Arid Agroecosystem Shrubs Enhance Enzyme Activities during the Dry Season (original) (raw)
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European Journal of Soil Biology, 2015
Chitinase Phosphatase Land use Mt. Kilimanjaro Carbon cycle Soil fertility a b s t r a c t Microbial and enzyme activities can be used to identify and assess the impacts of changes in land use management on soil quality. However, only few studies have investigated the effects of land use and nutrient additions on enzyme activities and microbial processes in tropical African soils. Glucose and nutrients (N and P) were added to soils (0e20 cm) from natural and agricultural ecosystems: (1) savannah, (2) maize fields, (3) lower montane forest, (4) coffee plantation, (5) grasslands (6) Chagga homegardens common at Mt. Kilimanjaro region and East Africa. Microbial biomass and activities of bglucosidase, cellobiohydrolase, chitinase and phosphatase were monitored over 60 days incubation period. Microbial biomass content and enzyme activities were generally higher in soils under natural vegetation compared to corresponding agricultural soils. Decline in microbial biomass C content over time was higher in natural ecosystems compared to agricultural soils. However, the microbial biomass C content in Chagga homegarden soils was relatively stable. Land use was negatively correlated to bglucosidase, cellobiohydrolase and chitinase activity, but positively correlated to phosphatase activity. bglucosidase and cellobiohydrolase, involved in the C-cycle, were the most sensitive to landuse change. Chitinase activity was 2e6 times higher in soils under natural vegetation compared to corresponding arable soils. Phosphatase displayed very high activities in all land use types. This is attributed to the high P retention capacity common for andic soils similar to those occurring at Mt. Kilimanjaro region. Increased P availability stimulated enzyme activities in lower montane forest and Chagga homegarden soils. Overall, microbial biomass and enzyme activities showed a strong decrease with increased land use intensity and should therefore be taken into consideration in monitoring and assessing the impact of land use change at Mt. Kilimanjaro region.
International Journal of Plant & Soil Science, 2018
This study relates the physical environment of Guiera senegalensis to spatial distribution of soil chemical and biochemical properties in semi-arid areas. Changes in some soil properties were measured at the center, beneath and outside the shrub canopy in relation to wind effect. Results show that with a wind of 5 ms-1 speed, blowing direction north-northeast (NNE), soil pH, soil organic carbon (SOC), soil total nitrogen (TN) and extractible phosphorus (EP) were not affected in their distribution excepted EP which showed greater contents (8.2 mg kg-1) from the center to the south. Soil biochemical properties such as Arylsulfatase (AS), ß-glucosidase (ß-G), Soil respiration (SR), and Microbial Biomass Carbon (MBC) showed a more significant influence of the wind dominate direction, except SR. The highest concentrations of AS (11,8 µg g-1 soilh-1), ß-G (75.4 µg g-1 soilh-1), and MBC (116.1 mg kg-1) soil were found at the center, at 1R, mainly in the north-southern direction. Results could contribute providing a basis for developing sustainable agriculture.
2012
Microbial activity is significantly influenced by soil texture, hydrological regimes, flow dynamics, chemical pollutants, and an assessment of these changes is essential for soil management. In the present investigation, soil microbial activity (as an index of soil enzymes i.e. amylase, invertase, protease and dehydrogenase) and its relationship with different physico-chemical properties with respect to seven different soils has been addressed. The variation of soil enzyme activity in question was significantly attributable to differences in soil texture, C, N and P content, bulk density, water holding capacity, moisture content and soil pH. Comparative analysis of soil enzyme revealed that there was gradual increase in amylase, invertase, protaease and dehydrogeanse activity from a nutrient deficient situation (fresh mine spoil) to an enriched soil (forest soil). Stepwise multiple regression analysis was performed to determine the contribution of different factors influencing the v...
2012
Enzymatic activities play a key role in the biochemical functioning of soils. As a consequence, they have been proposed as indicators of soil quality. This study was conducted at the Oumé benchmark site (Central-West, Côte d'Ivoire), and aimed at measuring the enzymatic activities involved in the phosphorus (acid phosphatase and alkaline phosphatase), nitrogen (N-acetyl-β-D glucosaminidase) and carbon (β-glucosidase and N-acetyl-β-D glucosaminidase) cycles. Soil from four main agro-ecological units (a secondary forest, a 20 year-old cocoa plantation, a 2 year-old Chromolaena odorata-based fallow and a continuous maize crop), representative of land-use systems in the area, were sampled for the measurement of enzymatic activities and chemical characteristics. Results showed that the enzymatic activity values were the highest in the fallow soil, whereas the maize crop displayed the lowest levels of enzymatic activity in soil. Moreover, soil from C. odorata fallow displayed the high...
Biotechnology, Agronomy, Society and Environment
Enzymatic activities play a key role in the biochemical functioning of soils. As a consequence, they have been proposed as indicators of soil quality. This study was conducted at the Oumé benchmark site (Central-West, Côte d'Ivoire), and aimed at measuring the enzymatic activities involved in the phosphorus (acid phosphatase and alkaline phosphatase), nitrogen (N-acetyl-β-D glucosaminidase) and carbon (β-glucosidase and N-acetyl-β-D glucosaminidase) cycles. Soil from four main agro-ecological units (a secondary forest, a 20 year-old cocoa plantation, a 2 year-old Chromolaena odorata-based fallow and a continuous maize crop), representative of land-use systems in the area, were sampled for the measurement of enzymatic activities and chemical characteristics. Results showed that the enzymatic activity values were the highest in the fallow soil, whereas the maize crop displayed the lowest levels of enzymatic activity in soil. Moreover, soil from C. odorata fallow displayed the high...
Applied Soil Ecology, 2020
Successful agriculture is dependent on soil quality and nutrition. Soil is the primary source of nutrients that are assimilated by plant root-systems to promote plant growth and development. The availability of these soil nutrients is regulated by factors such as pH, microbial composition and soil nutrient enzyme activities in ecosystem soils. This study aim was to determine the nutrition, microbe composition, and soil enzyme activities in four soils from different KwaZulu-Natal (KZN) grassland and savannah ecosystems. The four sites were found to differ significantly in their physical, chemical and biological properties. Microorganisms identified in the soils were from the families Bacillaceae, Hypocreaceae, Mucoraceae, and Nectriaceae. Bacterial and fungal genera identified among these soils showed varying diversity and species richness. Bergville soils had the lowest pH, cation exchange capacity, micro, and macro nutrient concentrations. Furthermore, Bergville soils showed reduced asparaginase and lignin peroxidase activities and had the lowest dehydrogenase activities. Therefore Bergville soils showed the minimum geochemical properties which may affect the growth of grassland and savannah ecosystem vegetation and sustainable agricultural practices.
Enzyme activities as affected by soil properties and land use in a tropical watershed
Applied Soil Ecology, 2007
Enzyme activities play key roles in the biochemical functioning of soils, including soil organic matter formation and degradation, nutrient cycling, and decomposition of xenobiotics. Knowledge of enzyme activities can be used to describe changes in soil quality due to land use management and for understanding soil ecosystem functioning. In this study, we report the activities of the glycosidases (b-glucosidase, a-galactosidase, and b-glucosaminidase), acid phosphatase, and arylsulfatase, involved in C (C and N for b-glucosaminidase), P, and S cycling, respectively, as affected by soil order and land use within a watershed in northcentral Puerto Rico (Caribbean). Representative surface soil (0-15 cm) samples were taken from 84.6% of the total land area (45,067 ha) of the watershed using a completely randomized design. The activity of a-galactosidase was greater in soils classified as Oxisols than in soils classified as Ultisols and Inceptisols, and it was not affected by land use. The activity of b-glucosidase was greater in Oxisols compared to the Inceptisols and Ultisols, and it showed this response according to land use: pasture -> forest > agriculture. The activity of b-glucosaminidase was higher in Oxisols than the other soil orders, and it was higher under pasture compared to forest and agriculture. Acid phosphatase and arylsulfatase activities were greater in Oxisols and Ultisols than in Inceptisols, and they decreased in this order due to land use: forest = pasture > agriculture. As a group, b-glucosaminidase, b-glucosidase, and acid phosphatase activities separated the sites under forest and pasture from those under agriculture in a threedimensional plot. Thus, enzyme activities in Inceptisols under agriculture could be increased to levels comparable to other soil orders with conservative practices similar to those under pasture and secondary forest growth. Our findings demonstrate that within this watershed, acid and low fertility soils such as Oxisols and Ultisols have in general higher enzyme activities than less weathered tropical soils of the order Inceptisols, probably due to their higher organic matter content and finer texture; and that the activities of these enzymes respond to management with agricultural practices decreasing key soil biochemical reactions of soil functioning. Published by Elsevier B.V.
European Journal of Soil Biology, 2020
The mobilization of soil nutrients bound in organic matter is largely mediated by enzymes derived from plants, soil microorganisms and animal residues. Land-use change alters important soil characteristics that may affect the activities of soil enzymes. However, mechanistic understanding of how land use and management practices influence the catalytic properties of enzymes in top-and subsoil are still scarce, especially in African ecosystems. We linked catalytic properties i.e. substrate affinity constant (K m) and maximum reaction rate (V max), determined by Michaelis-Menten kinetics, to a set of environmental and microbial variables in the soils of a landuse sequence (6 ecosystems) ranging from natural forests to agricultural fields at Mt. Kilimanjaro. The sensitivity of K m and V max of four extracellular hydrolytical enzymes, β-galactosidase, cellobiohydrolase, phosphatase and chitinase to changing environmental conditions were tested by fluorogenic substrates in topsoils and subsoils. The β-galactosidase activity increased with increasing soil depth. Other extracellular enzyme (cellobiohydrolase, phosphatase and chitinase) activities decreased with depth. The affinity of enzymes to substrates was higher in soils of natural compared to agricultural ecosystems: i.e. higher under forests than under cropland. The activity of β-galactosidase, cellobiohydrolase and chitinase enzyme were highest in lower mountain forest and grassland (less disturbed ecosystems). This indicated that changes in land use and management practice not only affects enzyme activity but also controls enzyme kinetics (K m and K a) thus pointing towards the expression of different enzyme systems. Therefore, we concluded that anthropogenic activities result in alteration of C and nutrient cycling by affecting microbial activities and enzymes catalytic properties.
2014
Little is known about the enzymatic response of microorganisms in soils having a low P status and being subjected to global change phenomena, such as forest disturbance and land-use change. Along a land-use sequence (natural forest -young pasture -old pasture -abandoned pasture -shrubland) in the Andes of southern Ecuador mineral topsoils of Cambisols/Umbrisols were investigated. We tested whether the activities of the six hydrolytic enzymes (cellobiohydrolase, -glucosidase, N-acetylglucosaminidase, ␣glucosidase, xylanase, acid phosphomonoesterase) were affected by nutrient status and land-use induced alterations in soil pH (pH H 2 O from 3.7 to 5.2), resource quantity and quality (e.g. a SOC:N:P ratio from 182:13:1 to 1050:38:1) and microbial community structure (as monitored by phospholipid fatty acids). Microbial production of acid phosphatase responded to the low P status of the sites by a higher investment in the acquisition of P compared to C. We determined three major drivers of enzyme activities: (1) microbial demand for P regulated the production of acid phosphatase, provided that N and C were available. At the natural forest site the two-fold higher specific activity of acid phosphatase pointed to a high microbial P-demand, whereas the production of acid phosphatase was constrained by the availability of N and DOC after pasture abandonment; (2) microbial biomass that was controlled by pH and resource availability (total soil N (organic and inorganic N), organic P (Bray-fraction)) was the main driver for cellobiohydrolase, -glucosidase and N-acetylglucosaminidase activities; and (3) substrate induction due to increased litter inputs of herbaceous plant species seemed to regulate ␣-glucosidase and xylanase activities during secondary succession. In contrast, alterations in the abundance of microbial groups affected the variation in extracellular enzyme activities only marginally. At the level of broadly defined microbial groups (PLFA), our results point to functional similarity in the decomposition of simple organic material.
Frontiers in Sustainable Food Systems, 2021
The Sahel is an ecologically vulnerable region where increasing populations with a concurrent increase in agricultural intensity has degraded soils. Agroforestry offers an approach to remediate these landscapes. A largely unrecognized agroforestry resource in the Sahel are the native shrubs, Piliostigma reticulatum, and Guiera senegalensis that to varying degrees already coexist with row crops. These shrubs improve soil quality, redistribute water from the deep soil to the surface (hydraulic lift), and can improve crop growth. However, little information is available on whether these shrubs affect spatial and temporal dynamics of microbial communities. Therefore, the objective of this study was to determine microbial composition and activity in the wet and dry seasons of soil in the: shrub rhizosphere (RhizS), inter-root zone (IntrS), and outside the influence of shrub soil (OutS) for both G. senegalensis and P. reticulatum in Senegal. A 3 × 2 factorial field experiment was imposed ...