Sensitivity and resistance of soil fertility indicators to land-use changes: New concept and examples from conversion of Indonesian rainforest to plantations

© 2016 Elsevier Ltd. All rights reserved.Tropical forest conversion to agricultural land leads to a strong decrease of soil organic carbon (SOC) stocks. While the decrease of the soil C sequestration function is easy to measure, the impacts of SOC losses on soil fertility remain unclear. Especially the assessment of the sensitivity of other fertility indicators as related to ecosystem services suffers from a lack of clear methodology. We developed a new approach to assess the sensitivity of soil fertility indicators and tested it on biological and chemical soil properties affected by rainforest conversion to plantations. The approach is based on (non-)linear regressions between SOC losses and fertility indicators normalized to their level in a natural ecosystem. Biotic indicators (basal respiration, microbial biomass, acid phosphatase), labile SOC pools (dissolved organic carbon and light fraction) and nutrients (total N and available P) were measured in Ah horizons from rainforests, jungle rubber, rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis) plantations located on Sumatra. The negative impact of land-use changes on all measured indicators increased in the following sequence: Forest < jungle rubber < rubber < oil palm. The basal respiration, microbial biomass and nutrients were resistant to SOC losses, whereas the light fraction was lost stronger than SOC. Microbial C use efficiency was independent on land use. The resistance of C availability for microorganisms to SOC losses suggests that a decrease of SOC quality was partly compensated by litter input and a relative enrichment by nutrients. However, the relationship between the basal respiration and SOC was non-linear; i.e. negative impact on microbial activity strongly increased with SOC losses. Therefore, a small decrease of C content under oil palm compared to rubber plantations yielded a strong drop in microbial activity. Consequently, management practices mitigating SOC losses in oil palm plantations would strongly increase soil fertility and ecosystem stability. We conclude that the new approach enables quantitatively assessing the sensitivity and resistance of diverse soil functions to land-use changes and can thus be used to assess resilience of agroecosystems with various use intensities

Phosphorus fractions in subtropical soils depending on land use

Land-use change from forest to agriculture, which is driven by the demands of sustaining the growing global population, affects nutrient dynamics and availability in soil. Although phosphorus (P) is one of the main limiting nutrients in agricultural production, little is known about the influence of soil microorganisms on the dynamics of P cycling in subtropical land use systems. The objective was to assess the impacts of land use (organic farming, conventional farming and forest) on forms and distribution of P in soil. After conversion of forest, the P stock significantly increased by 373% and 170% in soil under organic farming at 0–10 and 10–20 cm depth, respectively. In conventional farming, the P stock increased by 64% and 36% at 0–10 cm and 10–20 cm depth, respectively compared to forest. The larger (up to 4 times) fraction of organic P (Po) than inorganic P (Pi) implies that total P is regulated by organic P. Easily-available P fractions (microbial biomass P, NaHCO3-Pi and Po), moderately available P (NaOH-Po) and non-available P (HCl-Pi and Po) were much higher in organic farming than conventional farming and forest, especially at the 0–10 cm depth. Compared to organic farming, the higher (&gt;100) Corg: Po ratio that soils under conventional farming and forest are P limited which correspond with higher (2–8 times) activity of acid phosphatase in conventional farming and forest. Concluding, land use and management practices i.e. crop rotation, residue input and farmyard manure application significantly increase different fractions of P in organic farming. © 2018 Elsevier Masson SA

Sensitivity and resistance of soil fertility indicators to land-use changes: New concept and examples from conversion of Indonesian rainforest to plantations

© 2016 Elsevier Ltd. All rights reserved.Tropical forest conversion to agricultural land leads to a strong decrease of soil organic carbon (SOC) stocks. While the decrease of the soil C sequestration function is easy to measure, the impacts of SOC losses on soil fertility remain unclear. Especially the assessment of the sensitivity of other fertility indicators as related to ecosystem services suffers from a lack of clear methodology. We developed a new approach to assess the sensitivity of soil fertility indicators and tested it on biological and chemical soil properties affected by rainforest conversion to plantations. The approach is based on (non-)linear regressions between SOC losses and fertility indicators normalized to their level in a natural ecosystem. Biotic indicators (basal respiration, microbial biomass, acid phosphatase), labile SOC pools (dissolved organic carbon and light fraction) and nutrients (total N and available P) were measured in Ah horizons from rainforests, jungle rubber, rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis) plantations located on Sumatra. The negative impact of land-use changes on all measured indicators increased in the following sequence: Forest < jungle rubber < rubber < oil palm. The basal respiration, microbial biomass and nutrients were resistant to SOC losses, whereas the light fraction was lost stronger than SOC. Microbial C use efficiency was independent on land use. The resistance of C availability for microorganisms to SOC losses suggests that a decrease of SOC quality was partly compensated by litter input and a relative enrichment by nutrients. However, the relationship between the basal respiration and SOC was non-linear; i.e. negative impact on microbial activity strongly increased with SOC losses. Therefore, a small decrease of C content under oil palm compared to rubber plantations yielded a strong drop in microbial activity. Consequently, management practices mitigating SOC losses in oil palm plantations would strongly increase soil fertility and ecosystem stability. We conclude that the new approach enables quantitatively assessing the sensitivity and resistance of diverse soil functions to land-use changes and can thus be used to assess resilience of agroecosystems with various use intensities

Sensitivity and resistance of soil fertility indicators to land-use changes: New concept and examples from conversion of Indonesian rainforest to plantations

© 2016 Elsevier Ltd. All rights reserved.Tropical forest conversion to agricultural land leads to a strong decrease of soil organic carbon (SOC) stocks. While the decrease of the soil C sequestration function is easy to measure, the impacts of SOC losses on soil fertility remain unclear. Especially the assessment of the sensitivity of other fertility indicators as related to ecosystem services suffers from a lack of clear methodology. We developed a new approach to assess the sensitivity of soil fertility indicators and tested it on biological and chemical soil properties affected by rainforest conversion to plantations. The approach is based on (non-)linear regressions between SOC losses and fertility indicators normalized to their level in a natural ecosystem. Biotic indicators (basal respiration, microbial biomass, acid phosphatase), labile SOC pools (dissolved organic carbon and light fraction) and nutrients (total N and available P) were measured in Ah horizons from rainforests, jungle rubber, rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis) plantations located on Sumatra. The negative impact of land-use changes on all measured indicators increased in the following sequence: Forest < jungle rubber < rubber < oil palm. The basal respiration, microbial biomass and nutrients were resistant to SOC losses, whereas the light fraction was lost stronger than SOC. Microbial C use efficiency was independent on land use. The resistance of C availability for microorganisms to SOC losses suggests that a decrease of SOC quality was partly compensated by litter input and a relative enrichment by nutrients. However, the relationship between the basal respiration and SOC was non-linear; i.e. negative impact on microbial activity strongly increased with SOC losses. Therefore, a small decrease of C content under oil palm compared to rubber plantations yielded a strong drop in microbial activity. Consequently, management practices mitigating SOC losses in oil palm plantations would strongly increase soil fertility and ecosystem stability. We conclude that the new approach enables quantitatively assessing the sensitivity and resistance of diverse soil functions to land-use changes and can thus be used to assess resilience of agroecosystems with various use intensities

Phosphorus fractions in subtropical soils depending on land use

Land-use change from forest to agriculture, which is driven by the demands of sustaining the growing global population, affects nutrient dynamics and availability in soil. Although phosphorus (P) is one of the main limiting nutrients in agricultural production, little is known about the influence of soil microorganisms on the dynamics of P cycling in subtropical land use systems. The objective was to assess the impacts of land use (organic farming, conventional farming and forest) on forms and distribution of P in soil. After conversion of forest, the P stock significantly increased by 373% and 170% in soil under organic farming at 0–10 and 10–20 cm depth, respectively. In conventional farming, the P stock increased by 64% and 36% at 0–10 cm and 10–20 cm depth, respectively compared to forest. The larger (up to 4 times) fraction of organic P (Po) than inorganic P (Pi) implies that total P is regulated by organic P. Easily-available P fractions (microbial biomass P, NaHCO3-Pi and Po), moderately available P (NaOH-Po) and non-available P (HCl-Pi and Po) were much higher in organic farming than conventional farming and forest, especially at the 0–10 cm depth. Compared to organic farming, the higher (&gt;100) Corg: Po ratio that soils under conventional farming and forest are P limited which correspond with higher (2–8 times) activity of acid phosphatase in conventional farming and forest. Concluding, land use and management practices i.e. crop rotation, residue input and farmyard manure application significantly increase different fractions of P in organic farming. © 2018 Elsevier Masson SA

Sensitivity and resistance of soil fertility indicators to land-use changes: New concept and examples from conversion of Indonesian rainforest to plantations

© 2016 Elsevier Ltd. All rights reserved.Tropical forest conversion to agricultural land leads to a strong decrease of soil organic carbon (SOC) stocks. While the decrease of the soil C sequestration function is easy to measure, the impacts of SOC losses on soil fertility remain unclear. Especially the assessment of the sensitivity of other fertility indicators as related to ecosystem services suffers from a lack of clear methodology. We developed a new approach to assess the sensitivity of soil fertility indicators and tested it on biological and chemical soil properties affected by rainforest conversion to plantations. The approach is based on (non-)linear regressions between SOC losses and fertility indicators normalized to their level in a natural ecosystem. Biotic indicators (basal respiration, microbial biomass, acid phosphatase), labile SOC pools (dissolved organic carbon and light fraction) and nutrients (total N and available P) were measured in Ah horizons from rainforests, jungle rubber, rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis) plantations located on Sumatra. The negative impact of land-use changes on all measured indicators increased in the following sequence: Forest < jungle rubber < rubber < oil palm. The basal respiration, microbial biomass and nutrients were resistant to SOC losses, whereas the light fraction was lost stronger than SOC. Microbial C use efficiency was independent on land use. The resistance of C availability for microorganisms to SOC losses suggests that a decrease of SOC quality was partly compensated by litter input and a relative enrichment by nutrients. However, the relationship between the basal respiration and SOC was non-linear; i.e. negative impact on microbial activity strongly increased with SOC losses. Therefore, a small decrease of C content under oil palm compared to rubber plantations yielded a strong drop in microbial activity. Consequently, management practices mitigating SOC losses in oil palm plantations would strongly increase soil fertility and ecosystem stability. We conclude that the new approach enables quantitatively assessing the sensitivity and resistance of diverse soil functions to land-use changes and can thus be used to assess resilience of agroecosystems with various use intensities

Developing a Server-Side Scripting Language Converter for Translating ColdFusion to PHP

&lt;p&gt;This study aimed to develop a language converter to translate ColdFusion to PHP (Hypertext Preprocessor) codes. ColdFusion and PHP server- side scripting languages each have its own advantages and disadvantages. ColdFusion is a  commercial rapid  application development  platform while PHP is an open-source general-purpose scripting language. Ever since the emergence of open-source software that has led to the downfall of commercial software, several issues have stirred the IT industry. Thus, this research effort intended to address fundamental queries such as the technology conversion from ColdFusion to PHP and the maintenance of semantics codes involving these two scripting languages. The proponents used iterative model to successfully develop the converter basing on the following frameworks: tag parsing, semantic parsing and code generator. Findings revealed that the converter was able to translate ColdFusion into PHP but was delimited into basic syntax. It was evaluated by chosen respondents who were satisfied on the capability of the converter to translate ColdFusion into PHP.&lt;/p&gt;</jats:p

Microbial tradeoffs in internal and external use of resources regulated by phosphorus and carbon availability

A general strategy in modern agriculture to reduce phosphorus (P) fertilization is to rely on microbial efficiency of P acquisition and recycling from organic sources. However, this involves extracellular enzymes that require energy from ATP, so the process depends on the microbes' physiological state and soil P availability. To elucidate the key relationships we compared P acquisition processes in P-poor soil (Cambisol) and links between C:P stoichiometry, enzyme activity, and ATP with microbial communities in contrasting activity states (dormancy, growth followed by starvation and gradually activated, respectively induced by no, single large (50 mu g C g(-1) soil) and multiple low (five days of 10 mu g C g(-1) soil day(-1)) additions of glucose as a carbon (C) source). A sole P input, without C addition, almost doubled microbial C (C-mic) contents, maintained stable phosphatase activity at 36 nmol h(-1) per nmol ATP and raised microbial P (P-mic) 2.7-fold. In contrast, sole glucose addition increased P-mic by only 8%, confirming that P-limitation was much stronger than C limitation. Only 5-10 % of P potentially mineralized by phosphatase was recovered as microbial P. C-mic:P-mic ratios in microbial biomass 200 and 350 respectively reflected C starvation and strong P starvation. The ATP was a suitable predictor of microbial biomass in soil lacking fresh substrate, but weak predictor of microbial biomass after substrate input. Structural equation models revealed contrasting strategies of P utilization depending on microbial activity state. Dormant microorganisms (without glucose addition) invested most P to ATP production. In contrast, following substrate addition P-limited microorganisms accelerated phosphatase production, and hence capacity to mine P in organic sources. Thus, the P utilization/acquisition strategies depended on C accessibility and were modulated by P availability