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    Appraisal of Three Proximal Sensing Systems to Estimate Macronutrient Contents of Detached Soybean Leaves
    (Taylor & Francis Inc, 2021) Keskin, Muharrem; Say, Sait M.; Sekerli, Yunus Emre; Sehri, Mustafa
    Overapplication of fertilizers is common and may lead to plant toxicity and pollution of water resources in agriculture. A practical method is needed to estimate nutrient stress quickly, easily, and economically for a sustainable management. This study dealt with the prediction of leaf moisture content (MC) and macronutrient contents including nitrogen (N), phosphorus (P), and potassium (K) of soybean leaves using three different optical instruments of chromameter, chlorophyll meter and fluorometer. Forty-five leaf samples from a commercial soybean field were obtained. Color parameters (L*, a*, b*), SPAD (soil plant analysis development) values and quantum yield (QY) values were quantified for each leaf sample. Leaf and soil samples were analyzed using standard leaf and soil chemical analysis procedures. Correlation analysis, principal component analysis (PCA) and partial least square regression (PLSR) were used for data analysis. High correlation was found between two color parameters (L* and b*) with MC and macronutrient contents (r >= 0.65) and also, among SPAD, QY, MC, and macronutrient contents (r >= 0.70). The prediction models were evaluated based on the RMSEP (root mean square error of prediction) and R (2) (coefficient of determination) values. The results showed that soybean leaf N content can be estimated using all three optical instruments with chromameter giving slightly better results (RMSEP = 0.23%, R (2) = 0.80). Concerning the MC, chlorophyll meter gave slightly better prediction performance (RMSEP = 2.69%, R (2) = 0.73) than the other two instruments. Hence, results suggest that these three optical instruments can be used to assess the macronutrient contents of soybean leaves quickly, easily, and economically.
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    Comparing the Performance of Conventional and Stripping Headers in Wheat Harvest
    (Ankara Univ, Fac Agr, 2010) Say, Sait M.; Ince, Ahmet; Ugurluay, Selcuk; Soysal, Alper
    The aim of this study was to compare the performance of conventional and stripping headers, which can be an alternative for cereal harvesting, in terms of technical and management aspects. For this purpose, grain looses, effective field capacity and fuel consumption values of both two headers were determined. Field tests were conducted based on split plots in randomized blocks that header (conventional and stripping), forward speed (5, 7 and 9 km h(-1)) and moisture content of grain (11 and 16%) were chosen as independent variables. It was obtained that the forward speed and the moisture content were effective on grain looses and fuel consumption statistically (P < 0.01). In harvest with conventional header at 5 km h(-1) forward speed, total grain looses and fuel consumption were 0.79%, 10.4 l ha(-1) and 0.71%, 12.2 l ha(-1) for 11 and 16% moisture contents, respectively. Total grain looses decreased with increase in forward speed and moisture content in harvesting with stripping header. For stripping header, total grain looses ranged between 1.11-0.86% and 0.82%-0.59 for 11% and 16% moisture contents, respectively. Fuel consumption decreased with increasing forward speed, but it increased with increasing moisture content. These values varied from 6.4 to 8.0 l ha(-1) for high moisture content and varied from 7.6 to 8.8 l ha(-1) for low moisture content. Comparing the conventional header at ideal forward speed (5 km h(-1)) with the stripping header at highest forward speed (9 km h(-1)), it was found that the total losses were almost same for both two headers, the effective capacity was 153% higher and the fuel consumption was 32% less for stripping header.
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    Feasibility of low-cost GPS receivers for ground speed measurement
    (Elsevier Sci Ltd, 2006) Keskin, Muharrem; Say, Sait M.
    Ground speed measurement is required in many agricultural machinery operations. There are a number of techniques for the determination of the ground speed; however, each of these methods has some disadvantages. It is known that a GPS receiver is capable of calculating travel speed; however, no study has been reported on the performance of low-cost GPS receivers in measuring the ground speed in agricultural machinery operations. The objective of this work was to study the effectiveness of low-cost GPS receivers for measuring ground speed. Computer programs were written to read, store, and process the GPS data from two different low-cost GPS receivers. Differential correction was not used in the study since there was no correction service in the study area. A very strong relationship between the average GPS speeds and the average calculated speeds was found in the study (R-2 > 0.99). Also, the results showed that the GPS receivers followed the speed change quite well. GPS receivers can be used to determine both the position and the speed of the agricultural machinery. In this way, there is no need to use a separate speed sensor leading to simpler and more affordable instrumentation systems. In conclusion, low-cost GPS receivers can be confidently used to measure the ground speed in agricultural machinery operations. (c) 2006 Elsevier B.V. All rights reserved.