جستجوی مقالات مرتبط با کلیدواژه « Actual yield » در نشریات گروه « آب و خاک »

Due to limited water resources, increasing water productivity is very important to achieve water security and food security. One of the basic measures in this area is to determine the difference in product performance between the current situation and the potential situation. Crop potential yield is one of the parameters that can be used to calculate the yield gap and to manage water and soil resources based on the factors affecting production. In this study, the potential yield of major crops in the composition of irrigation network of Qazvin plain has been determined by agronomic method. The results showed that the yield gap in the crop composition of major crops in Qazvin plain was 3339 (kg / ha). Also, the average yield gap due to the composition of cultivation, yield gap of each crop and the area under cultivation of crops in the irrigation network of Qazvin plain, was 26.23%. The results of estimating the potential yield at the level of the irrigation network of Qazvin plain show that not all crops have reached the achievable yield level (75 to 85% of the potential yield) and there has been a high yield in crops such as sugar beet, tomato and alfalfa. Given that in the current situation of operation of the irrigation network, it is very difficult to achieve potential performance, in such cases, the gap between actual performance and achievable performance should be reduced.

Land suitability evaluation is inevitable for soil protection. Selection of an appropriate land suitabiliyty method seems to be necessary due to the limitation of the FAO method as a conventional method. In this regard, multi-criteria desision methods (MCDM) such as electrothermics, can be helpful due the considering the weights of effective factors and experts oponions in land suitability evaluation.
In this research, Square Root Method and ELECTRE Tri multiple criteria method have bean also used for suitability evaluation in an area about of 5000 ha of Chalderan region located between 47° 19′- 47° 23′ East longitude and 39° 01′-39° 08′ North latitude for potato cultivation. In general 60 soil profiles were dug, described and sampled and after soil samples analysis, soil texture, gravels, calsium carbonate, gypsum, EC, ESP, slope, flooding, drainage and region climate in different profile were produced by weighted coefficients. Criteria weights via pair-wise comparison matrix method and ELECTRE Tri profiles and thresholds limits determined using requirements table, soil and land properties data. In two selected land suitability method, land production potential was calculated by multiplication of the soil indices and radiation thermal production potential.
soils of study region has been classified on Entisols, Inceptisols and Aridisols based on 12th Keys to soil taxonomy. Statistics comparison of allocated grades mean to suitability classes’ reveald that results of two methods were significantly different and ELECTRE Tri method had the best grade. Also mean comparing of soil and land properties amount via Duncan test showed significant difference between suitability classes. The ELECTRE Tri methods was the best model from the viewpoint of statistical indices including R2 (0.87) and RMSE (241.2). Also, Root mean square method has a R2 (0.79) and RMSD (197.6). Predicted potential production by Root mean squre method and ELECTRE Tri method was 9330 to 30200 and 10140 to 32350, respectively. The GMER index also indicated lowestimation of two selected land evaluation method. ELECTRE Tri suitability evaluation that implies high accuracy of this method due to determination of transition suitable limits, appropriate values of thresholds and criteria weights as well as usage of fuzzy logic principals on calculation processes.
ELECTRE Tri method, integrated into expert opinion, is better suited to the problem of land suitability for agriculture. The time saving during the development of the land suitability evaluation for the agriculture of the potato was considerable. The coherence of the obtained rsults with observed yield confirms the system effectiveness.