Florin Sala

Using mathematical algorithms for classification of LANDSAT 8 satellite images

Satellite and aerial images are objective photographical representations of the reality from the field, related to spatial – temporal frames. The purpose of the present study is to create a comparative analysis of a LANDSAT 8 satellite image by supervised and unsupervised classification methods. The algorithms used in this research were maximum likelihood algorithm for supervised classification and ISODATA algorithm for unsupervised classification. From the multitude of possible combinations of spectral bands we chose the combination bands near infrared-red-green (543), image which has been subjected to the supervised and unsupervised classification process. This combination includes in addition the two bands from visible (R, G) the band near-infrared (NIR) which represents an area where the response of the vegetation is tinted and the cloudy formations are easier t penetrate. By analyzing the satellite image through supervised classification it enabled a result of 5 thematic classes defined by the user b...

Evaluation of agricultural yield in relation to the doses of mineral fertilizers

The present paper proposes a bifactorial model obtained by a generalization of the unifactorial Mitscherlich model. After analysing the graphic representation of the experimental data and the theoretical curves, one can conclude that they present good concordance. Treatments with nitrogen fertilizers within the limits of 0 – 200 kg a.i. ha-1 determined different optimum and maximum values for each of the four fertilization variants with phosphorus and potassium (optimum value 97 kg ha-1 N on P0K0 with yield increase of 1224 kg ha-1; optimum 107 kg ha-1 N on P50K50, with an increase of 952 kg ha-1; 111 kg ha-1 N on P100K100 with an increase of 968 kg ha-1 and 103 kg ha-1 N on P150K150 with an increase of 1413 kg ha-1). From an economical point of view, we will maximize the benefit corresponding to production value in the hypothesis that only one fertilizer is applied, namely a complex fertilizer of the type N15P15K15. For the actual price values q = 0.2 € ∙ kg−1, p = 0.6€ ∙ kg−1 the solution of the equation above is x = 221 kg ∙ ℎa−1.

Relation of normalized difference vegetation index with some spectral bands of satellite images

The satellite image is the current graphic document, containing the real data of the terrestrial surface when it was acquired, based on which the soil and the vegetation cover can be evaluated. The NDVI index is used for a large number of the vegetation properties. In this research we analyzed the variation of NDVI index depending on R, G, B and NIR spectral bands, based on the LANDSAT 8 images. The relation between NDVI index with the respective spectral bands was describe most accurately by an exponential regression equations of curves with negative coefficient in the case of R,G,B spectrum and by a logarithmic function for the NIR spectrum. The results show statistical certainty for all the relations of NDVI index with the analyzed spectral bands (RED:NDVI p<<0.001; r=-0.711), (GREEN:NDVI p<<0.001; r=-0.637), (BLUE:NDVI p<<0.001; r=-0.644), (NIR:NDVI p<<0.001; r=0.734). The relations of NDVI index with others synthetic indices was analyzed according with some linear regression function with statistical...

On the Optimization of the Doses of Chemical Fertilizers for Crops

The mono‐factorial model, which gives the relation between the yield and the dose of chemical fertilizers, is based on the Mitscherlich function f1(x) = f1(0)+a1(1−e−11x). In addition to this function, we can consider f2(x) = f2(0)+a2 tanh(b2x), to be the basis for a new mathematical model, where tanh(b2x) represents the hyperbolic tangent. In the case of a bi‐factorial model: f(x,y) = f(0,0)+a1 tanh(b1x)+a2 tanh(b2y)+a3 tanh(b1x)tanh(b2y) represents a generalization of the last relation. The constants that are involved in these functions are determined with the least squares method, by comparison with the experimental data. Taking into account both the market value of the products and the cost of fertilizers, we can find the optimal doses for maximizing certain economic indicators, such as revenue or profitability.The mono‐factorial model, which gives the relation between the yield and the dose of chemical fertilizers, is based on the Mitscherlich function f1(x) = f1(0)+a1(1−e−11x). In addition to this function, we can consider f2(x) = f2(0)+a2 tanh(b2x), to be the basis for a new mathematical model, where tanh(b2x) represents the hyperbolic tangent. In the case of a bi‐factorial model: f(x,y) = f(0,0)+a1 tanh(b1x)+a2 tanh(b2y)+a3 tanh(b1x)tanh(b2y) represents a generalization of the last relation. The constants that are involved in these functions are determined with the least squares method, by comparison with the experimental data. Taking into account both the market value of the products and the cost of fertilizers, we can find the optimal doses for maximizing certain economic indicators, such as revenue or profitability.

Aspects of modeling regarding the contribution of nitrogen to the formation of grape yields

The research focused on determining the influence of organic fertilization equivalent to 150, 200 and 250 kg ha−1 nitrogen, on the productivity indices that participate in the formation of the grape yield: grape berry weight, number of grape berries, rachis weight. Quality indices of grapes were also analyzed: structure index, berry index, as well as yield quality, through dry matter. The distribution analysis of the experimental data revealed that production increase dy/dx increases dramatically with the total fertilizer dose (x + x0), it being proportional to the saturation deficit (a−y), where a is the biologically maximum yield (asymptote). Constants a, b and x0 for each parameter were determined by confrontation with the experimental data, through the least square method, and they were used in modeling the contribution of nitrogen to the formation of grape yields. Although the equivalent quantity of nitrogen in the soil is 150 units, its use is different in the proposed model, depending on the parame...

Bifactorial model for the assessment of agricultural yield and economic efficiency of fertilization

Thepaperproposes a model which is helpful for obtaining some growth trajectories in relation to one factor, namely nitrogen-based fertilizers. Figures 1 - 4 show good concordance between the experimental data and the theoretical curves, which means that the model is good in assessing agricultural yield in relation to the dosesapplied. It is useful and important for farmers to knowthe optimum of some economic indicators. The present paper presents the results of our research of the maximum benefit, both theoretically and graphically.

Differentiated contribution of minerals through soil and foliar fertilization to the winter wheat yield.

Research has evaluated the contribution of minerals through soil and foliar fertilization on winter wheat yield, the purpose being to identify the interdependence relations for the optimization of the fertilization system. Two types of mineral and foliar fertilizers were tested. The complex mineral fertilizer of the type NPK (1:1:1) was used for achieving three differentiated nutrition levels: NPK0, NPK30 (30 kg active substance ha -1 ) and NPK60 (60 kg active substance ha -1 ). There are five types of foliar fertilizers applied and 18 experimental variants were studied. The research was conducted in Soil Science and Plant Nutrition (SSPN) and Mathematics and Statistics (MS), Banat University of Agricultural Sciences and Veterinary Medicine„ Regele Mihai I al României„ from Timisoara, Romania (USAMVBT), between 2011 and 2012. The influence of interaction between the two types of fertilizer compared to their individual influence on wheat production was analyzed. Based on Original Research Article Sala et al.; AJEA, 6(3): 158-167, 2015; Article no.AJEA.2015.075 159 regression analysis were obtained mathematical model of interdependence, reliability of the results and models have been certified by LSD, p and R 2 (maximum value is better). The complex fertilizers generated yield increase between 925*** and 1425*** kg ha -1 . The foliar fertilizers determined yield increase between 355 and 810*** kg ha with natural soil fertility (NPK0), between 550** and 900*** kg ha -1 with NPK30, and between 500** and 795*** kg ha -1 with NPK60. The yield increase determined by the joint effect of the two types of fertilization was between 1475*** and 2220*** kg ha -1 . The experimental results have high statistical confidence (p<.01; Fcrit<F for Alfa = .01). The study recorded a decrease in the potentiation effect of the foliar fertilizers and at the same time in their contribution to the winter wheat yield, when the doses of complex fertilizers applied on the soil were increased.

N2O, CO2, Production, and C Sequestration in Vineyards: a Review

Even if it is less polluting than other farm sectors, grape growing management has to adopt measures to mitigate greenhouse gas (GHG) emissions and to preserve the quality of grapevine by-products. In viticulture, by land and crop management, GHG emissions can be reduced through adjusting methods of tillage, fertilizing, harvesting, irrigation, vineyard maintenance, electricity, natural gas, and transport until wine marketing, etc. Besides CO2, nitrous oxide (N2O) and methane (CH4), released from fertilizers and waste/wastewater management are produced in vineyards. As the main GHG in vineyards, N2O can have the same harmful action like large quantities of CO2. Carbon can be found in grape leaves, shoots, and even in fruit pulp, roots, canes, trunk, or soil organic matter. C sequestration in soil by using less tillage and tractor passing is one of the efficient methods to reduce GHG in vineyards, with the inconvenience that many years are needed for detectable changes. In the last decades, among other methods, cover crops have been used as one of the most efficient way to reduce GHG emissions and increase fertility in vineyards. Even if we analyze many references, there are still limited information on practical methods in reducing emissions of greenhouse gases in viticulture. The aim of the paper is to review the main GHG emissions produced in vineyards and the approached methods for their reduction, in order to maintain the quality of grapes and other by-products.

Variation of chlorophyll content in sunflower under the influence of magnetic nanofluids

Various species of nanoparticles present the capacity to interact with vegetal structures, with stimulating or repressive effects, depending on the species of nanoparticles, the biological media and the reference level for the interaction. The present study targeted the influence of biocompatible magnetic nanofluid (F3O4/H2O - MNF) on the chlorophyll content of sunflower. An interdependence relation was found between chlorophyll and the MNF concentration in the tested interval (0.01 – 1% MNF), described by a second degree polynomial function, with high statistical confidence (p<0.01; R2 = 0.743). The average increase in the chlorophyll content given by MNF is between 1.01 and 4.58 SPAD units, with statistical confidence (p<0.01; R2 = 0.977). Chlorophyll variation rate ranged from 1.01 to -0.85, and negative increase Δ (growth rate) was recorded above the value 0.75% MNF with statistical confidence (p = 0.035; R2 = 0.814).

Mathematical and statistical analysis of the effect of boron on yield parameters of wheat

The main objective of this research is to investigate the effect of foliar applications of boron at different growth stages on yield and yield parameters of wheat. The contribution of boron in achieving yield parameters is described by second degree polynomial equations, with high statistical confidence (p<0.01; F theoretical < F calculated, according to ANOVA test, for Alfa = 0.05). Regression analysis, based on R2 values obtained, made it possible to evaluate the particular contribution of boron to the realization of yield parameters. This was lower for spike length (R2 = 0.812), thousand seeds weight (R2 = 0.850) and higher in the case of the number of spikelets (R2 = 0.936) and the number of seeds on a spike (R2 = 0.960). These results confirm that boron plays an important part in achieving the number of seeds on a spike in the case of wheat, as the contribution of this element to the process of flower fertilization is well-known. In regards to productivity elements, the contribution of macroelements ...