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Fritillaria thunbergii is a commonly used traditional Chinese medicine, which has the effects of clearing heat and resolving stagnation, eliminating phlegm and relieving cough. At present, it is mostly produced by cultivation, and the cultivation process requires application of base fertilizer, winter fertilizer, seedling fertilizer and late top dressing. Now farmyard manure or organic fertilizer can be used to replace the base fertilizer and winter fertilizer, but the research on the replacement of organic fertilizer has not been completed for the late top dressing. Potassium fulvate is a kind of fulvate fertilizer, which can not only regulate the growth of crops but also supplement potassium necessary for the growth of crops. In this paper, using F. thunbergii as a model plant with mature cultivation techniques, the effect of potassium fulvate on the quality and yield of rhizome traditional Chinese medicine F. thunbergii was systematically studied for the first time. HPLC-ELSD was used to determine the contents of peimine A and peimine B, hot dip method was used to determine the content of alcohol extract, and the SPAD-502 Plus chlorophyll meter was used to detect SPAD value. The results showed that applying 1.5 to 2.25 kg·hm~(-2) of potassium fulvic acid per hectare could effectively improve the yield of F. thunbergii and there was significantly difference between potassium phosphate monobasic and potassium fulvic acid in terms of quality. After the application of range 1.5 to 2.25 kg·hm~(-2) of potassium fulvic acid per hectare, the content of alcohol soluble extract of F. thunbergii was ranged 21.61% to 22.27%, the total amount of peimine A and peimine B were ranged 0.09% to 0.10%. Applying 1.5 to 2.25 kg·hm~(-2) of potassium fulvic acid per hectare could replace the conventional pure chemical fertilizer potassium phosphate monobasic, which could be used as top dressing fertilizer for the cultivation of F. thunbergii.

The changing trend of soil available phosphorus (Olsen-P) content in soil and its relationship with soil phosphorus surplus and crop yield are fundamental when making appropriate phosphate fertilizer recommendations. In this paper, the influences of long-term fertilization on crops phosphorus uptake, soil phosphorus surplus, changing trend of soil available phosphorus content and relationships of soil available phosphorus content with soil phosphorus surplus and crop yield were investigated through 34 years (1981-2015) long-term trial in loessial soil region on the Loess Plateau. The experiment had a completely-randomized-block split-plot design in triplicate. Two main-plot treatments were no farmyard manure and farmyard manure (M), and four subplot treatments were CK (no fertilizer), N (application of chemical fertilizer N), NP (application of chemical fertilizer NP) and NPK (balanced application of chemical fertilizer NPK), respectively. The results showed that fertilization treatments and crop types significantly influenced uptake amount of phosphorus and soil phosphorus surplus. Averaged over time from 1981 to 2015, wheat mean phosphorus uptake amounts of CK, N, NP, NPK, M, MN, MNP and MNPK were 8.63, 10.64, 16.22, 16.21, 16.25, 17.83, 20.39 and 20.27 kg·hm -2 , while rape phosphorus uptakeamounts of eight treatments were 4.40, 8.38, 15.08, 15.71, 10.52, 11.23, 17.96 and 17.66 kg·hm -2 , respectively. The surplus amount of soil phosphorus significantly correlated with the amount of phosphorus applied to soil. When soil phosphorus surplus amount equal zero, wheat and rape phosphorus input amounts were 10.47 kg·hm -2 and 6.97 kg·hm -2 , respectively. Soil phosphorus surplus amount significantly influenced the changing trend of available phosphorus content in soil. CK and N treatments had no phosphorus input, and soil available phosphorus content exhibited a declining trend, annually decreased by 0.16 mg·kg -1 and 0.15 mg·kg -1 , respectively. In contrast, NP, NPK, M, MN, MNP and MNPK six treatments were applied with phosphate fertilizer every years, and available phosphorus content gradually increased along with the duration of trial, with annual increase by 0.02-0.33 mg·kg -1 . Soil available phosphorus content significantly correlated with phosphorus accumulative surplus amount, and the linear models were y=0.012x+9.33 and y=0.009x+11.72 in manure and no manure treatments, respectively. In no manure treatments, wheat yields significantly positively correlated with soil available phosphorus content, however, in manure treatments, their relationships did not reach a significant level. The relationship of wheat grain yield with available phosphorus content could be significantly fitted by piecewise linear model, and available phosphorus agronomy threshold of wheat was 14.99 mg·kg -1 . Rape grain yield also increased with increasing soil available phosphorus content, but the relationship was not significant. This indicated when soil available P content is higher than 14.99 mg·kg -1 , application of phosphate fertili-zer should be reduced or even avoided for planting wheat in loessial soil region on the Loess Plateau.

Taking two long-term local field trials at the south edge of the Loess Plateau, which were found in 1990 and 2003, respectively, as test subjects, the effects of different fertilization practices on the maize root biomass and nutrient content were investigated in this paper. Maize roots in the 0-20 cm top soil post-maize harvest from the different fertilization practices were collected by hand in October 2011. The results showed that compared with control without fertilization and N, NK, or PK treatments, the NP, NPK, fertilizers plus manure (M1NPK and M2NPK) or plus straw return (SNPK) treatments significantly increased the dry mass of maize root. The C, N, P and K contents in maize roots in the NP, NPK, M1 NPK, M2NPK and SNPK treatments were also significantly higher than those of control, especially in the NPK plus organic manure treatments (M1 NPK and M2NPK) in the trial. Compared with the N fertilizer free treatment (N0), root biomass in the 120 kg N · hm(-2) (N120) and 240 kg N · hm(-2) ( N240) fertilization treatments increased by 38% and 45%, respectively, but there was no significant difference between N120 and N240 treatments. Nitrogen fertilizer application (N120 and N240) also improved the C, N, P and K contents in maize root. The water soluble organic C and total soluble N contents of maize root in the NP, NPK, M1NPK, M2NPK, SNPK and the N120 and N240 treatments were greater than those of control and other treatments. Otherwise, the cellulose and lignin contents in maize roots declined in the NPK, M1NPK, M2NPK, and SNPK treatments compared with other treatments. So the root C/N and lignin/N ratios in the control, PK and N0 treatments were significantly higher than those in the NP, NPK, M1NPK, M2NPK and SNPK treatments. We concluded that the optimum fertilization (e. g., NP, NPK, MNPK and SNPK treatments) could increase maize root growth and nutrient content and improve soil fertility and carbon sequestration through root residue into soil.

Nitrogen use efficiency (NUE) has received worldwide concern in the sphere of agronomic science and environmental science, and it is fundamentally important for evaluating N utilization status and optimizing N fertilization management in cultivated lands. In recent years, in consideration of low values and great variations of NUE in China' s cultivated lands, some scholars have discussed on the traditional concept and calculating method of NUE, and also have proposed some substituted NUE calculating methods. In this paper, we summarized some disadvantages of both conventional concept and calculating method of NUE, i.e. the subtraction method and the 15N labeling method. Furthermore, we particularly introduced several substituted NUE calculation methods and discussed research directions in the future. In summary, we strongly suggested the establishment of a comprehensive evaluation index system of N utilization in good accordance with the current agricultural production status in China, based on a correct understanding of the dialectical relationships among N application rate, crop yield, N utilization and N loss.

Social economy in Huaihe River Basin had undergone enormous changes during 1990-2010. The grain yield had increased by 58%, from 64.14 million tons to 101.21 million tons, and the urbanization rate had increased by 22%, from 13% to 35%. Assessing the negative impacts of these high intensive human activities caused by rapid social development on terrestrial ecosystem would serve as a scientific basis for quantitative management of regional ecology. This paper estimated the spatial and temporal distribution of net anthropogenic nitrogen input (NANI) in Huaihe River Basin during 1990-2010. The results showed that there was an increasing trend in NANI in the period of 1990-2001, and after that this trend was slower. The NANI increased from approximately 17232 kg N · km(-2) · a(-1) in 1990 to a peak of 28771 kg N · km(-2) · a(-1) in 2003, and then declined to 26415 kg N · km(-2) · a(-1) in 2010. Chemical fertilizer and atmospheric deposition were the largest two sources of NANI, followed by food & feed import and biological nitrogen. Contributions from both chemical fertilizer and atmospheric deposition had been increasing continuously, respectively from 64% and 16% in 1990 to 77% and 19%. Our findings implied that the shift from fertilizer-supported agriculture and fossil fuel-supported industry to sci-tech lead economic development is urgently needed.

It is of great importance to have a deep understanding of the spatial distribution of NPK fertilizers application and the potential threat to the ecological environment in Jiangsu Province, which is helpful for regulating the rational fertilization, strengthening the fertilizer use risk management and guidance, and preventing agricultural non-point pollution. Based on the environmental risk assessment model with consideration of different impacts of N, P, K fertilizers on environment, this paper researched the regional differentiation characteristic and environmental risk of intensity of NPK fertilizer usages in Jiangsu. Analystic hierarchy process ( AHP) was used to determine the weithts of N, P, K. The environmental safety thresholds of N, P, K were made according to the standard of 250 kg · hm(-2) for the construction of ecological counties sponsered by Chinese government and the proportion of 1:0.5:0.5 for N:P:K surposed by some developed countries. The results showed that the intensity of NPK fertilizer application currently presented a gradually increasing trend from south to north of Jiangsu, with the extremum ratio of 3.3, and the extremum ratios of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were 3.3, 4.5 and 4.4, respectively. The average proportion of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer of 13 cities in Jiangsu was 1:0.39:0.26. Their proportion was relatively in equilibrium in southern Jiangsu, but the nutrient structure disorder was serious in northern Jiangsu. In Jiangsu, the environmental risk index of fertilization averaged at 0.69 and in the middle-range of environmental risk. The environmental risk index of fertilizer application in southern and central Jiangsu was respectively at the low and moderate levels, while that of cities in northern Jiangsu was at the moderate, serious or severe level. In Jiangsu, the regional difference of fertilizer application and environmental risk assessment were affected by many factors, including physical and economic conditions, government policy, management system, technology, and management methods.

Plant growth retardant as one of plant growth regulator can inhibit the cell division, elongation and growth rate in shoot apical meristem (SAM), which can be reversed by gibberellin regulate the product of photosynthesis transfer to the root and rhizome part. As commonly used plant growth retardant, paclobutrazol, uniconazole, chlorocholine chloride, mepiquat chloride, choline chloride and daminozide are used to promote the growth of root and rhizome, call as "zhuanggenling", "pengdasu", "pengdaji" etc. Single or recombination of plant growth regulator is registered as pesticide, and called as pesticide "zhuanggenling" in this paper. Growth regulator which registered as a foliar fertilizer or fertilization was called agricultural fertilizer "zhuanggenling" in this paper. The author investigate the usage of "zhuanggenling" in the root and rhizome of medicinal plants cultivation from 2012 to 2014 in Sichuan province, Huangyuan town, Mianyang (Ophiopogonis Radix); Pengzhou Aoping town (Chuanxiong Rhizoma); Pengshan Xiejia town (Alismatis Rhizoma); Jiangyou Taiping town and Zhangming town (Aconiti Lateralis Radix Praeparata); Yunnan Wenshan (Notoginseng Radix et Rhizoma); Henan province, Wuzhidafeng Town (Rehmanniae Radix, Achyranthis Bidentatae Radix, Dioscoreae Rhizoma); Gansu Min county (Codonopsis Radix, Angelicae Sinensis Radix); Gansu Li county (Rhei Radix et Rhizoma). The result showed that "zhuanggenling" were applied in the most medicinal plant cultivation except Rhei Radix et Rhizoma. It has been applied widespreadly in Ophiopogonis Radix, Alismatis Rhizoma, Achyranthis Bidentatae Radix, Codonopsis Radix; Rehmanniae Radix, commonly in Angelicae Sinensis Radix application, and occasionally in Chuanxiong Rhizoma, Aconiti Lateralis Radix Praeparata, Notoginseng Radix et Rhizoma and Dioscoreae Rhizoma. In 53 collected sample from plantation areas, fifteen (28%) were pesticide "zhuanggenling", thirty-eight (72%) were pesticide "zhuanggenling". UPLC analysis results showed that 38 farmers fertilizer "zhuanggenling" content of 6 kinds of plant growth retardant. It is regarded that fertilizer "zhuanggenling" was dominant in medicinal plant cultivation, and that the plant growth retardant is added widespreadly in farm fertilizer "zhuanggenling". All evidence proves conclusively that "zhuanggenling" have been used in the proper way, whereas some others have been misused or even abused in the use regarding to type, number, use frequency. The root or rhizoma are increased to 20%-200%. But there is lack of evaluation to appraise the quality of medicinal materials from the aspects of research or industry. "zhuanggenling" has become a important Chemical control material besides fertilizer, insecticidal sterilization of pesticide

In recent years, some scholars from China have deeply discussed about the concept, connotation and calculating method of nitrogen use efficiency (NUE), and have raised questions and also put forward some improved methods for NUE calculation in cultivated lands. In this paper, we compared advantages and disadvantages of these improved NUE calculation methods by using the data from a 5-year positioning field experiment under a wheat-maize rotation system. The results indicated that it made mistakes when the traditional subtraction method was used to calculate NUE for wheat season and maize season separately, since the soil fertility level of experimental plots had differed significantly from each other after several seasons or years of different fertilization managements. Additionally, the calculated NUE increased markedly with the cropping season going, thus making it difficult to mirror the actual situation of N utilization in cultivated lands. For the wheat-maize rotation system, the cumulative NUE calculation method considered wheat season and maize season as a whole part, and skillfully avoided mistakes which could be caused by inhomogeneity of soil fertility levels between experimental plots. Moreover, the calculated NUE were comparably smaller, with smaller coefficient variations (CVs), in contrast with the traditional subtraction method. The NUE calculated by using the ratio method were bigger, with the smallest CVs, than that computed by using the cumulative calculation method. The soil N balance method took a thoughtful consideration about the budgets and losses of soil nutrients before and after crop growth, but obtained the largest values of NUE and CVs within these methods.

In this paper, we monitored different forms of nitrogen (N) transported by the subsurface flow under three different natural rainfall events and different fertilizations and conducted an associated risk evaluation on environmental health, which provides scientific basis for controlling N non-point pollution and establishing a reasonable fertilization system in purple soil area. The results showed that there were different forms of N transport by subsurface flow under different rainfall events, where in dissolved nitrogen (DN) accounted for about 53.74% - 99.21%, and nitrate (NO3(-) -N) accounted for about 35.70% - 93.65% of DN, and especially under the moderate rainfall, NO3(-) -N could reach 84.09% - 93.65% of DN. The different N fluxes were the highest under moderate rainfall among different rainfall events, in which the flux of total nitrogen (TN), DN, particle nitrogen (PN), ammonia (NH4(+) -N) and nitrite (NO2(-) -N) reached 737.17, 711.12, 26.06, 12.70 and 0.46 mg x m(-2), respectively, and the NO3(-)-N flux was as high as 686.12 mg x m(-2), showing a huge potential threat on groundwater health. Through the risk assessment on N pollution for groundwater quality, we concluded that the straw returning could be used to effectively alleviate the N leaching and groundwater N pollution; especially, the combined application of organic and chemical fertilizer could effectively mitigate the groundwater pollution, improve soil fertility and increase crop yield.

Aiming at the low content of available phosphorus in upland red soil of Southern China, this paper studied the effects of combined application of biochar and inorganic fertilizers on the available phosphorus and organic carbon contents and the pH of this soil. With the combined application of biochar and inorganic fertilizers, the soil physical and chemical properties improved to different degrees. As compared with the control, the soil pH and the soil organic carbon and available phosphorus contents at different growth stages of oil rape after the combined application of biochar and inorganic fertilizers all had an improvement, with the increments at bolting stage, flowering stage, and ripening stage being 16%, 24% and 26%, 23%, 34% and 38%, and 100%, 191% and 317% , respectively. The soil pH and the soil organic carbon and available phosphorus contents were increased with the increasing amount of applied biochar. Under-the application of biochar, the soil available phosphorus had a significant correlation with the soil pH and soil organic carbon content. This study could provide scientific basis to improve the phosphorus deficiency and the physical and chemical properties of upland red soil.

Based on the long-term fixed position experimental data from Qianyanzhou Ecological Experiment Station, Chinese Academy of Sciences in 1998, this paper analyzed the effects of applying different kind fertilizers (straw, ST; pig manure, OM; and chemical fertilizer, NPK) on the nutrients (C, N, and P) status and the activities of related enzymes ( beta-1,4-glucosidase, betaG; beta-1,4-N-acetylglucosaminidase, NAG; L-leucine aminopeptidase, LAP; and acid phosphatase, AP) in reddish paddy soil. With the application of OM, the activities of soil betaG, NAG, and LAP increased significantly, as compared with other treatments, and were 1.4, 2. 6, and 1.9 times higher than the control (CK) , respectively. Applying OM also improved the ratio of soil organic carbon to total nitrogen (C/N), but decreased the soil betaG/(NAG+LAP) ratio, suggesting that pig manure could benefit the degradation of soil cellulose and the accumulation of soil organic carbon. Applying NPK increased the activities of soil betaG, NAG, and LAP, but decreased the AP activity, with a decrement of 34% as compared with CK. Under the application of NPK, the soilbetaG/AP and (NAG+ LAP)/AP ratios increased, but the ratios of soil organic carbon to total phosphorus (C/P) and of soil total nitrogen to total phosphorus (N/P) decreased, indicating that chemical fertilizers could induce the accumulation of soil inorganic phosphorus, and inhibit the microbial functions of degrading polysaccharides and phosphate phospholipids.

Based on the 7-year field experiment on the dryland of east Gansu of Northwest China in 2005-2011, this paper analyzed the variations of soil moisture content, bulk density, and nutrients content at harvest time of winter wheat and of the grain yield under no-tillage and conventional tillage and five fertilization modes, and approached the effects of different tillage and fertilization modes on the soil water storage and conservation, soil fertility, and grain yield under winter wheat/ spring corn rotation. In 2011, the soil moisture content in 0-200 cm layer and the soil bulk density and soil organic matter and available nitrogen and phosphorus contents in 0-20 cm and 20-40 cm layers under different fertilization modes were higher under no-tillage than under conventional tillage. Under the same tillage modes, the contents of soil organic matter and available nitrogen and available phosphorus were higher under the combined application of organic and inorganic fertilizers, as compared with other fertilization modes. The soil available potassium content under different tillage and fertilization modes decreased with years. The grain yield under conventional tillage was higher than that under no-tillage. Under the same tillage modes, the grain yield was the highest under the combined application of organic and inorganic fertilizers, and the lowest under no fertilization. In sum, no-tillage had the superiority than conventional tillage in improving the soil water storage and conservation and soil fertility, and the combined application of organic and inorganic fertilizers under conventional tillage could obtain the best grain yield.

This paper studied the effects of 30 years (1981-2010) fertilization with chemical N, P, and K, pig manure (PM), and rice straw (RS) on the soil organic carbon (SOC) and its components contents under intensive double rice cropping. The experiment was established on a typic Hapli-Stagnic Anthrosols in Hunan in 1981, and the soil samples were collected in November 2010. In treatment NPK, the contents of SOC, particulate organic C (POC), and KMnO4-oxidizable C (KMnO4-C) were higher than those in treatments NP and NK. The combined application of chemical and organic fertilizers (treatments NK+PM, NP+RS, and NPK+RS) made the contents of SOC, POC, and KMnO4-C have a significant increase, as compared with chemical fertilizations. Treatment NK+PM had the highest contents of SOC (84.71 t C.hm-2), POC (8.94 t C.hm-2), and KMnO4-C (21.09 t C.hm-2) in top soil (0-45 cm), followed by treatment NPK+RS. Treatment NK+PM had the highest C sequestration (485 kg C.hm-2.a-1) , followed by treatment NPK+RS (375 kg C.hm-2.a-1). The C sequestration efficiency (CSE) of SOC in the treatments of chemical fertilizers plus pig manure or rice straw was obviously higher than that in the treatments of chemical fertilizations, and the CSE of the POC in fertilization treatments (ranging from 0.4% and 1.2%) was lower than that of the KMnO4-C (ranging from 3.0% to 8.3%). By using the values of humification constant (h) and the decay constant (k) in Jenkinson' s equation, it was possible to predict the SOC storages in different treatments in the year 2010; and by using Jenkinson' s equation, it was possible to calculate the C input required to maintain the SOC storages in the year 1981 (AE). The increase of the SOC in treatments NK+PM, NP+RS, and NPK+RS was due to the annual C input being higher than the AE. It was considered that in the double rice cropping areas in subtropical region of China, long-term application of chemical fertilizers combined with pig manure or rice straw could promote the organic carbon sequestration in paddy soils.

By using phospholipid fatty acid (PLFA) method, this paper studied the changes of soil microbial community structure in an alpine meadow under six years continuous enclosure and its combination with fertilization, taking grazing area as the control. Both continuous enclosure and its combination with fertilization had significant effects on the microbial flora and total PLFA in different soil layers, and the effects were greater for 0-10 cm than for 10-20 cm soil layer. The species of PLFA in different soil layers also changed significantly. Under enclosure and its combination with fertilization, the number of gram-negative bacteria in different soil layers was lower than that of the control, and the numbers of bacteria, fungi, and gram-positive bacteria and the total PLFA in 0-10 cm soil layer were also lower, but the number of actinomycetes was higher than that of the control. In 10-20 cm soil layer, the number of gram-positive bacteria had no significant differences among different treatments, whereas the numbers of bacteria, fungi, and actinomycetes and the total PLFA were notably higher under enclosure but decreased markedly after fertilization. As compared with that of the control, the ratio of bacteria and fungi in different soil layers under enclosure and its combination with fertilization increased, the ratios of saturated fatty acid to monounsaturated fatty acid (SAT/MONO) and of gram-positive bacteria to gram-negative bacteria (G+/G-) under enclosure were all lower, but those after fertilization were in adverse. It was suggested that continuous enclosure and its combination with fertilization led to the decline of soil microbial diversity and activity and soil ecosystem stability.

Under the conditions of applying water soluble fertilizer and its bulk blending with controlled release fertilizer (BB-CRF), and by using micro-lysimeter, this paper quantitatively studied the nitrogen (N) uptake by mustard, the soil N losses from N2O emission, leaching and others, and the N residual in soil in three rotations of continuously cropped mustard. In the treatment of BB-CRF with 25% of controlled release nitrogen, the N uptake by mustard increased with rotations, and the yield by the end of the experiment was significantly higher than that in the treatment of water soluble fertilizer. The cumulated N2O emission loss and the N leaching loss were obviously higher in treatment water soluble fertilizer than in treatment BB-CRF. NO3(-)-N was the primary form of N in the leachate. In relative to water soluble fertilizer, BB-CRF altered the fates of fertilizer nitrogen, i.e., the N uptake by mustard and the N residual in soil increased by 75.4% and 76.0%, and the N leaching loss and other apparent N losses decreased by 27.1% and 66.3%, respectively. The application of BB-CRF could be an effective way to reduce the various losses of fertilizer N while increase the fertilizer N use efficiency, and the controlled release fertilizer is the environmentally friendly fertilizer with the property of high N use efficiency.

This paper studied the development, survival, and feeding of B-biotype Bemisia tabaci on Euphorbia pulcherrima under the conditions of 26 +/- 1 degrees C and 60% - 80% relative humidity after applying calcium fertilizer, taking applying fresh water as the control. There existed significant differences in the developmental duration of B. tabaci between treatment applying calcium fertilizer and the control. After applying calcium fertilizer, the egg stage of B. tabaci shortened significantly, and the development from egg to adult took 20.18 days (for the control, it took 18.72 days). However, there were no significant differences in the survival rates of B. tabaci at different development stages between the two treatments. The feeding of B. tabaci on E. pulcherrima induced the plant leaf chlorophyll fluorescence parameters changed, i. e., the photochemical efficiency (Fv/Fm), photochemical quenching coefficient (q(p)), light use efficiency (alpha), maximum photosynthesis rate (rETRmax), and tolerance to light (I(k)) decreased significantly, while the non-photochemical quenching coefficient (NPQ) had a significant increase. After applying calcium fertilizer, the plant leaf photoinhibition parameter (beta), rETRmax, and I(k) had less difference with th e control. The nail polish blot observation on the lower epidermis structure of plant leaf showed that calcium fertilizer could effectively compensate the decrease in the photosynthesis of E. pulcherrima damaged by B-biotype B. tabaci.

By using traditional staining and DNA cloning and sequencing techniques, this paper studied the effects of fertilization on the arbuscular mycorrhizal (AM) colonization and AM fungal community in Elymus nutans roots across an 8-year nitrogen (N) and phosphorus (P) fertilization gradient. With the increasing level of fertilization, the AM colonization and arbuscular colonization per unit root length reduced from 67.5% to 7.3% and from 5.2% to 0.1%, respectively. A total of 24 AM fungal phylotypes were detected in E. nutans roots, whilst the mean AM fungal richness reduced from 6 to 2.6 across the fertilization gradient. Different fertilization had significant effects on the AM fungal community composition, and there existed significant correlations between the AM fungal community composition and the soil available P and root N contents. The availability of N and P increased gradually across the fertilization gradient, and had significant negative correlations with both AM colonization and AM fungal richness. It was suggested that high level fertilization would reduce the activity of AM symbionts, and result in the large loss of AM fungal biodiversity.

In a long-term site-specific experiment with rice straw return (RSR) and in a short-term experiment with different RSR modes, this paper studied the effects of RSR on the soil organic carbon (SOC) sequestration, methane emission, and net carbon sink in a double season paddy field. RSR increased the SOC content, and the annual increasing rate of soil carbon sink in plow layer (0-15 cm) under long-term RSR was 0.07 t C x hm(-2) x a(-1). With the increasing amount of RSR, the apparent SOC transformation rate decreased. RSR promoted the methane emission from the paddy field significantly, and the methane emission flux in treatment RSR plus NPK during early- and late rice growth seasons increased by 75.0% and 251.5% (P < 0.01), respectively, compared with that in treatment NPK. The methane emission increased with the increasing amount of RSR. Under the similar tillage mode and rice yield, the rice straw returned had the similar apparent methane transformation rate. Considering the soil carbon sequestration and the net carbon sink after methane emission in the paddy field comprehensively, treatment RSR plus NPK had significant negative effect on the carbon sink which was basically approached to the bio-fixation of carbon by rice and increased by 158.3%, as compared with treatment NPK. Among different RSR modes, rice straw mulching plus no tillage decreased soil methane emission significantly, with the net carbon sink decreased by 50.9% as compared with the treatment high stubble plus tillage, and benefited the high and stable yielding of rice.

Based on a 20-year field site-specific fertilization experiment in Taoyuan Experimental Station of Agriculture Ecosystems under Chinese Ecosystem Research Network (CERN), this paper studied the effects of different fertilization modes of N, P, and K on the accumulation and allocation of C and N in rice plant. The fertilization mode N-only showed the highest C and N contents (433 g kg(-1) and 18.9 g kg(-1), respectively) in rice grain, whereas the modes balanced fertilization of chemical N, P and K (NPK) and its combination with organic mature recycling (NPKC) showed the highest storage of C and N in rice plant. In treatments NPK and NPKC, the C storage in rice grain and in stem and leaf was 1960 kg hm(-2) and 2015 kg hm(-2), and 2002 kg hm(-2) and 2048 kg hm(-2), and the N storage in rice grain was 80.5 kg hm(-2) and 80.6 kg hm(-2), respectively. Treatment NPK had the highest N storage (59.3 kg hm(-2)) in stem and leaf. Balanced fertilization of chemical N, P, and K combined with organic manure recycling increased the accumulation of C and N in rice plant significantly. Comparing with applying N only, balanced fertilization of chemical N, P, and K was more favorable to the accumulation and allocation of C and N in rice plant during its growth period.

In this paper, silkworm excrement was harmless-treated via controlled fermentation to prepare silkworm excrement organic fertilizer (SEOF). The nutrient properties of the SEOF were determined, and a pot experiment was conducted to examine the application effect of the fertilizer. After fermentation, the total N, P, and K contents in the SEOF had a significant increase, being 58.0%, 84.4% , and 29.7% higher than those in the raw material, respectively. The addition of microbial inoculants shortened the fermentation period, and decreased the carbon and nitrogen losses during fermentation. With the application of SEOF, the seed germination index of cabbage and tomato was higher than 80% , suggesting that the fertilizer had no inhibitory effect on the seed germination. The application of SEOF not only increased the Chinese cabbage yield and its nutrients and Vc contents, decreased the plant nitrate content, but also improved the soil pH value, and increased the soil available nutrients and organic matter contents and soil enzyme activities, with better effect than applying composted goat feces.

This paper studied the effects of combined application of biogas slurry and chemical fertilizer under same N application rate on the quantities of bacteria, actinomycetes and fungi as well as the activities of urease, protease and catalase in winter wheat rhizosphere soil. With the growth of winter wheat, the quantities of test microorganisms and the activities of urease and catalase showed a trend of increasing after an initial decrease, while the protease activity showed an S-type change. Combined application of biogas slurry and chemical fertilizer increased the quantities of test microorganisms significantly, and improved the activities of soil urease and protease. Applying 50% biogas slurry N as basal plus 50% chemical N as topdressing and applying 25% biogas slurry N as basal plus 75% chemical N as topdressing had the best effect, while applying single conventional urea or biogas slurry had the worst effect. At all growth stages, the activity of soil catalase was the highest in treatments 25% biogas slurry N as basal plus 75% chemical N as topdressing and single biogas slurry, but had greater differences in other treatments among the growth stages. The results suggested that proper biogas slurry application combined with chemical fertilization could increase the microbial quantity and enzyme activities in winter wheat rhizosphere soil.

Occurrence of antibiotics in the soils substantially fertilized with antibiotics-enriched animal manures is very of concern. This paper investigated the concentration and distribution of four tetracycline antibiotics in soils from vegetable field chronically fertilized with manures in subtropical area using solid-phase extraction followed by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS). The sum concentrations of four tetracycline compounds ranged from 1.35 microg/kg to 22.52 microg/kg with an average of 7.35 microg/kg. There were thirty one to one hundred percent of the soil samples were detected with average concentrations of 0.63- 3.11 microg/kg for four tetracycline compounds which dominated mostly with oxytetracycline and secondly with deoxytetracycline. Composition and levels of tetracycline compounds varied obviously in both horizontal and vertical soils. The concentration of tetracycline compounds in soil profile decreased rapidly with the depth and some of the compounds were still detected in 60 to 80 centimeter depth of soil. It is concluded that tetracycline antibiotics in soils from vegetable field chronically fertilized with manures in subtropical area were generally lower and less ecotoxic risk for soil ecosystem. But it should not be ignored in view of combined toxic effect and resistance of various compounds.

The effects of paper mill sludge, red mud and zinc fertilizer addition on remediation of acid cadmium contaminated paddy soil were studied in a pot experiment, and their beneficial effects were verified in a field experiment, by using lime as comparison. The pot experiment results showed that a single application (2 g x kg(-1)) of lime, paper mill sludge or red mud increased soil pH significantly. Compared with no applying alkaline substances, the soil exchangeable Ca content was increased by 33.1%-76.0% at 7 days after applying alkaline substances and 31.0%-78.3% at 30 days after rice transplanting, respectively. The soil available Cd content was significantly decreased by 38.4%-45.0% at 7 days after the three alkaline substances applications, and was decreased by 37.4%-52.9% and 33.2%-38.7% at 30 days and 60 days after rice transplanting, respectively. The Cd content in rice root and brown rice was decreased by 24.0%-48.5% and 26.3%-44.7%, respectively. With equal applications of lime, paper mill sludge and red mud, the effects on increase of soil pH and decrease in Cd accumulation by rice was lime > red mud > paper mill sludge. Compared with a single application (2 g x kg(-1)) of paper mill sludge or red mud, Cd accumulation decreased significantly following the application of zinc fertilizer (0.2 g x kg(-1)) field experimental results were similar to the pot experiment that Cd accumulation apparently declined in the first and second crops (late rice and autumn rape) following the application of paper mill sludge, red mud and addition of zinc fertilizer. The Cd content in brown rice and rape seeds was decreased by 27.1-65.1% and 16.4%-41.6%, respectively, compared with no alkaline substances application. The Cd content in brown rice reached the National Hygienic Standard for Grains (GB 2715-2005). Therefore, combined application of paper mill sludge or red mud with zinc fertilizer was a feasible method to remediate acid cadmium contaminated paddy soil. Rice quality was guaranteed by determination of rational amount of alkaline wastes and a proportion of zinc fertilizer which was in accord with soil Cd contamination level and chemical properties, etc.

This paper investigated the spatial variability of the correlations between grain yields and fertilization quantity within the selected agricultural watershed, in the typical black soil region, and then optimized the fertilization quantity at different landscape farmlands within the watershed based on the regression equations. Study simulated the surface runoff water quality before and after fertilization spatial adjustment with the achieved parameters by Soil and Water Assessment Tool (SWAT) model. The results showed that watershed scale fertilization adjustment is possible and necessary according to the spatial heterogeneity about fertilization and grain yields. Based on grain yield stability, spatial adjustment of fertilization reduced the whole watershed total N fertilization quantity by 1.88%, and the total non-point nutrients load reduction of NH4+ -N and NO3- -N was 9.7%, 5.6%, respectively.

By the method of thermostatic culture, this paper studied the effects of different application rates (0.5, 1.5, and 2.5 ml x kg(-1)) of organic fish protein liquid fertilizer on the enzyme activities and microbial biomass C and N in a silt soil, and the relationships between these parameters and soil nutrient contents. Under the application of the liquid fertilizer, soil pH varied in the range of 7.07-7.31, but had no significant difference from the control. With the increasing application rate of the liquid fertilizer, the activities of soil phosphatase, urease, and protease, as well as the soil biomass C and N, all increased significantly, and the increment was 127, 190 and 196%, 39.81, 78.06 and 173.24%, 56.37, 108.29 and 199.98%, 167, 395 and 474%, and 121, 243 and 406%, respectively, compared with the control. The peak time of the soil urease and protease activities and microbial biomass C and N differed with the fertilization treatments. Soil phosphase, urease, and protease activities and microbial biomass C and N were significantly positively correlated with soil nutrient contents, suggesting that applying organic fish protein liquid fertilizer to silt soil could improve soil microbial growth and enzyme activities, and accordingly, promote the decomposition and transformation of soil organic matter and the release of soil available nutrient elements.

Based on the long-term (1982-2007) field experiment of "anthropogenic mellowing of raw soil" at the Qiyang red soil experimental station under Chinese Academy of Agricultural Sciences, and by using numerical theory, this paper studied the variations of the fertility level of granite red soil, quaternary red soil, and purple sandy shale soil under six fertilization patterns. The fertilization patterns included non-fertilization (CK), straw-returning without fertilizers (CKR), chemical fertilization (NPK), NPK plus straw-return (NPKR), rice straw application (M), and M plus straw-return (MR). The soil integrated fertility index (IFI) was significantly positively correlated with relative crop yield, and could better indicate soil fertility level. The IFI values of the three soils all were in the order of NPK, NPKR > M, MR > CK, CKR, with the highest value in treatment NPKR (0.77, 0.71, and 0.71 for granite red soil, quaternary red soil, and purple sandy shale soil, respectively). Comparing with that in the treatments of no straw-return, the IFI value in the treatments of straw return was increased by 6.72%-18.83%. A turning point of the IFI for all the three soils was observed at about 7 years of anthropogenic mellowing, and the annual increasing rate of the IFI was in the sequence of purple sandy shale soil (0.016 a(-1)) > quaternary red clay soil (0.011 a(-1)) > granite red soil (0.006 a(-1)). It was suggested that a combined application of organic and chemical fertilizers and/or straw return could be an effective and fast measure to enhance the soil fertility level in red soil region.

Nitrification inhibitors exert inhibition function in soil nitrification process (NH4(+)-N to NO3(-)-N) and are widely applied in order to improve N fertilizer use efficiency. Before the new nitrification inhibitor is used, its effects on denitrification process must be investigated and denitrifying enzyme activity (DEA) is an effective indicator to show this process. In the present paper, a mass spectrometery (MS) method was taken to measure the denitrifying enzyme activity in the new nitrification inhibitor 3, 4-dimethylpyrazole phosphate (DMPP) incubation system. The results showed that the method measured the concentration of N2O in the incubation system accurately and the concentration measured by MS had marked correlation with that measured by gas chromatogram (GC) (MS(N2O) = -0.45 + 1.03GC(N2O, R2 = 0.995). At the same time, enrichment of 15 N2O and 15 N2 was measured to discriminate the nitrate reductase and N2O reductase. Differed with traditional method, the enzymatic inhibitor-acetylene was not appended. The results showed that DMPP had no influence on the denitrifying enzyme activity and indicated that the denitrification process was not influenced by DMPP.

By using sustainable yield index (SYI), this paper analyzed the sustainability of maize, rice, and wheat yields at 20 long-term fertilization experiment sites in China under different fertilization system and ecological conditions. The SYI value of test crops varied significantly with fertilization system, crop kind, effective accumulated temperature, and sunshine hour. Irrespective of fertilization, the SYI value of rice was generally higher than that of maize and wheat. Under long-term no fertilization, the SYI values of rice, wheat, and maize were lower, being 0.55, 0.44, and 0.43, respectively. Fertilization, especially a combined application of NPK and manure, promoted the sustainability of crop yields, with the SYI values of rice, wheat, and maize being 0.66, 0.58, and 0.57, respectively. Under the application of N and NK, the SYI values ranged in 0. 36-0. 47. SYI value > 0.55 represented the better sustainability of crop yields, while SYI < 0.45 represented a worse one. Longitude, altitude, and weather factors also affected the SYI values, especially that of maize. Under no fertilization, maize had the largest variation of SYI value, followed by wheat, and rice. Our results indicated that a combined application of chemical fertilizers with manure benefited high and stable yielding, being the optimal fertilization mode for maintaining the sustainability of grain yield.

This paper studied the source-sink characters and grain-filling traits of six genotype summer maize varieties under 2 years (from 2007 to 2008) application of low dosage (105 kg x hm(-2)) and normal dosage (337.5 kg x hm(-2)) fertilizer nitrogen. Under low nitrogen stress, the population yield, leaf area index (LAI), source-sink characters, and grain-filling traits of test varieties differed significantly. The varieties tolerant to low nitrogen, e.g., Xianyu 335 and Zhengdan 958, had longer active grain-filling stage, higher maximum filling rate, longer duration of maximum LAI, and more harmonious sink-source relation; while less tolerant species, e.g., Shaandan 902 and Yuyu 22, had shorter active grain-filling hours, lower maximum filling rate, lower mass increment and LAI under maximum grain-filling rate after silking, and significantly decreased source supply capacity. Low nitrogen stress increased the yield difference among the test varieties significantly.

Composting is an effective way to realize livestock manure treatment and recycling. However, the nitrogen loss during manure composting is relatively serious. Studies on this nitrogen loss and its control could provide theoretic basis and practical reference for efficient nitrogen loss control. This paper described the nitrogen transformation and the main nitrogen loss ways during the composting, and summarized the main factors (including raw material characteristics, environment factors, and technological conditions) affecting the nitrogen loss in the composting. In addition, the research progress in the nitrogen loss control, including adjusting carbon and nitrogen metabolism, changing nitrogen form, adding ammonia adsorbent, and controlling pile aeration and temperature, was reviewed, and the prospects for future research were presented.

The clayey farmland soil in black soil region of Northeast China, due to the existence of thicker plough pan created by unreasonable tillage, is a main limiting factor for local agricultural production. In this paper, a field experiment was conducted to study the construction effect of fertile cultivated layer on crop yield, soil physical properties, soil moisture content, and soil microbial number. After the construction of fertile cultivated layer, the soil had a thicker cultivated layer, and the crop yield was increased. Comparing with traditional tillage, applying straw and organic manure into 20-35 cm soil layer decreased soil bulk density by 9.88% and 6.20%, increased soil porosity by 9.58% and 6.02%, and enhanced soil saturated hydraulic conductivity by 167.99 and 73.78%, respectively, indicating that the construction of fertile cultivated layer could improve soil aeration and water permeability, and enhance the infiltration of rainfall. The soil moisture content and water use efficiency under the application of straw and organic manure into plough pan were higher than those under traditional tillage, and a positive correlation was observed between the moisture content in 0-35 cm soil layer and the emergence of maize seedlings. Due to the increased organic carbon source and aeration in the constructed fertile cultivated layer, soil microbial number was also increased.

This paper studied the seasonal dynamics of soil microbial biomass C (Cmic) and N (Nmic), and of bacteria (cfu(b)), fungi (cfu(f)), and actinomyces (cfu(a)) in Larix gmelinii and Fraxinus mandshurica plantations in 2007-2008 under N fertilization. The two-year averaged soil Cmic and Nmic in L. gmelinii plantation were 13.8% and 18.3% lower than those in F. mandshurica plantation, respectively, but the soil Cmic and Nmic in the two plantations had similar seasonal patterns, being the lowest in May and the highest in September. The Cmic and Nmic, and the cfu(b), cfu(r), and cfu(a), were all greater in topsoil (0-10 cm) than in subsoil (10-20 cm), but the seasonal patterns of cfu(b), cfu(f), and cfu(a), were different from those of Cmic and Nmic. N fertilization decreased the Cmic and Nmic, and the cfu(b), cfu(f), and cfu(a), significantly, with the decrements of Cmic and Nmic being 24% and 63% in L. gmelinii plantation, and 51% and 68% in F. mandshurica, respectively, which suggested that N fertilization limited soil microbial biomass and altered soil microbial communities in the two plantations.

The level and form of nitrogen fertilizer could significantly influence the growth and development of plant. The present paper studied the content of chlorophyll by the instrument SPAD-502 after treated with different nitrogen fertilizer level and different nitrogen fertilizer form. The results showed that the contents of chlorophyll in the last expanding leaf of maize seedling treated by levels of 0, 100 and 200 kgN x hm(-2) respectively had no significant difference, with the value of SPAD ranging from 43.3 to 43.7, but when the nitrogen fertilizer level got to 400 kgN x hm(-2), the content of chlorophyll in the last expanding leaf of maize seedling increased significantly, which can be caused by other components in the nitrogen fertilizer, which needs to be further studied. The experiments of nitrogen form showed that maize seedling treated by ammonia nitrogen ((NH4)2SO4) contained more chlorophyll than that treated by saltpeter nitrogen (Ca(NO3)2), and the statistical analysis was significant. The reason for the effect of nitrogen form on the content of chlorophyll of maize seedling leaf could be: (1) it is easier for plants to absorb ammonia nitrogen ((NH4)2SO4) than saltpeter nitrogen (Ca(NO3)2); (2) ammonia nitrogen ((NH4)2SO4) contains more trace elements which can promote the growth and development of plants.

The agronomic, environmental, and ecological significances of applying nitrification inhibitor (NI) have been demonstrated by many researches, but the efficiency of NI application was affected by many factors. In this paper, the effects of NI on soil N transformation, nitrate leaching and greenhouse gases emission, fertilizer N use efficiency, yield and quality of agricultural products, and availability of soil nutrients besides N were reviewed, and the factors affecting the efficiency of NI application as well as the evaluation criteria of NI were summarized.

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.

With five-year old 'Zaodaguo' sweet-cherry (Prunus avium L.) as test material, this paper studied the characteristics of its urea 15N absorption, allocation, and utilization when applied before bud-break. The results showed that the Ndff of different organs increased gradually with time, and was higher in fine roots and storage organs at full-blooming stage. At fruit core-hardening stage, the Ndff of long shoots and leaves increased quickly, reaching to 0.72% and 0.59% , respectively. From fruit core-hardening to harvesting stage, the Ndff of fruit had a rapid increase, with the peak (1.78%) at harvesting stage. After harvest, the Ndff of neonatal organs increased slowly while that of storage organs increased quickly. At full-blooming stage, the absorbed 15N in roots was firstly allocated to storage organs, with the highest allocation rate (54.91%) in large roots. At fruit core-hardening stage, the allocation rate in fine roots and storage organs decreased from 85.43% to 55.11%, while that in neonatal branches and leaves increased to 44.89%. At harvesting stage, the allocation rate in different organs had no significant change, but after harvest, the absorbed 15N had a rapid translocation to storage organs, and the allocation rate in fine roots and storage organs reached the highest (72.26%) at flower bud differentiation stage. The 15N allocation rate in neonatal branches and leaves at flower bud differentiation stage was decreased by 19.31%, compared with that at harvesting stage. From full-blooming to flower bud differentiation stage, the utilization rate of urea 15N was increasing, and reached the peak (16.86%) at flower bud differentiation stage.

In this paper, black soil samples at the depths of 0-20 cm and 20-40 cm were collected from the Hailun Agricultural Ecology Station of Chinese Academy of Sciences to study the effects of long-term fertilization on their urease, invertase, phosphatase and catalase activities and total C and N contents. The results showed that long-term application of chemical fertilizers and organic manure increased the activities of urease, invertase and phosphatase in 0-20 cm and 20-40 cm soil layers in different degree, and the combined application of them increased the activities of the three enzymes significantly, with an increment of 43.6%-113.2%, 25.9%-79.5% and 14.7%-134.4% in 0-20 cm soil layer and 56.1%-127.2%, 14.5%-113.8% and 16.2%-207.2% in 20-40 cm soil layer, respectively. However, long-term application of chemical fertilizers without organic manure had little effects on catalase activity. The activities of urease, invertase and phosphatase decreased with increasing soil depth. Long-term application of N fertilizer increased urease activity, and P fertilization had obvious positive effect on phosphatase activity. Long-term fertilization also had obvious effects on the soil total C and N contents and C/N ratio.

Paddy rice-upland crop rotation system is a major cropping system in China, and practiced widely along the Yangtze River basin. A unique feature of this system is the annual conversion of soil from aerobic to anaerobic and then back to aerobic condition, which can result in the changes of soil physical, chemical, and biological prosperities among seasons, making a special agroecosystem. The major challenges faced by this system include declining or stagnating productivity, increasing shortage of irrigation water, improper management of nutrients, low efficiency of resource utilization, and environmental pollution. Based on an overview of the characteristics and problems of paddy rice-upland crop rotation system, this paper put forward a strategy of practicing integrated nutrient management to solve the contradictions between nutrient input, crop production and environmental risk. The key points of this strategy included nutrient management from the whole rotation system perspective, integrated use of nutrients from various sources (chemical fertilizers, organic fertilizers, and nutrients from the environment), synchronization of nutrient supply and crop nutrient demand, application of different management technologies based on the characteristics of different nutrient resources, and integration of nutrient management with other cropping system technologies like water saving and high-yielding cultivation, etc.

With enclosed and static chambers, this paper studied the effects of different fertilization modes, i.e., top-dressing nitrogen (N) fertilizer followed by tillage (SF), drilling N fertilizer followed by covering soil (TF), and top-dressing N fertilizer followed by irrigation (SS), on soil ammonia (NH3) volatilization and nitrous oxide (N2O) emission. The results showed that fertilization mode had significant effects on the NH3 volatilization and N2O emission. SS promoted NH3 volatilization obviously, with the maximum NH3 volatilization rate higher than other treatments and the total amount of cumulative NH3 volatilization up to 2.465 kg N x hm(-2). There were significant differences (P < 0.05) in the N2O flux among different treatments, and the peak appeared at different time. The N2O flux in SS got to its peak (193.66 miccrog x m(-2) x h(-1)) after two days of fertilization, while that in TF got to the peak (51.13 microg x m(-2) x h(-1), the lowest among different treatments) after five days of fertilization. The net cumulative N2O emission in SS was 121.55 g N x hm(-2), much higher than that of SF and TF. SF and TF reduced NH3 volatilization and N2O emission markedly, suggesting that both of them could be the rational and practicable N fertilization modes.

In this paper, the first order roots of Larix gmelinii plantation under N fertilization were sampled from different soil depths in different seasons to study their morphology under effects of ectomycorrhizal fungi. The results showed that the infection rate of ectomycorrhizal fungi on the first order roots was significantly affected by soil N availability, soil depth, and season. N fertilization induced a decrease of the infection rate, and the decrement varied with soil depth and season. In comparing with the control, the infected first order roots had an obvious variation of their morphology, e. g., averagely, root diameter increased by 18.7%, root length decreased by 23.7%, and specific root length decreased by 16.3%, which differed significantly with N application rate, soil depth, and season. The infection of ectomycorrhizal fungi changed the first order root morphology of L. gmelinii, which might substantially affect the physiological and ecological processes of host plant fine roots.

By using leakage pond to simulate the double cropping paddy fields in Dongtinghu Lake area, this paper studied the effects of urea (CF) and controlled release nitrogen fertilizer (CRNF) on the dynamics of surface water pH, electrical conductivity (EC), total nitrogen (TN), ammonia nitrogen (NH4(+)-N) and nitrate nitrogen (NO3(-)-N) and the runoff loss of TN in alluvial sandy loamy paddy soil and purple calcareous clayed paddy soil, the two main paddy soils in this area. The results showed that after applying urea, the surface water TN and NH4(+)-N concentrations reached the peak at the 1st and 3rd day, respectively, and decreased rapidly then. Surface water NO3(-)-N concentration was very low, though it showed a little raise at the 3rd to 7th day after applying urea in purple calcareous clayed paddy soil. In early rice field, surface water pH rose gradually within 15 days after applying urea, while in late rice field, it did within 3 days. EC kept consistent with the dynamics of NH4(+)-N. CRNF, especially 70% N CRNF, gave rise to distinctly lower surface water pH, EC, and TN and NH4(+)-N concentrations within 15 days after application, but NO3- concentration rose slightly at late growth stages, compared with urea application. The monitoring of TN runoff loss indicated that during double cropping rice growth season, the loss amount of TN under urea application was 7.70 kg x hm(-2), accounting for 2.57% of applied urea-N. The two runoff events occurred within 20 days after urea application contributed significantly to the TN runoff loss. CRNF application resulted in a significantly lower TN concentration in runoff water from the 1st runoff event occurred within 10 days of its application, and thereafter, the total TN runoff loss for CRNF and 70% N CRNF application was decreased by 24.5% and 27.2%, respectively, compared with urea application.

Employing an inverted 'W' investigation procedure with 9 sampling locations and adopting a biodiversity analysis approach integrated with typical statistic method, this paper studied the effects of different long-term stationary fertilization regimes on the weed biodiversity in winter wheat fields on loess soil. The results showed that in the experimental plots, there were 16 weed species belonging to 10 family and 16 genera, occupying about 34% of the total number of weed species in winter wheat fields in Shaanxi Province. The weed biodiversity was decreased with the improvement of soil nutrient status. There were 3-5 weed populations in treatments NPK and NPK plus organic materials, and 6-8 populations in treatments CK, N, NK and NP. The relative abundance of weeds ranged from 0 to 73%, and the ranges of Shannon's diversity index, Shannon's evenness index and Margalef' s species richness index were 0.2-1.08, 0.05-0.26 and 0.26-1.26, respectively. All of these 3 parameters were higher in unbalanced than in balanced fertilization treatments, and the differences between unbalanced and balanced fertilization treatments were significant in most case, which was probably due to the different status of available soil nutrients and might have different effects on the growth of weeds.

With 16 years old Larix kaempfersoil plantation in the mountainous area of eastern Liaoning Province as test object, this paper studied the effects of fertilization on the fine root diameter, root length, and specific root length (SRL) of the first to fifth order roots. The results showed that with ascending root orders, the mean fine root diameter and root length increased, while the SRL decreased significantly. Among the five order roots, the first order roots were the thinnest in diameter, the shortest in length, and the highest in SRL, but the fifth order roots were in reverse. The variance coefficients for the fine root diameter, root length, and SRL increased from the first to the fifth order roots. Except for the first order roots, soil depth had no significant influence on the fine root diameter, root length and SRL. Fertilization affected the fine root diameter, root length, and SRL of the first and the second order roots significantly, hut had little effects on other order roots. N fertilization decreased the mean diameter of the first and the second order roots significantly, and N or N + P fertilization decreased the mean length of the first order roots in surface soil (0-10 cm) significantly. The SRL of the first order roots in surface soil increased significantly under N fertilization.

In this paper, the dynamics of microflora and microbial activity in soil added with 0, 100, 200 and 400 mg x kg(-1) of Cu2+ were studied under effects of inoculating earthworm and applying straw. Four treatments were installed, i.e., CK, surface application of straw (M), inoculation of earthworm (E), and M plus E (ME). The results showed that Cu contamination had inhibitory effect on soil bacteria and actinomycetes, but no effect on soil fungi. Straw amendment increased soil fungi significantly, while earthworm inoculation could increase the numbers of soil bacteria and actinomycetes significantly but had little effect on soil fungi. When the Cu concentration was higher than 200 mg x kg(-1, soil microbial biomass carbon was depressed, but earthworm inoculation and straw amendment could enhance it, with most significant effect under the combination of these two treatments. Earthworm inoculation and straw amendment could enhance soil basal respiration markedly. When the Cu concentration was lower than 200 mg x kg(-1), treatment M had the highest soil basal respiration, being about 3.06-5.58 times higher than that of CK, while at Cu > or =200 mg x kg(-1), soil qCO2 followed the sequence of ME > E > M > CK. Treatments M and E had no effects on soil NH4+ -N. As for soil NO3- -N, treatment E could increase it significantly, but treatment M was in adverse. Treatment ME induced the lowest soil NO3- -N. In a definite degree, earthworm inoculation and straw amendment could mitigate the negative impact of Cu contamination on soil microflora and microbial activity.

By using X-ray diffraction and laboratory simulation, this paper studied the effects of long-term potassium (K) fertilization on K fixation in black soil, loess soil, and grey desert soil under different ecological conditions and cropping systems. The results showed that long-term K fertilization had greater effects on the K fixation capacity of soils with lower hydromica content. When the K application rate was 400 to 4 000 mg x kg(-1), the K fixation capacity of black soil and loess soil, whose hydromica contents were low or relatively low, decreased by 75-747 mg x kg(-1) and 16-238 mg x kg(-1), respectively, compared with no K application, while no change was observed in grey desert soil whose hydromica content was high. Long-term K application could affect the changes of soil K-bearing minerals, i.e., slowing down or holding back the transformation of hydromica into mixed-layered mica-smectite, and consequently, decreased the K fixation capacity of soil. The increase of soil slow-available K content and K+ saturation owing to the long-term K application also induced the decrease of the K fixation capacity.

With 16 years old Larix kaempferi plantation in eastern mountain area of Liaoning Province as test object, this paper studied its total fine root biomass, fine root biomass at different soil depths, and biomass of different root orders under effects of fertilization. The results showed that compared with no fertilization, applying N decreased the total fine root biomass significantly (P < 0.05), while the difference between applying P and N + P was not significant. The fine root biomass in top soil (0-10 cm) was significantly (P < 0.01) higher than that in subsoil (10-20 cm), and in all treatments, it accounted for 64%-73% of the total. The effects of fertilization on fine root biomass varied with soil depth and root orders. In top soil, N fertilization decreased five orders (except the second order) fine root biomass significantly (P < 0.05), while P and P + N fertilization had no significant effects (P > 0.05), except the fifth order root in treatment P, and the second order root in treatment P + N (P < 0.05). In subsoil, treatments N and P had no effects on five orders fine root biomass (P > 0.05), while treatment N + P increased the first order fine root biomass significantly (P < 0.05).

Water and fertilizer are the keys in improving dry land productivity, and the main factors limiting the agricultural development in dry land regions. For our food security and agricultural sustainable development, it' s of significance to bring the effect of water and fertilizer on increasing yield into full play. This paper introduced the design principles of several commonly used methods in researching the effect of water and fertilizer, e.g., irrigation experiment, rainproof-shed experiment and long-term experiment, compared their advantages and disadvantages, and discussed the mechanisms and models of water-fertilizer interaction on dry land farmland, based on the sum-up of the achievements of related qualitative and quantitative researches. It was indicated that under appropriate conditions, there was a positive interaction between water and fertilizer on grain yield, but the effect differed with research method and natural condition. The development trend of the researches on the water-fertilizer effect on dry land farmland in light of the characteristics of agro-ecosystern was also prospected.

Through a consecutive 15 years field trial on the aquic brown soil in Shenyang suburb of Northeast China, this paper studied the soil potassium budget and crop potassium allocation under effects of different fertilization systems. The results indicated that applying nitrogen or nitrogen plus phosphorous without potassium application accelerated the deficit of soil potassium. The potassium concentration in soybean grain and stalk was higher under potassium application than with no potassium supply, while that in maize grain had no significant difference in different fertilization treatments. The reutilization of recycled nutrients in farming system could mitigate the deficit of soil potassium budget, and such reutilization assorted with appropriate amount of potassium fertilization could not only produce high crop yield, but also balance soil potassium budget.

Under field condition, this paper measured the leaf gas exchange parameters and photosynthetic pigments content of different drought-resistance wheat varieties at all growth stages, with their responses to different nitrogen fertilization levels studied. The results showed that in treatment N180, the leaf G(s), P(n), and total photosynthetic pigments content of dry land varieties increased by 43.75%, 18.54% and 49.66% , while those of watered land varieties increased by 12.12% , 20.88% and 29.25%, respectively, compared with control. On the contrary, the respiration rate of dry land and watered land varieties decreased by 4.8% and 4.5%, respectively. Nitrogen supply accelerated the photosynthetic carbon assimilation, because the gas exchange capacity and photosynthetic pigments content increased while the respiration rate decreased with increasing nitrogen supply. The difference in photosynthetic capacity between different winter varieties was mainly dependent on non - stomatal factors. The dry land varieties had higher capacities of light energy absorption and photosynthetic carbon assimilation, because they had higher leaf photosynthetic pigments content but lower respiration rate. Compared with watered land varieties, dry land varieties had an 8.9% decrease of respiration rate and a 14.12% increase of P(n). At the same growth stage, the photosynthetic and respiration rates in the control varied consistently, while in treatments N180 and N360, the photosynthetic rate increased but the respiration rate decreased. Nitrogen fertilization promoted the absorbed light energy allocating to the process of photosynthetic carbon assimilation. It could be concluded that nitrogen supply was favorable to the improvement of winter wheat drought-resistance, because it could improve leaf gas exchange capacity, increase leaf photosynthetic pigments content, and optimize the allocation of absorbed light energy.

This paper studied the exterior cost of applying chemical fertilizer on the farmland in Dongting Lake area, one of the main foodstuff production regions in China, aimed to search for an optimal chemical fertilizer application rate accorded with local economic and ecological benefits. The exterior cost was estimated by the method of economic and environmental evaluation, while the optimal application rate was calculated based on Exterior Diseconomy Theory and by using production function model, with both ecological and farmers' economic benefits considered. The results showed that in 2002, the exterior cost of inappropriately applying chemical fertilizer was about 1.35 x 10(8) yuan, equivalent to 0.3 yuan x kg(-1) fertilizer N. Under current situation of test area, the optimal application rate of chemical fertilizer should be 208.26 - 210.65 kg x hm(-2), and the corresponding foodstuff supply would be 5528 - 5539 kg x hm(-2). However, the actual fertilizer application rate in 2002 exceeded the optimal one. A suggestion was made to impose tax for the environmental pollution of over-using chemical fertilizer.