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
The mineral fertilizers (NPK) and pesticide, including herbicides, insecticides and fungicides, were applied alone or in combination and the soil sampling was done at different growth stages during the crop cycle to s...The mineral fertilizers (NPK) and pesticide, including herbicides, insecticides and fungicides, were applied alone or in combination and the soil sampling was done at different growth stages during the crop cycle to study the changes in soil organic matter, microbial biomass and their activity parameters in a paddy soil with different nutrient and pest management practices in a hybrid rice double-cropping system. A consistent increase in the electron transport system (ETS) activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or with pesticides increased ETS activity, while a decline of ETS activity was noticed with pesticides alone as compared with the control. Nearly an increasing trend in soil phenol content was observed with the progression of crop growth stages, while the usage of pesticides alone caused maximum increments in the soil phenol content. The soil protein content was found nearly stable with fertilizers and/or pesticides application at various growth stages in both crops taken. But notable changes were noticed at different growth stages probably because of fluctuations in moisture and temperature at particular stages, which might have their effects on N mineralization. Marked depletions in the phospholipid content were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also produced slight changes, in which a higher decline was noticed with pesticide application alone compared with the control.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
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 supported by the National Natural Science Foundation of China (No. 39970146) the Interna- tional Rice Research Institute (IRRI) under project of Reversing Trends of Declining Productivity (RTDP).
文摘The mineral fertilizers (NPK) and pesticide, including herbicides, insecticides and fungicides, were applied alone or in combination and the soil sampling was done at different growth stages during the crop cycle to study the changes in soil organic matter, microbial biomass and their activity parameters in a paddy soil with different nutrient and pest management practices in a hybrid rice double-cropping system. A consistent increase in the electron transport system (ETS) activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or with pesticides increased ETS activity, while a decline of ETS activity was noticed with pesticides alone as compared with the control. Nearly an increasing trend in soil phenol content was observed with the progression of crop growth stages, while the usage of pesticides alone caused maximum increments in the soil phenol content. The soil protein content was found nearly stable with fertilizers and/or pesticides application at various growth stages in both crops taken. But notable changes were noticed at different growth stages probably because of fluctuations in moisture and temperature at particular stages, which might have their effects on N mineralization. Marked depletions in the phospholipid content were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also produced slight changes, in which a higher decline was noticed with pesticide application alone compared with the control.
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.
