scholarly journals Soil Macronutrient Responses in Diverse Landscapes of Southern Tallgrass to Two Stocking Methods

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 329 ◽  
Author(s):  
Brian K. Northup ◽  
Patrick J. Starks ◽  
Kenneth E. Turner

Macronutrient (N, P, S, K, Ca, and Mg) availability and distribution in soils of grassland ecosystems are affected by diverse factors, including landscape position, climate, and forms of management. This study examined flux in plant-available macronutrients in production-scale (60 to 80 ha) paddocks of southern tallgrass prairie of central Oklahoma, United States, managed (2009–15) under two contrasting stocking methods (continuous yearlong; rotational stocking among 10 sub-paddocks). Macronutrient availability within the 0–7.5 cm and 7.5–15 cm soil depths were determined with sets of anion-cation exchange membrane probes at 16 locations within paddocks, oriented along transects from water sources to far corners. No clear overall effect related to stocking method was recorded for all macronutrient distributions. The only significant stocking method × location interaction occurred for K (p = 0.01). All other macronutrients displayed significant (p < 0.08) location effects that were common across stocking methods. Effects relatable to stocking method occurred in interactions with soil depth or time of year (p < 0.10), but responses of macronutrient flux to stocking method in these interactions varied. Higher flux occurred in available S, Ca, and Mg in proximity (<24 m) to water sources, which may be related to grazing, but local features of the landscape may also have been involved. More attention to landscape features included within paddocks, and standardized organization of water and other features within paddocks, would improve the potential to define grazing effects on macronutrient distribution.

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 281 ◽  
Author(s):  
Brian K. Northup ◽  
Patrick J. Starks ◽  
Kenneth E. Turner

Broad ranges of factors (parent materials, climate, plant community, landscape position, management) can influence macronutrient availability in rangeland soils. Two important factors in production-scale paddocks are the influences of location in space and land management. This study examined plant-available macronutrients (total mineral and nitrate-N, P, S, K, Ca, and Mg) in soils, with paired sets of probes (anion and cation exchange membranes) that simulate uptake by plant roots. Data were collected from sets of paddocks of southern tallgrass prairie in central Oklahoma, managed by four stocking methods during the 2015 growing season (mid-March, growth initiation by native grasses, and early-August, time of peak living plant biomass). Macronutrient availability in the 0–7.5 cm and 7.5–15 cm depths were determined at locations in close proximity to water (water tanks and 25% of the distance between tanks and paddock mid-points (PMP)), and distances near the mid-points of paddocks (70% of the distance between water and mid-points (0.7 PMP), and PMP). All of the tested stocking methods affected levels of availability of macronutrients at different times of the growing season, and among different locations within paddocks. Such responses indicated stocking methods may not result in uniform distributions of flux in plant-available macronutrients. The overall exposure of landscapes and arrangement of features within paddocks also appeared to influence macronutrient distributions.


Mycologia ◽  
1986 ◽  
Vol 78 (2) ◽  
pp. 316-320 ◽  
Author(s):  
J. M. Zajicek ◽  
B. A. Daniels Hetrick ◽  
C. E. Owensby

Author(s):  
Ingrid C. Burke ◽  
William K. Lauenroth

Where lies the future of the shortgrass steppe? In prior chapters we have described the remarkable resilience of the shortgrass steppe ecosystem and its organisms to past drought and grazing, and their sensitivity to other types of change. Emerging from this analysis is the idea of vulnerability to two main forces: future changes in precipitation or water availability, and direct human impacts. What are the likely changes in the shortgrass steppe during the next several decades? Which of the changes are most likely to affect major responses in the plants, animals, and ecosystem services of the shortgrass steppe? In this chapter we evaluate the current status of the shortgrass steppe and its potential responses to three sets of factors that will be driving forces for the future of the steppe: land-use change, atmospheric change, and changes in diseases. Referring to the early 1900s, James Michener in his novel Centennial (1974) wrote the following:… The old two-part system that had prevailed at the end of the nineteenth century— rancher and irrigator—was now a tripartite cooperation: the rancher used the rougher upland prairie; the irrigation farmer kept to the bottom lands; and the drylands gambler plowed the sweeping 0 eld in between, losing his seed money one year, reaping a fortune the next, depending on the rain. It was an imaginative system, requiring three different types of man, three different attitudes toward life. . . . (p. 1081)… Even today, because of the strong water limitation for cropping, the shortgrass steppe remains relatively intact, or at least unplowed, in contrast to other grassland ecosystems (Samson and Knopf, 1994). More than half of the shortgrass steppe remains in untilled, landscape-scale tracts, compared with only 9% of tallgrass prairie and 39% of mixed-grass prairie (The Nature Conservancy, 2003). These large tracts, including those in the national grasslands (Pawnee, Cimarron, Comanche, and Kiowa/Rita Blanca), provide the greatest opportunity for preserving key ecological processes and biological diversity.


1987 ◽  
Vol 65 (4) ◽  
pp. 787-791 ◽  
Author(s):  
D. C. Hayes ◽  
T. R. Seastedt

Root dynamics were studied using root windows at Konza Prairie, a tallgrass prairie in north central Kansas, during dry (1984) and wet (1985) years. Amounts, production, and disappearance of root length decreased during drought but increased when rains resumed; however, standing crop remained low. The 1985 root lengths increased throughout the growing season, while production and disappearance remained constant. Yearly summaries of amounts, productivity, and decomposition by 10-cm increments in soil depth show that the effect of drought on these variables decreased with increasing soil depth. Turnover rates of root length averaged 564 in the dry year versus 389% in the wet year, with the largest difference noted in the 0- to 10-cm depth (800 in 1984 versus 540% in 1985). Production and decay patterns observed using root windows were also noted in root biomass data (obtained from soil cores). The average total root biomass turnover rate was 31%. Failure to sort below-ground materials into tissue types (rhizomes, roots) and live versus dead status results in reduced estimates of biomass turnover rates. The greatest possible separation of plant components presents the most comprehensive picture of (belowground) growth dynamics.


Mycologia ◽  
1986 ◽  
Vol 78 (2) ◽  
pp. 316 ◽  
Author(s):  
J. M. Zajicek ◽  
B. A. Daniels Hetrick ◽  
C. E. Owensby

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Hongbin Zhao ◽  
Wenling Zheng ◽  
Shengwei Zhang ◽  
Wenlong Gao ◽  
Yueyue Fan

Abstract Purpose Soil microorganisms play an indispensable role in the material and energy cycle of grassland ecosystems. The abundance of these organisms vary according to environmental factors, such as time of year and soil depth. There have been few studies on the transformation of soil microbial communities in degraded typical steppe according to these temporal and spatial changes. In this study, we analyze the community structure and diversity of soil bacteria and fungi, and the impact of these changing temporal and spatial factors upon the community structure. Methods From May to September 2018, we collected 90 soil samples from different depths (10, 20, and 30 cm) from the typical degraded steppe area of Xilingol. We carried out studies on soil physical and chemical properties and soil microbial diversity using high-throughput sequencing technology. Results We found that depth significantly affected abundance and diversity of bacteria and fungi. Bacteria and fungi diversity at 10 cm was higher than that at 20 cm and 30 cm. The abundance of Acidobacteria, Proteobacteria, Actinomycetes, Ascomycetes, and Basidiomycetes varies significantly with depth. In addition, soil pH increased significantly with increasing depth, while soil organic matter (SOM), available nitrogen (AN), volume water content of soil (VWC), and soil temperature (ST) decreased significantly with increasing depth. Finally, the depth, total organic carbon (TOC), and AN had a significant impact on the bacterial and fungal communities’ abundance (p < 0.05). Conclusions Spatial heterogeneity (in soil depth) is more significant than the time of year (month) in predicting changes in microbial community composition and soil properties. SOM, VWC, and the abundance of Proteobacteria and Actinomycetes positively correlate with soil depth, while pH and the abundance of Acidobacteria, Ascomycetes, and Basidiomycetes negatively correlate with soil depth. We speculate that SOM and VWC account for the variations in the abundance of Acidobacteria and Proteobacteria, while pH causes variations in the abundance of Actinomycetes, Ascomycetes and Basidiomycota.


Author(s):  
Linda Sicko-Goad

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.


Author(s):  
S. Lehner ◽  
H.E. Bauer ◽  
R. Wurster ◽  
H. Seiler

In order to compare different microanalytical techniques commercially available cation exchange membrane SC-1 (Stantech Inc, Palo Alto), was loaded with biologically relevant elements as Na, Mg, K, and Ca, respectively, each to its highest possible concentration, given by the number concentration of exchangeable binding sites (4 % wt. for Ca). Washing in distilled water, dehydration through a graded series of ethanol, infiltration and embedding in Spurr’s low viscosity epoxy resin was followed by thin sectioning. The thin sections (thickness of about 50 nm) were prepared on carbon foils and mounted on electron microscopical finder grids.The samples were analyzed with electron microprobe JXA 50A with transmitted electron device, EDX system TN 5400, and on line operating image processing system SEM-IPS, energy filtering electron microscope CEM 902 with EELS/ESI and Auger spectrometer 545 Perkin Elmer.With EDX, a beam current of some 10-10 A and a beam diameter of about 10 nm, a minimum-detectable mass of 10-20 g Ca seems within reach.


Sign in / Sign up

Export Citation Format

Share Document