تقييم أداء نظام الري بالرش باستخدام أطوال مختلفة لارتفاع حامل الرشاش عند زراعة محصول الذرة

Abstract

The study was conducted during the summer of 2019 at the Agricultural Research Station (Assafsaf - Jabal Al Akhdar), which is located to the east of the city of Al-Bayda in northeastern Libya, at 32.5° latitude and 21.5° longitude. The study aims to evaluate the performance of the sprinkler irrigation system during the growth stages of the corn plant and its relationship to the height of the sprinkler riser. By measuring the uniformity coefficient as the most important element of the evaluation, where it indicates the homogeneity of water distribution in the field. Whereas, if the uniformity coefficient in the fixed sprinkler irrigation system is less than 80%, the water distribution is not good. Engineering experiments were conducted to determine the specifications of the (Modil: Dw20) sprinkler of DONEWELL company present in the local market without any specifications. Different relationships between pressure- flow rate and pressure- wetting diameter were found and necessary engineering equations were identified, uniformity coefficients, and wetting overlap ratios relationships were found. Timing of changing sprinkler riser heights during the irrigation season were determined. The results of the sprinkler evaluation showed that operating pressure of the sprinkler used in the research could be used from1.7 to 2.3 bar to cover wetting diameters from20 to 24meters, respectively, and an equation describe the relationship between sprinkler flow and operating pressure was derived. The land was prepared and plowed, and divided into three experimental units, the dimensions of each unit (33mby 11m) to start planting maize seeds (single hybrid 3062), where the average planting date was May 20. The distance between corn rows was 70 cm, and the distance between the seeds in the row was 25 cm. The experiment was designed in a completely random manner. So that the source of the difference between the three parameters (T1, T2, and T3) is the height of sprinkler risers (1, 2, and 3) meters, respectively, and with three replicates . The results showed at the beginning up to one meter height, the uniformity coefficient values were (87, 86, and 88)% in the first, second, and third treatment, respectively, where the plant heights were less than the heights of the sprinkler risers and the resultant uniformity coefficient values were good in the three treatments. While the results of the uniformity coefficient values at the end of the growing season were (24, 24.3, and 83%) in the first, second, and third treatment respectively. The results of the uniformity coefficient values at the end of the season showed that the value of the third treatment is the best and is considered good; As the height of the sprinkler riserwas increased at the right time during the growth stages of corn plant; The height of the plant was always less than the height of the sprinkler riser in the third treatment, in contrast to the first and second treatments. This resulted in improvement of some plant characteristics such as plant height, plant stemdiameter, and corn cob length (3m, 3 cm, and 21.2 cm) respectively in the third treatment, compared to the first treatment that resulted in plant characteristics such as plant height, stem diameter, and cob length of (1.4m, 2cm, and 9.5cm) respectively. These plant growth characteristics give indication of yield.