Productivity and Density of Soil Algae in an Agricultural System

Abstract

Soil algal productivity and biomass were monitored in a conventional tillage agricultural system from December 1981 through December 1982. Productivity was based on the fixation rate of radiolabeled carbon dioxide. Biomass estimates (cell number and volume) were based on cell counts radiolabeled carbon dioxide. Biomass estimates (cell number and volume) were based on cell counts and measurements done with epifluoroscence microscopy. Algal productivity values (measured as carbon fixation) ranged from 0 to 76 mg°m—2°h—1, values for cell number ranged from 5.85 x 108 to 5.19 x 1010 cells/m2 and the volume of cells was between 34.8 and 7540 mm3/m2. Regression analysis indicates that algal productivity was most closely correlated with the product of cell number and light intensity, while a number of cells per square metre was most closely correlated with the product of temperature and moisture. The logarithm of the average volume per cell was inversely correlated with soil moisture and temperature. The percentage of algae present as aggregates was proportional to moisture and the square of temperature. Total annual productivity (as carbon) was estimated to be 39 g/m2.

Cyanobacterial blooms and the occurrence of the neurotoxin, beta-N-methylamino-l-alanine (BMAA), in South Florida aquatic food webs

“…This possibility includes not only natural water bodies, but also nutrient rich habitats such as aquaculture ponds and flooded rice fields that have high concentrations of cyanobacteria (Paerl and Tucker, 1995; Massout, 1999; Kankaanpaa et al, 2005; Zimba, 2008). Agricultural soils can also have high concentrations of cyanobacteria (Ramsey and Ball, 1983; Shimmel and Darley, 1985; Whitton, 2000). …”

Soil Ecosystem Changes During the Transition to No-Till Cropping

“…Numbers of algae are positively related to soil moisture and light (Shimmel and Darley, 1985), and negatively related to soil depth. Algae assist in N fixation and soil aggregate stability.…”

Soil surface colonization by phototrophic indigenous organisms, in two contrasted soils treated by formulated maize herbicide mixtures

“…These organisms are well anchored in soil health and food webs because of their major roles in carbon and nitrogen cycles. Indeed, some cyanobacteria are able to fix atmospheric nitrogen and the contribution of the overall microbial phototrophic community to primary production can reach up to 10 % of total microbial biomass in farmland soils (Reisser 2007;Shimmel and Darley 1985). Moreover, microbiotic crusts of soil surfaces (assemblages of non-vascular plants including mosses, algae, lichens, fungi, bacteria) favor seeding (Langhans et al 2009) and stabilize the soil against water and wind erosion, increasing landscape stability (Eldridge and Greene 1994).…”