Effects of Nitrogen Fertilizer Regulation with Straw-return on Wheat Yield and Different Forms of Potassium in the Soil

In order to study the effects of nitrogen fertilizer application methods and nitrogen fertilizer regulation with straw-return on wheat yield and potassium forms in the soil, field experiment was arranged in Pinyuan County, and the effects of the regulation of different ratios of basal to topdressed nitrogen on the yield of wheat and the contents of different forms of potassium in the soil were studied. The re- sults indicated that in the condition of straw-return, the yield of wheat was the high- est after the treatments of the ratios of basal to topdressed nitrogen of 7：3 and 6：4. As to the contents of different forms of potassium, the contents of water-soluble potassium, exchangeable potassium and total potassium treated by the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the highest, and the differences of non-exchangeable potassium among all treatments were not significant. Under the experiment condition, the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the best treatments, they can increase the wheat yield and the contents of available potassium and total potassium in the soil.

Nitrogen Use Efficiency as Affected by Phosphorus and Potassium in Long-Term Rice and Wheat Experiments

Improving nitrogen use efficiency （NUE） and decreasing N loss are critical to sustainable agriculture. The objective of this research was to investigate the effect of various fertilization regimes on yield, NUE, N agronomic efficiency （NAE） and N loss in long-term （16- or 24-yr） experiments carried out at three rice-wheat rotation sites （Chongqing, Suining and Wuchang） in subtropical China. Three treatments were examined： sole chemical N, N＋phosphorus （NP）, and NP＋potassium （NPK） fertilizations. Grain yields at three sites were significantly increased by 9.3-81.6% （rice） and 54.5-93.8% （wheat） under NP compared with N alone, 1.7-9.8% （rice） and 0-17.6% （wheat） with NPK compared with NP. Compared to NP, NUE significantly increased for wheat at Chongqing （9.3%） and Wuchang （11.8%）, but not at Suining, China. No changes in NUE were observed in rice between NP and NPK at all three sites. The rice-wheat rotation＇s NAE was 3.3 kg kg1 higher under NPK than under NP at Chongqing, while NAE was similar for NP and NPK at Suining and Wuchang. We estimated that an uptake increase of 1.0 kg N hal would increase 40 kg rice and 30 kg wheat ha-1. Nitrogen loss/input ratios were -60, -40 or -30% under N, NP or NPK at three sites, indicating significant decrease of N loss by P or PK additions. We attribute part of the increase in NUE soil N accumulation which significantly increased by 25-55 kg ha-1 yr1 under NPK at three sites, whereas by 35 kg ha-1 yr-1 under NP at Chongqing only. This paper illustrates that apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China.

Effect Models of Nitrogen,Phosphorus and Potassium Fertilizer Formulation in Banana

[Objective] The aim was to modify the application amount of N,P and K fertilizer so as to provide a reference for establishing balanced fertilization index system of banana.[Method]The N,P and K fertilizer ＂3414＂ test was carried out on banana,and then regression analysis was performed on the fertilizer effect.Ternary quadratic,binary quadric and one-variable quadratic regression equations for the fertilizer effect on the banana yield were constructed.[Result]Suitable amount of N,P and K fertilizer had significant yield improving effect,whereas overdose of fertilizer application led to decreasing of utilization rate of fertilizer.Therefore,suitable amount of N,P and K fertilizer should be selected in production.It could be concluded that one-variable quadratic regression equations was the best model to calculate the suitable fertilizer amount.The best yield range of banana in the tested field was 44.193-45.904 t/hm2,while the corresponding optimum application amount of N,P2O5 and K2O was 795.1,262.3 and 1 236.9 kg/hm2 respectively,and the ratio among nitrogen,phosphorus and potassium are 1∶0.33∶1.55.[Conclusion]The result in this study could provide references for the soil types similar to the tested field.

Nitrogen, phosphorus and potassium recycling in an agroforestry ecosystem of Huanghuaihai Plain: with Paulownia elongata intercropped wheat and maize as an example

The studies show that in the whole community, P is deficient, and N and K are basically balanced. N, P and K are accumulated in plant tissues and litters, but depleted in soil. N and P contents in surface soil(0—20 cm) are the main factors affecting crop growth, and P contents in 20 80 cm soil layer is the major affecting Paulownia elongata growth. The absorption coefficients of N, P and K in the communities are 0 078, 0 014 and 0 052 respectively, their utilization coefficients are 0 95, 0 90 and 0 94, and the recycling coefficients are 0 042, 0 05 and 0 063 respectively.

Effects of Nitrogen and Potassium Fertigation on Yield and Quality of Pineapple during Late Growing Period

[Objective] The aim was to compare effects of nitrogen and potassium fertigation on yield and quality of pineapple during the late growing period. [Method] Urea, potassium sulfate, and potassium chloride were taken as three fertilizers which were set at three levels, respectively, and the group without additional fertilizers was taken as control group. [Result] Compared with control group, weight of individual pineapple was significantly increased by fertigation of urea at 7.5 kg or potassium sulfate at 18 kg per 667 m 2 and the increase yields were 22.5% and 28.9%, respectively. Effects of nitrogen and potassium fertigation on yield and quality of pineapple were compared. [Conclusion] Potassium sulfate fertigation would promote sugar accumulation and improve quality of fruits. Furthermore, chlorophyll content can be enhanced and photosynthetic capacity can be reinforced.

Study on Absorption Law of Nitrogen,Phosphorus and Potassium and Proper Nitrogen Application in Chuanxiangyou 9838 under No-tillage Cultivation

The aim of the study is to investigate the absorption laws of nitrogen, phosphorus, and potassium, and proper nitrogen application in Chuanxiangyou 9838 under no-tillage cultivation. Five nitrogen application treatments were designed to analyze the absorption laws of N, P and K, and to discuss the effects of different N fertilizer application amounts on yield and yield composition factors of Chuanxiangyou 9838. The results showed that gross nutrient absorption in Chuanxiangyou 9838 was greatly varied at different developmental stages under rice-rape rotation with no-tillage. The maximum N absorption in Chuanxiangyou 9838 appeared at jointing stage followed by heading stage, thirdly the tillefing stage ; the P absorption in Chuanxiangyou 9838 presented the consecutively slight increase during seedling stage and mature stage ; the K absorption in Chuanxiangyou 9838 was mainly conducted from jointing stage to heading stage, during which K absorption accounts for 73.4% of the total absorption in whole developmental stage. Consequently, N fertilizer should be applied earlier （ before jointing stage）, P fertilizer is suitable as base fertilizer and application of K fertilizer should be preferably conducted at early-middle period. When the yield reached 11 t/hm^2, the optimal N application amount in Chuanxiangyou 9838 was about 165 kg/hm^2.

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.

Production Benefits of Double-Cropping Rice Under Optimized Application of Nitrogen and Potassium Fertilizers Combined with Chinese Milk Vetch and Straw Co-Returning to Fields

In order to explore the technology and effects of reducing nitrogen and potassium fertilizer applications in double-cropping rice,a field plot experiment was conducted to study the effects of optimized application of nitrogen and potassium fertilizers combined with returning Chinese milk vetch and straw to fields on yield,fertilizer utilization efficiency,net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO_(2) concentration(Ci),chlorophyll content(SPAD value)and soil physical and chemical properties in late rice harvest period.The results showed that the optimized application of nitrogen and potassium fertilizers combined with the integrated technology of Chinese milk vetch and straw co-returning to the field could enhance the photosynthetic efficiency of double-cropping rice,increase rice yield,and enhance soil biological activity,especially T4 treatment involving the returning of Chinese milk vetch and straw to the field instead of 30%nitrogen fertilizer achieved the highest rice yield,fertilizer use efficiency,net photosynthetic rate and soil biological activity.Compared with the conventional fertilization treatment T2,the total rice yield of T4 treatment increased by 4.1%,among which the early rice and late rice increased by 6.3%and 2.4%,respectively;Pn,Gs and SPAD values of flag leaves at full heading stage significantly increased,and the contents of soil active organic carbon,alkali hydrolyzed nitrogen,available phosphorus and readily available potassium significantly increased.

Effects of Cadmium Stress on Key Enzymes Involved in Nitrogen Metabolism and Nitrogen,Phosphorus, Potassium Accumulation of Different Varieties of Rice

In this study, the pot experiment was used to explore the differences of activity of key enzymes involved in N metabolism and NPK accumulation under Cd stress during the til iering stage of differen varieties of rice. The results showed that：Cd stress could increase the NPK concentration of different rice type in the til ering stage, while Shen-Liangyou 5867,Yongyou 5550 and Wu-Yunjing 27 showed the highest amplification respectively. Morever, Cd stress can also contribute to the ac-tivity of NR,GS,GOGAT increasing.A s for NR,the Cd stress significantly contribute to NR activity increasing of Huang-Huazhan and Yongyou 538 but is not significant for Wu-Yunjing 27, Shen-Liangyou 5867 and Yongyou 5550, however, the difference among them is not obvious.However, for the activity of GS , Cd stress promote the GS activity. Huang-Huazhan and Wu-Yunjing 27 with low activity in Cd normal level are the most sensitive. Meanwhile the difference between two treatment is the most significant. To the contrary, restrain the GS activity of Shen-Liangyou 5867, Yongy-ou 5550 and the difference is not significant. And under Cd stress, either difference reached significant in GS activity. Cd stress also improve the activity of GOGAT, Wu-Yunjing 27 showed the highest inprovement which showed the lowest GOGAT activity under Cd normal level. Cd stress on rice growth and development of ad-verse, make its lower seed setting rate, 1 000 grain weight decreased, resulting in different degrees of reduction of output of rice.

Effect of nitrogen fertilizer on the uptake and utilization of potassium by various rice varieties in purple soil

Nitrogen and potassium are important nutrientelements for rice.Besides supplied by the or- ganic manure,potassium nutrition of ricecomes dominantly from purple soils in Sichuanbasin.Potassium exists abundantly in mineralforms in the purple soils.Availability of soilpotassium for crop depends on the potassiumforms,the uptake ability of crops,and fertiliz-er practices.A pot culture experiment wasconducted to study the kinetics of potassiumuptake in the purple soil(total N 22.64g·kg,total K 24.36g·kg,available N 102.6mg·kg,available K 140.6mg·kg,acidsoluble K 936.0mg·kg,and pH 6.8).Ma-terials used were three Fhybrid rices,Eryou

Transgenic approaches for improving use efficiency of nitrogen, phosphorus and potassium in crops

The success of the Green Revolution largely relies on fertilizers, and a new Green Revolution is very much needed to use fertilizers more economically and efficiently, as well as with more environmental responsibility. The use efficiency of nitrogen, phosphorus, and potassium is controlled by complex gene networks that co-ordinate uptake, re-distribution, assimilation, and storage of these nutrients. Great progress has been made in breeding nutrient-efficient crops by molecularly engineering root traits desirable for efficient acquisition of nutrients from soil, transporters for uptake, redistribution and homeostasis of nutrients, and enzymes for efficient assimilation. Regulatory and transcription factors modulating these processes are also valuable in breeding crops with improved nutrient use efficiency and yield performance.

Impact of Nitrogen, Phosphorus and Potassium on Brown Planthopper and Tolerance of Its Host Rice Plants

The brown planthopper(BPH),Nilaparvata lugens(St?l),appeared as a devastating pest of rice in Asia. Experiments were conducted to study the effects of three nutrients,nitrogen(N),phosphorus(P) and potassium(K),on BPH and its host rice plants. Biochemical constituents of BPH and rice plants with varying nutrient levels at different growth stages,and changes in relative water content(RWC) of rice plants were determined in the laboratory. Feeding of BPH and the tolerance of rice plants to BPH with different nutrient levels were determined in the nethouse. Concentrations of N and P were found much higher in the BPH body than in its host rice plants,and this elemental mismatch is an inherent constraint on meeting nutritional requirements of BPH. Nitrogen was found as a more limiting element for BPH than other nutrients in rice plants. Application of N fertilizers to the rice plants increased the N concentrations both in rice plants and BPH while application of P and K fertilizers increased their concentrations in plant tissues only but not in BPH. Nitrogen application also increased the level of soluble proteins and decreased silicon content in rice plants,which resulted in increased feeding of BPH with sharp reduction of RWC in rice plants ultimately caused susceptible to the pest. P fertilization increased the concentration of P in rice plant tissues but not changed N,K,Si,free sugar and soluble protein contents,which indicated little importance of P to the feeding of BPH and tolerance of plant against BPH. K fertilization increased K content but reduced N,Si,free sugar and soluble protein contents in the plant tissues which resulted in the minimum reduction of RWC in rice plants after BPH feeding,thereby contributed to higher tolerance of rice plants to brown planthopper.

Identification of microRNAs involved in crosstalk between nitrogen, phosphorus and potassium under multiple nutrient deficiency in sorghum

Nitrogen(N),phosphorus(P),and potassium(K)are important for plant growth and development.MicroRNAs(miRNAs)play important roles in regulating plant response to nutrient(N,P,and K)deficiencies.Several miRNAs have been identified under nutrient deficiency conditions in many plant species.However,the manner in which miRNAs regulate the interaction between NPK signaling pathways under multiple nutrient deficiency remains largely unknown.We systematically compared and identified microRNAs involved in both single and triple NPK nutrient deficiency responses.We identified 32 shoot and 17 root miRNAs differentially expressed under potassium deficiency.Several NP starvation-associated miRNAs including miR169s and miR399s,were also regulated by K deficiency.Several identified miRNAs including miR5565c,miR5564,and miR1432 have not previously been associated with respectively N,P,and K deficiency(−N,−P,and−K).Expression correlation analysis between miRNAs and their predicted targets showed that miR169,miR172,and miR160 displayed expression trends exactly opposite to those of their corresponding predicted targets.Of 550 predicted novel miRNAs,novel_mir_42 was upregulated in shoots under−K but was downregulated under−N and−P.The effects of combined NPK starvation were not a simple addition of the individual stresses on sorghum seedlings.The identified common and specific differentially expressed miRNAs were observed under single and combined NPK deficiencies.These findings will help to further elucidate the functions of microRNAs and their interactions under multiple nutrient deficiency.

Nitrogen doping and graphitization tuning coupled hard carbon for superior potassium-ion storage

Hard carbon material is one of the most promising anode materials for potassium ion batteries(PIBs)due to its distinct disordered and non-expandable framework.However,the intrinsically disordered microarchitecture of hard carbon results in low electric conductivity and poor rate capability.Herein,nitrogendoped and partially graphitized hard carbons(NGHCs)derived from commercial coordination compound precursor-ethylenediaminetetraacetic acid(EDTA)disodium cobalt salt hydrate are designed and prepared as high-performance PIBs anode materials.By means of a facile annealing method,nitrogen elements and graphitic domains can be controllably introduced to NGHCs.The resulting NGHCs show structural merits of mesoporous construction,nitrogen doping and homogeneous graphitic domains,which ensures fast kinetics and electron transportation.Applying in anode for PIBs,NGHCs exhibit robust rate capability with high reversible capacity of 298.8 m Ah g^-1 at 50 m A g^-1,and stable cycle stability of 137.6 mAh g^-1 at 500 m A g^-1 after 1000 cycles.Moreover,the ex situ Raman spectra reveal a mixture"adsorption-intercalation mechanism"for potassium storage of NGHCs.More importantly,full PIBs by pairing with perylenetetracarboxylic dianhydride(PTCDA)cathode demonstrate the promising potential of practical application.In terms of commercial precursor,facile synthesis and long cycle lifespan,NGHCs represent a brilliant prospect for practical large-scale applications.

Kinetics of Nitrogen and Potassium Uptake by Various Rice Cultivars at Different Nitrogen Levels from Purple Soil

A pot experiment was conducted to study the effect of nitrogen fertilizer on nitrogen and potassium uptake by four rice cultivars. Results showed that the quadatic parabola relationship between biomass of rice and nitrogen levels was observed, with the maximum biomass at the nitrogen level of 150 mg kg-1.The rates of nitrogen and potassium uptake by the four rice cultivars depended on growth stage and rice cultivar with the maximum rate of N in Shanyou-63 and maximum rate of K in Kaiyou-5 (hybrid rice),respedively. The kinetics of nitrogen and potasssium uptake by rice plant could be quantitstively described by the following equations: y = a + blogt, y = ab + t1/2 and y = ae-bt. The b value in the equations was correlated significantly to the rates of nitrogen and potassium uptake (NR and KR, r=0.901**～0.990**),suggesting that the b value could be used to distinguish the index of nitrogen and potassium uptake capacity of rice. The maximum values of nitrogen uptake by plant (b value) and apparent recovery of fertilizer nitrogen were observed in Shanyou-63, and the minimum value in Eryou-6078. However, the capacity of potassium uptake (b value) by Kaiyou-5 ranked first and that by Shanyou-63 second. There was a significant linear relationship between nitrogen level and nitrogen uptake by rice, but a quadratic parabola relationship was found between nitrogen level and patassium uptake by rice. The application of nitrogen fertilizer decreased the ratios of potassium to nitrogen uptake by rice plant. The greatest reduction in the ratio was observed at high nitrogen level, and the least reduction was found in Kaiyou-5 and Shanyou-63 due to their greater ability to absorb potassium.

Effects of Potassium and Manganese Promoters on Nitrogen-Doped Carbon Nanotube-Supported Iron Catalysts for CO_2 Hydrogenation

Nitrogen-doped carbon nanotubes （NCNTs） were used as a support for iron （Fe） nanoparticles applied in car- bon dioxide （CO_2） hydrogenation at 633 K and 25 bar （1 bar = 10-5 Pa）. The Fe/NCNT catalyst promoted with both potassium （K） and manganese （Mn） showed high performance in CO_2 hydrogenation, reaching 34.9% conversion with a gas hourly space velocity （GHSV） of 3.1 L-（g·h）-1. Product selectivities were high for olefin products and low for short-chain alkanes for the K-promoted catalysts. When Fe/NCNT catalyst was promot- ed with both K and Mn, the catalytic activity was stable for 60 h of reaction time. The structural effect of the Mn promoter was demonstrated by X-ray diffraction （XRD）, temperature-programmed reduction （TPR） with molecular hydrogen （H2）, and in situ X-ray absorption near-edge structure （XANES） analysis. The Mn pro- moter stabilized wtistite （FeO） as an intermediate and lowered the TPR onset temperature. Catalytic ammo- nia （NH_3） decomposition was used as an additional probe reaction for characterizing the promoter effects. The Fe/NCNT catalyst promoted with both K and Mn had the highest catalytic activity, and the Mn-promoted Fe/NCNT catalysts had the highest thermal stability under reducing conditions.

High Capacity and Fast Kinetics of Potassium‑Ion Batteries Boosted by Nitrogen‑Doped Mesoporous Carbon Spheres

In view of rich potassium resources and their working potential,potassium-ion batteries(PIBs)are deemed as next generation rechargeable batteries.Owing to carbon materials with the preponderance of durability and economic price,they are widely employed in PIBs anode materials.Currently,porosity design and heteroatom doping as efficacious improvement strategies have been applied to the structural design of carbon materials to improve their electrochemical performances.Herein,nitrogen-doped mesoporous carbon spheres(MCS)are synthesized by a facile hard template method.The MCS demonstrate larger interlayer spacing in a short range,high specific surface area,abundant mesoporous structures and active sites,enhancing K-ion migration and diffusion.Furthermore,we screen out the pyrolysis temperature of 900°C and the pore diameter of 7 nm as optimized conditions for MCS to improve performances.In detail,the optimized MCS-7-900 electrode achieves high rate capacity(107.9 mAh g^(−1) at 5000 mA g^(−1))and stably brings about 3600 cycles at 1000 mA g^(−1).According to electrochemical kinetic analysis,the capacitive-controlled effects play dominant roles in total storage mechanism.Additionally,the full-cell equipped MCS-7-900 as anode is successfully constructed to evaluate the practicality of MCS.

Nitrogen/sulphur dual-doped hierarchical carbonaceous fibers boosting potassium-ion storage

The carbon materials as anode electrodes have been widely studied for potassium ion batteries(PIBs).However,the large size of potassium ions prevents their intercalation/deintercalation,resulting in poor storage behaviors.Herein,a novel design of N/S codoped hierarchical carbonaceous fibers(NSHCF)formed from nanosheets self-assembled by catalyzing Aspergillus niger with Sn is reported.The asprepared NSHCF at 600℃(NSHCF-600)exhibits a high reversible capacity of 345.4 m Ah g^(-1) at 0.1 A g^(-1) after 100 cycles and an excellent rate performance of 124.5 m Ah g^(-1) at 2 A g^(-1).The excellent potassium storage performance can be ascribed to the N/S dual-doping,which enlarges interlayer spacing(0.404 nm)and introduces more defects.The larger interlayer spacing and higher pyridinic N active sites can promote K ions diffusion and storage.In addition,the ex situ transmission electron microscopy reveals the high reversibility of potassiation/depotassiation process and structural stability.

Effects of Application of Nitrogen, Potassium and Glycinebetaine on Alleviation of Water Stress to Summer Maize

A pot experiment was conducted under water deficit and adequate water-supplied conditions with two maize genetypic varieties （Shaandan 9 and Shaandan 911） to study the effects of nitrogen, potassium and glycinebetaine （GlyBet） on the dry matter and grain yields as well as water use efficiency （WUE）. Determinations were made at different stages of the two varieties for revealing the function of these factors in increasing plant resistance to drought. Results showed that under a water-stressed condition, dry matter and grain yield were significantly reduced. However, the response of the two varieties to water stress was different： Shaandan 9 was significantly higher in dry matter and grain yields, and therefore could be regarded as a drought-resistant variety compared to Shaandan 911.Application of nitrogen, potassium and glycinebetaine raised dry matter and grain yield to different levels, and thereby alleviated the water stress and increased water use efficiency. These effects were higher for Shaandan 911 than for Shaandan 9. Under water-stressed conditions application of N fertilizer, either at low rate or at high rate, significantly increased dry matter, grain yield and water use efficiency. A significant different effect was found for Shaandan 911 between N rates, but not so for Shaandan 9. However, with supplemental water supply, effects of N fertilization were obviously decreased, showing that in addition to supplying nutrient, N fertilizer has a function in increasing drought-resistance of the crop. Potassium and glycinebetaine exhibited a remarkable function in increasing dry matter and grain yields as well as water use efficiency under water stress while such effects were obviously declined, even vanished, with supplemental water supply, indicating the important contribution of these factors in rise of drought-resistance ability of a crop.

Cu_(3)P nanoparticles confined in nitrogen/phosphorus dual-doped porous carbon nanosheets for efficient potassium storage

Immobilizing primary electroactive nanomaterials in porous carbon matrix is an effective approach for boosting the electrochemical performance of potassium-ion batteries (PIBs) because of the synergy among functional components. Herein, an integrated hybrid architecture composed of ultrathin Cu_(3)P nanoparticles (~20 nm) confined in porous carbon nanosheets (Cu_(3)P⊂NPCSs) as a new anode material for PIBs is synthesized through a rational self-designed self-templating strategy. Benefiting from the unique structural advantages including more active heterointerfacial sites, intimate and stable electrical contact, effectively relieved volume change, and rapid K^(+) ion migration, the Cu_(3)P⊂NPCSs indicate excellent potassium-storage performance involving high reversible capacity, exceptional rate capability, and cycling stability. Moreover, the strong adsorption of K^(+) ions and fast potassium-ion reaction kinetics in Cu_(3)P⊂NPCSs is verified by the theoretical calculation investigation. Noted, the intercalation mechanism of Cu_(3)P to store potassium ions is, for the first time, clearly confirmed during the electrochemical process by a series of advanced characterization techniques.