scholarly journals Enumeration of carbon and nitrogen contents of water-stable aggregates in layers of topsoils from cultivated and adjacent bush-fallow loamy soils

Agro-Science ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 103-113
Author(s):  
C.B. Okebalama ◽  
C.A. Igwe ◽  
A.O. Onunwa

Soil organic carbon (SOC) and total soil nitrogen (TSN) dynamics have both pedological and agronomic basis. Knowledge of their retention within aggregate hierarchies of varying soil textures as influenced by land use change is limited. The capacity of loam (L), clay loam (CL), sandy loam (SL) and sandy clay loam (SCL) soils to retain SOC and TSN in water-stable aggregate (WSA) at 10-cm intervals of 0-30 cm topsoil depths under cultivated and bushfallow/ uncultivated systems was investigated. The soils showed high dispersion ratio and great variations in aggregate silt and clay indices (CL > L > SCL > SL) under both land uses. Across soil depths, the uncultivated CL, SL and SCL soils had moderate to high > 2.00 mm WSA whose reduction due to cultivation impact was more pronounced in SL than in CL soil. Across soil depths and land uses, SOC content seemed higher in the macro- (> 0.50 mm) than in the micro- (< 0.50 mm) aggregates of all the soils while the reverse marked aggregate TSN content in almost all the soils. Cultivation mostly reduced macro-aggregate-associated SOC and TSN in L > CL > SL and in L > SL > CL > SCL soils, respectively. However, cultivation showed no reduction influence on micro-aggregate-associated SOC of all the soils. Cultivation-related reduction in micro-aggregate-associated TSN was more pronounced in the generally more ‘clayey’ CL and SCL than the L and SL soils. So, the potential of bush-fallowing to enhance micro-aggregateassociated TSN storage and stabilization against adverse influence of cultivation depends on soil texture.

2021 ◽  
Vol 54 (4) ◽  
pp. 586-596
Author(s):  
M. M. Tahir ◽  
A. B. Khalid ◽  
K. Mehmood ◽  
A. Khaliq ◽  
N. Rahim

2021 ◽  
pp. 37-57
Author(s):  
Joel Yesaya Pallangyo ◽  
Nsajigwa Emmanuel Mbije

This study was done to determine the contribution of selected herbivores’ dung in the grazed ecosystem of Serengeti National Park, Tanzania. To achieve this Soil Organic Carbon and Nitrogen were determined in four distinct textural soils in three sites, namely Serena with clay and clay loam, Barafu with sandy loam, sandy clay loam, and Seronera with sand clay loam. Thereafter the decomposition of dung pats in terms of weight change and percentage of nutrients in dung pats of four herbivore species (buffalo, zebra, wildebeest and elephant) incorporated into the soil beneath the dung pats were determined. Fresh dung, soil cores beneath the dung pats and control soils 1 m adjacent to the pats were taken for laboratory analysis. Dung pats and soil samples were analysed for initial percentage OC, N, pH and soil particle size distribution. Weight changes of the dung pats after each three weeks period were monitored. Similarly, monthly rainfalls during the study period were recorded from the rain gauges near the sites. The results indicate that the surface soil (0-15 cm depth) pH ranged from 6.0 - 7.5, 7.4 -7.9 and 6.1 - 7.4 for Serena, Barafu and Seronera respectively. While the soil texture was highly significantly different in percentage OC added after 18 weeks, the treatments and texture were both not significant for percentage N increased in the soil after 18 weeks. There was a difference of 1% between the ruminants and non-ruminants in percentage N increase although they were fluctuating over time due to weather changes. The C/N ratios of the controls and the treatments were on average 11 and 15 respectively, being highly significantly different and indicating that, treatments had a potential contribution to the soil OC and N in the ecosystem.


Soil Research ◽  
2019 ◽  
Vol 57 (8) ◽  
pp. 814 ◽  
Author(s):  
Arkadiusz Telesiński ◽  
Teresa Krzyśko-Łupicka ◽  
Krystyna Cybulska ◽  
Barbara Pawłowska ◽  
Robert Biczak ◽  
...  

This study used laboratory experiments to compare the effects of coal tar creosote on the activity of oxidoreductive enzymes in sandy loam, loamy sand and sandy clay loam soils. Different amounts of coal tar creosote were added to soil samples as follows: 0 (control), 2, 10 or 50 g kg–1 dry matter. The activity of soil dehydrogenases (DHAs), o-diphenol oxidase (o-DPO), catalase (CAT), nitrate reductase (NR) and peroxidases (POX) was determined. Contamination of soil with coal tar creosote affected oxidoreductase activity. Oxidoreductive enzyme activity following soil contamination with coal tar creosote was in the following order: DHAs &gt; CAT &gt; NR &gt; POX &gt; o-DPO in loamy sand and in sandy loam; and DHAs &gt; POX &gt; CAT &gt; NR &gt; o-DPO in sandy clay loam. The index of soil oxidoreductive activity (IOx) introduced in this study confirms the negative effect of coal tar creosote on oxidoreductase activity in soil. DHAs were the most sensitive to the contamination of soil with coal tar creosote. Moreover, the greatest changes in oxidoreductase activities were observed in loamy sand. Knowledge of the mechanism underlying the effects of coal tar creosote on oxidoreductive processes may enable development of a method for the bioremediation of polycyclic aromatic hydrocarbon-contaminated soils.


2017 ◽  
Vol 64 (7) ◽  
pp. 930-938 ◽  
Author(s):  
J. D. Jabro ◽  
W.B. Stevens ◽  
W. M. Iversen

1992 ◽  
Vol 72 (3) ◽  
pp. 201-216 ◽  
Author(s):  
P. M. Rutherford ◽  
N. G. Juma

Modelling in soil ecological research is a means of linking the dynamics of microbial and faunal populations to soil processes. The objectives of this study were (i) to simulate bacterial-protozoan interactions and flows of C and N in clay loam Orthic Black Chernozemic soil under laboratory condtions; and (ii) to quantify the flux of C and N (inputs and outputs) through various pools using the simulation model. The unique features of this model are: (i) it combines the food chain with specific soil C and N pools, and (ii) it simultaneously traces the flows of C, 14C, N and 15N. It was possible to produce a model that fitted the data observed for the soil. The simulated CO2-C evolved during the first 12 d was due mainly to glucose addition (171 μg C g−1 soil) and cycling of C in the soil (160 μg C g−1 soil). During this interval, bacterial C uptake was 5.5-fold greater than the initial bacterial C pool size. In the first 12 d protozoa directly increased total CO2-C evolution by 11% and increased NH4-N mineralization 3-fold, compared to soil containing only bacteria. Mineralization of C and N was rapid when bacterial numbers were increased as a result of glucose addition. Key words: Acanthamoeba sp., modelling, N mineralization-immobilization, organic matter, Pseudomonas sp., Typic Cryoboroll


1986 ◽  
Vol 66 (1) ◽  
pp. 125-130 ◽  
Author(s):  
G. H. FRIESEN ◽  
D. A. WALL

McCall, Maple Presto, Maple Amber and OT80-3 soybean (Glycine max (L.) Merr.) cultivars were evaluated under field conditions for their response to metribuzin. Maple Amber was found to be less tolerant than the other cultivars. In controlled environment chamber studies, injury to this cultivar was more severe on a sandy loam soil than on a clay loam soil. Fall applications of metribuzin, alone or tank-mixed with trifluralin, were tolerant to Maple Amber soybeans and such applications may offer a practical alternative to spring treatments for broad spectrum weed control in the less tolerant soybean cultivars grown in Manitoba.Key words: Metribuzin, trifluralin, preplant incorporation, fall treatments, soybean cultivars


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