Effects of Different Nitrogen Fertilizer Levels on Lodging and Yield of Rice

[Objective] This study aimed to investigate the effects of different fertilizer levels on lodging and yield of rice. [Method] A total of four treatments were designed and applied with 6, 9, 12 and 15 kg of nitrogen fertilizer, respectively. After seedling transplanting, the biological characteristics of rice at different growth stages in each treatment and the biological and economic characteristics of rice after lodging were determined for statistical analysis. [Result] Application with 15 kg of nitrogen fertilizer had significant promotion effect on the increase of rice yield; compared with the control (6 kg of nitrogen fertilizer), rice yield in three experimental treatments (9, 12 and 15 kg of nitrogen fertilizer, respectively) increased by 50.74%, 89.11% and 94.48%, respectively; lodging-resistance mechanical strengths of the three experimental treatments were 103.97%, 132.01% and 89.83% of the control, respectively; rice lodging resistance of treatment C (12 kg of nitrogen fertilizer) was the strongest, with the highest yield. [Conclusion] This study provides reference data and technical support for the rational fertilization of rice production.

Interactions of Water Management and Nitrogen Fertilizer on Nitrogen Absorption and Utilization in Rice

The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw increased and the percentage of nitrogen translocation (PNT) from vegetative organs, nitrogen dry matter production efficiency (NDMPE) and nitrogen grain production efficiency (NGPE) decreased with nitrogen increasing. The nitrogen uptake and NGPE decreased when severe water stressed. However, rice not only decreased the nitrogen uptake but also increased the PNT from vegetative organs, NDMPE and NGPE when mild water stressed. There were obvious interactions between nitrogen fertilizer and water management, such as with water stress increasing the effect of nitrogen on increasing nitrogen uptake was reduced and that on decreasing NDMPE was intensified.

Nitrogen and Phosphorus Loss Law and Emission Reduction Effects Under Water and Fertilizer Management Integrated Mode in Dike Paddy Field

To achieve the purpose of reducing farm non-point source pollution, we integrated site specific nitrogen management precise irrigation, controlled drainage, and wetland eco-repair system in dike area of Taihu basin. During investigation, it had given prominence for the water and fertilizer coupling effects of precise irrigation and site specific nutrient management, the characteristics of integration on controlled irrigation, controlled drainage and wetland ecosystem non-point source pollution control. Then the water and fertilizer integrated management mode of paddy field was put forward in Taihu basin where the water production efficiency increased to 1.64 kg. m-3, water saved 37.8%, fertilizer use efficiency raised 15,4%, yield raised 10%, and N, P load decreased 26%-72%. The modern agricultural and farmland ecosystems that control and cut down the farm non-point source pollution came into being, which can be a reference by Taihu basin to control its agricultural non-point source pollution and eutrophicated water body.

Efficient Management of Nitrogen Fertilizers for Flooded Rice in Relation to Nitrogen Transformations in Flooded Soils

Recent progresses in efficient management of nitrogen fertilizers for flooded rice in relation to nitrogen transformations in flooded soil were reviewed.Considerable progress has been achieved in the investigation on the mechanism of ammonia loss and the factors affecting it .However,little progress has been obtained in the investigations on nitrification-denitrification loss owing to the lack of method for estimating the fluxes of gaseous N products.Thus,so far the management practices developed or under investigation primarily for reducing ammonia loss are feasible or promising,while those for reducing nitrification-denitrification loss seem obscure,except the point deep placement. In addition,it was emphasized that the prediction of soil N supply and the recommendation of the optimal rate of N application based on it are only semi-quantitative.The priorities in research for improving the prediction are indicated.

Modified fertilization management of summer maize(Zea mays L.) in northern China improves grain yield and efficiency of nitrogen use

Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are efficient methods for increasing crop yield.Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer＇s practice（FP）, high-yielding and high efficiency cultivation（HH）, super high-yielding cultivation（SH）, and the control（CK）.Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China.Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers.However, with an increase in planting density, the demand of N increased along with grain yield.Due to the input of too much N fertilizer, the efficiency of N use in SH was low.Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils.However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.

Challenge and Opportunity in Improving Fertilizer-nitrogen Use Efficiency of Irrigated Rice in China

Today, about 30% of world nitrogen (N) fertilizer is consumed by China. Rice crops in China consume about 37% of the total N fertilizer used for rice production in the world. Average rate of N application for rice production in China is high and fertilizer-N use efficiency is low compared with other major rice growing countries. Research progresses have been made internationally and domestically on the application method, fertilizer-N sources, computer-based decision support systems, and real-time N management in order

Effects of Nitrogen Application Rate and Ratio on Lodging Resistance of Super Rice with Different Genotypes

The objective of this study was to determine the morphology mechanism of nitrogen （N） fertilizer rates and ratio on lodging resistance through analying its effects among lodging index （LI）, lodging-related morphological traits and physical strength in basal intemodes by comparing japonica and indica super rice cultivars. Field experiments, with three nitrogen levels （0, 150 and 300 kg ha-L） and two ratios of basal to topdressing （8：2 and 5：5） with two super rice cultivars （Yliangyou 2 and Wuyunjing 23）, were conducted in the Baolin Farm, Danyang Country, Jiangsu Province, China, in 2011 and 2012. Effects of N fertilizer rates and ratios on morphology of whole plant, morphology traits in basal intemodes and culm＇s physical strength parameters were investigated at 20 d after full heading stage. LI of Yliangyou 2 was significant greater than that of Wuyunjing 23 due to larger bending moment by whole plant （WP） with higher plant height and gravity center height. With higher volume of N fertilizer, LI of two super rice cultivars was increased conspicuously. However, no significant effect was detected with increase of panicle fertilizer ratio. The size of breaking strength （M） in basal intemodes was the key factor determining LI among N fertilizer treatments. Correlation analysis revealed that M value was positively related bending stress （BS） of Wuyunjing 23 and section modulus （Z） of Yliangyou 2, respectively. The higher N fertilizer levels induced reduction ofBS of Wuyunjing 23 due to weak culm and leaf sheath plumpness status and reduced Z of Yliangyou 2 owning to small diameter and culm wall thickness, consequently, influencing their M indirectly. These results suggested that breaking strength was the key factor influencing LI with increase of N fertilizer levels. However, the lodging-related morphology mechanism was different with genotypes. Culm wall thickness and diameter in basal internodes of indica super rice and culm and leaf sheath plumpness status of japonica super rice influenced breaking strength, as well as lodging index, respectively.

A Dynamic Knowledge Model for Nitrogen Fertilizationin Wheat Management

By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dressing nitrogen under different environments and cultivars in wheat was developed with principle of nutrient balance and by integrating the quantitative effects of grain yield and quality targets, soil characters, variety traits and water management levels. Case studies on the nitrogen fertilization model with the data sets of different eco-sites, cultivars, soil fertility levels, grain yield and quality targets and water management levels indicate a good performance of the model system in decision-making and wide applicability.

Residue Placement and Rate, Crop Species, and Nitrogen Fertilization Effects on Soil Greenhouse Gas Emissions

High variability due to soil heterogeneity and climatic conditions challenge measurement of greenhouse gas (GHG) emissions as influenced by management practices in the field. To reduce this variability, we examined the effect of management practices on CO2, N2O, and CH4 fluxes and soil temperature and water content from July to November, 2011 in a greenhouse. Treatments were incomplete combinations of residue placements (no residue, surface placement, and incorporation into the soil) and rates (0%, 0.25%, and 0.50%), crop species (spring wheat [Triticum aestivum L.], pea [Pisum sativum L.], and fallow), and N fertilization rates (0.11 and 0.96 g.N.pot-1). Soil temperature was not influenced by treatments but water content was greater under fallow with surface residue than in other treatments. The GHG fluxes peaked immediately following water application and/or N fertilization, with coefficient of variation (CV) ranging from 21% to 46%, 2 and N2O fluxes across measurement dates were greater under wheat or fallow with surface residue and 0.96 g.N.pot-1 than in other treatments. Average CH4 uptake was greater under fallow with surface or incorporated residue and 0.11 g.N.pot-1 than in other treatments. Doubling the residue rate increased CO2 flux by 9%. Greater root respiration, N substrate availability, and soil water content increased CO2 and N2O emissions under wheat or fallow with surface residue and high N rate but fallow with low N rate increased CH4 uptake. Controlled soil and environmental conditions substantially reduced variations in GHG fluxes.

Water,Nitrogen and Plant Density Affect the Response of Leaf Appearance of Direct Seeded Rice to Thermal Time

Field experiments were conducted in the Ebro Delta area （Spain）, from 2007 to 2009 with two rice varieties： Gleva and Tebre. The experimental treatments included a series of seed rates, two different water management systems and two different nitrogen fertilization times. The number of leaves on the main stems and their emergence time were periodically tagged. The results indicated that the final leaf number on the main stems in the two rice varieties was quite stable over a three-year period despite of the differences in their respective growth cycles. Interaction between nitrogen fertilization and water management influenced the final leaf number on the main stems. Plant density also had a significant influence on the rate of leaf appearance by extending the phyllochron and postponing the onset of intraspecific competition after the emergence of the 7th leaf on the main stems. Final leaf number on the main stems was negatively related to plant density. A relationship between leaf appearance and thermal time was established with a strong nonlinear function. In direct-seeded rice, the length of the phyllochron increases exponentially in line with the advance of plant development. A general model, derived from 2-year experimental data, was developed and satisfactorily validated; it had a root mean square error of 0.3 leaf. An exponential model can be used to predict leaf emergence in direct-seeded rice.

An assessment of response of soil-based indicators to nitrogen fertilizer across four tropical eucalyptus plantations

Low nitrogen （N） availability often results in reduced productivity of Eucalyptus plantations. We studied the response of four eucalyptus plantations （two plantations of E. tereticornis on the coastal lowlands, and two plantations of E. grandis in the upland region of the Western Ghats, Kerala, India） to N addition and related this response to seasonal N mineralization as well as other indices of N availability, in order to examine the utility of soil based indicators of N mineralization for predicting the response of eucalyptus growth to added N ferti- lizer. Several biochemical indicators were examined for their capacity to predict response to N fertilizer, including total soil N, soil C：N ratio, and N released during anaerobic and aerobic incubation. Results show that nitrogen fertilizer addition increased productivity across the 4 sites from 7% to 70%, N released during an aerobic incubation had the highest correlation with fertilizer response across the 4 sites （R^2=0.92/ p〈0.01）, and that Modelled seasonal soil N mineralisation was a poorer predictor of fertilizer response than N released during an aerobic incubation. Whilst some of these indicators are promising, they need wider validation and testing before they could be routinely applied.

An assessment of response of soil-based indicators to nitrogen fertilizer across four tropical eucalyptus plantations

Low nitrogen (N) availability often results in reduced productivity of Eucalyptus plantations. We studied the response of four eucalyptus plantations (two plantations of E. tereticornis on the coastal lowlands, and two plantations of E. grandis in the upland region of the Western Ghats, Kerala, India) to N addition and related this response to seasonal N mineralization as well as other indices of N availability, in order to examine the utility of soil based indicators of N mineralization for predicting the response of eucalyptus growth to added N fertilizer. Several biochemical indicators were examined for their capacity to predict response to N fertilizer, including total soil N, soil C:N ratio, and N released during anaerobic and aerobic incubation. Results show that nitrogen fertilizer addition increased productivity across the 4 sites from 7% to 70%, N released during an aerobic incubation had the highest correlation with fertilizer response across the 4 sites (R2=0.92, p<0.01), and that Modelled seasonal soil N mineralisation was a poorer predictor of fertilizer response than N released during an aerobic incubation. Whilst some of these indicators are promising, they need wider validation and testing before they could be routinely applied.

Spatial and temporal variations in nitrogen retention effects in a subtropical mountainous basin in Southeast China

Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidification. Here, we adopted the Soil and Water Assessment Tool(SWAT) model to describe the riverine N output and retention effects in the Shanmei Reservoir Basin, a subtropical mountainous basin located in Quanzhou City, Southeast China. The results revealed that farmlands and orchards in the upstream and central parts of the basin were the dominant land use types, which contributed large N yields. Fertilizer application was the key source of riverine N output and N retention within the basin. On average, approximately 64% of anthropogenic N inputs were retained within the basin, whereas 36% of total N was exported to the downstream and coastal areas. The average N retention efficiency was 80% in a dry year, and within the year, N retention occurred in spring and summer and N release occurred in autumn and winter. The annual variation in N retention within the basin was largely dominated by changes in rainfall and runoff, whereas the seasonal characteristics of N retention were mainly affected by fertilization. Even with a large decrease in fertilizer application, owing to the contributions of the residual N pool and river background, the riverine N output still maintained a certain base value. The effects of precipitation, land use types, and agricultural fertilizer on N retention should be comprehensively considered to implement reasonable N management measures.

Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows： maize straw （MS）, compost made from maize straw （MC）, methane-generating maize residue （MR）, and black carbon made from maize straw （BC）. These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control （CK）. The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen （N） application （ON） and site-specific N management （SSNM）. Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either ON or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane （CH4） carbon dioxide （CO2）, or nitrous oxide （N20） from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas （except N20 emission in the BC treatment） and global warming potential （GWP）. Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer （MS, MC or MR） could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.

Cotton Response to Variable Nitrogen Rate Fertigation through an Overhead Irrigation System

Recent increases in irrigated hectares in the Southeastern US have enabled growers to obtain higher yields through applying nutrients through irrigation water. Therefore, many growers apply nutrients through irrigation systems, known as fertigation. Currently, there are no practical decision-making tools available for variable-rate application of nitrogen (N) through overhead sprinkler irrigation systems. Therefore, field tests were conducted on cotton (Gossypium hirsutum L.) during the 2016 and 2017 growing seasons to 1) adapt the Clemson sensor-based N recommendation algorithms from a single side-dress application to multiple applications through an overhead irrigation system;and 2) to compare sensor-based VRFS with conventional nutrient management methods in terms of N use efficiency (NUE) and crop responses on three soil types. Two seasons of testing Clemson N prediction algorithms to apply multiple applications of N were very promising. The multiple applications of N compared to the grower’s conventional methods (even though less N was applied) had no impact on yields in either growing season. There was no difference in cotton yields between 101 and 135 kg/ha N applications in either management zone. Also, there were no differences in yield between sensor-based, multiple N applications and conventional N management techniques. In relation to comparisons of the sensor methods only applying N in three or four applications, statistically increased yields compared to single or split applications in 2016. Applying N in four applications, statistically increased yields compared to single, split or triple applications in 2017. When the sensor-based methods were compared to the grower’s conventional methods averaged over four treatments, the sensor-based N applications reduced fertilizer requirement by 69% in 2016 and 57% in 2017 compared to grower’s conventional methods. When comparing N rates among the four sensor-based methods (three or four) applications, increased N rates by 22 kg/ha in 2016 and 26 kg/ha in 2017 compared to single or split applications but increased the cotton lint yields by 272 and 139 kg/ha, for 2016 and 2017, respectively.

Changes in foliar nitrogen resorption of Phyllostachys edulis with culm development

Leaf nitrogen resorption is very important to Phyllostachys edulis development because the withdrawn nitrogen can help newly emerging and growing culms.However, few studies have focused on the ontogenetic changes in leaf nitrogen resorption of P. edulis. Here, we examined the variability in mature leaf nitrogen concentrations(Nm), nitrogen resorption efficiency(NRE) and proficiency(NRP or Ns) and leaf-level nitrogen use efficiency(NUE) of the current-, 3 rd-and 5 th-year culms in P.edulis stands under extensive management. Analyses of variance and correlation indicated that patterns of Nm,NRP, NRE and NUE were markedly affected by culm age and leaf nitrogen status. Nm, Nsand NRE were significant higher in younger(current-year) culms with 1-year lifespan leaves, while NUE was markedly higher in older(3 rd-or 5 th-year) culms with 2-year lifespan leaves. Significant linear correlations between Nmand NRP, NRE and NUE,Nmand NUE, Nsand NRE were found for each culm age,and Nmwas significantly positively correlated to NRE for all culms pooled. Higher proficiency in older culms led to higher NUE and lower NRE, these relationships can be modulated by Nm, which in turn, is restrained by leaf N availability and acquisition. Our results revealed that at the intraspecific level, P. edulis can adjust its leaf NRE, NRP,and leaf-level NUE in concert with culm development.Understanding nitrogen resorption characteristics and NUE of P. edulis can help decision-makers design appropriate deforestation strategies and achieve precise N fertilization for sustainable bamboo forest management.

高寒区‘青引1号’燕麦种子产量对氮、磷、钾肥的响应

为明确青藏高原高寒地区施用氮、磷、钾肥对‘青引1号’燕麦(Avena sativa‘Qingyin No.1’)种子产量的影响,本研究以‘青引1号’燕麦为研究对象,在青海省西宁市湟中区分别设置氮磷钾单施试验,其中氮肥水平为(N_(0)、N_(30)、N_(45)、N_(60)、N_(75)、N_(90)和N_(105))、磷肥水平为(P_(0)、P_(15)、P_(30)、P_(45)、P_(60)、P_(75)和P_(90))、钾肥水平为(K_(0)、K_(10)、K_(20)、K_(30)、K_(40)、K_(50)和K_(60))。以确定最佳施肥水平,明确不同肥料对燕麦种子增产的效果,完善该品种在种子生产过程中的肥料管理技术,为青海地区燕麦种子生产中肥料的施用配比提供科学指导。结果表明:氮、磷、钾肥分别以60、60和50kg·hm^(-2)处理时种子产量最高,分别达4 358.6、6 285.0和6 729.1 kg·hm^(-2),以钾肥对燕麦种子增产效果最为明显;氮肥可显著提高燕麦小穗数、穗长和千粒重,磷肥可促进燕麦有效分蘖、粒宽和单序籽粒重增加,而钾肥则有助于有效分蘖数、粒长、粒宽、单序籽粒重和千粒重提升;氮、磷、钾肥单施水平下以粒宽和小穗数对种子产量直接效应最大,小花数和粒宽通过对其他产量性状的间接作用对种子产量产生增益效果。高寒地区‘青引1号’燕麦种子生产中,钾肥的施用可有效提高‘青引1号’燕麦种子产量。

施肥模式对菜-稻轮作周年氮素吸收及产量的影响

为探明不同施肥模式对菜-稻轮作体系周年氮素吸收及其产量的影响,以长期定位试验中菜-菜-稻轮作和菜-菜-菜轮作各季作物为研究对象进行田间试验。2种轮作体系分别采用推荐施肥和习惯施肥2种施肥模式,于2020—2022年对各季作物氮含量和产量进行测定,研究不同施肥模式和轮作下各季作物周年氮素吸收积累量、氮肥偏生产力及其对产量效益的影响。结果表明,2个轮作周年内菜-菜-稻轮作方式下推荐施肥模式第二季作物(芥菜)和第三季作物(水稻)氮素年均吸收积累量为415.71 kg/hm^(2),显著高于习惯施肥模式(381.43kg/hm^(2))。第一和第二轮作周年,不同轮作施肥方式下四季豆作物的氮素收获指数为0.61~0.65,各处理之间无显著差异;推荐施肥处理水稻作物氮素收获指数分别为0.72和0.73,显著高于习惯施肥处理(0.62和0.62)。通过各季作物氮素吸收量与产量的相关分析表明推荐施肥处理能够提高作物氮素吸收利用率。菜-菜-稻轮作结合推荐施肥处理的年均产投比(1.79)高于习惯施肥处理(1.47),菜-菜-菜轮作结合推荐施肥处理的年均产投比(1.56)高于习惯施肥处理(1.36)。因此,推荐施肥处理作物的周年氮素吸收积累量和产量均高于习惯施肥,该施肥模式有利于菜-菜-稻轮作方式实现作物高产和氮肥高效利用,可获得较好的经济效益。

施氮量对两个强筋小麦品种品质的影响

为了探究施氮量对强筋小麦品质特性的影响,以强筋小麦品种‘郑麦366’和‘郑农46’为试验材料,分别设置0、120、240和360 kg/hm^(2)的施氮量,研究不同氮水平对小麦面筋蛋白组成及二级结构、淀粉的粒度分布和粘度特性、面团流变学特性的影响。结果表明,‘郑麦366’和‘郑农46’分别在N_(1)(120 kg/hm^(2))和N_(2)(240 kg/hm^(2))水平下流变学特性达到最佳,这可能是因为两个小麦品种分别在N_(1)和N_(2)下蛋白质含量较高、总淀粉含量较低、B型淀粉相对含量较高;相比于N_(0)(0 kg/hm^(2)),N_(3)(360 kg/hm^(2))条件下的面团流变学特性显著降低,可能是由于过量施氮分别影响了‘郑麦366’的蛋白含量和‘郑农46’的B型淀粉含量。综上,相比于其他品质性状,蛋白含量对‘郑麦366’品质的影响更大,而B型淀粉含量的变化在‘郑农46’品质形成中起主导作用。本研究为强筋小麦‘郑麦366’和‘郑农46’的氮素施用提供理论依据。

氮素管理对水稻产量和食味品质的影响

氮素管理对于保证水稻产量、提高食味品质具有重要的调控作用。近年来,过量氮肥施用大幅提升了水稻产量但由此造成的环境污染、增加种植成本、危害人类健康引起了广泛关注。同时,消费者更加关注水稻食味品质,因此如何在保证水稻产量的前提下提高食味品质成为该领域的研究热点。从水稻产量、淀粉和蛋白质特性以及食味品质的角度,综述了对水稻进行优化氮素管理的国内外研究现状,分析了现阶段水稻氮素管理在实际应用中存在的问题,并对其发展前景进行了展望,以期为今后水稻生产中的氮素管理提供重要参考,实现高产和更好的食味品质。