Effects of different nitrification inhibitors on nitrification, maize yield, and nitrogen use efficiency in red soil.

We examined the effects of nitrification inhibitors (NIs) on soil nitrification, maize yield and nitrogen use efficiency (NUE), aiming to screen out high efficiency stabilized ammonium chloride fertilizer in red soil. Nitrification inhibitors 2-chloro-6-trimethyl-pyridine (CP), 3, 4-dimethyl-pyrazolate phosphate (DMPP), and dicyandiamide (DCD) and their combinations were added into ammonium chloride (NH4Cl) to make six stabilized nitrogen fertilizers. With blank (CK) and NH4Cl (N) as the controls, we conducted a maize pot experiment with the same amount of nitrogen addition. The results showed that compared with the treatment of N, soil ammonium content in CP+DMPP and DMPP+DCD increased by 56%-62%, which was significantly higher than that in CP, DMPP, and DCD, while the apparent nitrification rate of red soil was significantly reduced by 33%-34%. All the six treatments with nitrification inhibitors and their combinations significantly improved biomass and nitrogen absorption efficiency of maize. Compared with the N treatment, the application of adding NIs alone was significantly higher than that of the treatments of NIs combinations, with an average of 1.3 times increase. DCD was the most efficient one in improving maize yield, nitrogen uptake, and nitrogen adsorption efficiency, which increased by 4.1, 6.3 and 4.4 times, respectively. Comprehensively, DCD performed the best in reducing cost and improving yield and nitrogen use efficiency in red soil.

[Application effect of high efficiency and stability urea added with biochemical inhibitors and humic acid in loess]. / æ·»åŠ ç”ŸåŒ–æŠ‘åˆ¶å‰‚å’Œè æ¤é ¸çš„ç¨³å®šæ€§å¢žæ•ˆå°¿ç´ åœ¨é»„åœŸä¸­çš„æ–½ç”¨æ•ˆæžœ.

We carried out pot experiment to investigate nitrogen transformation characteristics, yield increasing effect, and apparent utilization rate of nitrogen fertilizer in loess soils by combining chemi-cal inhibitor and biostimulant humic acid to investigate the application effect and provide a theoretical basis for new type highly efficient and stable urea in loess soil. In this study, blank (CK) and urea (N) were set as controls, and humic acid alone (F), N-butyl thiophosphate-triamine (NBPT), 3,4-dimethyl-pyrazolate phosphate (DMPP), 2-chloro-6-trimethyl-pyridine (CP) and humic acid were respectively combined with three biochemical inhibitors to urea. The results showed that compared with N treatment, F, NBPT+F, DMPP+F, CP+F treatments significantly increased maize yield, chlorophyll content, leaf area index and nitrogen uptake, and had obvious effects on soil available nitrogen contents. The addition of humic acid increased chlorophyll content of maize leaves in all cases compared to the application of biochemical inhibitors alone. Compared with CP treatment, CP+F treatment could significantly increase nitrogen uptake, chlorophyll content, and nitrogen adsorption efficiency of maize. Addition of humic acid with NBPT increased nitrification inhibition rate by 10.7% compared with NBPT alone, but decreased yield, leaf area index, nitrogen uptake, nitrogen use efficiency. Compared with DMPP treatment, DMPP+F treatment significantly reduced maize yield, leaf area index, nitrogen uptake, nitrogen use efficiency and nitrification inhibition rate. Considering maize yield, plant N uptake, N fertilizer uptake rate and soil ammonium N and nitrate N contents, the addition of humic acid and CP is recommended for urea application in loess areas to enhance urea performance, yield, and fertilizer utilization.

[Effect of urease/nitrification inhibitor on urea nitrogen conversion in black soil and cinnamon soil.] / è„²é ¶/ç¡åŒ–æŠ‘åˆ¶å‰‚åœ¨é»‘åœŸå’Œè¤åœŸä¸­å¯¹å°¿ç´ æ°®è½¬åŒ–çš„è°ƒæŽ§æ•ˆæžœ.

We studied the effects of urease/nitrification inhibitor combinations on urea hydrolysis and nitrification, aiming to screen out the effective inhibitor combinations for black soil and cinnamon soil in Northeast China. Urease inhibitor, N-butyl thiophosphate-triamine (NBPT), and its combination with nitrification inhibitor dicyandiamide (DCD), 3, 4-dimethylpyrazole phosphate (DMPP), 2-chloro-6 (trichloromethyl)-pyridine (CP), 2-amino-4-chloro-6-methylpyrimidine (AM) and 3-methylpyrazole (MP) were added to urea separately. Samples were collected 15 times in each of all the treatments during 125 days. We examined the changes of urea nitrogen, ammo-nium, nitrate, and nitrification inhibition rate in the two soils. Our results showed the hydrolysis of urea in black soil and cinnamon soil was about 7 d, and the addition of NBPT with or without diffe-rent nitrification inhibitors slowed down the hydrolysis to 21 d at least. Compared with the treatment with common urea, inhibitor addition significantly increased soil NH4+-N, decreased soil NO3--N, and maintained the high NH4+-N content in soil for a longer time. In black soil, application with nitrification inhibitor inhibited soil nitrification significantly and lasted for more than 125 d. DMPP and CP combined with NBPT increased the NH4+-N content in black soil by 1.6-1.8 times, while the nitrification inhibition rate was 47.9% and 24.1% at 125 d, respectively. In the cinnamon soil, the application of nitrification inhibitor could prolong the duration of ammonium oxidation from 80 d to 110 d. DCD and DMPP combined with NBPT increased the NH4+-N content in cinnamon soil by 2.1-3.4 times, while the nitrification inhibition rates at 125 d were 25.3% and 23.2%, respectively. Therefore, NBPT+DMPP combination with urea was recommended for utilization in black soil, followed by NBPT+CP. In cinnamon soil, NBPT+DCD combination with urea was recommended, followed by NBPT+DMPP.

[Effects of high efficiency and stability ammonium sulfate fertilizer applied in black soil]. / é«˜æ•ˆç¨³å®šæ€§ç¡«é ¸é“µæ°®è‚¥åœ¨é»‘åœŸä¸­çš„æ–½ç”¨æ•ˆæžœ.

To develop high efficiency stabilized N fertilizer, a pot experiment was conducted to examine the effects of stabilized ammonium sulfate with different nitrification inhibitors on soil avai-lable nitrogen (N) contents, nitrification inhibition rate, apparent nitrification rate, yield, some agronomic parameters and N fertilizer utilization rate of corn in black soil of Jilin Provinve. In this study, blank (CK) and (NH4)2SO4 (N) were set as controls, and nitrification inhibitor 3,4-dimethyl-pyrazolate phosphate (DMPP), 2-chloro-6-trimethyl-pyridine (CP), ammonia protectant N-GD and nitrogen fertilizer synergist HFJ and their combination applied to ammonium sulfate to form nine treatments. The results showed that compared with the treatment of N, application of DMPP and its combinations in black soil significantly affected soil available N contents and the apparent nitrification rate. The contents of ammonium increased by 1.4-2.0 times, while the contents of nitrate and the apparent nitrification rate of soil decreased by 13.6%-17.9% and 55.3%-59.8%, respectively. DMPP, DMPP+HFJ, DMPP+N-GD had the highest nitrification inhibition rate, which reached higher than 16.5%. DMPP+HFJ+N-GD and HFJ increased the chlorophyll content in maize leaves by 4.5-5.3 times. The addition of nitrification inhibitors and fertilizer synergist to ammonium sulfate did not affect plant height. Compared with the treatment of N, HFJ increased corn biomass, grain yield, economic coefficient, harvest index, agronomic utilization rate of fertilizer, N uptake utilization rate, fertilizer contribution rate and N partial productivity of corn by 1.2, 2.5, 0.7, 0.6, 2.7, 2.1, 1.3 and 2.5 times, respectively. In general, HFJ, DMPP, DMPP+HFJ, DMPP+N-GD performed best in black soil. By considering both the cost and N utilization rate, N fertilizer synergist HFJ is the first choice for stable ammonium sulfate N fertilizer biochemical inhibitor, followed by DMPP+HFJ or DMPP+N-GD.

[Effects of inhibitors and pig manure on the transformation of urea nitrogen in paddy soil].

With the aim to understand the response of different nitrogen forms in paddy soil under the conditions of urea combined with inhibitors and pig manure, and to explore the nitrogen retention and supply capacity of paddy soil under different management strategy, we conducted a pot experiment with 15N labeled urea. There were six treatments: no nitrogen fertilizer (CK), pig manure (M), urea (N), urea+pig manure (NM), urea+inhibitor (NI), urea+inhibitor+pig manure (NIM). Urease inhibitor (PPD+NBPT) and nitrification inhibitor (DMPP) were used as the inhibitor combination. Soil nitrogen pools, conservation of 15N labeled urea, and rice N adsorption were measured in rice seedling, tillering, and mature stages. Results showed that pig manure significantly increased soil ammonium concentration, soil microbial biomass nitrogen and fixed ammonium, as well as the storage of urea nitrogen in various pools at tillering stage, and significantly increased rice yield. Addition of the inhibitors increased NH4+ fixation by clay minerals and nitrogen immobilization by microorganisms compared with treatment N, and increased urea-derived NH4+ fixation by clay minerals compared with treatment NM. Pathway analysis showed that pig manure increased urea-N assimilation and yield of rice. The urea-derived ammonium fixed by clay minerals was temporarily stored after inhibitors application. NIM treatment stored more N in microbial biomass, and the released ammonium coupled the turnover and mineralization of microbial provided more available nitrogen for the later growth of rice. Both NM and NIM treatments are recommended in paddy fields of north China.

[Nitrogen transformation of stable ammonium fertilizer in black soil and cinnamon soil]. / ç¨³å®šæ€§é“µæ€æ°®è‚¥åœ¨é»‘åœŸå’Œè¤åœŸä¸­çš„æ°®ç´ è½¬åŒ–ç‰¹å¾.

A chamber culture experiment was conducted to measure soil nitrogen transformation following application of stabilized ammonium fertilizers in black soil and cinnamon soil. There were three application levels (0.20, 0.50, 1.00 g N·kg-1 dry soil, respectively) of nitrogen fertilizer. The results showed that nitrification gradually delayed with the increased amount of ammonium application in the cinnamon soil. The treatment of 1.00 g N·kg-1 significantly inhibited nitrification. Nitrification in the cinnamon soil occurred at day 3 and day 7 with 0.20, 0.50 g N·kg-1 dry soil respectively. In the black soil, nitrification occurred at day 3 in all treatments, with nitrification potential decreasing with the increases of ammonium application amount. Nitrification maintained three weeks and two weeks under treatment of 0.20 g N·kg-1 dry soil in cinnamon soil and in black soil, and maintained four weeks and three weeks under treatment of 0.50 g N·kg-1 dry soil. The application with nitrification inhibitors 3,4-dimethylpyrazole phosphate (DMPP) of 1.0% of total nitrogen and dicyandiamide (DCD) of 4.0% of total nitrogen significantly inhibited nitrification, decreased nitrate concentration and nitrification potential. Our results suggested that nitrification would be inhibited as increased ammonium amount in cinnamon and higher than in black soil. In addition, nitrification was significantly inhibited under the ammonium addition rate of 0.20, 0.50 g N·kg-1 dry soil with nitrification inhibitor. Therefore, for the nitrification inhibitor culture experi-ment, it is recommended that the amount of ammonium addition does not exceed 1.00 g N·kg-1 dry soil, and the best concentration is 0.50 g N·kg-1 dry soil.

[Effects of stabilized N fertilizer combined with straw returning on rice yield and emission of N2O and CH4 in a paddy field]. / ç¨³å®šæ€§æ°®è‚¥é åˆç§¸ç§†è¿˜ç”°å¯¹æ°´ç¨»äº§é‡åŠN2O和CH4排放的影响.

Based on a two-year field experiment located at Shenyang Applied Ecological Experiment Station of Chinese Academy of Sciences, we examined the effects of stabilized N fertilizer combined with straw returning on rice yield and emission of N2O and CH4 in aquic brown soil. Six treatments were set up, i.e. control (CK), urea(U), urea+urease inhibitor+nitrification inhibitor (U+I), straw (S), straw+urea (S+U), straw+urea+ urease inhibitor+nitrification inhibitor (S+U+I). The results showed that urea application increased rice yield, cumulative N2O and CH4 emission, and global warming potential. The treatment of U+I significantly mitigated cumulative N2O emission. Returning rice straw to the field significantly increased cumulative N2O emission, cumulative CH4 emission, global warming potential, and greenhouse gas emission intensity. The S+U+I treatment had the highest rice yield and greenhouse gas emission intensity. U+I treatment had the the second highest rice yield and the lowest greenhouse gas emission intensity. Rice yield in the S treatment showed no significant difference with CK. Our results indicated that S+U+I and U+I are relatively better agricultural strategies compared with other treatments in paddy fields on aquic soil.

[Characteristics of ammonia volatilization and nitrous oxide emission from a paddy soil under continuous application of different slow/controlled release urea.] / 持续施用缓/æŽ§é‡Šå°¿ç´ æ¡ä»¶ä¸‹æ°´ç”°åœŸå£¤NH3挥发与N2O排放特征.

The characteristics of ammonia volatilization and nitrous oxide emission from a paddy soil were examined under 9-year application of different slow/controlled release urea with the common large granule urea (U) as the control. The results showed that compared with the control, all slow/controlled release urea treatments, except 25.8% increase of ammonia volatilization under 1% 3,4-dimethylpyrazole phosphate (DMPP)+U, could decrease the ammonia volatilization. Polymer coated urea (PCU) dominated the highest reduction of 73.4% compared to U, followed by sulfur coated urea (SCU) (72.2%), 0.5% N-(N-butyl) thiophosphoric triamide (NBPT)+1% DMPP+U (71.9%), 1% hydroquinone (HQ)+3% dicyandiamide (DCD)+U (46.9%), 0.5% NBPT+U (43.2%), 1% HQ +U (40.2%), 3% DCD+U (25.5%), and the ammonia volatilization under different slow/controlled release urea treatments were statistically lower than that of U (P<0.05). 1% DMPP+U caused the lowest emission of N2O under different slow/controlled release urea treatments. The slow/controlled release urea also had a significant potential of N2O emission reduction: 1% DMPP+U showed the highest reduction of 74.9% compared to U, followed by PCU (62.1%), 1% HQ+3% DCD+U (54.7%), 0.5% NBPT+1% DMPP+U (42.2%), 3% DCD+U (35.9%), 1% HQ +U (28.9%), 0.5% NBPT+U (17.7%), SCU (14.5%), and N2O emissions under different slow/controlled release urea treatments were statistically lower than that of U (P<0.05). The comprehensive analysis showed that 0.5% NBPT+1% DMPP+U, SCU and PCU had similar effects on decreasing the ammonia volatilization and N2O emission and were remarkably better than the other treatments. The slow release urea with the combination of urease and nitrification inhibitors should be the first choice for reducing N loss and environmental pollution in paddy field, in view of the higher costs of coated urea fertilizers.

[Analysis of the character of film decomposition of starch acetate (SA) coated urea by infrared spectrum].

The degradability characteristics of film with 4 kinds of starch acetate coated and inhibitors amended urea were analyzed by FTIR, which was purposed to supply theoretical basis for applying starch acetate coated urea fertilizers in farming. The result showed that the chemical component, molecule structure and material form of the membrane were not changed because of adding different inhibitors to urea. The main peaks of the film degradation process were brought by the H--O, --OH, CO2, C==O, --CH2, --CH3, C--O, C--O--H and C--O--C vibrancy in asymmetry and symmetry. In brown soil, the trend of absorbing value of the most high peak was 0>15>30>60>90>120>150>310 d. The infrared spectra of 4 kinds of fertilizers were not different remarkably, and the film was comparatively slowly degraded before 15 d. But a majority of the film had been already degraded after 150 days. The main components of film materials were degraded fastest in 310 days. The speed of film degradation wasn't more impacted by different inhibitors. The characteristic of starch acetate film degradation may be monitored entirely and degradation speed difference of the film could be represented through infrared spectrum.

[Analysis of the character of film decomposition of methyl methacrylate (MMA) coated urea by infrared spectrum].

The degradability characteristics of film with 4 kinds of methyl methacrylate coated urea amended with inhibitors were analyzed by FITR, which was purposed to supply theoretical basis for applying the FITR analysis method to film decomposition and methyl methacrylate coated urea fertilizers on farming. The result showed that the chemical component, molecule structure and material form of the membrane were not changed because of adding different inhibitors to urea. the main peaks of expressing film degradation process were brought by the -C-H of CH3 & CH2, -OH, C-O, C-C, C-O-C, C=O, C=C flexing vibrancy in asymmetry and symmetry in 3 479-3 195, 2 993--2 873, 1 741-1 564, 1 461-925 and 850-650 cm(-1). The peak value changed from smooth to tip, and from width to narrow caused by chemical structural transform of film The infrared spectrum of 4 kinds of fertilizers was not different remarkably before 60 days, and the film was slowly degraded. But degradation of the film was expedited after 60 days, it was most quickened at 120 day, and the decomposition rate of film was decreased at 310 day. The substantiality change of film in main molecule structure of 4 kinds of fertilizers didn't happen in 310 days. The main component of film materials was degraded most slowly in brown soil. The speed of film degradation wasn't heavily impacted by different inhibitors. The characteristic of film degradation may be monitored entirely by infrared spectrum. The degradation dynamic, chemical structure change, degradation speed difference of the film could be represented through infrared spectrum.

[Analysis of soil humus and components after 26 years' fertilization by infrared spectroscopy method].

The infrared spectrum was used to discuss structure change of soil humus and components of chemical groups in soil humic acids (HA) and fulvic acids (FA) isolated from soils in different fertilization treatment after 26 year's fertilization. The result indicated that using the infrared spectroscopy method for the determination of humus, humus fractions (HA and FA) and their structure is feasible. Fertilization affected the structure and content of soil humus and aromatization degree. After 26 years' fertilization, the infrared spectrum shapes with different treatments are similar, but the characteristic peak intensity is obviously different, which reflects the effects of different fertilization treatments on the structure and amounts of soil humus or functional groups. Compared with no fertilization, little molecule saccharides decreased and aryl-groups increased under application of inorganic fertilizer or combined application of organic and chemical fertilizer. The effect was greater in Treatment NPK and M+NPK than in Treatment M1 N and M2 N. Organic and NPK fertilizer increased the development of soil and increased soil quality to a certain extent. Results showed that organic fertilization increased aromatization degree of soil humus and humus fractions distinctly. The authors could estimate soil humus evolvement of different fertilization with infrared spectroscopy.

[Variations in IR spectra of three coating materials under outdoor illumination and pot incubation].

In the present paper, polylactic acid (PLA), poly (butylenes succinate) (PBS) and polycarbonate (PC) were selected as test coating materials, and the variations in their IR spectra under conditions of outdoor illumination and pot incubation were studied, aimed to approach the degradability of these coating materials under sunlight and in soil. The IR spectra showed that after 4 months under outdoor illumination and pot incubation with brown soil and black soil, all the test coating materials had definite variations in their structural configuration, being more obvious under pot incubation than under outdoor illumination, which suggested that the test materials were degradable, and the degradability was greater in soil than under sunlight. PC had the greatest degradability, followed by PLA, and PBS. The degradability of PLA and PC was greater in black soil than in brown soil, while that of PBS was reverse.

[A microplate fluorimetric assay for sacchariase activity measurement].

With the fluorescent compound conjugates substrates, soil xylanase and cellulose in a free-air carbon dioxide enrichment (FACE) experiment were measured on the base of 96 microplate and fluorescence detection, aiming at testing its feasibility in sacchariase activity measurement. The results show that sacchariase activity can be tested and the data exhibit better repeatability(coefficient of variability <= 4.879%). Compared with spectrophotometric assay, this method allows a large number of soil samples and/or enzymes to be analyzed in a short time accurately and conveniently. Soil xylanase activity tends to be greater at elevated CO2 which significantly increases in jointing, heading and ripening stages of wheat and in heading and ripening stages of rice (P < 0.05), and the crop metabolizes rapidly under FACE condition and soil microorganisms are affected, which causes elevation of xylanase acitivy. Compared with ambient CO2, soil cellulose activity decreased slightly under elevated CO2 but there was no significant difference between treatments, indicating the cellulose activity was not influenced intensively in a short time.

[Impact of chemical fertilizers application on soil ecological environment].

China heads the list in the world's chemical fertilizers production and consumption. In 2006, the chemical fertilizers production in this country was 5304.8 x 10(4) t, being 14.2% higher than that in 2005. At present, its chemical nitrogen application rate is averagely more than 220 kg hm(-2), and phosphorous fertilizer application rate is more than 102 kg hm(-2) (P2O5) in single growing season. Some chemical fertilizers in use contain toxic by-components such as heavy metals, inorganic acids and organic pollutants, and thus, a long-term application of these chemical fertilizers can possibly induce the accumulation of these by-components in soil, resulting in the worsening of soil ecological environment, and making the heavy metals, nitrate, and other harmful components in agricultural products including vegetables, grains and fruits seriously surpassed the standards. In this paper, the causes, characteristics, and consequences of soil contamination via chemical fertilizers application were discussed, and some countermeasures for the mitigation of agro-ecological environmental pollution by chemical fertilizers were put forward.