Changes of Organic Matter, N, P and K Content of Soils in Red Soil Areas Under Long-Term Experiment

The content of organic matter （OM）, nitrogen （N）, phosphorus （P）, and potassium （K） in the three selected soils, including Calcaric Purpli-Orthic Primosols （purple sand-shale parent material）, Dystric Turbi-Anthric Primosols （quaternary red clay parent material） and Typic Udi-Sandic Primosols （granite parent material） were studied under a long-term experiment by using crop straw and inorganic fertilizers at the Hunan Red Soil Experiment Station of Chinese Academy of Agricultural Sciences. The results showed that the contents of OM, N, P and K in the three selected soils increased after 23 years application of crop straw and inorganic fertilizers, but the contents increased much less when crop straw or inorganic fertilizers was applied alone. The nutrient contents in the three soils developed from granite changed more remarkably than those in the soil derived from quaternary red clay and purple sand-shale. It was also found that the contents of OM, N, and P increased slightly in the treatments without applying fertilizers or returning the crop straw to the root bed. Combined application of inorganic fertilizers and crop straw could remarkably increase the contents of OM, alkalihydrolyzable N and available K, the positive correlation between application of organic fertilizers and increase of OM in soil did not always happened, it provided evidence for the relation between appropriate C/N ratio and accumulation of OM in soil. The increase of nutrient content was influenced by the soil properties. By comparing the contents of nutrient in 0-20 cm depth in the three different soils, it was concluded that the most increases of OM, alkali-hydrolyzable N, and available P were observed in Typic Udi-Sandic Primosols with the average increase by 3.03, 27.38, and 21.73 mg kg^-1, respectively. The available K increased in Dystric Turbi-Anthric Primosols with the average increase by 25.82 mg kg^-1, while it decreased in Calcaric Purpli-Orthic Primosols and Typic Udi-Sandic Primosols. It was concluded that the application of inorganic fertilizer and crop straw was important to improve the soil fertility for all of three selected soils. The straw return to the field had played a significant role for enhancement of the soil quality in the study areas. The application of inorganic fertilizer combined with the straw return to the fields could remarkably improve the soil fertility.

Crop yields and soil organic carbon dynamics in a long-term fertilization experiment in an extremely arid region of northern Xinjiang, China

A long-term fertilization experiment was set up in northern Xinjiang, China to evaluate the dynamics of crop production and soil organic carbon （SOC） from 1990 to 2012 with seven fertilization treatments. The seven treatments included an unfertilized control （CK） and six different combinations of phosphorus （P）, potassium （K）, nitrogen （N）, straw （S） and animal manure （M）. The balanced fertilization treatments had significantly （P〈0.05） higher average yields than the unbalanced ones. The treatment with 2/3 N from potassium sulfate （NPK） and 1/3 N from farmyard manure （NPKM） had a higher average yield than the other treatments. The average yields （over the 23 years） in the treatments of NPK, and urea, calcium superphosphate （NP） did not differ significantly （P〉0.05） but were higher than that in the treatment with urea and potassium sulfate （NK; P〈0.05）. The results also show that the highest increases in SOC （P〈0.05） occurred in NPKM with a potential increase of 1.2 t C/（hm2.a）. The increase in SOC was only 0.31, 0.30 and 0.12 t C/（hm2.a） for NPKS （9/10 N from NPK and 1/10 N from straw）, NPK and NP, respectively; and the SOC in the NP, NK and CK treatments were approaching equilibrium and so did not rise or fall significantly over the 23-year experiment. A complete NPK plus manure fertilization program is recommended for this extremely arid region to maximize both yields and carbon sequestration.

The principles and guidelines for designing long-term agronomic experiments

Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term objectives; (2) study important soil processes or ecological processes; and (3) be related to the productivity and sustainability of systems. A well established LTAE can provide both insights into how the system operates and foresight into where the system goes. The prerequisites for setting up a LTAE are the secured land, continuous funding and dedicated scientists. A number of principles must be considered carefully when establishing a LTAE, (1) the site must be representative of large areas; (2) the treatments should be simple, but focusing on the big questions; (3) the plots should be large enough to allow subsequent modification of the experiment if this becomes necessary; (4) crop rotations should minimise, wherever possible, the risk of build-up of pests and diseases, and rotational phase should be considered in a rotational experiment; (5) a clearly defined experimental protocol should be developed to ensure data collected is scientifically valid and statistically analysable, but with flexibility to allow essential changes; (6) soil samples, possibly plant samples, should be achieved to provide better answer to the original questions when new, perhaps more accurate analytical techniques are developed, or answer new research questions that were not considered in the original design. The MASTER experiment in Australia was used as a case study to demonstrate how these principles are implemented in practice.

Experimental study on rheological deformation and stress properties of limestone

The systematic experiment regarding the general uniaxial compression test and the creep deformations of the typical limestones from the surrounding rock of the highway tunnels were made.The relationship between the axial stress and the delayed deformation steady value was obtained from the creep tests under low loading stresses.By the least square method,the parameters of Nishihara creep model were calculated from the creep curves.The results indicate that the strain change always lags behind the increase of stress,and the long-term strength of the limestone is about 80.6% of the stress at the volumetric strain reversal which is obtained from the conventional uniaxial compression test.

Flexural failure experiment on cracked PC simply supported box girders

Long-term load and flexural failure experiments are carried out on two prestressed concrete(PC) simply supported box girders. In the long-term load experiment, girder-1(G1) is in an elastic state, while girder-2(G2) is in a cracking state. To investigate the influence of cracking on the flexural behaviors of PC simply supported box beams, the experiment results are analyzed from many aspects, such as load–deflection, load–strain, and failure mode. Experiment results show the following: 1) the shrinkage and creep of concrete have considerable influences on the long-term deflection and strain of the two girders; 2) in the flexural failure experiment, the cracks and ultimate loads of the two girders are close. The rigidity degeneration of G2 is significantly faster than that of G1, and thus G2 shows nonlinear characteristics earlier; 3) to prove the validity and rationality of the current code, the cracking load and ultimate load of the two girders are calculated according to the current code.

QUICK ASSESSMENT METHODOLOGY FOR RELIABILITY OF SOLDER JOINTS IN BALL GRID ARRAY(BGA)ASSEMBLY——PART Ⅱ:RELIABILITY EXPERIMENT AND NUMERICAL SIMULATION

In the present study,a facility,i.e.,a mechanical deflection system (MDS),was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly.It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days,but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests. Based on the MDS and ATC reliability experiments,the acceleration factors (AF) were obtained for different reliability testing conditions.Furthermore,by using the creep constitutive relation and fatigue life model developed in part I,a numerical approach was established for the purpose of virtual life prediction of solder joints. The simulation results were found to be in good agreement with the test results from the MDS.As a result,a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.

Long-Term Survival in Traumatic Brain Injury and Near-Death Experience Increases Suicide Risks: A Personal Experience and Related Literature

Background: Traumatic brain injury (TBI) remains a cause of lifelong disability, death, and suicide worldwide. TBI-induced near-death experience (NDE) could increase suicide risks. Objective: We investigated TBI coupled with NDE and posttraumatic stress disorder (PTSD) as a possible indicator of suicide. Methods: A 17-year-old male who sustained an acute severe TBI in a traffic collision, was comatose 14 days, had an NDE awakening from the coma, and, years after rehabilitation, suffered PTSD, clinical depression, and survived a suicide attempt. This personal experience of a TBI-induced NDE and lingering PTSD was acquired directly from the patient by interview. We discuss his case while considering relevant literature. Results: Longitudinal data from 1961 to 2021 generated from the PubMed interface revealed 4056 TBI patients committed suicide. NDE was only reported in one of those cases and, although not a suicide, in the personal experience. Neuropsychological assessment at long-term follow-ups revealed few TBI patients exhibited normal mental/physical functions compared to the general population. Unfavorable GOS scores were risk predictors for neuropsychological/physical impairments later in life, with outcomes of depression, PTSD, poor QOL, and/or suicide. Conclusions: For TBI-NDE survivors, including those with PTSD, long-term periodic neuropsychological follow-ups and psychosocial support may help decrease suicide risks.

Long-term variation of Arctic Sudden Stratospheric Warmings(SSW)and potential causes

Utilizing the European Centre for Medium-Range Weather Forecast(ECMWF)Reanalysis v5(ERA5),for the first time,we have confirmed close links among Sudden Stratospheric Warmings(SSWs)in the Northern Hemisphere(NH),the polar vortices,and stratospheric Planetary Waves(PWs)by analyzing and comparing their trends.Interestingly,within overall increasing trends,the duration and strength of SSWs exhibit increasing and decreasing trends before and after the winter of 2002,respectively.To reveal possible physical mechanisms driving these trends,we analyzed the long-term trends of the winter(from December to February)polar vortices and of stratospheric PWs with zonal wave number 1.Notably,our results show that in all three time periods(the entire period of 41winters,1980 to 2020,and the two subperiods—1980-2002 and 2002-2020)enhancing SSWs were always accompanied by weakening winter polar vortices and strengthening polar PWs like Stationary Planetary Waves(SPWs)and 16-day waves,and vice versa.This is the first proof,based on ERA5 long-term trend data,that weakening polar vortices and enhancing stratospheric PWs(especially SPWs)could cause an increase in SSWs.

Effects of Long-term Fertilization on Fertility of Lateritic Red Loam Paddy

The change rules of the fertility of red soil paddy under the long-term different fertilization were investigated, and the reasonable fertilization mode to improve the fertility of red soil paddy was discussed. There were eight treatments in the experiment, which were CK （no fertilizer）, N1 （N of 60 kg/hm2）, N2 （N of 120 kg/hm2）, N1P1 （P2O5 of 30 kg/hm2）, N2P1 and N2P2 （P2O5 of 60 kg/hm2）, N2P2K1 （K2O of 45 kg/hm2） and N2P2K2 （K2O of 90 kg/hm2）. All treatments were applied with composted cow dung as the base fertilizer, and each season 50% of the straws were returned to the field. The content of organic matter, nitrogen, phosphorous and potassium in red soil paddy was observed continuously for ten years and their correlation was also analyzed. Under cow manure and straw return to field, organic matter content of different treatments was positively correlated to year. After ten years, organic matter content of surface soil rose by 2.5 g/kg averagely with an annual increase of 0.25 g/kg. Total nitrogen content and organic matter content of different treatments presented similar variation trend. Total nitrogen content rose by 0.35 g/kg averagely with an annual increase of 0.035 g/kg. Among all the treatments, N2P2K1 and N2P2K2 showed the biggest increase, which went up by 0.052 and 0.48 g/kg, respectively. Phosphorous-free treatments （CK, N1, N2） had steady phosphorous content with irregular changes of different years. Total phosphorous content of phosphorous treatments increased year by year. Total phosphorous content of N1P1 and N2P1 rose by 0.008 g/kg every year. The increment range of total phosphorous content of N2P2, N2P2K1 and N2P2K2 was 0.012 -0.013 g/kg annually. Available phosphorous content varied vastly among different treatments. Available phosphorous content of organic fertilizer treatments basically remained stable with irregular changes of different years. Available phosphorous content of organic fertilizer with phosphate fertilizer treatments rose year by year. Available phosphorous content of N1P1 and N2P1 rose approximately by 0.8 mg/kg. Available phosphorous content of N2P2, N2P2K1 and N2P2K2 rose approximately by 1.4 -1.6 mg/kg annually. Potassium fertilizer amount greatly affected total potassium content. Total potassium content of no-potassium treatments （CK, N1, N2, N1P1, N2P1 and N2P2） remained the same. Total potassium content of N2P2K markedly increased year by year, which was 0.014 g/kg annually. Rapid available potassium content of no-potassium treatments （CK, N1, N2, N1P1, N2P1 and N2P2） showed a decreasing trend. With phosphate fertilizer, rapid available potassium content of N2P2K1 and N2P2K2 remained the same or increased year by year. The change trend of slow available potassium content and rapid available potassium content resembled. Rational allocation of organic fertilizer, nitrogenous fertilizer, phosphate fertilizer and potassium fertilizer can significantly improve soil fertility and economic benefits. Balanced fertilization is an effective measure for soil fertility improvement as it＇s shown that nutrients of surface soil accumulate annually.

Geothermal extraction performance in fractured granite from Gonghe Basin,Qinghai province,China:Long-term injection and production experiment

The efficient exploitation of geothermal energy through enhanced geothermal systems(EGS)has been a relevant topic for hot dry rock(HDR)geothermal resources.When cryogenic fluid is injected into a thermal reservoir,improving heat exchange efficiency is key to achieving the optimal exploitation of HDR.In this paper,granite outcrops from Gonghe Basin were used as the testing sample.The natural fractures in the granite samples were relatively well developed.To simulate long-term injection and production from multi-wells in situ,physical ex-periments were performed in a newly-developed,in-house large-scale true triaxial experimental system.Geothermal extraction performance of an HDR was simulated for long-term injection and production operations.Simultaneously,the mode of one-injection and multiple-production wells was represented.In the paper,the ef-fects of the production-injection well spacing,the number of production wells and the injection rate on the production temperature and flow rate are discussed.The results show that,during long-term injection and pro-duction,there are two stages of production temperature variation,namely stabilization and attenuation.When the number of the production wells is increased,the heat extraction efficiency is accelerated.Moreover,competitive diversion of fluid among fractures occurred due to different conductivities.Furthermore,under different pro-duction modes,the production flow rate contributed differently to the heat extraction.Finally,the effect of the production-injection wells spacing on the heat exchange performance was analyzed;this is mainly reflected in the change of the effective heat exchange area between the rock and the injected fluid.The results emphasize the importance of designing an appropriate production mode and optimizing the injection-production parameters to ensure efficient HDR exploitation.

Effect of Long-Term Rice Straw Return on Soil Glomalin, Carbon and Nitrogen

A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted in a significant increase in both soil easily extractable glomalin (EEG) and total glomalin (TG) concentrations, as compared with application of only chemical fertilizer or no fertilizer application. The EEG and TG concentrations of the NPKS (nitrogen, phosphorus, and potassium fertilizer application + rice straw return) plot were 4.68% and 5.67% higher than those of the CK (unfertilized control) plot, and 9.87% and 6.23% higher than those of the NPK (nitrogen, phosphorus, and potassium fertilizer applied annually) plot, respectively. Application of only chemical fertilizer did not cause a statistically significant change of soil glomalin compared with no fertilizer application. The changes of soil organic C (SOC) and total N (TN) contents demonstrated a similar trend to soil glomalin in these plots. The SOC and TN contents of NPKS plot were 15.01% and 9.18% higher than those of the CK plot, and 8.85% and 14.76% higher than those of the NPK plot, respectively. Rice straw return also enhanced the contents of microbial biomass C (MBC) and microbial biomass N (MBN) in the NPKS plot by 7.76% for MBC and 31.42% for MBN compared with the CK plot, and 12.66% for MBC and 15.07% for MBN compared with the NPK plots, respectively. Application of only chemical fertilizer, however, increased MBN concentration, but decreased MBC concentration in soil.

Effects of Long-Term Winter Planted Green Manure on Physical Properties of Reddish Paddy Soil Under a Double-Rice Cropping System

Soil physical properties are important indicators of the potential for agricultural production.Our objective was to evaluate the effects of long-term inputs of green manures on physical properties of a reddish paddy soil（Fe-Typic Hapli-Stagnic Anthrosols） under a double cropping system.The common cropping pattern before the study was early-late rice-fallow（winter）.The field treatments included rice-rice-fallow（R-R-WF）,rice-rice-rape（R-R-RP）,rice-rice-Chinese milk vetch（RR-MV）,and rice-rice-ryegrass（R-R-RG）.The rape,Chinese milk vetch and ryegrass were all incorporated as green manures 15 d before early rice transplanting during the following year.The soil bulk density in all green manure treatments was significantly reduced compared with the winter fallow treatment.Soil porosity with green manure applications was significantly higher than that under the winter fallow.The green manure treatments had higher 0.25-5 mm water stable aggregates and aggregates stabilities in the plow layer（0-15 cm depth） compared with the fallow treatment.The mean weight diameter（MWD） and normalized mean weight diameter（NMWD） of aggregates in the green manure treatment were larger than that with the winter fallow.Soil given green manure retained both a higher water holding capacity in the plow layer soil,and a larger volume of moisture at all matric potentials（-10,-33 and-100 kPa）.We conclude that the management of double-rice fields in southern central China should be encouraged to use green manures along with chemical fertilizers to increase SOC content,improve soil physical properties and soil fertility.

Long-Term Effect of Fertilizer and Rice Straw on Mineral Composition and Potassium Adsorption in a Reddish Paddy Soil

Increasing K＋ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K＋ adsorption because of changes in the chemical and mineralogical properties of a rice （Oryza sativa L.）. The aims of this study were （i） to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagramdecomposition method; （ii） to measure K＋ adsorption isotherms before and after H202 oxidation of organic matter, and （iii） to investigate whether K＋ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr longterm fertilization treatments caused little change in soil organic C （SOC） but a large variation in soil mineral composition. The whole-clay fraction （〈5 Jam） corresponded more to the fertilization treatment than the fine-clay fraction （〈1 gin） in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage ofillite peak area in the 〈5 lam soil particles （R=-0.946, P〈0.0006）. Different fertilization treatments gave significantly different results in K＋ adsorption. The SOC oxidation test showed positive effects of SOC on K＋ adsorption at lower K＋ concentration （≤120 mg L-0 and negative effects at higher K＋ concentration （240 mg L-l）. The K＋ adsorption by soil clay minerals after SOC oxidization accounted for 60-158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K＋ adsorption. The K＋ adsorption potential was significantly correlated to the amount of poorly crystallized illite present （R--0.879, P=0.012）. The availability of adsorbed K＋ for plant growth needs further study.

Effects of Long-Term Combined Application of Organic and Mineral Fertilizers on Microbial Biomass,Soil Enzyme Activities and Soil Fertility

Soil health is important for the sustainable development of terrestrial ecosystem. In this paper, we studied the relationship between soil quality and soil microbial properties such as soil microbial biomass and soil enzyme activities in order to illustrate the function of soil microbial properties as bio-indicators of soil health. In this study, microbial biomass C and N contents （Cmic ＆ Nmic）, soil enzyme activities, and soil fertility with different fertilizer regimes were carried out based on a 15-year long-term fertilizer experiment in Drab Fluvo-aquic soil in Changping County, Beijing, China. At this site, 7 different treatments were established in 1991. They were in a wheat-maize rotation receiving either no fertilizer （CK）, mineral fertilizers （NPK）, mineral fertilizers with wheat straw incorporated （NPKW）, mineral fertilizers with incremental wheat straw incorporated （NPKW＋）, mineral fertilizers plus swine manure （NPKM）, mineral fertilizers plus incremental swine manure （NPKM＋） or mineral fertilizers with maize straw incorporated （NPKS）. In different fertilization treatments Cmic changed from 96.49 to 500.12 mg kg^-1, and Nmic changed from 35.89 to 101.82 mg kg^-1. Compared with CK, the other treatments increased Cmic ＆ Nmic, Cmic/Corg （organic C） ratios, Cmic/Nmic, urease activity, soil organic matter （SOM）, soil total nitrogen （STN）, and soil total phosphorus （STP）. All these properties in treatment with fertilizers input NPKM＋ were the highest. Meantime, long-term combined application of mineral fertilizers with organic manure or crop straw could significantly decrease the soil pH in Fluvo-aquic soil （the pH around 8.00 in this experimental soil）. Some of soil microbial properties （Cmic/Nmic, urease activity） were positively correlated with soil nutrients. Cmic/Nmic was significantly correlated with SOM and STN contents. The correlation between catalase activity and soil nutrients was not significant. In addition, except of catalase activity, the soil pH in this experiment was negatively correlated with soil microbial properties. In conclusion, soil microbial properties reflect changes of soil quality and thus can be used as bio-indicators of soil health.

Discrepancy in Response of Rice Yield and Soil Fertility to Long-Term Chemical Fertilization and Organic Amendments in Paddy Soils Cultivated from Infertile Upland in Subtropical China

From 1990,over 17 years field experiment was carried out in paddy field cultivated from infertile upland to evaluate the response of rice productivity,soil organic carbon（SOC）,and total N to long-term NPK fertilization or NPK combined with organic amendments.The field trials included NPK（N,P,K fertilizer）,NPKRS（NPK combined with rice straw）,NPK2RS（NPK combined with double amount of rice straw）,NPKPM（NPK combined with pig manure） and NPKGM（NPK combined with green manure） and the cropping system was rice-rice（Oryza sativa L.） rotation.Annual rice yield,straw biomass,and harvesting index increased steadily with cultivation time in all treatments.Average annual rice yield from 1991 to 2006 was ranged from 7 795 to 8 572 kg ha-1 among treatments.Rice yields in treatments with organic amendments were usually higher than that in treatment with NPK.Contents of SOC and total N also increased gradually in the cultivation years and reached the level of 7.82 to 9.45 and 0.85 to 1.03 g kg-1,respectively,in 2006.Soil fertilities in treatments with chemical fertilization combined with organic amendments were relatively appropriate than those in treatment with NPK.There was obvious discrepancy between cumulative characters of rice yield and soil organic fertility in newly formed paddy field.Compared with relatively high rate of crop productivity improvement,cumulative rates of SOC and total N were much lower in our study.SOC and total N contents were still less than half of those in local highly productive paddy soils after 17 years cultivation in subtropical China.Present work helps to better understand the development of infertile paddy soils and to estimate the potential of yield improvement in this region.

Effects of Long-Term Organic Amendments on Soil Organic Carbon in a Paddy Field: A Case Study on Red Soil

Soil organic carbon （SOC） is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expansion in south China. A study was carried out to evaluate the relationship between the SOC content and organic carbon input under various organic amendments at a long-term fertilization experiment that was established on a red soil under a double rice cropping system in 1981. The treatments included non-fertilization （CK）, nitrogen-phosphorus-potassium fertilization in early rice only （NPK）, green manure （Astragalus sinicus L.） in early rice only （OM1）, high rate of green manure in early rice only （OM2）, combined green manure in early rice and farmyard manure in late rice （OM3）, combined green manure in early rice, farmyard manure in late rice and rice straw mulching in winter （OM4）, combined green manure in early rice and rice straw mulching in winter （OMS）. Our data showed that the SOC content was the highest under OM3 and OM4, followed by OM1, OM2 and OM5, then NPK fertilization, and the lowest under non-fertilization. However, our analyses in SOC stock indicated a significant difference between OM3 （33.9 t ha^-1） and OM4 （31.8 t ha^-1）, but no difference between NPK fertilization （27 t ha^-1） and nonfertilization （28.1 t ha^-1）. There was a significant linear increase in SOC over time for all treatments, and the slop of linear equation was greater in organic manure treatments （0.276-0.344 g kg-1 yr^-1） than in chemical fertilizer （0.216 g kg^-1 yr^-1） and no fertilizer （0.127 g kg^-1 yr^-1）.

Short-and long-term behaviors of drifts in the Callovo-Oxfordian claystone at the Meuse/Haute-Marne Underground Research Laboratory

Since 2000, the French National Radioactive Waste Management Agency （ANDRA） has been constructing an Underground Research Laboratory （URL） at Bure （east of the Paris Basin） to perform experiments in order to obtain in situ data necessary to demonstrate the feasibility of geological repository in the Callovo- Oxfordian claystone. An important experimental program is planned to characterize the response of the rock to different drift construction methods, Before 2008, at the main level of the laboratory, most of the drifts were excavated using pneumatic hammer and supported with rock bolts, sliding steel arches and fiber shotcrete. Other techniques, such as road header techniques, stiff and flexible supports, have also been used to characterize their impacts. The drift network is developed following the in situ major stresses. The parallel drifts are separated enough so as they can be considered independently when their hydromechanical （HM） behaviors are compared. Mine-by experiments have been performed to measure the HM response of the rock and the mechanical loading applied to the support system due to the digging and after excavation. Drifts exhibit extensional （mode I） and shear fractures （modes II and III） induced by excavation works. The extent of the induced fracture networks depends on the drift orientation versus the in situ stress field. This paper describes the drift convergence and deformation in the surrounding rock walls as function of time and the impact of different support methods on the rock mass behavior. An observation based method is finally applied to distinguish the instantaneous and time-dependent parts of the rock mass deformation around the drifts.

Effect of long-term fertilization on phosphorus fractions in different soil layers and their quantitative relationships with soil properties

Investigating the dynamics and distribution of soil phosphorus(P) fractions can provide a basis for enhancing P utilization by crops. Four treatments from a 29-year long-term experiment in black soil with maize cropping were involved in this study: no fertilizer(CK), inorganic nitrogen and potassium(NK), inorganic nitrogen, phosphorus, and potassium(NPK), and NPK plus manure(NPKM). We analyzed soil P fractions in different soil layers using a modified Hedley sequential method. The long-term NPKM treatment significantly increased total P by 0.6–1.6 times in the different soil layers. The Olsen-P concentration far exceeded the environmental threshold for soil Olsen-P(50.6 mg kg) in the NPKM treatment in the 0–60 cm soil profile. Moreover, the concentrations and proportion of labile and partially labile inorganic P(Pi) fractions(i.e., Na HCO-extracted Pi, Na OH-extracted Pi, and dilute HClextracted Pi) to the sum of all P fractions(Pt) in the 0–60 cm soil profile were higher in the NPKM treatment than in the NPK treatment, indicating that manure could promote the transformation of non-labile into more labile forms of P in soil, possibly by manure reducing P fixation by soil particles. Soil organic matter, Mehlich-3 extractable iron(Fe), and organic-bound aluminum were increased by fertilization, and were the main factors influencing the differences in the P fractions in the 0–20 cm soil layer. Soil mineral components, i.e., free Fe oxide and Ca CO, were the main factors influencing the P fractions in the subsoil. The soil P transformation process varied with soil layer and fertilization. Application of manure fertilizer can increase the labile(Olsen) P concentrations of the various soil layers, and thus should reduce the mineral P fertilizer requirement for crop growth and reduce potential environmental damage.

Effect of long-term fertilization on soil nitrate distribution

A thirteen years long-term field fertilizer experiment was conducted to monitor the effect of different fertilization on soil nitrate distribution. The results showed: (1) Applying relative excessive N fertilizer could result large quantities of NO3- residue and NO3- movement downward in soil profiles; amending phosphate fertilizer or organic manure with nitrogen fertilizer together could significantly improve the status of NO3- leaching downward due to the balanced uptake of nutrients by crops. ( 2) Appropriate amounts of nitrogen fertilizer which was equal or smaller than the optimal fertilization rate could not result in more NO3- leaching in Northern China. (3) Precipitation influenced the amounts and depth of soil NO3- leaching: NO3- could move to 80 cm depth or below at autumn or at the next spring when rainfall was higher during the rainy season through July to September in North China.

Effects of long-term fertilization on soil gross N transformation rates and their implications

Application of fertilizer has been found to significantly affect soil N cycling. However, a comprehensive understanding of the effects of long-term fertilization on soil gross N transformation rates is still lacking. We compiled data of observations from 10 long-term fertilization experiments and conducted a meta-analysis of the effects of long-term fertilization on soil gross N transformation rates. The results showed that if chemical fertilizers of N, P and K were applied in balance, soil p H decreased very slightly. There was a significantly positive effect of long-term fertilization, either chemical or organic fertilizers or their combinations, on gross N mineralization rate compared to the control treatment（the mean effect size ranged from 1.21 to 1.25 at 95% confidence intervals（CI） with a mean of 1.23）, mainly due to the increasing soil total N content. The long-term application of organic fertilizer alone and combining organic and chemical fertilizer could increase the mineralization-immobilization turnover, thus enhance available N for plant while reduce N losses potential compared to the control treatment. However, long-term chemical fertilizer application did not significantly affect the gross NH4＋ immobilization rate, but accelerated gross nitrification rate（1.19; 95% CI： 1.08 to 1.31）. Thus, long-term chemical fertilizer alone would probably induce higher N losses potential through NO3– leaching and runoff than organic fertilizer application compared to the control treatment. Therefore, in the view of the effects of long-term fertilization on gross N transformation rates, it also supports that organic fertilizer alone or combination of organic and chemical fertilizer could not only improve crop yield, but also increase soil fertility and reduce the N losses potential.