, P < 0.05). Important feedbacks may exist between N availability and litter quality and quantity.


1996 ◽  
Vol 76 (4) ◽  
pp. 469-472 ◽  
Author(s):  
J. W. Paul ◽  
E. G. Beauchamp

A spring application of dairy cattle slurry (300 kg total N ha−1) on high- and low-fertility sites resulted in higher microbial biomass C during the growing season than on a control soil or a soil receiving 100 kg N ha−1 as urea. Microbial biomass C was also significantly higher on the high-fertility site and was reflected in greater N mineralization and N uptake by corn. There was no greater net N mineralization in the manured soil than in the control or fertilized soil as would be expected as a result of higher microbial biomass C and significant organic N contribution from the manure. Key words: Animal manure, nitrogen mineralization, corn, grain yields, soil fertility


2016 ◽  
Vol 96 (4) ◽  
pp. 427-434 ◽  
Author(s):  
Ben W. Thomas ◽  
Joann K. Whalen ◽  
Mehdi Sharifi

Concurrent N mineralization and immobilization in soils receiving poultry litter containing woodchip bedding may reduce synchrony between the short-term N supply and crop N demand. Therefore, we used soil chemical tests, ion exchange membranes, and wheat N uptake to assess N dynamics in a poultry-litter-amended soil. Air-dried soil was thoroughly mixed with five poultry litter rates (50, 100, 150, 200, or 250 mg total N kg−1) and preincubated for 7 d in a controlled environment chamber. After preincubating, soil was placed in 10-cm-diameter pots and planted with spring wheat (Triticum aestivum ‘Wilkin’), or left unplanted and monitored with anion and cation exchange membranes for 45 d. Soil nitrate (NO3-N) concentration increased with poultry litter application rate at the end of the preincubation period, but subsequent wheat N uptake did not, suggesting that little net N mineralization occurred during the 45 d of wheat growth. The membrane data indicated a shift from net N immobilization during the early part of the wheat growth period to net mineralization during the latter portion of the wheat growth period. We conclude that alternating N mineralization and immobilization in soils receiving poultry litter containing woodchip bedding limited the short-term N supply to wheat.


1996 ◽  
Vol 76 (2) ◽  
pp. 307-315 ◽  
Author(s):  
V. O. Biederbeck ◽  
O. T. Bouman ◽  
C. A. Campbell ◽  
G. E. Winkleman ◽  
L. D. Bailey

Partial replacement of fallow with legume green manures has the potential to improve cereal production and agricultural sustainability in the northern Great Plains. This is possible if N gains by annual legumes and enhancement of soil N availability are optimized. The objectives of the study were to (i) determine the N distribution in different vegetative components of four annual legumes; (ii) estimate their ability to accumulate N through fixation; and (iii) compare the N uptake of the cereal crop that follows legume green manure with that of cereal grown on fallow or of cereal receiving N fertilizer. Black lentil (Lens culinaris Medik.), Tangier flatpea (Lathyrus tingitanus L.), chickling vetch (Lathyrus sativus L.), and feedpea (Pisum sativum L.) were grown in rotation with spring wheat (Tnticum aestivum L.). Nitrogen concentration in legume nodules was several times greater than in any other plant part. However, N concentration in legume shoots was, on average, 27% greater than in legume roots. Total legume N content (% × mass) ranged from 41 to 126 kg ha−1 in years of low weediness. In those years, below-ground legume N content ranged between 2 and 29 kg ha−1 and averaged 7, 8, 17 and 6 kg ha−1 for black lentil, Tangier flatpea, chickling vetch and feedpea, respectively. Estimates of N2 fixation varied between 6 and 69 kg ha−1 and averaged 18 kg ha−1 for black lentil, 16 for Tangier flatpea, 49 for chickling vetch and 40 for feedpea. Within 3 mo of green-manure incorporation, average net N mineralization across years was greatest after black lentil and chickling vetch (38 kg N ha−1). The average 49 kg N ha−1 lost through cereal grain harvest was balanced by gains through symbiotic N2 fixation when chickling vetch and feedpea were used as green manure, but black lentil and Tangier flatpea replaced only about 35% of the N removed in the grain. Key words: Symbiotic N2 fixation, N mineralization, Tangier flatpea, black lentil, chickling vetch, feedpea


2020 ◽  
Vol 255 ◽  
pp. 107863 ◽  
Author(s):  
Xiaogang Yin ◽  
Kurt-Christian Kersebaum ◽  
Nicolas Beaudoin ◽  
Julie Constantin ◽  
Fu Chen ◽  
...  

1994 ◽  
Vol 24 (12) ◽  
pp. 2424-2431 ◽  
Author(s):  
C.E. Prescott ◽  
C.M. Preston

To determine if western red cedar (Thujaplicata Donn) litter contributes to low N availability in cedar–hemlock forests, we measured concentrations of N and rates of net N mineralization in forest floors from single-species plantations of cedar, western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the same site in coastal British Columbia. Concentrations of total and extractable N and rates of net N mineralization during laboratory incubations were lowest in the cedar forest floor and highest in Douglas-fir. Less C was mineralized in the cedar forest floor during incubation, and the amount of N mineralized per unit C was least in cedar. Rates of mass loss of foliar litter of the three species were similar during the first 50 weeks of a 70-week laboratory incubation, but cedar lost mass more quickly during the final 20 weeks. Rates of net N mineralization in the forest floors were significantly correlated with the initial percent N, C/N, % Klason lignin, and lignin/N of foliar litter. Foliar litter of cedar had lower concentrations of N and greater proportions of alkyl C (based on 13C NMR spectroscopy) than Douglas-fir litter. These characteristics of cedar litter may contribute to low N availability in cedar–hemlock forest floors. Concentrations of alkyl C (waxes and cutin) may be better than lignin for predicting rates of mass loss and N mineralization from litter.


Sign in / Sign up

Export Citation Format

Share Document