A field experiment was conducted to study the combined effect of nutrient andpest managements on soil biomass phospholipid contents, functional biodiversity and substrateutilization patterns of soil microbial populati...A field experiment was conducted to study the combined effect of nutrient andpest managements on soil biomass phospholipid contents, functional biodiversity and substrateutilization patterns of soil microbial populations in hybrid rice cropping system. The mineral N, Pand K fertilizers (as urea, calcium superphosphate and KCl respectively) were incorporated at 100,25, and 100 kg ha^(-1), respectively, and the various pesticides were applied at the recommendedrates. The results of the experiment demonstrated a decline in the microbial abundance and soilmicrobial biomass phospholipid contents with the advancement of crop growth, and significant changesin substrate utilization pattern of soil microbial population studied were observed with differentmanagement practices and at different growth stages. The principal component analysis (PCA) usingall 95-carbon sources (BIOLOG plates) gave good differentiation among the treatments, indicatingthat they have different patterns of carbon utilization under different habitats. The data showedthat diversity in microbial community continuously changed with the progression in crop stage,particularly at physiological maturity (PM) stage that was evident from the utilization of differentcarbon sources at various crop stages.展开更多
The effects of individual and combined additions of urea (100 μg N g-1 soil) and insecticide (triazophos at field rate, FR) under different moisture levels of air-dried soil (AD), 50% of water-holding capacity (WHC),...The effects of individual and combined additions of urea (100 μg N g-1 soil) and insecticide (triazophos at field rate, FR) under different moisture levels of air-dried soil (AD), 50% of water-holding capacity (WHC), 100% WHC and flooded soil (FS) on some selected soil properties in a paddy field soil were examined in a laboratory incubation study. The results indicated that after 21-day incubation at 25℃, the different moisture levels led to significant changes in the parameters studied. Flooding of soil with distilled water significantly increased the electron transport system (ETS) /dehydrogenase activity and phenol contents of the soil compared to the other moisture levels, while protein and phospholipids behaved differently at varied moisture levels with or without the addition of urea and/or triazophos. Increased ETS activity was observed with N addition at higher moisture levels while insecticide incorporation decreased it at all moisture levels as compared to the control (moisture only). The phenol contents slightly decreased and increased with N and insecticide applications, respectively. The soil protein contents were found to be unaffected among all the soil treatments at all moisture levels. However, among different moisture levels, reduced quantities of proteins were estimated at 50% WHC, suggesting more N-mineralization. Lower quantities of soil biomass phospholipids, among all treatments, were recorded at higher moisture levels (100% WHC and FS) than at the lower levels. An overall slight enhancement in phospholipid contents with N and small reduction with insecticide addition, respectively, was noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the soil moisture contents increased, suggesting rapid degradation of agrochemicals.展开更多
A 21-d incubation experiment was conducted under controlled laboratory conditions to study the effects of elevated temperatures (10, 25, and 40 ℃) on some microbiological and biochemical properties in flooded paddy s...A 21-d incubation experiment was conducted under controlled laboratory conditions to study the effects of elevated temperatures (10, 25, and 40 ℃) on some microbiological and biochemical properties in flooded paddy soil amended or unamended with urea at 100 μg N g-1 soil and/or insecticide (triazophos) at field rate (FR). Enhancements in temperature led to increase the electron transport system (ETS) / dehydrogenase activity and phospholipid contents of the soil, while soil organic matter phenol and protein contents decreased with increasing temperature with or without the addition of inputs. An increase of temperature from 10 ℃ to 25 or 40 ℃ enhanced the ETS activity 2 folds (on average for all soils), while the inclusion of N and insecticide increased and decreased it, respectively, compared to the control. The soil phenol and protein contents were highly correlated with temperatures (for all soils, r = -0.936 and -0.971, respectively) and the additions of N and insecticide produced slight reductions and enhancements in them, respectively. At a particular temperature, the soil protein contents remained unaffected among all the soil treatments. An overall slight increase in phospholipid contents with N and a small decline with insecticide addition were noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the incubation temperature increased, suggesting faster degradation of agrochemicals with raising temperature.展开更多
Combined effects on soil microbial activity of nutrient and pesticide management in hybrid rice double annual cropping system were studied. Results of field experiment demonstrated significant changes in soil microbia...Combined effects on soil microbial activity of nutrient and pesticide management in hybrid rice double annual cropping system were studied. Results of field experiment demonstrated significant changes in soil microbial biomass phospholipid contents, abundance of heterotrophic bacteria and proteolytic bacteria, electron transport system (ETS)/dehydrogenase activity, soil protein contents under different management practices and at various growth stages. Marked depletions in the soil microbial biomass phospholipid contents were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also induced slight changes, and the lowest microbial biomass phospholipid content was found with pesticides application alone. A decline in the bacterial abundance of heterotrophic bacteria and proteolytic bacteria was observed during the continuance of crop growth, while the lowest abundance of heterotrophic bacteria and proteolytic bacteria was found with pesticides application alone, which coincided with the decline of soil microbial biomass. A consistent increase in the electron transport system activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or combined with pesticides increased it, while a decline was noticed with pesticides application alone as compared with the control. The soil protein content was found to be relatively stable with fertilizers and/or pesticides application at various growth stages in both crops undertaken, but notable changes were detected at different growth stages.展开更多
基金the National Natural Science Foundation of China.
文摘A field experiment was conducted to study the combined effect of nutrient andpest managements on soil biomass phospholipid contents, functional biodiversity and substrateutilization patterns of soil microbial populations in hybrid rice cropping system. The mineral N, Pand K fertilizers (as urea, calcium superphosphate and KCl respectively) were incorporated at 100,25, and 100 kg ha^(-1), respectively, and the various pesticides were applied at the recommendedrates. The results of the experiment demonstrated a decline in the microbial abundance and soilmicrobial biomass phospholipid contents with the advancement of crop growth, and significant changesin substrate utilization pattern of soil microbial population studied were observed with differentmanagement practices and at different growth stages. The principal component analysis (PCA) usingall 95-carbon sources (BIOLOG plates) gave good differentiation among the treatments, indicatingthat they have different patterns of carbon utilization under different habitats. The data showedthat diversity in microbial community continuously changed with the progression in crop stage,particularly at physiological maturity (PM) stage that was evident from the utilization of differentcarbon sources at various crop stages.
基金supported by the International Rice Research Institute (IRRI) under project of Reversing Trends of Declining Productivity (RTDP
文摘The effects of individual and combined additions of urea (100 μg N g-1 soil) and insecticide (triazophos at field rate, FR) under different moisture levels of air-dried soil (AD), 50% of water-holding capacity (WHC), 100% WHC and flooded soil (FS) on some selected soil properties in a paddy field soil were examined in a laboratory incubation study. The results indicated that after 21-day incubation at 25℃, the different moisture levels led to significant changes in the parameters studied. Flooding of soil with distilled water significantly increased the electron transport system (ETS) /dehydrogenase activity and phenol contents of the soil compared to the other moisture levels, while protein and phospholipids behaved differently at varied moisture levels with or without the addition of urea and/or triazophos. Increased ETS activity was observed with N addition at higher moisture levels while insecticide incorporation decreased it at all moisture levels as compared to the control (moisture only). The phenol contents slightly decreased and increased with N and insecticide applications, respectively. The soil protein contents were found to be unaffected among all the soil treatments at all moisture levels. However, among different moisture levels, reduced quantities of proteins were estimated at 50% WHC, suggesting more N-mineralization. Lower quantities of soil biomass phospholipids, among all treatments, were recorded at higher moisture levels (100% WHC and FS) than at the lower levels. An overall slight enhancement in phospholipid contents with N and small reduction with insecticide addition, respectively, was noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the soil moisture contents increased, suggesting rapid degradation of agrochemicals.
基金Project (No. G1999011809) supported by the National Key Basic Research Support Foundation (NKBRSF)of China.
文摘A 21-d incubation experiment was conducted under controlled laboratory conditions to study the effects of elevated temperatures (10, 25, and 40 ℃) on some microbiological and biochemical properties in flooded paddy soil amended or unamended with urea at 100 μg N g-1 soil and/or insecticide (triazophos) at field rate (FR). Enhancements in temperature led to increase the electron transport system (ETS) / dehydrogenase activity and phospholipid contents of the soil, while soil organic matter phenol and protein contents decreased with increasing temperature with or without the addition of inputs. An increase of temperature from 10 ℃ to 25 or 40 ℃ enhanced the ETS activity 2 folds (on average for all soils), while the inclusion of N and insecticide increased and decreased it, respectively, compared to the control. The soil phenol and protein contents were highly correlated with temperatures (for all soils, r = -0.936 and -0.971, respectively) and the additions of N and insecticide produced slight reductions and enhancements in them, respectively. At a particular temperature, the soil protein contents remained unaffected among all the soil treatments. An overall slight increase in phospholipid contents with N and a small decline with insecticide addition were noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the incubation temperature increased, suggesting faster degradation of agrochemicals with raising temperature.
文摘Combined effects on soil microbial activity of nutrient and pesticide management in hybrid rice double annual cropping system were studied. Results of field experiment demonstrated significant changes in soil microbial biomass phospholipid contents, abundance of heterotrophic bacteria and proteolytic bacteria, electron transport system (ETS)/dehydrogenase activity, soil protein contents under different management practices and at various growth stages. Marked depletions in the soil microbial biomass phospholipid contents were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also induced slight changes, and the lowest microbial biomass phospholipid content was found with pesticides application alone. A decline in the bacterial abundance of heterotrophic bacteria and proteolytic bacteria was observed during the continuance of crop growth, while the lowest abundance of heterotrophic bacteria and proteolytic bacteria was found with pesticides application alone, which coincided with the decline of soil microbial biomass. A consistent increase in the electron transport system activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or combined with pesticides increased it, while a decline was noticed with pesticides application alone as compared with the control. The soil protein content was found to be relatively stable with fertilizers and/or pesticides application at various growth stages in both crops undertaken, but notable changes were detected at different growth stages.
