Physiological Basis of Photosynthetic Function and Senescence of Rice Leaves as Regulated by Controlled-Release Nitrogen Fertilizer

The physiological mechanism of photosynthetic function and senescence of rice leaves was studied by using early rice variety Baliangyou 100 and late rice variety Weiyou 46, treated with controlled-release nitrogen fertilizer （CRNF）, urea and no nitrogen fertilizer. CRNF showed obvious effects on delaying the senescence and prolonging photosynthetic function duration of rice leaves. Compared with urea, CRNF could significantly increase the chlorophyll content of functional leaves in both early and late rice varieties, and this difference between the treatments became larger as rice growth progressed; CRNF increased the activities of active oxygen scavenging enzymes super oxide dismutase （SOD） and peroxidase （POD）, and decreased the accumulation amount of malondialdehyde （MDA） in functional leaves during leaf aging; Photosynthetic rate of functional leaves in CRNF treatment was significantly higher than that in urea treatment. The result also indicated that CRNF could effectively regulate the contents of indole-3-acetic acid （IAA） and abscisic acid （ABA） in functional leaves; IAA content was higher and ABA content was lower in CRNF treatment than those in urea treatment. Therefore, application of CRNF could increase the rice yield significantly due to these physiological changes in the functional leaves.

Effects of mixed fertilizers formed by the compounding of two targeted controlled-release nitrogen fertilizers on yield,nitrogen use efficiency,and ammonia volatilization in double-cropping rice

One-time application of mixed fertilizer formed by the compounding of two controlled-release nitrogen fertilizers(CRUs)with targeted N supply during the periods from transplantation(TS)to panicle initiation(PI)and from PI to heading(HS)is expected to synchronize the double-peak N demand of rice.However,its effects on the yield and N use efficiency(NUE)of labor-intensive double-cropping rice were unknown.Two targeted CRU(CRU_(A)and CRU_(B))were compounded in five ratios(CRU_(A):CRU_(B)=10:0,7:3,5:5,3:7,and 0:10)to form five mixed fertilizers(BBFs):BBF1-5.A field experiment was performed to investigate the characteristics of N supply in early and late seasons under different BBFs and their effects on N uptake,yield,and ammonia volatilization(AV)loss from paddy fields of double-cropping rice.Conventional high-yield fertilization(CK,three split applications of urea)and zero-N treatments were established as controls.The N supply dropped significantly with the increased compound ratio of CRU_(B)during the period from TS to PI,but increased during the period from PI to HS.With the exception of the period from TS to PI in the late rice season,the N uptake of early and late rice maintained close synchronicity with the N supply of BBFs during the double-peak periods.Excessive N supply(BBF1 and BBF2)in the late rice season during the period from TS to PI increased N loss by AV.The effect of BBF on grain yield increase varied widely between seasons,irrespective of year.Among the BBFs,the BBF2 treatment of early rice not only stabilized the spikelets per panicle but also ensured a high number of effective panicles by promoting N uptake during the period from TS to PI and a high grain-filling percentage by appropriately reducing the N supply at the later PI stage,resulting in the highest rice yield.While stabilizing the effective panicle number,the BBF4 treatment of late rice increased the number of spikelets per panicle by promoting N uptake during the period from PI to HS,resulting in the highest rice yield.The two-year average yield and apparent N recovery efficiency of the BBF2 treatment during the early rice season were 9.6 t ha 1 and 45.3%,while those of late rice in BBF4 were 9.6 t ha 1 and 43.0%,respectively.The yield and NUE indexes of BBF2 in early rice and BBF4 in late rice showed no significant difference from those of CK.The AVs of BBF2 during the early rice season and of BBF4 during the late rice season were 50.0%and 76.8%lower,respectively,than those of CK.BBF2 and BBF4 could effectively replace conventional urea split fertilization in early and late rice seasons,ensuring rice yield and NUE and reducing AV loss in paddy fields.

Biochar-compost-based controlled-release nitrogen fertilizer intended for an active microbial community

Nitrogen(N) fertilizers in agriculture suffer losses by volatilization of N to the air, surface runoff and leaching into the soil, resulting in low N use efficiency(NUE)( 50%) and raising severe environmental pollutions. Controlledrelease nitrogen fertilizers(CRNFs) can control the release of N nutrients to NUE in crop production. Different methods were used to develop new CRNFs.However, different CRNF technologies are still underdeveloped due to inadequate controlling on N releasing time and/or unsustainable diffusion. The study on the influences of CRNF processing parameters on microbial conditions are lacking when the CRNFs composed of various bio-ingredients such as biochar, composts, and biowaste. The complexity of processing methods, material biodegradability, and other physical properties make current CRNFs of questionable value in agricultural production. This research aims to develop a novel biochar-compost-based controlled-release urea fertilizer(BCRUF) to preserve microbial properties carried by the compost. The BCRUF was synthesized by pelletizing the 50:50(dry, wt/wt) mixture of biochar and compost. BCRUF was loaded with urea and then spray-coated with polylactic acid(PLA). The releasing time of two types of BCRUFs, coated and uncoated with PLA, for 80% of N release in water was up to 6 h at three different temperatures(4, 23, and 40 °C), compared to conventional urea fertilizer and commercial environmentally smart N(ESN) fertilizer. The releasing time of coated BCRUF for 80% N release in soil was up to 192 h(8 days). Fourier-transform infrared spectroscopy(FTIR) analysis revealed that no new functional groups were found in the release solution, indicating no new chemical hazards generated. The differential scanning calorimetry(DSC)tests also verified that its thermal stability could be up to 160 °C. The microbe populations in the BCRUF pellets were reduced after the pelleting and drying processes in BCRUF fabrication, but a few bacteria can endure in the air-drying process. BCRUF pellets soaked in water for 4 days retained some bacteria. The BCRUF showed very promising characteristics to improve NUE and sustainability in agricultural production.

One-time application of controlled-release bulk blending fertilizer enhances yield,quality and photosynthetic efficiency in late japonica rice

Controlled-release urea(CRU)releases nitrogen(N)at the same pace that rice takes it up,which can effectively improve N use efficiency,increase rice yield and improve rice quality.However,few studies have described the effects of CRU application on the photosynthetic rate and endogenous enzyme activities of rice.Accordingly,a twoyear field trial was conducted with a total of seven treatments:CK,no N fertilizer;BBF,regular blended fertilizer;RBBF,20%N-reduced regular blended fertilizer;CRF1,70%CRU+30%regular urea one-time base application;CRF2,60%CRU+40%regular urea one-time base application;RCRF1,CRF1 treatment with 20%N reduction;and RCRF2,CRF2 treatment with 20%N reduction.Each treatment was conducted in triplicate.The results showed that the N recovery efficiency(NRE)of the controlled-release bulk blending fertilizer(CRBBF)treatments was significantly greater over the two years.There were significant yield increases of 4.1–5.9%under the CRF1treatment and 5.6–7.6%under the CRF2 treatment compared to the BBF treatment,but the differences between the reduced-N treatments RBBF and RCRF2 were not significant.Photosynthetic rates under the CRF1 and CRF2treatments were significantly higher than under the other treatments,and they had significantly greater RuBPCase,RuBisCO,glutamate synthase(GOGAT)and glutamine synthetase(GS)enzyme activities.Additionally,the soil NH_(4)^(+)-N and NO_(3)^(–)-N contents under the CRBBF treatments were significantly higher at the late growth stage of rice,which was more in-line with the fertilizer requirements of rice throughout the reproductive period.CRBBF also led to some improvement in rice quality.Compared with the BBF and RBBF treatments,the protein contents under the CRBBF treatments were reduced but the milling,appearance,eating and cooking qualities of the rice were improved.These results showed that the application of CRBBF can improve the NRE,photosynthetic rate and endogenous enzyme activities of rice,ensuring sufficient N nutrition and photosynthetic material production during rice growth and thereby achieving improved rice yield and quality.

Effects of a New Long-term Controlled-release Fertilizer on Growth and Development and Yield of Summer Maize

[Objective] The aim was to select the optimal amount of controlled-release fertilizer and provide theoretical references for controlled-release fertilizers use in summer maize. [Method] Long-term controlled-release fertilizers were applied once at sowing summer maize to explore effects on maize growth, yield, economic profits and environment. [Result] Maize yield reduced a little in the treatment group with 60% CRF, and increased in varying degrees in the rest groups in the range of 1.1%-7.4%, and some showed significant differences. [Conclusion] Controlled-release fertilizers can be applied once at the amount of 80% common fertilizer＇s, with con- sideration of maize yield, nitrogen use rate and economic profits, which is beneficial for summer maize application and promotion in North China.

Yields and Nitrogen Use Efficiencies of Rice (Oryza sativa) at Different Sites Using Different Nitrogen Fertilizer Application Rates and Controlled-release Urea to Conventional Urea Ratios

Rice yields and nitrogen use efficiencies were studied at five sites in southwest China using two nitrogen fertilization rates and five controlled-release urea（ CRU） to ordinary urea（ U） ratios. The fertilizer treatments significantly increased rice yields compared with the control（ no nitrogen added） yields to different degrees at different sites. Applying CRU and U increased the rice yield more than adding the same amount of nitrogen as U only. Higher increasing production rate were found using a nitrogen application rate of 105 kg/hm2 than 150 kg/hm2. A 70∶ 30 CRU∶ U ratio increased the yield more than other four ratios. Nitrogen use efficiency was 21. 9% higher using a nitrogen application rate of 105 kg/hm^2 than 150 kg/hm^2,and 46. 6%,38. 1%,34. 7%,and 22. 2% higher than when only U was applied when CRU∶ U ratios of 70 ∶ 30,50 ∶ 50,100 ∶ 0,and 30 ∶ 70,respectively,were used. A 70 ∶ 30 CRU ∶ U ratio gave the highest economic output（ yuan/hm^2）. Applying both CRU and U gave an output 3 078. 87 yuan/hm^2 higher at a nitrogen application rate of 150 kg/hm^2 than at a nitrogen application rate of 105 kg/hm^2. Economic output was always higher using both CRU and U than using U only. The highest economic output was given using a 70∶ 30 CRU∶ U ratio.Increasing the amount of nitrogen added decreased the output efficiency（ per hm2） because CRU is expensive. Significant relationships were found between the yield increase rate and the proportion of CRU added（ regression equation y = 7. 429 x-185. 7,R^2= 0. 663） and between the total rainfall over the whole growth period and the proportion of CRU added（ y =-0. 087 1 x ＋ 112. 29,R^2= 0. 687 9）. These regression equations can be used to determine the appropriate proportion of CRU that should be added at a site,depending on the rainfall and target rice yield.

Integrated assessment of yield,nitrogen use efficiency and ecosystem economic benefits of use of controlled-release and common urea in ratoon rice production

Controlled-release urea(CRU)is commonly used to improve the crop yield and nitrogen use efficiency(NUE).However,few studies have investigated the effects of CRU in the ratoon rice system.Ratoon rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested main crop.In this study,a 2-year field experiment using a randomized complete block design was conducted to determine the effects of CRU on the yield,NUE,and economic benefits of ratoon rice,including the main crop,to provide a theoretical basis for fertilization of ratoon rice.The experiment included four treatments:(i)no N fertilizer(CK);(ii)traditional practice with 5 applications of urea applied at different crop growth stages by surface broadcasting(FFP);(iii)one-time basal application of CRU(BF1);and(iv)one-time basal application of CRU combined with common urea(BF2).The BF1 and BF2 treatments significantly increased the main crop yield by 17.47 and 15.99%in 2019,and by 17.91 and 16.44%in 2020,respectively,compared with FFP treatment.The BF2 treatment achieved similar yield of the ratoon crop to the FFP treatment,whereas the BF1 treatment significantly increased the yield of the ratoon crop by 14.81%in 2019 and 12.21%in 2020 compared with the FFP treatment.The BF1 and BF2 treatments significantly improved the 2-year apparent N recovery efficiency,agronomic NUE,and partial factor productivity of applied N by 11.47-16.66,27.31-44.49,and 9.23-15.60%,respectively,compared with FFP treatment.The BF1 and BF2 treatments reduced the chalky rice rate and chalkiness of main and ratoon crops relative to the FFP treatment.Furthermore,emergy analysis showed that the production efficiency of the BF treatments was higher than that of the FFP treatment.The BF treatments reduced labor input due to reduced fertilization times and improved the economic benefits of ratoon rice.Compared with the FFP treatment,the BF1 and BF2 treatments increased the net income by 14.21-16.87 and 23.76-25.96%,respectively.Overall,the one-time blending use of CRU and common urea should be encouraged to achieve high yield,high nitrogen use efficiency,and good quality of ratoon rice,which has low labor input and low apparent N loss.

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.

Studies on the Mechanism of Single Basal Application of Controlled-Release Fertilizers for Increasing Yield of Rice (Oryza sativa L.)

This paper was to explore the mechanism of single basal application of controlled-release fertilizers for increasing yield of rice （Oryza sativa L.）. Pot trials and cylinder trials were carried out from 2002 to 2005 to study the influences of single basal application of 3 controlled-release fertilizers on the changes of soil available N, root development, senescence and lodging resistance at late growth stages. Results showed that at 30 days after fertilization, single basal application of controlled-release fertilizers coated with vegetal-substance （CRF1） and polymer materials （CRF3） increased soil available N to 12.0 and 147.9%, respectively, in comparison to split fertilization of rice-specific fertilizer （RSF1）. Treatments of the two CRFs obviously benefited the development of root system, resulting in greater rice root weights with extensive distribution and higher root activity. In addition, the two CRF treatments, in comparison to RSF1, enhanced chlorophyll consents of the flag leaves to 9.5 and 15.5%, and soluble protein up to 89.7 and 108.0% respectively. Application of the two CRFs also made the base of rice stems strong and large, declined the proportion of shoot and root, increased root depth index. Though relatively low K rate, single basal application of the CRF3 coated with NH4MgPO4 could also promote the development of root system, enhance root activity and some physiological functions of flag leaves. Based on these results, it was concluded that major mechanisms for increasing rice yield by single basal application of the CRFs should be attributed to grater soil available N supply, superior development of root systems, better nutrient absorption capacity, slower senescence and enhancement of lodging resistance at late stages.

Controlled-release fertilizer(CRF): A green fertilizer for controlling non-point contamination in agriculture

Fertilizers contribute greatly to high yields but also result in environmental non-point contamination, including the emission of greenhouse gas(N 2O) and eutrophication of water bodies. How to solve this problem has become a serious challenge, especially for China as its high ecological pressure. Controlled-release fertilizer(CRF) has been developed to minimize the contamination while keeping high yield and has become a green fertilizer for agriculture. Several CRFs made with special coating technology were used for testing the fertilizer effects in yield and environment through pot experiment and field trial. The result indicated that the CRFs had higher N use efficiency, thus reducing N loss through leaching and volatilization while keeping higher yields. Comparing with imported standard CRFs, the test on CRFs showed similar fertilizer effect but with much lower cost. CRFs application is becoming a new approach for minimizing non-point contamination in agriculture.

Shifts in soil bacterial communities induced by the controlled-release fertilizer coatings

Coated controlled-release fertilizers （CRFs） have been widely applied in agriculture due to their increased efficiency. However, the widespread and a lot of coated CRFs application may leave undesired coating residues in the soil due to their slow degradation. Limited information is available on the effects of substantial residual coatings on the soil bacterial community. By adding 0, 5, 10, 20, and 50 times quantities of residual coating from conventional application amount of resin and water-soluble coated CRFs, we studied the responses of soil properties and bacterial community composition to these two residual coatings in black soil. The results showed that the resin and water-soluble coatings did not essentially alter the properties of black soil or cause dramatic changes to bacterial diversity within the test concentration range. The residual resin and water-soluble coatings also did not distinctly alter the relative abundance of the top ten bacteria at phylum level. Heatmap results suggested that the treatments were basically clustered into two groups by concentration rather than types of coating material. Pearson correlation analysis showed that the Simpson＇s diversity index of the bacterial community was significantly correlated with microbial biomass carbon （MBC, r=0.394, P〈0.05）, and the richness index abundance-based coverage estimator （ACE） of the bacterial community was significantly correlated with microbial biomass nitrogen （MBN, t=0.407, P〈0.05）. Overall, results of this study suggested that substantial residual resin and water-soluble coatings with 0-50 times quantities of residual coating from conventional application amount of coated CRFs did not generate obviously negative impacts on the bacterial community in black soil.

Effects of different types of slow-and controlled-release fertilizers on rice yield

This experiment explored the effects of single application of seven types of slow-and controlled-release fertilizers on rice yield and various population characteristics.Based on a study of the nitrogen(N)release characteristics of these fertilizers,pot experiments were conducted in 2018 and 2019 with split fertilization(CK,urea applied split equally at basal and panicle initiation stages,respectively)as control,which assessed the effects on SPAD value,yield and yield components,dynamic changes of rice tillers and dry matter accumulation.The results showed that the N release characteristics of different types of slow-and controlled-release fertilizers were significantly different.Polymer-coated urea(PCU)showed a controlledrelease mode and provided sustained release throughout the whole growth stages.Sulfur-coated urea(SCU)exhibited a slow-release mode,providing insufficient release at the middle and late stages.Urease inhibitor urea(AHA)and ureaformaldehyde(UF)yielded a rapid-release mode,with an explosive N release at the early stage and no release at the middle and late stages.These results showed that PCU delayed the peak seedling stage.Compared with CK,dry matter accumulation and SPAD showed no significant differences,and due to the continuous release of N throughout the growth stages,rice yield,spikelets per panicle,seed setting rate,and 1000-grain weight were all increased.Owing to the lack of N supply at the late stage and the low number of spikelets,SCU led to a reduction of rice yield,which is nevertheless not statistically significant.AHA and UF were susceptible to environmental factors and had varying effects on rice yield.The results of this experiment indicated that given a fixed amount of N applied in a pot,the stronger the N supply capacity and the longer the effective duration time of the fertilizer,the higher the dry matter accumulation at the late growth stage,and the higher the rice yield.

Preparation and characterization of controlled-release fertilizers coated with marine polysaccharide derivatives

Encapsulation of water-soluble nitrogen fertilizers by membranes can be used to control the release of nutrients to maximize the fertilization ef fect and reduce environmental pollution.In this research,we formulated a new double-coated controlled-release fertilizer(CRF)by using food-grade microcrystalline wax(MW)and marine polysaccharide derivatives(calcium alginate and chitosan-glutaraldehyde copolymer).The pellets of water-soluble nitrogen fertilizer were coated with the marine polysaccharide derivatives and MW.A convenient and eco-friendly method was used to prepare the CRF.Scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)were used to characterize the morphology and composition of the products.The nitrogen-release properties were determined in water using UV-Vis spectrophotometry.The controlled-release properties of the fertilizer were improved dramatically after coating with MW and the marine polysaccharide derivatives.The results show that the double-coated CRFs can release nitrogen in a controlled manner,have excellent controlled-release features,and meet the European Standard for CRFs.

Effects of Controlled-Release Fertilizers and Their Application Methods on Germination and Seedling Growth of Dent and Sweet Corns

Effects of controlled-release fertilizers (CRFs) (C-AS, polyolefin coated ammonium sulfate, 50-day-type; Dd-LP, polyolefincoated urea with dicyandiamide, 40-day-type; C-ANP, polyolefin coated ammonium nitrate phosphate, 40-day-type; andC-DAP, polyolefin coated diammonium acid phosphate, 40-day-type), ammonium sulphate and no fertilizer control, andtheir application methods (spot, band, surface and mixed) on germination and seedling development of sweet corn (Zeamays L.var. saccharata Sturt.) and dent corn (Zea mays L.var. indentata Sturt.) were investigated in a greenhouse. Underco-situs application (band and spot) of CRFs, there were no obvious differences in the germination speed and rate for bothdent corn and sweet corn relative to control. Mortality rates of sweet corn seedlings under co-situs application were highin experiment 1, but were very low in experiment 2, because the environmental conditions were different in the twoexperiments. That is, under lower temperature and weaker sunlight, young seedlings easily die due to high soil nutrientconcentration and slow growth speed of corn. Shoot weight of both dent and sweet corn did not greatly decrease inexperiment 1. In experiment 2, there were no significant differences in shoot and root weight of both corns between co-situs and surface or mixed application methods. However, with spot and band application of ammonium sulfate, shoot androot weight were significantly reduced. Soil EC and pH were considerably affected by co-situs application, especially atthe fertilizer application site. For both dent and sweet corn, EC in the 0-3 cm soil was significantly higher under co-situsapplication and surface application than that under mixed application, whereas in the 3-6 cm soil depth the situation wasreversed. Compared with control, mixed application of CRFs decreased soil pH slightly (0-3 cm depth) or greatly (3-6 cmdepth).

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 Controlled-Release Nitrogen on Yield and Nitrogen Use Efficiency of Summer Maize

The field experiments were conducted in Anhui during 2016 to investigate the effects of controlled-release nitrogen （CRN） rates and mixture of controlled-re- lease nitrogen and conventional nitrogen （CN） on the yield and nitrogen efficiency of summer maize. Six treatments included CK （with no application of N）, CNIO0% splits （CN）, CRFIO0% （CRN1）, CRN60%＋CN40% （CRN2）, CRN85% （CRN3） and CRN70% （CRN4）. The results showed proper CRN increased yields and output val- ue. Compared with CN, CRN2 significantly increased by 13.74%, CRN1 increased by 4.84%, and CRN3 was equal to CN. CRN increased yield by grain number per spike of yield components. CRN2 had the highest apparent nitrogen fertilizer recov- ery efficiency and CRN1 was the second, which were significantly higher than CN. Nitrogen agronomic efficiency of CRN2 was significantly higher than CN. Nitrogen physiological efficiency of CRN2 was higher than CN. The partial productivity of CRN1 was higher than that with CN. And the effect of nitrogen fertilizer of CRN2 was the highest, which was increased 758 yuan/hm2. Considering yield, nitrogen use efficiency and economic benefit, applying the mixture of CRN and CN was the most beneficial treatment. CRN1 was the second treatment, and CRN3 didn＇t reduce yield.

Effects of Controlled Release Fertilizer on Loss of Nitrogen and Phosphorus from Farmland

[Objective] The aim was to study on effects of controlled release fertilizer on loss of nitrogen and phosphorus from farmland. [Method] Experiment was conducted in fields planted with rice and corn around Chao Lake and effects of compound fertilizer, controlled release fertilizer and controlled release fertilizer （reduced by 20%） on loss of nitrogen and phosphorus through runoff and leaching were analyzed. [Result] Loss of nitrogen and phosphorus mainly occurred in early stage of fertilizing; loss caused by runoff accounted for over 98% and caused by leaching was lower than 2%, indicating that nutrients of rice and corn mainly lost through runoff. As for controlled release fertilizers with 20% reduced, total loss of N and P decreased by 60% and 63% in rice field and reduced by 27.8% and 34% in corn field, respectively, indicating that controlled release fertilizer would maintain nutrients in soils high in later period of plant growth, improve use efficiency of N and P, reduce N and P loss in rice and corn fields in rainy season, and decrease non-point pollution. [Conclusion] The research suggested that controlled release fertilizer would slow down the loss of nutrients in farmlands, providing scientific references and technological support for extension of controlled release fertilizer and reduction of agricultural non-point pollution.

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 Spraying Nitrogen and Zinc Fertilizers after Flowering on Grain Weight and Nutritional Quality of Winter Wheat

In order to explore the effect of spraying fertilizers after flowering on grain weight and nutritional quality of different winter wheat cultivars, twenty wheat culti- vars in wheat zones along Yellow River and Huai River, were used to investigate the change of thousand kernel weight （TKW）, phytic acid content （PAC）, contents of Fe, Zn and Mg and bioavailability by spraying zinc and nitrogen fertilizers after flowering. The results showed that both of TKW and protein content in grains in- creased by spraying Zn and N fertilizers, and the effect of N fertilizer proved more significant. The PAC decreased significantly after Zn treatment, for example, PAC of ＂955159＂, a wheat cultivar, decreased by 27.95%. However, PAC was in- significantly influenced by N fertilizer. On the other hand, Zn content in wheat grains were improved after spraying Zn fertilizer and the increase aveaged 54.38%. Furthermore, Fe and Zn contents grew significantly after spraying N fertilizer, and the increase averaged 36.88% and 11.25% respectively. However, Mg content in grains declined by N fertilizer. Still, the bioavailability of zinc in grains was enhanced after spraying Zn fertilizer, and of Fe was also increased greatly after spraying N fertilizer. In conclusion, grain weight, and content and effectiveness of mineral ele-ments can be improved simultaneously by rational spraying of N and Zn fertilizers to improve quality of grains.