Soil nutrient availability and relationships with aboveground biomass production on postharvested upland white spruce sites in interior Alaska

1993 ◽  
Vol 23 (6) ◽  
pp. 1223-1232 ◽  
Author(s):  
David Paré ◽  
Keith Van Cleve

Soil nutrient availability was assessed on unharvested white spruce (Piceaglauca (Moench) Voss) sites, on a recently harvested site and on 14-year-old postharvested sites stratified into four different regeneration types defined by surface soil conditions and colonizing species. These values were compared with field aboveground biomass production that had been estimated in a previous study and with biomass production of bioassay seedlings. All sites were upland and south facing. On this range of sites, laboratory net N mineralization was the soil characteristic that was the most strongly associated with plant growth in the field as well as in the greenhouse bioassay. The significance of this relationship was mainly caused by the presence of sites regenerating to aspen (Populustremuloides Michx.) which showed high plant biomass production and high soil N availability. Total soil N content, cumulative field soil temperature and soil moisture content were poorly related to N mineralization estimates and to plant biomass production. Soil temperature had an effect on N mineralization and plant growth only when sites where the forest floor had been scraped during the harvesting operations, were included in the computations. Despite a higher soil temperature, these sites showed decreased N mineralization rates and decreased plant biomass production. These results suggest that on south facing postharvested white spruce sites (i) soil temperature does not show enough variability to be an important factor controlling nutrient availability and plant growth unless the soil is severely disturbed, (ii) the rate of N mineralization is controlled by a small pool of rapidly cycling N which is poorly related to forest floor total N concentrations, and (iii) N availability and vegetation production vary with regeneration type.

Author(s):  
L. M. Manici ◽  
F. Caputo ◽  
G. A. Cappelli ◽  
E. Ceotto

Abstract Soil suppressiveness which is the natural ability of soil to support optimal plant growth and health is the resultant of multiple soil microbial components; which implies many difficulties when estimating this soil condition. Microbial benefits for plant health from repeated digestate applications were assessed in three experimental sites surrounding anaerobic biogas plants in an intensively cultivated area of northern Italy. A 2-yr trial was performed in 2017 and 2018 by performing an in-pot plant growth assay, using soil samples taken from two fields for each experimental site, of which one had been repeatedly amended with anaerobic biogas digestate and the other had not. These fields were similar in management and crop sequences (maize was the recurrent crop) for the last 10 yr. Plant growth response in the bioassay was expressed as plant biomass production, root colonization frequency by soil-borne fungi were estimated to evaluate the impact of soil-borne pathogens on plant growth, abundance of Pseudomonas and actinomycetes populations in rhizosphere were estimated as beneficial soil microbial indicators. Repeated soil amendment with digestate increased significantly soil capacity to support plant biomass production as compared to unamended control in both the years. Findings supported evidence that this increase was principally attributable to a higher natural ability of digestate-amended soils to reduce root infection by saprophytic soil-borne pathogens whose inoculum was increased by the recurrent maize cultivation. Pseudomonas and actinomycetes were always more abundant in digestate-amended soils suggesting that both these large bacterial groups were involved in the increase of their natural capacity to control soil-borne pathogens (soil suppressiveness).


2019 ◽  
Vol 116 (25) ◽  
pp. 12550-12557 ◽  
Author(s):  
Jaynee E. Hart ◽  
Stuart Sullivan ◽  
Paweł Hermanowicz ◽  
Jan Petersen ◽  
L. Aranzazú Diaz-Ramos ◽  
...  

The ability to enhance photosynthetic capacity remains a recognized bottleneck to improving plant productivity. Phototropin blue light receptors (phot1 and phot2) optimize photosynthetic efficiency in Arabidopsis thaliana by coordinating multiple light-capturing processes. In this study, we explore the potential of using protein engineering to improve photoreceptor performance and thereby plant growth. We demonstrate that targeted mutagenesis can decrease or increase the photocycle lifetime of Arabidopsis phototropins in vitro and show that these variants can be used to reduce or extend the duration of photoreceptor activation in planta. Our findings show that slowing the phototropin photocycle enhanced several light-capturing responses, while accelerating it reduced phototropin’s sensitivity for chloroplast accumulation movement. Moreover, plants engineered to have a slow-photocycling variant of phot1 or phot2 displayed increased biomass production under low-light conditions as a consequence of their improved sensitivity. Together, these findings demonstrate the feasibility of engineering photoreceptors to manipulate plant growth and offer additional opportunities to enhance photosynthetic competence, particularly under suboptimal light regimes.


Ecosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Peter A. Wilfahrt ◽  
Andreas H. Schweiger ◽  
Nelson Abrantes ◽  
Mohammed A. S. Arfin‐Khan ◽  
Michael Bahn ◽  
...  

2021 ◽  
Vol 35 (3) ◽  
pp. 774-786
Author(s):  
Jiankun Bai ◽  
Yuchen Meng ◽  
Ruikun Gou ◽  
Jiacheng Lyu ◽  
Zheng Dai ◽  
...  

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Takashi Kunito ◽  
Takashi Shiroma ◽  
Hitoshi Moro ◽  
Hirotaka Sumi

Annual variations in enzyme activities involved in carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling and soil physicochemical properties were examined in a Japanese paddy field. All the enzyme activities determined at the field soil temperature (range, 2.2°C–28.3°C) increased exponentially with soil temperature (p<0.001). Significant negative correlations were found between Bray-2P concentration and the ratio of acid phosphatase to β-D-glucosidase activity (Spearman r = −0.631, p = 0.005) and between total N and the ratio of L-asparaginase to β-D-glucosidase activity (r = −0.612, p=0.007), suggesting that in accordance with the resource allocation model, acid phosphatase and L-asparaginase were synthesized by microorganisms depending on the temporal changes in soil P and N availability. These results suggest the significance of soil temperature in controlling in situ enzyme activities in paddy soil and also that the stoichiometry of enzyme activities associated with C, N, and P acquisition reflects the soil nutrient availability.


2018 ◽  
Vol 35 (3) ◽  
pp. 227-233 ◽  
Author(s):  
Natalie P Lounsbury ◽  
Nicholas D Warren ◽  
Seamus D Wolfe ◽  
Richard G Smith

AbstractHigh-residue cover crops can facilitate organic no-till vegetable production when cover crop biomass production is sufficient to suppress weeds (>8000 kg ha−1), and cash crop growth is not limited by soil temperature, nutrient availability, or cover crop regrowth. In cool climates, however, both cover crop biomass production and soil temperature can be limiting for organic no-till. In addition, successful termination of cover crops can be a challenge, particularly when cover crops are grown as mixtures. We tested whether reusable plastic tarps, an increasingly popular tool for small-scale vegetable farmers, could be used to augment organic no-till cover crop termination and weed suppression. We no-till transplanted cabbage into a winter rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) cover crop mulch that was terminated with either a roller-crimper alone or a roller-crimper plus black or clear tarps. Tarps were applied for durations of 2, 4 and 5 weeks. Across tarp durations, black tarps increased the mean cabbage head weight by 58% compared with the no tarp treatment. This was likely due to a combination of improved weed suppression and nutrient availability. Although soil nutrients and biological activity were not directly measured, remaining cover crop mulch in the black tarp treatments was reduced by more than 1100 kg ha−1 when tarps were removed compared with clear and no tarp treatments. We interpret this as an indirect measurement of biological activity perhaps accelerated by lower daily soil temperature fluctuations and more constant volumetric water content under black tarps. The edges of both tarp types were held down, rather than buried, but moisture losses from the clear tarps were greater and this may have affected the efficacy of clear tarps. Plastic tarps effectively killed the vetch cover crop, whereas it readily regrew in the crimped but uncovered plots. However, emergence of large and smooth crabgrass (Digitaria spp.) appeared to be enhanced in the clear tarp treatment. Although this experiment was limited to a single site-year in New Hampshire, it shows that use of black tarps can overcome some of the obstacles to implementing cover crop-based no-till vegetable productions in northern climates.


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