Effects of Slow-release Nitrogen Fertilizer on Yield and Nitrogen Accumulation of Summer Maize in Shajiang Black Soil Area

[Objectives] This study was conducted to verify the field application effect of slow-release nitrogen fertilizer on summer maize in Shajiang black soil area by simultaneous sowing and fertilization, and explore the application scope and nitrogen metabolism mechanism, so as to lay a foundation for fertilizer reduction and efficiency improvement. [Methods] With maize variety Beiqing 340 and sulfur-coated urea as experimental materials, five nitrogen application levels were set, namely, control (C0), slow-release nitrogen 70 kg/hm^(2) (C70), slow-release nitrogen 140 kg/hm^(2) (C140), slow-release nitrogen 210 kg/hm^(2) (C210) and slow-release nitrogen 280 kg/hm^(2) (C280). The phosphorus and potassium fertilizers were all in accordance with the unified standard. [Results] With the application rate of slow-release nitrogen increasing, the nitrogen accumulation in organs increased first and then decreased after tasseling stage of maize. In order to reduce the fertilizing amount and increase efficiency, 210 kg/hm^(2) of slow-release nitrogen fertilizer was the best fertilizing amount for summer maize in Shajiang black soil area. [Conclusions] This study provides reference for fertilizer reduction, efficiency improvement and sustainable development of summer maize in Shajiang black soil area.

Improvement of Wolfberry(Lycium barbarum L.)Fruit Yield and Quality and Enhancement of Soil Fertility by Nitrogen Reduction Combined with Organic Fertilizers

Excessive amounts of nitrogen(N)fertilizers are applied during wolfberry production,resulting in some soil problems as well as potential environmental risks in the Qinghai-Tibet Plateau.In this study,organic fertilizers were used to replace part of the N fertilizer in wolfberry fields with different fertility levels.N fertilizer rates had 0,50,100,150,200,and 250 g N/plant.Organic fertilizer rates had 0,2,4,6,8,and 10 kg organic fertilizer/plant.The experimental treatments included 6 combinations of N0M10,N50M8,N100M6,N150M4,N200M2,and control was N250M0.The results showed that in the high-fertility soils,combinations of N150M4,N100M6 and N50M8 treatments were increased in yields,fruit shape index,flavonoid content,total phenol content,mineral nutrient content,and antioxidant activity of wolfberry fruits.Also they were improved in soil fertility and decreased in residual nitrate through the soil depth of 0-300 cm.In the soil with less fertility,fruit yield,amino acid contents,flavonoids,total phenols,mineral nutrients and antioxidant activity of fruits were increased by the N200M2,N150M4 and N100M6 treatments and soil fertility was improved as well.Also more residual nitrate was found in the depth of 0-100 cm of soil with both chemical and organic fertilizer compared with the control.Therefore,in the Qinghai-Tibet Plateau,combining decreased N fertilizer with organic fertilizer rather than chemical fertilizer alone could help farmers achieve satisfactory yields and quality of wolfberry fruits and reduce the risk of nitrate leaching.In conclusion,50-150 g/plant of N fertilizer combined with 4-8 kg/plant of organic fertilizer in high-fertility gardens and 100-200 g/plant of N fertilizer combined with 2-6 kg/plant of organic fertilizer in low-fertility gardens are recommended for wolfberry cultivation.

Total Amount Control Test of Nitrogen Fertilizer and Phosphate Fertilizer on Winter Wheat

[Objective] This study was conducted to optimize the suitable application amounts of nitrogen fertilizer and phosphate fertilizer for winter wheat.[Method] A field experiment was carried out to investigate the effects of the application amounts of nitrogen fertilizer and phosphate fertilizer on the yield of winter wheat.[Result]The quadratic simulation function between the application of nitrogen fertilizer and wheat yield was y =-0.6611x^2＋20.091 x ＋234.85,with a correlation coefficient of0.970 8,and the yield of winter wheat was the highest at the application amount of nitrogen fertilizer of 228.0 kg/hm^2.The quadratic simulation function between the application of phosphate fertilizer and wheat yield was y =-0.572 6x^2＋13.168 x ＋340.4,with a correlation coefficient of 0.921 95,and the yield of winter wheat was the highest at the application amount of phosphate fertilizer of 172.5 kg/hm^2.[Conclusion] This study provides a scientific basis for the rational application of nitrogen fertilizer and phosphate fertilizer on winter wheat.

Effects of nitrogen fertilizer on protein synthesis, accumulation, and physicochemical properties in common buckwheat

Nitrogen(N)fertilization affects grain quality in common buckwheat(Fagopyrum esculentum Moench).But the effects of N fertilizer on various buckwheat protein parameters are not fully understood.This study aimed to investigate the synthesis,accumulation,and quality of buckwheat protein under four N application rates in the Loess Plateau,China.Optimal N application(180 kg N ha-1)improved yield,agronomic traits,and N transport and increased protein yield and protein component accumulation.Prolamin and glutelin accumulation first increased and then decreased with increasing N application.The relationships between the contents of protein components and the amount of applied N generally followed quadratic functions.Nitrate reductase and glutamine synthetase activities first increased and then decreased with increasing N levels.Optimal N fertilizer increased the waterholding capacity and thermal stability of buckwheat protein and reduced its emulsification capacity,but negligibly changed its oil-absorption capacity.Hydrophobic amino acids and glutelin content were the main factors affecting protein quality.

Yield of Roselle (Hibiscus sabdariffa L.) as Influenced by Manure and Nitrogen Fertilizer Application

Field experiments were carried out on roselle (Hibiscus sabdariffa L) during the 2019 and 2020 cropping seasons at the CSIR-SARI Research Station at Manga in the Upper East Region of Ghana. The aim of the experiment was to study the response of roselle to cowdung, nitrogen fertilizer and their interaction on the growth and yield of roselle. The treatments consisted of factorial combination of five rates of cowdung (0, 1.5, 2.5, 3.5 and 4.5 t/ha) and five levels of nitrogen (0, 20, 40, 60 and 80 kgN/ha) laid out in a randomized complete block design and replicated three times. Data were collected on days to 50% flowering, plant height, number of leaves per plant and dry calyx yield. The results indicated that differences in dry calyx yield due to the manure and nitrogen fertilizer effects were highly significant (P 0.01). Application rate of 2.5 t/ha manure recorded the highest yield of 340 kg/ha and 308.1 kg/ha in 2019 and 2020 respectively. Increasing manure rate from 2.5 - 3.5 t/ha did not result in significant increases in dry calyx yield. The four rates differed significantly from the control which had the least calyx yield of 190.3 kg/ha and 180 kg/ha in 2019 and 2020 respectively. Nitrogen rate of 60 kg/ha recorded the highest dry calyx yield of 510.5 kg/ha and 370.4 kg/ha in 2019 and 2020 respectively which were significantly different from calyx yields recorded by other treatments. The trend on partial budget analysis was consistent in both seasons with the highest yielding treatments (2.5 t/ha cowdung manure and 60 kg/ha) recording the highest net benefit while the control (0 kg/ha) ranked last. The application rate of 2.5 t/ha of cowdung and 60 kg/ha of Nitrogen is thus recommended for optimum roselle production and productivity in the study area.

Effects of Combined Application of Biochar-based Organic Fertilizer and Reduced Nitrogen Fertilizer on Soil Enzyme Activity and Yield of Purple Cabbage(Brassica oleracea var.capita rubra)in Yuanmou County

[Objectives]In response to the issue of soil improvement in Yuanmou County,the effects of combined application of biochar-based organic fertilizer and reduced nitrogen fertilizer on soil nutrients,soil enzyme activity,and yield of purple cabbage(Brassica oleracea var.capita rubra)were investigated in the field base of Institute of Thermal Zone Ecological Agriculture,Yunnan Academy of Agricultural Sciences in Yuanmou County.[Methods]A total of 13 treatments were set up by applying biochar-based organic fertilizer at three levels of 15,30 and 45 t/hm^(2)(T_(1),T_(2),T_(3)),combined with top application of nitrogen fertilizer(urea)at four levels:375(N_1),300(N_(2)),225(N_(3))and 0 kg/hm^(2),with non-fertilizing treatment as control check(CK),in order to explore the optimal ratio for the combined application of biochar-based organic fertilizer with nitrogen fertilizer.[Results]The application of biochar-based organic fertilizer could significantly improve soil nutrients,enzyme activity,and purple cabbage yield.The improvement effect of combined application with nitrogen fertilizer was higher than that of single application of biochar-based organic fertilizer,and the improvement effect was enhanced with the application amount of biochar-based organic fertilizer increasing.The contents of organic matter and total nitrogen were the highest in treatment T_(3)N_(3),of which the values increased by 81.39%and 56.09%compared with the CK,respectively.The contents of soil hydrolyzable nitrogen,available phosphorus,and available potassium were all the highest under treatment T_(3)N_(2),with increases of 92.76%,171.01%and 235.50%,respectively.There was a significant positive correlation between the activity of soil catalase,urease,and sucrase and organic matter,total nitrogen,and available nutrients.The overall soil enzyme activity was relatively higher in treatment T_(3)N_(2).The yield of purple cabbage treated with biochar-based organic fertilizer combined with nitrogen fertilizer could reach 85750 kg/hm^(2),which was 94.78%higher than that treated with biochar-based organic fertilizer alone.Based on comprehensive analysis,the optimal combination ratio was 45 t/hm^(2)of biochar-based organic fertilizer and 300 kg/hm^(2)of urea(T_(3)N_(2)).[Conclusions]This study provides data support for the promotion of biochar-based organic fertilizers and reduced fertilizer in agricultural soil in the Dam area of Yuanmou County.

Effects of Different Nitrogen and Phosphorus Synergistic Fertilizer on Enzymes and Genes Related to Nitrogen Metabolism in Wheat

In recent years,in order to improve nutrient use efficiency,especially nitrogen use efficiency,fertilizer valueadded technology has been developed rapidly.However,the mechanism of the effect of synergistic fertilizer on plant nitrogen utilization is not clear.A study was,therefore,conducted to explore the activities and gene expression of key enzymes for nitrogen assimilation and the gene expression of nitrogen transporters in wheat after the application of synergistic fertilizer.Soil column experiment was set up in Qingdao Agricultural University experimental base from October 2018 to June 2019.Maleic acid and itaconic acid were copolymerized with acrylic acid as cross-linking monomer to make a fluid gel,which was sprayed on the fertilizer surface to make nitrogen and phosphorus synergistic fertilizer.A total of 6 treatments was set according to different nitrogen and phosphorus fertilizer ratios:(1)100%common nitrogen fertilizer+100%common phosphate fertilizer(2)70%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer;(3)100%nitrogen synergistic fertilizer+70%phosphorus synergistic fertilizer;(4)100%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer;(5)70%nitrogen synergistic fertilizer+70%phosphorus synergistic fertilizer;(6)100%commercial nitrogen synergistic fertilizer+100%commercial phosphorus synergistic fertilizer.The results are as follows:(1)the enzyme activities of wheat plants under synergistic fertilizer condition were higher than those under ordinary fertilizer,except under the treatment that nitrogen and phosphorus synergistic fertilizer were both reduced;(2)the expression level of the genes under the treatment“100%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer”was significantly higher than those in other treatments.Combined with the higher performance of nitrogen concentration in various parts of the plant under the condition of applying synergistic fertilizer,this study indicated that the application of synergistic fertilizer can improve the nitrogen metabolism of the plant by increasing the nitrogen level in the rhizosphere soil,inducing the expression of nitrogen transporter genes and key assimilation enzymes genes.

Effects of Different Row Ratios of Male and Female Parents and Application Amount of Nitrogen Fertilizer on Hybrid Wheat Seed Production and Its Component Factors

In order to screen suitable high hybrid wheat seed production technology,the split-plot experiment design was adopted and study was carried out about the effects of the different row ratios of male and female parents and application amount of nitrogen fertilizer on hybrid wheat seed production and its component factors. The results showed that the seed production increased with the increase in the number of female parent row. When the row ratio of male and female parents was 2 ∶ 6,the seed production was 3 683. 8 kg/ha; when the application amount of nitrogen fertilization was 50 kg/ha,the seed production was 3 649. 4 kg/ha; the interaction between the row ratio of male and female parents and the application amount of nitrogen fertilizer indicated that when the row ratio of male and female parents was 2∶ 6 and the application amount of nitrogen fertilizer was 300 kg/ha,the seed production reached the highest( 4160. 6 kg/ha). The row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the component factors of seed production,including the number of grains per spike,spike weight and setting percentage. When the row ratio of male and female parents was 2∶ 5,the number of grains per spike,spike weight and setting percentage were the highest at 26. 7 grains,1. 12 g,and 62. 6% respectively; when application amount of nitrogen fertilizer was 450 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 26. 0 grains,1. 08 g,and59. 2% respectively; the interaction of row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the number of grains per spike,spike weight and setting percentage; when the row ratio of male and female parents was 2∶ 5 and the application amount of nitrogen fertilizer was 300 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 29. 6grains,1. 24 g,and 71. 6% respectively. The number of grains per spike is the largest component factor for seed production. Increasing the number of grains per spike can increase the seed production. According to the effects of row ratio of male and female parents and application amount of nitrogen fertilizer on the component factors of seed production,the optimal condition was 2∶ 5-2∶ 6 for row ratio of male and female parents and 300-450 kg/ha for application amount of nitrogen fertilizer.

Synergistic effects of planting density and nitrogen fertilization on chlorophyll degradation and leaf senescence after silking in maize

Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the activities of Chl a-degrading enzymes after silking,and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates.The dynamic change of GLA_(ear)after silking fitted to the logistic model,and the GLA_(ear) duration and the GLAearat 42 d after silking were affected mainly by the duration of the initial senescence period(T_(1))which was a key factor of the leaf senescence.The average chlorophyllase(CLH)activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content,indicating that CLH is a key enzyme for degrading Chl a in maize.Increasing density increased the CLH activity and decreased the Chl content,T1,GLAear,and GLA_(ear) duration.Under high density,appropriate N application reduced CLH activity,increased Chl content,prolonged T1,alleviated high-density-induced leaf senescence,and increased post-silking dry matter accumulation and grain yield.

Effects of Slow-release Nitrogen on Dry Matter Accumulation,Translocation and Yield of Summer Maize

[Objectives]This study was conducted to investigate the effects of slow-release nitrogen fertilizer on dry matter accumulation and translocation of summer maize.[Methods]With Zhoudan 9 as the test variety,six different treatment were set up:blank control(CK1),slow-release urea 75 kg/hm^(2)(C1),slow-release urea 150 kg/hm^(2)(C2),slow-release urea 225 kg/hm^(2)(C3),slow-release urea 300 kg/hm^(2)(C4)and ordinary urea 300 kg/hm^(2)(CK2),to study the change law of dry matter accumulation and translocation in summer maize.[Results]Treatment slow-release urea 225 kg/hm^(2)(C4)showed summer maize yield,dry matter translocation between organs,grain contribution rate and proportion of grain dry matter in the full ripe stage higher than other treatments.Considering the weight loss and cost factors,slow-release urea 225 kg/hm^(2)(C3)could be recommended as the fertilizing amount for summer maize.[Conclusions]This study provides theoretical reference for rational selection of fertilizers for reducing fertilizer application and increasing fertilizer efficiency,and for production of summer maize in Shajiang black soil region.

Nitrogen recovery and nitrate leaching of controlled release nitrogen fertilizer in irrigated paddy soil

Ordinary high nitrogen fertilizer often results in nitrate (NO3--N) leaching and low recovery. Microplot and field plot experiments were conducted to determine the effect of controlled release nitrogen fertilizer (CRNF) on reco very and nitrate leaching on paddy soils. During two early rice cropping seasons (2002 and 2003), a single basal application of CRNF at 90 kg N ha-1 increased grain yields by 7.7%to 11.6%compared with two applications of urea. Estimated by the difference method fertilizer N recovery of CRNF (mean 76.3%) was 38.9 pe rcentage point higher than that of urea (mean 37.4%); estimated by 15N isotope method (mean 49.6%) CRNF (mean 67.1%) was 35.9 percentage point higher than ur ea (mean 31.2%). NO3--N leaching losses were 9.19 and 6.70 kg ha-1 for urea and CRNF, respectively. NO3--N leaching during the early rice cropping season was 27.1 %lower from CRNF than from two applications of urea. These losses repr esent 10.2%and 7.4%of applied urea-N and CRNF-N. Results from this study ind icate that CRNF improves N recovery and reduces NO3--N leaching and increases rice yield.

Effects of Nitrogen Fertilizer Application Mode on Sugarcane Yield and Soil Nutrient Change

[Objective] The aim was to improve use ratio of N fertilizer in sugarcane production and reduce N pol ution in agricultural production. [Method] With ROC22 as materials, N fertilizer quantities were set, including 38, 276 and 414 kg N/hm2, according to three fertilization approaches （approach 1： N fertilizer at 10% as base fertilizer, 30% N fertilizer applied to soil dressing, 60% N fertilizer applied to big ridging; approach 2： 30% N fertilizer as base fertilizer, 70% N fertilizer applied to soil dressing; approach 3： 100% N fertilizer as base fertilizer）. Some sugarcane in-dices, such as agronomic traits, yield and soil nutrients, were measured to research the relationship of N fertilizer with sugarcane growth and soil nutrients. [Result] Sug-arcane yield was increasing upon N fertilizer and reached the peak with N fertilizer at 276 kg N/hm2. In addition, early application of N fertilizer would promote sugar-cane jointing, growth and increase sugarcane yield. Nitrogen and available K con-tents were increasing upon N fertilizer, but excessive N fertilizer also caused soil acidification. N fertilizer applied early could help dissolve soil phosphate and improve phosphorus absorption and utilization. Applying N fertilizer completely as base fertil-izer was likely to cause N loss and low use efficiency. [Conclusion] The appropriate application mode for sugarcane is to apply N fertilizer twice at 138-276 kg N/hm^2.

Effects of the Application of Controlled Release Nitrogen Fertilizer on Rapeseed Yield, Agronomic Characters and Soil Fertility

In order to study the effects of controlled release nitrogen fertilizer （CRNF） application on rapeseed, a simulated experiment was carried out with 3 types of paddy soils in Dongting Lake area for 4 consecutive years of applying CRNF under double rice cropping system after planting rapeseed crop in the fallow season. The effects of CRNF application on rapeseed yield, agronomic characters and soil fertility were studied in this paper. The results showed that CRNF application improved the growth of rapeseed plant and increased rapeseed yield of CRNF treatments in the purple calcareous clayed paddy soil （PCS） and alluvial loamy paddy soil （ALS） which respectively increased by 12.2% and 9.8% compared with applying urea, re- spectively. The rapeseed yield in 70% CRNF treatment obviously decreased com- pared with urea treatment. The contents of available N and organic carbon in soil increased by 25.0% and 3.2% in CRNF treatment in the ALS after rapeseed crop, respectively; and available N increased by 13.5% in the PCS. Both rapeseed yield and soil fertility in CRNF treatment and 70% CRNF treatment were lower than those in CK treatment in the reddish yellow clayed paddy soil （RYS）. The results al- so indicated that the functions of CRNF application on rapeseed yield increase and soil nitrogen fertility improvement were very obvious in the PCS and ALS.

Effects of Panicle Fertilizer Application on Source-Sink Characteristics and Nitrogen Fertilizer Use Efficacy of Ganxin688

[Objective]The paper was to explore the effect of postponing application of N fertilizer on source-sink characteristics of super hybrid rice Ganxin688.[Method] With super hybrid rice Ganxin688 as test material,the source organ traits（leaf area index,leaf weight,chlorophyll content,photosynthetic rate of flag leaf,stem and sheath dry matter accumulation and output） and yield were measured,the effects of nitrogen application on source-sink relationship,yield and N fertilizer use efficiency were also studied.[Result] Appropriate postponing of N fertilizer was benefit for optimizing population quality,harmonizing source-sink relation,enhancing leaf function,prolonging leaf function period and increasing N fertilizer use efficiency.After heading,the leaves area index（LAI） and chlorophyll content increased with the increasing application amount of panicle fertilizer,and their reduction rate slowed down with the increased application amount of panicle fertilizer.Appropriate increased application of panicle fertilizer could prolong the function period of leaves in lower position,increase storage amount of stem and sheath matter,total sink capacity and sink capacity per unit leaf area during heading stage,improve panicle rate and seed setting rate,reduce the demand of grain sink on stem and sheath matter,and increase lodging resistance of plant,which could also increase dry matter productivity and rice productivity of N fertilizer,and increase absorption and application ratio and total accumulation amount of N fertilizer.For Ganxin 688,when N application amount was 175-205 kg/hm2,the proportion of panicle fertilizer in total nitrogen application should be better as 40%-45%.[Conclusion] The study provided basis for making reasonable and efficient N application strategy to establish a coordinated huge sink and strong source relationship for super rice.

Effects of Nitrogen Application Amount during Various Periods on Yield of High Grade Hybrid Rapeseed

[Objective] The paper was to study the nitrogen application amount and nitrogen application model for high grade hybrid rapeseed （Brassica napus L.） to get high yield. [Method] With ＂Youyan 599＂ and ＂Sanbei 98＂ as materials, using quadratic regression orthogonal gyration combination design, the impact of nitrogen application amount during various periods on rapeseed yield was studied. [Result] The combinations of factors to obtain the highest yield index （2 898.211 kg / hm 2 ） of ＂Youyan 599＂ were as follows： living rape fertilizer 89.27 kg / hm 2 , opening fertilizer 120 kg / hm 2 , 12 th lunar month fertilizer 101.12 kg / hm 2 , total nitrogen application amount 310.39 kg / hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12th lunar month fertilizer were 28.76%, 38.66% and 32.58%, respectively. The combinations of factors to obtain the highest yield index （2 870.14 kg/hm 2 ） of ＂Sanbei 98＂ were as follows： living rape fertilizer 120 kg / hm 2 , opening fertilizer 120 kg / hm 2 , 12 th lunar month fertilizer 37.55kg / hm 2 , total nitrogen application amount 277.55 kg / hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12 th lunar month fertilizer were 43.24%, 43.24% and 13.53%, respectively. The combinations of factors to obtain the highest yield index of two combined varieties （2 813.82 kg/hm 2 ）were as follows： living rape fertilizer 120 kg/hm 2 , opening fertilizer 120 kg/hm 2 , 12 th lunar month fertilizer 76.23 kg/hm 2 , total nitrogen application amount 316.23 kg/hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12 th lunar month fertilizer were 37.95% , 37.95% and 24.11% , respectively. [Conclusion] The paper provided theoretical basis for high yield cultivation of high grade hybridized rapeseed.

Effects of Nitrogen, Phosphate and Potassium Fertilizers on Soft Rot of Konjac Based on Grey Correlation Analysis

[Objective] The effects of different application amounts of nitrogen, phos-phate and potassium fertilizers on soft rot of konjac were investigated in this study. [Method] The grey correlation analysis was adopted to evaluate the correlation be-tween the application amount of nitrogen, phosphate and potassium fertilizers and the occurrence of soft rot of konjac. [Result] The excessive application of nitrogen fertilizer would induce the occurrence of soft rot of konjac, but the application of potassium fertilizer had a good control effect on soft rot. [Conclusion] The applica-tion amount of nitrogen fertilizer should be control ed reasonably in the planting of konjac, but the application amount of phosphate and potassium fertilizer could be in-creased to some extent, reducing the occurrence of soft rot of konjac.

Effect of Continuous Application of Controlled Release Nitrogen Fertilizer in Various Types of Soil in Dong-Ting Lake Region under Double Rice Cropping System

[Objective] This study aimed to explore the effects of continuous application of controlled release nitrogen fertilizer under double rice cropping system. [Method] By modeling three types of paddy soils in Dong-Ting Lake area, four treatments as no fertilizer （CK）, urea, controlled release nitrogen fertilizer （CRNF） and 70% controlled release nitrogen fertilizer （70% CRNF） were designed in the micro-plot trials from 2005 to 2008. [Result] The rice yield in treatment CRNF at N 150 kg/hm2 was increased by 10.3%, 8.0% and 2.4% compared with treatment of urea, in alluvial sandy loamy paddy soil （ALS）, purple calcareous clayey paddy soil （PCS）, and reddish yellow loamy paddy soil （RYS）, respectively; and the yield in treatment of 70% CRNF was increased by 6.1%, 2.6% and -0.8%, respectively. The ranking order of nitrogen uptake amount by plant in early rice and late rice was CRNF 70% CRNF urea CK in all three types of soil. Nitrogen utilization efficiency of CRNF in above three types of soil was 60.7%, 59.6% and 56.3%, increased by 23.8%, 19.4% and 16.3% compared with that in treatment of urea, respectively. Nitrogen utilization efficiency of CRNF in early rice was increased year by year, and was higher than that of 70% CRNF during the whole experiment stage, while that in late rice was increased first and then decreased from the 3rd year. [Conclusion] Continuous application CRNF could alleviate the decreasing of soil nitrogen fertility and organic carbon especially in ALS, increase rice yield and nitrogen utilization efficiency in double-rice cropping system.

Effects of Soil Nitrate Nitrogen Residues and Leaching for Different Kinds of Slow-release Nitrogen Fertilizers in Tall-fescue Soil

ObjectiveThe aim was to explore the movement of nitrate nitrogen in tall-fescue soils by different kinds of slow release nitrogen fertilizers. MethodBased on infiltration-tanks and test plots, a new and environment friendly fertilizer was explored. ResultThe results show that compared with urea treatment, slow-release nitrogen fertilizer treatments could reduce nitrate nitrogen content and leaching amount in soils. Compared with PCU30 and IU treatments, the PCU60 treatment became more efficient in reducing nitrate content and leaching amount in 0-90 cm soil layer. ConclusionIn summary, slow-release nitrogen fertilizer, which can reduce soil nitrate content and leaching losses, is a kind of novel fertilizer with high environmental benefit and promising application.

Effects of Nitrogen Fertilizer on Rhizosphere Microbial Populations under Cotton Intercropped with Red Date in Arid Desert Oasis of Southern Xinjiang

[Objective]This study aimed to determine the number of microorganisms of cotton rhizosphere in a soil at various amounts of applied nitrogen fertilizer in a red date-cotton intercropping system. [Method] In the field experiment, nitrogen fer-tilizer was applied at 0, 150, 300, 450, 600, and 750 kg/hm2, respectively. The dy-namic changes of the populations of bacteria, fungi and actinomycetes at the rhizo-sphere of cotton intercropped with red date were investigated. [Result] Microbial populations significantly increased at nitrogen fertilizer of 300 and 450 kg/hm2 during bud, flowering and bol opening periods. The numbers of bacteria and actinomycetes were higher during flowering and bol opening stages than at bud stage. The num-ber of fungi slightly changed during the entire growth period. Appropriate amount of nitrogen fertilizer （300 to 600 kg/hm2） was favorable to the survival of the microor-ganisms in the soil under the intercropping system. [Conclusion] The study provides a guideline for screening and determining the optimum amount of applied nitrogen fertilizer.

Application Effect of Water-absorbent Slow Release Nitrogen Fertilizer in Latosol

[Objective] A new-type water-absorbent slow release nitrogen fertilizer（WASRNF） was produced through polymerization reaction. Its physicochemical property and application effect in latosol were studied. Feasibility of using WASRNF to improve the serious problems of latosol in rubber planting area in Hainan Island including vulnerable nutrient, free-running fertilizer and water was studied. [Result] The results showed that raw materials of WASRNF, urea and water-retention material formed co-polymer through hydrogen-bond interaction that the WASRNF contained many hydrophilic groups. The p H value of WASRNF is near neutral and its water absorbent rate in tap water could reach 167.17 g·g-1. The water absorbent rates in latosol leach liquors with water/soil ratios of 1：5, 1：10 and 1：20 were 104.66, 122.93 and 145.38 g·g^-1, respectively. The maximum water holding ratio of latosol increased by 23.72%, 30.89% and 39.68% when 0.5%, 1% and 2% WASRNFs were added to latosol, and water evaporation rate of latosol decreased efficiently. Compared with common urea, WASRNF could slow down the leaching rate of nitrogen and the initial leaching amount was only 22.17% of the total amount. [Conclusion]The results indicated that WASRNF in latosol had strong water absorption and water-retention abilities in addition to the good slow release effect, and could efficiently decrease nutrient loss, increase utilization ratio of water and fertilizer and promote interaction between water and fertilizer.