Carbon sequestration rate,nitrogen use efficiency and rice yield responses to long-term substitution of chemical fertilizer by organic manure in a rice–rice cropping system

Combined application of chemical fertilizers with organic amendments was recommended as a strategy for improving yield,soil carbon storage,and nutrient use efficiency.However,how the long-term substitution of chemical fertilizer with organic manure affects rice yield,carbon sequestration rate(CSR),and nitrogen use efficiency(NUE)while ensuring environmental safety remains unclear.This study assessed the long-term effect of substituting chemical fertilizer with organic manure on rice yield,CSR,and NUE.It also determined the optimum substitution ratio in the acidic soil of southern China.The treatments were:(i)NPK0,unfertilized control;(ii)NPK1,100%chemical nitrogen,phosphorus,and potassium fertilizer;(iii)NPKM1,70%chemical NPK fertilizer and 30%organic manure;(iv)NPKM2,50%chemical NPK fertilizer and 50%organic manure;and(v)NPKM3,30%chemical NPK fertilizer and 70%organic manure.Milk vetch and pig manure were sources of manure for early and late rice seasons,respectively.The result showed that SOC content was higher in NPKM1,NPKM2,and NPKM3 treatments than in NPK0 and NPK1 treatments.The carbon sequestration rate increased by 140,160,and 280%under NPKM1,NPKM2,and NPKM3 treatments,respectively,compared to NPK1 treatment.Grain yield was 86.1,93.1,93.6,and 96.5%higher under NPK1,NPKM1,NPKM2,and NPKM3 treatments,respectively,compared to NPK0 treatment.The NUE in NPKM1,NPKM2,and NPKM3 treatments was higher as compared to NPK1 treatment for both rice seasons.Redundancy analysis revealed close positive relationships of CSR with C input,total N,soil C:N ratio,catalase,and humic acids,whereas NUE was closely related to grain yield,grain N content,and phenol oxidase.Furthermore,CSR and NUE negatively correlated with humin acid and soil C:P and N:P ratios.The technique for order of preference by similarity to ideal solution(TOPSIS)showed that NPKM3 treatment was the optimum strategy for improving CSR and NUE.Therefore,substituting 70%of chemical fertilizer with organic manure could be the best management option for increasing CSR and NUE in the paddy fields of southern China.

Long-Term Application of Organic Manure and Mineral Fertilizer on N_2O and CO_2 Emissions in a Red Soil from Cultivated Maize-Wheat Rotation in China

A long-term field experiment was established to determine the influence of mineral fertilizer and organic manure on soil fertility. A tract of red soil （Ferralic Cambisol） in Qiyang Red Soil Experimental Station （Qiyang County, Hunan Province, China） was fertilized beginning in 1990 and N20 and CO2 were examined during the maize and wheat growth season of 2007-2008. The study involved five treatments： organic manure （NPKM）, fertilizer NPK （NPK）, fertilizer NP （NP）, fertilizer NK （NK）, and control （CK）. Manured soils had higher crop biomass, organic C, and pH than soils receiving the various mineralized fertilizers indicating that long-term application of manures could efficiently prevent red soil acidification and increase crop productivity. The application of manures and fertilizers at a rate of 300 kg N ha-1 yr-1 obviously increased NzO and CO2 emissions from 0.58 kg N20-N ha-~ yr-~ and 10565 kg C ha-~ yr-~ in the CK treatment soil to 3.0l kg N20-N ha-~ yr-~ and 28 663 kg C ha-~ yr-I in the NPKM treatment. There were also obvious different effects on N20 and CO2 emissions between applying fertilizer and manure. More N20 and CO2 released during the 184-d maize growing season than the 125- d wheat growth season in the manure fertilized soils but not in mineral fertilizer treatments. N20 emission was significantly affected by soil moisture only during the wheat growing season, and CO2 emission was affected by soil temperature only in CK and NP treatment during the wheat and maize growing season. In sum, this study indicates the application of organic manure may be a preferred strategy for maintaining red emissions than treatments only with mineral fertilizer. soil productivity, but may result in greater N20 and CO2

Effects of Organic Manure Application with Chemical Fertilizers on Nutrient Absorption and Yield of Rice in Hunan of Southern China

To evaluate the effect of organic manure application with chemical fertilizers on rice yield and soil fertility under long-term double-rice cropping system, a six year field experiment was conducted continually in the paddy soil derived from Quaternary red clay in Hunan Province of southern China. Four different treatments, i.e., no nitrogen with chemical P and K （PK）, swine manure only （M）, N, P and K chemical fertilizers only （NPK）, and half chemical fertilizers combined with half swine manure （NPKM） with four replications were included. Each N, P and K application rate was the same at all the treatments （except the N application rate at PK） and N application rate was 150 kg N ha^-1. All fertilizers were applied to soil tillage layer with once application as baseal fertilizers. The nutrients uptake rate, grain yield, nitrogen use efficiency, and soil organic matter content at each treatment were investigated. The NPKM treatment achieved the highest mean annual yield of 12.2 t ha^-1 （68% higher than that of PK）. Higher dry matter accumulation and nutrients absorption were observed during the middle-late growth period in the NPKM treatment, with higher panicle number per unit and filled-grain number per panicle. Its average nitrogen use efficiency was 36.3% and soil organic matter increased by 18.5% during the experimental period in the NPKM treatment, which were significantly higher than those in the NPK treatment. Organic manure application with chemical fertilizers increased the yield and nitrogen use efficiency of rice, reduced the risk of environmental pollution and improved soil fertility greatly. It could be a good practical technique that protects the environment and raises the rice yield in this region.

Effects of long-term amendment of organic manure and nitrogen fertilizer on nitrous oxide emission in a sandy loam soil

To understand the effects of long-term amendment of organic manure and N fertilizer on N2O emission in the North China Plain, a laboratory incubation at different temperatures and soil moistures were carried out using soils treated with organic manure （OM）, half organic manure plus half fertilizer N （HOM）, fertilizer NPK （NPK）, fertilizer NP （NP）, fertilizer NK （NK）, fertilizer PK （NK） and control （CK） since 1989. Cumulative N2O emission in OM soil during the 17 d incubation period was slightly higher than in NPK soil under optimum nitrification conditions （25℃ and 60% water-filled pore space, WFPS）, but more than twice under the optimum denitrification conditions （35℃ and 90% WFPS）. N2O produced by denitrification was 2.1-2.3 times greater than that by nitrification in OM and HOM soils, but only 1.5 times greater in NPK and NP soils. These results implied that the long-term amendment of organic manure could significantly increase the N2O emission via denitrification in OM soil as compared to NPK soil. This is quite different from field measurement between OM soil and NPK soil. Substantial inhibition of the formation of anaerobic environment for denitrification in field might result in no marked difference in N2O emission between OM and NPK soils. This is due in part to more rapid oxygen diffusion in coarse textured soils than consumption by aerobic microbes until WFPS was 75% and to low easily decomposed organic C of organic manure. This finding suggested that addition of organic manure in the tested sandy loam might be a good management option since it seldom caused a burst of N2O emission but sequestered atmospheric C and maintained efficiently applied N in soil.

N_2O emissions from agricultural soils in the North China Plain: the effect of chemical nitrogen fertilizer and organic manure

An enclosed chamber technique was used to measure N 2O emissions from intensively agricultural soils of the North China Plain during the periods of 1995—1996 and 1997—1998, to reflect distinct components of winter wheat and summer maize growing seasons. The results showed that the continuous application of fertilizer in agricultural soils increased N\-2O emissions by a factor of 24.1—28.1, the calculated annual chemical N fertilizer\|transformed N\-2O\|N emissions was 0.67%. Our results indicated that the application of organic manure also had a significant influence on soil N 2O emissions, which combined with the use of chemical N increased about 20% in a year. It was calculated that there were about 0.11% N of organic manure transformed as N 2O N. Annual mean N 2O emission from our study area of fertilized soils was estimated to be 57.1 μgN 2O/(m 2·h). A weak correlation was also found between N 2O emissions and soil available nitrogen content NH + 4.

Effect of Organic Manure,Passivator and Their Complex on the Bioavailability of Soil Cd

A field experiment of organic manure, passivator and their complex was conducted to study the soil Cd bioavailability in the Cd polluted paddy soil. The results showed that the rice yield increased with the applications of organic manure, passivator and their complex, especially, the rice yields of applying 3 000 and 6 000 kg/hm^2 of organic manure increased significantly by 18.6% （ P 〈0.05） and 20.9% （P 〈0.05） because of the increase of rice economic coefficient. There had no significant change of the soil pH values and the soil available Cd contents, but the Cd distribution ratios in rice were lowered by applying organic manure, and the Cd contents of rice applying 3 000 and 6 005 kg/hm^2 of organic manure dropped by 14.3% （ P 〉 0.05） and 21.4% （ P 〉 0.05） compared with chemical fertilizer treatment, respectively. But applying with passivator and passivator fertilized with 3 000 and 6 000 kg/hm^2 of organic manure, the soil pH values increased and the soil available Cd contents decreased significantly, so that to restrain the rice＇s Cd absorption and accumulation. The rice Cd contents lowered by 28.6% （ P 〈 0.05）, 28.6% （ P 〈 0.05） and 42.9% （ P 〈 0.05）, the stem C,d contents lowered by 8.9% （ P 〉 0.05）, 29.7% （ P 〈 0.05） and 43.6% （ P 〈 0.05）, and the leaf Cd contents decreased by 18.8% （ P 〈 0.05）, 25.0% （ P 〈 0.05） and 25.0% （ P 〈 0.05）, respectively. It enhanced the inactivate effect of passivator significantly when fertilized with organic manure.

Nitrogen transformation in maize soil after application of different organic manures

The nitrogen transformation in maize soil after application of different organic manure was studied. The nitrogen mineralization in surface soil, NO - 3-N dynamics and distribution in soil profile, and N 2O emission were investigated. Eight treatments were laid out randomizing with three replications in 24 plots: maize plantation without fertilizer(CK1), bare soil without maize plantation and fertilization(CK2), swine manure(S1, S2), poultry manure(P1, P2), and cattle manure(C1, C2). Three manures were applied at two application levels(15 t/hm 2 and 30 t/hm 2). The results indicated that NH + 4-N in surface soil showed the same temporal pattern without much variation among different treatments. But NO - 3-N in the same layer exhibited large temporal pattern in all treatments, which was mainly due to its easy eluviations of NO - 3-N in soil, its transformation to N 2O and the influence of precipitation. The distribution of NO - 3-N in the soil profile during maize growing season showed the leaching tendency from surface soil to subsoil, which was different among the treatments. The poultry treatments showed the largest leaching tendency. The study also revealed that the emissions of N 2O were affected by the application of organic manures in the order of P2>S2>C2>P1>S1>C1>CK1>CK2. All these results showed that organic manure applications significantly affect nitrogen transformation and distribution in maize soil. Considering N 2O emission and NO - 3-N leaching, the management of organic manure in the agriculture needs further studies.

Effects of Substitution of Organic Manure for Chemical Fertilizer on Phosphorus Accumulation and Grain Yield in Maize

In order to explore the response of maize phosphorus absorption to the appropriate proportion of organic fertilizer substitution for reduced chemical fertilizer,a field experiment with eight treatments was conducted in 2018.The eight treatments in the trial were:(1)CK;(2)M0+F;(3)M1+F1;(4)M1+F2;(5)M2+F1;(6)M2+F2;(7)M3+F1 and(8)M3+F2.In these treatments,M0,M1,M2 and M3 were organic fertilization of 0,15(low),30(medium)and 45(high)m3•hm-2,respectively.F1 and F2 indicated 20%and 40%reduction of conventional chemical fertilization.The soil nutrient content,phosphorus accumulation,dry weight,yield and yield components of maize were analyzed.The results showed that the phosphorus accumulation of maize stalks and leaves were 3.30%-43.17%and 10.98%-84.95%higher in M3+F1 treatment(20%reduction of chemical fertilizer with organic fertilizer of 45 m3•hm-2)than those in the conventional treatment(M0+F)during the maize reproductive period.At R2 stage,stalk and shoot P accumulation of M3+F1 treatment were 24.67%-43.18%and 20.34%-25.19%higher than other treatments,respectively.At V12 stage,leaf P accumulation of M3+F1 increased by 84.95%compared with other treatments.The maize yield of M3+F1 was significantly higher than that of other treatments,even though the partial productivity of the total phosphorus fertilizer of M3+F2 was the highest in the treatments.It could be found that the substitution of organic fertilizer for chemical fertilizer improved crop yield,phosphorus fertilizer efficiency and accumulation.M3+F1 treatment had the most positive effects on improving maize phosphorus accumulation and yield.

Application of organic manure as a potential strategy to alleviate the limitation of microbial resources in soybean rhizospheric and bulk soils

The development and vigor of soil microorganisms in terrestrial ecosystems are frequently constrained by the limited availability of essential elements such as carbon(C),nitrogen(N),and phosphorus(P).In this study,we investigated the impact of long-term application of varying levels of organic manure,low(7.5 Mg ha^(−1)yr^(−1)),moderate(15.0 Mg ha^(−1)yr^(−1)),and high(22.5 Mg ha^(−1)yr^(−1)),on the stoichiometry of enzymes and the structures of the microbial communities in soybean rhizospheric and bulk soils.The main goal of this research was to examine how soil microbial resource limitations in the rhizosphere respond to different long-term fertilization strategies.The soil enzymatic activities were quantified,and the structure of the microbial community was assessed by analyzing phospholipid fatty acid profiles.When compared to the bulk soil,the rhizospheric soil had significant increases in microbial biomass carbon(MBC),nitrogen(MBN),and phosphorus(MBP),with MBC increasing by 54.19 to 72.86%,MBN by 47.30 to 48.17%,and MBP by 17.37 to 208.47%.Compared with the unfertilized control(CK),the total microbial biomasses of the rhizospheric(increased by 22.80 to 90.82%)and bulk soils(increased by 10.57 to 60.54%)both exhibited increases with the application of organic manure,and the rhizospheric biomass was higher than that of bulk soil.Compared with bulk soil,the activities of C-,N-and P-acquiring enzymes of rhizospheric soil increased by 22.49,14.88,and 29.45%under high levels of organic manure,respectively.Analyses of vector length,vector angle,and scatter plots revealed that both rhizospheric and bulk soils exhibited limitations in terms of both carbon(C)and phosphorus(P)availability.The results of partial least-squares path modelling indicated that the rhizospheric soil exhibited a more pronounced response to the rate of manure application than the bulk soil.The varying reactions of rhizospheric and bulk soils to the extended application of organic manure underscore the crucial function of the rhizosphere in mitigating limitations related to microbial resources,particularly in the context of different organic manure application rates.

Effects of chemical fertilizer combined with organic manure on Fuji apple quality,yield and soil fertility in apple orchard on the Loess Plateau of China

To evaluate the effects of chemical fertilizer combined with organic manure on apple yield,quality and soil fertility,an experiment was conducted in an apple orchard on the Loess Plateau of China.Six treatments,i.e.,1)no nitrogen(N)with chemical phosphorus(P)and potassium(K)(PK),2)no P with chemical N and K(NK),3)no K with chemical N and P(NP),4)N,P and K chemical fertilizers only(NPK),5)swine manure(M)only(M),and 6)half chemical fertilizers combined with half swine manure(NPKM)were included with three replications for each.The NPKM treatment achieved 36.9 t/ha average annual yield,which was 42.5%greater than the yield of PK treatment.The average annual yields followed the sequence of NPKM>NPK>M>NK>NP>PK.In NPKM treatment 71.3%of the collected apples had an apple diameter greater than 80 mm compared with 58.2%,41.5%and 37.2%in NK,PK and NP treatments,respectively.The sugar to acid(S:A)ratio was the greatest in NPKM treatment.The results of Vitamin C,soluble solid and firmness showed that NPKM treatment had the highest values.The concentration of soil organic carbon(SOC)in the 0 to 20 cm depth of soil was significantly affected by addition of M.Compared to the antecedent soil properties,the SOCS in the NPKM and M treatments were increased by 28.8%,29.4%,and TN contents were 56.5,49.8%more for soil at 0-20 cm depths,respectively.The major soil nutrients of N,P and K were also significantly increased by M and NPKM treatments in surface soil for five years.The data support the conclusion that,for a production of 35-40 t/ha in an apple orchard on the Loess Plateau of China,the 25-30 t/ha organic manure,160-200 kg/ha N,100-150 kg/ha P2O5 and 120-160 kg/ha K2O were the most suitable fertilizer application.The finding will be helpful for harmonious development of apple production technology,economic income increase for farmers,and improvement of the apple orchard ecosystem.

Production and characterization of organic manure from liquorice residues

In present investigation,organic manure was produced and characterized from liquorice residues using activated Effective Microoganism(AEM).The liquorice waste residues were fermented for the period of 6 months in the presence of activated AEM at the rate of 2.5%and 5%of total fermented mixture.Nitrogen(62.5 g)was used per 10 kg of liquorice and moister was maintained at 55–60%during fermentation.The AEM manure production efficiency was evaluated on the basis of pH,C/N ratio,electrical conductivity(EC)and mineral contents.The final pH of organic manure was 6.2,C/N ratio reduced from 13.5 to 6.5,EC and the mineral contents were increased of composted liquorice.Results revealed that the AEM are effective to produce organic manure from agricultural waste matter since the organic manure physico-chemical properties were within the permissible limit and AEM could be used for the production of compost liquorice.Moreover,this technique can also be extended to other agricultural waste materials for the production of organic manure.

Garden Egg (Solanum melongena L.) Performance under Different Sources of Animal Manure as a Sustainable Alternative Fertilizer for Farmers

To ensure food security, continuous intensive farming systems with limited fallowing periods and other farming systems like crop rotation have led to poor soil health with extremely low organic matter, especially in tropical regions with high organic matter mineralization. Small-scale farmers in developing countries cannot afford intensive agricultural systems with heavy chemical inputs, which have not improved soil health. Inorganic fertilizers are harmful to the environment, so farmers should use cheap, locally available organic fertilizers like animal manure, which supports organic agricultural systems and soil health. Animal manure is used as a soil amendment to improve soil health, fertility, and crop yields, but data on how different manures affect specific crops is scarce. Poultry, cattle, and goat manure were compared to no fertilizer and mineral fertilizer on garden egg phenology, vegetative growth, and yield. Poultry manure improved garden egg vegetative growth, phenology, yield, and yield components compared to the negative control and the other treatments. Poultry manure yielded the most fruit at 0.921 kg∙ha-1, followed by cattle and goat manure at 0.709 kg∙ha-1 and 0.698 kg∙ha-1. In conclusion, poultry manure may be a better alternative to synthetic NPK with yield performance similar to garden eggs and long-term soil health benefits similar to other manure sources.

Effects of Long-Term Winter Planted Green Manure on Distribution and Storage of Organic Carbon and Nitrogen in Water-Stable Aggregates of Reddish Paddy Soil Under a Double-Rice Cropping System

In agricultural systems, maintenance of soil organic matter has long been recognized as a strategy to reduce soil degradation. Manure amendments and green manures are management practices that can increase some nutrient contents and improve soil aggregation. We investigated the effects of 28 yr of winter planted green manure on soil aggregate-size distribution and aggregateassociated carbon（C） and nitrogen（N）. The study was a randomized completed block design with three replicates. The treatments included rice-rice-fallow, rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass. The experiment was established in 1982 on a silty light clayey paddy soil derived from Quaternary red clay（classified as Fe-Accumuli-Stagnic Anthrosols） with continuous early and late rice. In 2009, soil samples were collected（0-15 cm depth） from the field treatment plots and separated into water-stable aggregates of different sizes（i.e., 〉5, 2-5, 1-2, 0.5-1, 0.25-0.5 and 〈0.25 mm） by wet sieving. The long-term winter planted green manure significantly increased total C and N, and the formation of the 2-5-mm water-stable aggregate fraction. Compared with rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass, the rice-rice-fallow significantly reduced 2-5-mm water-stable aggregates, with a significant redistribution of aggregates into micro-aggregates. Long-term winter planted green manure obviously improved C/N ratio and macro-aggregate-associated C and N. The highest contribution to soil fertility was from macro-aggregates of 2-5 mm in most cases.

Determining the Effects of Selected Organic Fertilizer on Growth and Yields of Tomato (Lycopersicon esculentum: Var. Rio Grande Tomatoes) in Mundri West County, Western Equatoria State, South Sudan

Worldwide, the demand for agro-organic foods that are healthy, nutritious, and environmentally friendly is increasing dramatically across all nations among consumers. Tomatoes being one of the dietary requirements in almost every meal is not exceptional and its availability in the market all year round is very important to farmers as well as consumers because it is highly demanded as a vegetable par excellence;which is either eaten raw in salads, cooked or processed into liquid ingredients. This study investigates the impact of chicken, goat, and cow manure treatments on tomato plant growth response to height, leaf length, and width, as well as fruit yield. The experimental field trials were conducted over two planting seasons in Mundri West County. It followed a Complete Randomized Design (CRD) approach, consisting of four blocks. Each block contained three treatments replicated four times and a control group. The data of measured parameters from all 16 plots were subjected to one-way Analysis of Variance (ANOVA) using the Gen Stat 14th Edition software. The findings indicate significant differences (P < 0.05) among all the different organic manure applications on tomato plant growth parameters compared to the control group. Chicken manure resulted in the tallest tomato plants (30.1 and 37.9 cm), longest leaves (9.9 and 10.4 cm), and widest leaves (2.1 and 2.5 cm) in both seasons respectively. The study showed plots treated with chicken manure had a highly significant impact (P < 0.05) on the prevalence of aphids (1.0) and white flies (1.4) with the lowest value compared to those with cow and goat manure applied. Additionally, chicken manure led to the highest yields (39.30 and 49.49 tons/ha) in both seasons. Based on these findings, it can be concluded that using chicken manure effectively improves the performance of Rio Grande Tomatoes, and thus, farmers are encouraged to utilize chicken manure to maximize their tomato yields.

Changes in soil organic carbon pools following long-term fertilization under a rain-fed cropping system in the Loess Plateau,China

Understanding the mechanism of soil organic carbon(SOC)sequestration is of paramount importance in sustaining crop productivity and mitigating climate change.Long-term trials were employed to investigate the responses of total SOC and its pools,i.e.,mineral-associated OC(MOC),particulate OC(POC,containing Light-POC and Heavy-POC),to fertilization regimes at Yangling(25-year),Tianshui(35-year)and Pingliang(37-year)under a rain-fed cropping system in the Loess Plateau.The fertilization regimes in each trial included three treatments,i.e.,control(no nutrient input,CK),chemical fertilizers(CF),and organic manure plus chemical fertilizers(MCF).Relative to the CK,long-term fertilization appreciably increased SOC storage by 134,89 and 129 kg ha^(–1)yr^(–1)under CF,and 418,153 and 384 kg ha^(–1)yr^(–1)under MCF in plough layer soils(0–20 cm),respectively,at the Yangling,Tianshui and Pingliang sites.The MOC pools accounted for 72,67 and 64%of the total SOC at the above three sites with sequestration rates of 76,57 and 83 kg ha^(–1)yr^(–1)under CF and 238,118 and 156 kg ha^(–1)yr^(–1)under MCF,respectively.Moreover,the MOC pool displayed a saturation behavior under MCF conditions.The POC accordingly constituted 27,33 and 36%of SOC,of which Light-POC accounted for 11,17 and 22%and Heavy-POC for 17,16 and 15%of SOC,respectively.The sequestration rates of POC were 58,32 and 46 kg ha^(–1)yr^(–1)under CF,and 181,90 and 228 kg ha^(–1)yr^(–1)under MCF at the three respective sites,in which Light-POC explained 59,81 and 72%of POC under CF,and 60,40 and 69%of POC under MCF,with Heavy-POC accounting for the balance.Compared with CK,the application of CF alone did not affect the proportions of MOC or total POC to SOC,whereas MCF application markedly reduced the proportion of MOC and increased the POC ratio,mainly in the Light-POC pool.The distribution of SOC among different pools was closely related to the distribution and stability of aggregates.The present study confirmed that organic manure amendment not only sequestered more SOC but also significantly altered the composition of SOC,thus improving SOC quality,which is possibly related to the SOC saturation level.

Effects of Inorganic-organic Incorporation on Productivity and Soil Fertility of Rice Cropping System in Red Soil Area of China

Results from ten-year (1990 - 1999) field experiments indicated that the productivity and the soil fertility of rice cropping system were significantly influenced by the fertilization system adopted in red soil area of China. Contrasting with no-fertili/er treatment (CK), yield-increase rate of organic matter cycling, chemical NPK and inorganic-organic fertilizer incorporation treatments were 56.5% , 62.5% and 80.7% , respectively. In the case of optimum fertilization system, the largest contribution of inorganic fertilizer to the yield was 38.5% while that of inorganic-organic fertilizer incorporation was 44.7%. The content of soil organic matter changed in tendency from decrease to equilibrium with heightened the extent of N, P and K incorporation while that of inorganic-organic fertilizer incorporation could be enhanced further. After N, P and K entered into the rice cropping system and maintained organic matter cycling in the system, the pools of total N, P and K could be strengthened.

The Effects of Applying Organic Matter in Wind Blown Soil on Microbial Biomass and Enzyme Activity

Field experiment was conducted to study the effect of applying organic matter in wind blown soil on microbial biomass and enzyme activity.The results showed that microbial biomass and enzyme activity keep dynamic changes during wheat growing season in wind blown soil,and reached the peak level in wheat booting stage.Compared with chemical fertilizer,all the other treatments could increase the microbial biomass in different degree,the same as catalsae and alkaline phosphatase activity,But urease activity was slightly difference from them.

Changes in Phosphorus Fractions and Nitrogen Forms During Composting of Pig Manure with Rice Straw

The study was conducted to reveal P fractions and N forms changing characters during composting of pig manure with rice straw.During composting,the NH 4 ＋-N concentration decreased and reached at a relatively low value（〈400 mg kg-1） in the final compost,while the NO 3--N concentration increased.Total N losses mainly occurred during thermophilic phase due to the high temperature,the high NH 4 ＋-N concentration and the increase of pH value.Labile inorganic P was dominated in the pig manure and initial compost mixture.During composting,the proportion of labile inorganic P of total extracted P decreased,while the proportion of Fe＋Al-bound P,Ca＋Mg-bound P and residual P increased.The evolutions of the proportion of labile inorganic P,Fe＋Al-bound P and Ca＋Mg-bound P were well correlated with the changes of pH value,organic matter and C/N ratio.Therefore,composting could increase the concentration of N and P and decrease the presence of NH 4 ＋-N and labile P fractions which might cause environmental issues following land application.

A Field Study on Effects of Nitrogen Fertilization Modes on Nutrient Uptake,Crop Yield and Soil Biological Properties in Rice-Wheat Rotation System

Rational application of nitrogen （N） fertilizers is an important measure to raise N fertilizer recovery rate and reduce N loss.A two-year field experiment of rice-wheat rotation was employed to study the effects of N fertilization modes including a N fertilizer reduction and an organic manure replacement on crop yield,nutrient uptake,soil enzyme activity,and number of microbes as well as diversity of microbes.The result showed that 20% reduction of traditional N fertilizer dose of local farmers did not significantly change crop yield,N uptake,soil enzyme activity,and the number of microbes （bacteria,actinomycetes,and fungi）.On the basis of 20% reduction of N fertilizer,50% replacement of N fertilizer by organic manure increased the activity of sucrose,protease,urease,and phosphatase by 46-62,27-89,33-46,and 35-74%,respectively,and the number of microbes,i.e.,bacteria,actinomycetes,and fungi by 36-150,11-153,and 43-56%,respectively.Further,organic fertilizer replacement had a Shannon＇s diversity index （H） of 2.18,which was higher than that of other modes of single N fertilizer application.The results suggested that reducing N fertilizer by 20% and applying organic manure in the experimental areas could effectively lower the production costs and significantly improve soil fertility and biological properties.

Effects of straw addition on increased greenhouse vegetable yield and reduced antibiotic residue in fluvo-aquic soil

Organic manure application is an important measure for high yield and good quality vegetable production, whereas organic manure is also a main source of residual antibiotic in soils. A 3-yr experiment was conducted on a fluvo-aguic soil in Tianjin of northern China. The objective of this study was to investigate the effects of different fertilization patterns on yield of six-sea- son vegetables with celery and tomato rotation, and dynamic change of tetracyclines residues in the soil during the sixth growing season （tomato season）. The field experiment comprised six treatments depending on the proportion of nitrogen of each type of fertilizer： 4/4 CN （CN, nitrogen in chemical fertilizer）, 3/4 CN＋1/4 MN （MN, nitrogen in pig manure）, 2/4 CN＋2/4 MN, 1/4 CN＋3/4 MN, 2/4 CN＋1/4 MN＋I/4 SN （SN, nitrogen in corn straw）, and CF （conventional fertilization, the amounts of nitrogen application were 943 and 912 kg N ha-1 for celery and tomato season, respectively）. In addition to CF treatment, the amount of nitrogen application in other treatments was greatly reduced and equal （450 and 450 kg N ha-1 for celery and tomato season, respectively）. Results showed that the combined application of 3/4 CN＋1/4 MN achieved the highest yield and economic benefit in the first four seasons, but addition of straw （2/4 CN＋1/4 MN＋I/4 SN treatment） performed better in the subsequent two seasons, and the average yields of 2/4 CN＋1/4 MN＋I/4 SN treatment were respectively higher by 9.9 and 12.8% than those of 4/4 CN treatment, and by 5.6 and 10.5% than those of CF treatment. The residual chlortet- racycline （CTC） in manure-amended soil for three consecutive years increased along with the increase of applied amount of pig manure. Under the same amount of pig manure application, content of CTC in straw-amended soil was obviously decreased compared with no straw-amended soil （3/4 CN＋1/4 MN treatment）, and averagely decreased by 41.9% for four sampling periods in the sixth season. Addition of crop straw facilitated the degradation of CTC in manure-amended soil. As a whole, the conventional fertilization was not the desirable pattern based on yield, economic benefit and environment, the optimal fertilization pattern with the highest yield and profit and the least soil chlortetracycline residue was the treatment of 2/4 CN＋1/4 MN＋I/4 SN under this experimental condition.