Temporal fluctuations in biochemical properties of soil under pasture. II. Nitrogen mineralization and enzyme activities

Soil Research ◽  
1984 ◽  
Vol 22 (3) ◽  
pp. 319 ◽  
Author(s):  
DJ Ross ◽  
TW Speir ◽  
JC Cowling ◽  
KN Whale

Temporal fluctuations in rates of nitrogen mineralization and the activities of six enzymes were measured in topsoil, predominantly a Typic Haplaquoll, from two plots that contained pastures of different age in the Wairarapa area. Samples were taken at c. 4-weekly intervals for over one year. Organic carbon contents averaged 6.7 and 3.6% in soil from the older and younger pastures respectively. Net mineral-nitrogen production at 25�C was higher in soil at a standardized water potential (-3 and -4 kPa for soil from the older and younger pastures respectively) than at field moisture content. It was initially higher in soil from the younger than from the older pasture. Generally, distinct seasonal patterns were not apparent. All of the enzyme activities showed significant temporal fluctuations. Amylase and cellulase activities fluctuated more than invertase activity, but all three carbohydrase activities were generally high in wet spring samples. When plot effects were removed, only the fluctuations in amylase activity were related positively and significantly to soil moisture content. Fluctuations in cellulase, urease, phosphatase and sulphatase activities were correlated negatively with soil moisture content. The temporal fluctuations in enzyme activities were, when plot effects were removed, mainly independent of the small variations that occurred in soil organic carbon and total nitrogen contents. Interrelationships of these biochemical properties, and relationships with rates of CO2 production and indices of microbial biomass, are discussed.

Soil Research ◽  
1984 ◽  
Vol 22 (3) ◽  
pp. 303
Author(s):  
DJ Ross ◽  
VA Orchard ◽  
DA Rhoades

Temporal fluctuations in respiratory activity (CO2 production) and two indices of microbial biomass (biomass carbon and mineral-nitrogen flush contents) were determined in topsoil, predominantly a Typic Haplaquoll, from a site under grazed pastures in the Wairarapa area. Samples, with organic carbon contents averaging 6.7 and 3.6%, were taken from two separate plots at c. 4-weekly intervals for over a year. Biomass indices were estimated by the chloroform fumigation technique. The suitability of a physiological procedure for indicating biomass fluctuations was also investigated. Correlations between properties were calculated with plot effects removed. Rates of CO2 production by field-moist soil, and soil at a standardized water potential, were lowest in samples taken at the driest time of the year and correlated significantly with field-moisture content. In contrast, biomass carbon estimates were generally highest in late summer and autumn, and lowest in winter, and were correlated negatively with soil moisture content. Mineral-nitrogen flush fluctuations were less marked, and not significantly related to soil moisture or biomass carbon content. In the physiological procedure, using field-moist soil, neither rates of CO2 production by soil + glucose, nor net glucose response values, were correlated significantly with biomass carbon estimated by the fumigation technique. This procedure therefore appears unsuitable for estimating temporal fluctuations in the biomass of an individual soil under pasture.


2015 ◽  
Vol 12 (11) ◽  
pp. 3655-3664 ◽  
Author(s):  
Y. J Zhang ◽  
S. L Guo ◽  
M. Zhao ◽  
L. L. Du ◽  
R. J. Li ◽  
...  

Abstract. Temperature sensitivity of soil organic carbon (SOC) mineralization (i.e., Q10) determines how strong the feedback from global warming may be on the atmospheric CO2 concentration; thus, understanding the factors influencing the interannual variation in Q10 is important for accurately estimating local soil carbon cycle. In situ SOC mineralization rate was measured using an automated CO2 flux system (Li-8100) in long-term bare fallow soil in the Loess Plateau (35°12' N, 107°40' E) in Changwu, Shaanxi, China from 2008 to 2013. The results showed that the annual cumulative SOC mineralization ranged from 226 to 298 g C m−2 yr−1, with a mean of 253 g C m−2 yr−1 and a coefficient of variation (CV) of 13%, annual Q10 ranged from 1.48 to 1.94, with a mean of 1.70 and a CV of 10%, and annual soil moisture content ranged from 38.6 to 50.7% soil water-filled pore space (WFPS), with a mean of 43.8% WFPS and a CV of 11%, which were mainly affected by the frequency and distribution of precipitation. Annual Q10 showed a quadratic correlation with annual mean soil moisture content. In conclusion, understanding of the relationships between interannual variation in Q10, soil moisture, and precipitation are important to accurately estimate the local carbon cycle, especially under the changing climate.


Author(s):  
Erwin Prastowo ◽  
Laily Mukaromah

Litter plays a crucial role in the formation of soil organic carbon (SOC), and potentially affects different pools in the context of soil carbon cycle. To improve knowledge and understanding with respect to the dynamics of carbon in coffee and cocoa cropping systems, there is a need to develop a mechanistic model to explain the formation of carbon especially in different background of soil, climate and agronomic management. Short-term observation was performed in different cropping systems, i.e. coffee (Coff) and cocoa (CoL) with lamtoro(Leucaena sp.) shade trees, and cocoa with oil palm (Elaeis guineensis) shade trees (CoP), and teak (Tectona grandis) conservation area, to investigate the quantitative amount of leaf litter-derived carbon. Additionally, to improve the understanding with respect to the formation of soil organic carbon, a simple model is developed by employing organic carbon storage coefficient (hi) as parameter to validate the observation data from Coff and CoL plots. Leaf litter is collected daily with concomitant microclimate records, i.e. air temperature, relative humidity, light intensity, and soil temperature. Composite soil and leaf samples are collected for organic carbon, soil moisture content, and leaf relative water content (RWC), for laboratory identification. Analysis of data suggests the presence of cropping system effect, i.e. shading condition and agronomical practices such as pruning, to microclimate variations except for soil temperature. Furthermore, cropping systems do not significantly influence soil moisture content, amount of organic carbon, and RWC. With higher model efficiency (EF), the simulated model fits better for CoL, EF 0.95, than Coff, EF 0.58. Model simulation, with both hi values are 0.017 and 0.014 in Coff and CoL, reveals a possibly cropping system specific curve pattern. A faster SOC formation in Coff plot has suggested a crucial role the amount of leaf litter to support with continuous carbon supply. The simulation implies the presence of soil related-maximum point limiting carbon storage capacity


1998 ◽  
Vol 13 (2) ◽  
pp. 83-89 ◽  
Author(s):  
A.J. Tenge ◽  
F.B.S. Kaihura ◽  
R. Lal ◽  
B.R. Singh

AbstractSoil erosion is a major threat to sustaining agricultural production in Tanzania. However, quantitative information is scanty on its effects on yields of major crops for principal soils and management practices. We conducted this study to determine erosion effects on soil moisture, related properties and corn yield on Tropeptic Haplustox and Ultic Haplustalf soils at Mlingano in Tanzania. Four erosion classes (least, slight, moderate, and severe) on Tropeptic Haplustox and three erosion classes (slight, moderate, and severe) on Ultic Haplustalf were established according to the thickness of the Ap horizon under natural field conditions. Accelerated soil erosion reduced soil moisture content, soil organic carbon, available water capacity and water use efficiency. Mean volumetric soil moisture content (average of both soils) during the growing season was 23.3% for severe, 24.8% for moderate, and 25.7% for slight erosion. Mean soil organic carbon content was 1.15% for severe, 1.64% for moderate and 1.97% for slight erosion. Mean available water capacity was 2.6 cm for severe, 3.5 cm for moderate, and 4.0 cm for slight erosion. Soil bulk density and excessive degree days of soil temperature above 25°C increased with severity of erosion. These adverse changes accentuated constraints on crop growth and reduced corn (Zea mays) yield on severely eroded soil by 45% and 59% for Tropeptic Haplustox and Ultic Haplustalf soils, respectively. The water use efficiency of corn was 21.6 kg ha-1cm-1in the least eroded class versus 17 kg ha-1cm-1in the severely eroded class for the Tropeptic Haplustox, and 23 kg ha-1cm-1in the slightly eroded and 18.1 kg ha-1cm-1in the severely eroded class for Ultic Haplustalf.


2004 ◽  
pp. 20-29
Author(s):  
Csaba Varga ◽  
Balázs Helmeczi

The purpose of our experiments is to discover the effect of different soil cover matters (agrofoil and black polyethylene) on the activity of some enzymes (phosphatase, saccharase, urease, catalase, dehydrogenase) occuring in soil. Soil samples were taken from a cider apple plantation of the Fruit Producing Research and Advisory Kht Újfehértó. The enzyme activity was measured according to Krámer and Erdei (1959a), Kuprevič and Tsherbakova (1956), Kuprevič et al. (1966), Frankenberger and Johanson (1983), Mersi and Schinner (1991). Soil moisture content was by conventional (drying chamber) method measured during every sampling and enzyme activity was transpolated to absolute dry soil. Results were estimated by mathematical methods (variation analysis, correlation counting). Soil samples were taken by trials 5 times (in every two months) a year in the vegetation period from March to November.By recording the monthly changes of the enzyme activity we have observed the following. The activity of the phosphatase was generally the highest in May and the lowest in November. Depending on the trials, high values were also measured in March and September. The activity of the saccharase was generally the highest in November and the lowest in June, but at the same time peaks even occured in May and September. The highest urease avtivity was measured in September and November, and the lowest activity in May and July, also depending on the trials. In the year 2000, after a deep point in March, the activity of the catalase was the highest in November or by certain trials in September. In 2001, the lowest activity was also measured in March, but the highest activity appeared in November in case of one-minute trial, and in May in consequence of two-minute trial. Finally the activity of dehydrogenase was the highest in November and the lowest in July apart from the model years.There were essential differences in rainfall of the two experimental years which was reflected in the enzyme activities. There was a poor positive significant relationship between soil moisture content and enzyme activity values in case of phosphatase, saccharase, urease (r=0,426; 0,480; 0,396) respectively. In case of catalase1 (r=0,518), catalase (r=0,556), dehydrogenase (r=0,559) we obtained a medium strong positive relationship between soil moisture content and enzyme activity values. By evaluating the effect of different trials in case of every examined enzyme significantly higher values were detected in soils covered by agrofoil (a porous black polyethylene) than in soils covered by black polyethylene or in uncovered soils. Moreover, the soil covered by black polyethylene showed significantly higher enzyme activities (besides phosphatase) than the control soil. Thus soil-covering meant statistically significant advantages in enzyme activity as opposed to uncovered soil proved.


Soil Research ◽  
1984 ◽  
Vol 22 (3) ◽  
pp. 303
Author(s):  
DJ Ross ◽  
VA Orchard ◽  
DA Rhoades

Temporal fluctuations in respiratory activity (CO2 production) and two indices of microbial biomass (biomass carbon and mineral-nitrogen flush contents) were determined in topsoil, predominantly a Typic Haplaquoll, from a site under grazed pastures in the Wairarapa area. Samples, with organic carbon contents averaging 6.7 and 3.6%, were taken from two separate plots at c. 4-weekly intervals for over a year. Biomass indices were estimated by the chloroform fumigation technique. The suitability of a physiological procedure for indicating biomass fluctuations was also investigated. Correlations between properties were calculated with plot effects removed. Rates of CO2 production by field-moist soil, and soil at a standardized water potential, were lowest in samples taken at the driest time of the year and correlated significantly with field-moisture content. In contrast, biomass carbon estimates were generally highest in late summer and autumn, and lowest in winter, and were correlated negatively with soil moisture content. Mineral-nitrogen flush fluctuations were less marked, and not significantly related to soil moisture or biomass carbon content. In the physiological procedure, using field-moist soil, neither rates of CO2 production by soil + glucose, nor net glucose response values, were correlated significantly with biomass carbon estimated by the fumigation technique. This procedure therefore appears unsuitable for estimating temporal fluctuations in the biomass of an individual soil under pasture.


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