大豆生产中氮磷钾肥和有机肥施用与大豆生物量和能量分析相关性研究

该研究试图量化大豆的根生物量和密度、根瘤、作物生物量和籽粒产量,从而分析作物生长和能量输入(可再生和不可再生)与施用氮磷钾肥和有机肥的关系。观察并记录不施肥、施用氮磷钾肥及氮磷钾+农家肥的生长状况。与施用氮磷钾肥相比,施用氮磷钾+农家肥的根生物量显著增加。根生物量的增长趋势,符合这样一个规律:施用氮磷钾+农家肥根长密度较高。施用氮磷钾+农家肥处理中茎、叶柄和叶片生物量明显大于其他处理。在成熟期大豆的生物量中,茎生物量占29%,叶柄生物量占9%,叶片生物量占17%,豆荚生物量占46%,二次回归模式很好的反应了茎、叶柄和叶片生物量的数据。最大LAI为4.88,在成熟期总生物量为633gm2,施用氮磷钾+农家肥时CGR为18.4g/m2?d。在施用氮磷钾肥和氮磷钾+农家肥处理中,籽粒产量分别增加了72.5%到98.5%,秸秆产量增加56%到94.8%,均高于对照处理。尽管施用氮磷钾+农家肥处理能量输入高于施用氮磷钾肥和对照处理,但是施用氮磷钾+农家肥与施用氮磷钾肥相比具有较多的可再生能源、较大的能量输出和不可再生能源。施用氮磷钾+农家肥处理对不可再生资源的利用效率较高。因此,在大豆生产中氮磷钾肥与有机肥(农家肥)配合施用,是一种可行的营养管理方式。

Dynamical behaviors of a constant prey refuge ratio-dependent prey-predator model with Allee and fear effects

In this paper,we consider a nonlinear ratio-dependent prey-predator model with constant prey refuge in the prey population.Both Allee and fear phenomena are incorporated explicitly in the growth rate of the prey population.The qualitative behaviors of the proposed model are investigated around the equilibrium points in detail.Hopf bifurcation including its direction and stability for the model is also studied.We observe that fear of predation risk can have both stabilizing and destabilizing effects and induces bubbling phenomenon in the system.It is also observed that for a fixed strength of fear,an increase in the Allee parameter makes the system unstable,whereas an increase in prey refuge drives the system toward stability.However,higher values of both the Allee and prey refuge parameters have negative impacts and the populations go to extinction.Further,we explore the variation of densities of the populations in different bi-parameter spaces,where the coexistence equilibrium point remains stable.Numerical simulations are carried out to explore the dynamical behaviors of the system with the help of MATLAB software.

Bifurcation analysis and optimal control of an epidemic model with limited number of hospital beds

This paper deals with a three-dimensional nonlinear mathematical model to analyze an epidemic's future course when the public healthcare facilities,specifically the number of hospital beds,are limited.The feasibility and stability of the obtained equilibria are analyzed,and the basic reproduction number(Ro)is obtained.We show that the system exhibits transcritical bifurcation.To show the existence of Bogdanov-Takens bifurcation,we have derived the normal form.We have also discussed a generalized Hopf(or Bautin)bifurcation at which the first Lyapunov coefficient evanescences.To show the existence of saddle-node bifurcation,we used Sotomayor's theorem.Furthermore,we have identified an optimal layout of hospital beds in order to control the disease with minimum possible expenditure.An optimal control setting is studied analytically using optimal control theory,and numerical simulations of the optimal regimen are presented as well.

Detection of plant leaf diseases using image segmentation and soft computing techniques

Agricultural productivity is something on which economy highly depends.This is the one of the reasons that disease detection in plants plays an important role in agriculture field,as having disease in plants are quite natural.If proper care is not taken in this area then it causes serious effects on plants and due to which respective product quality,quantity or productivity is affected.For instance a disease named little leaf disease is a hazardous disease found in pine trees in United States.Detection of plant disease through some automatic technique is beneficial as it reduces a large work of monitoring in big farms of crops,and at very early stage itself it detects the symptoms of diseases i.e.when they appear on plant leaves.This paper presents an algorithm for image segmentation technique which is used for automatic detection and classification of plant leaf diseases.It also covers survey on different diseases classification techniques that can be used for plant leaf disease detection.Image segmentation,which is an important aspect for disease detection in plant leaf disease,is done by using genetic algorithm.

A MATHEMATICAL MODEL FOR THE DEPLETION OF FORESTRY RESOURCES DUE TO POPULATION AND POPULATION PRESSURE AUGMENTED INDUSTRIALIZATION

In this paper,a nonlinear mathematical model is proposed and analyzed to study the depletion of forestry resources caused simultaneously by population and population pressure augmented industrialization.The control of population pressure,using economic efforts is also considered in the modeling process.It is assumed that cumulative biomass density of forestry resources and the density of population follow logistic models.It is further assumed that the density of population and the level of industrialization increase as the cumulative biomass density of forestry resources increases.The cumulative density of economic efforts,which are applied to control the population pressure,is considered to be proportional to the population pressure.The model analysis shows that as the population pressure increases,the level of industrialization increases leading to decrease in the cumulative biomass density of forestry resources.It is found that if population pressure is controlled by using some economic efforts,the decrease in cumulative biomass density of forestry resources can be made much less than the case when no control is applied.It is also noted that if the population pressure augmented industrialization increases without control,the forestry resources may become extinct.

A mathematical model to achieve sustainable forest management

Forest resources are important natural resources for all living beings but they are continuously depleting due to overgrowth of human population and their development activities.Therefore,conservation of forest resources is an important problem for sustainable development.In view of this,in this paper,we have proposed and analyzed a nonlinear mathematical model to study the effects of economic and technological efforts on the conservation of forest resources.In the modeling process,it is assumed that due to increase in population size,the demand of population(population pressure)for forest products,lands,etc.,increases and to reduce this population pressure,economic efforts are employed proportional to the population pressure.Further,it is assumed that technological efforts in the form of genetically engineered plants are applied proportional to the depleted level of forest resources to conserve them.Model analysis reveals that increase in economic and technological efforts increases the density of forest resources but further increase in these efforts destabilizes the system.Numerical simulation is carried out to verify analytical findings and explore the effect of different parameters on the dynamics of model system.