انتشار گازهاي گلخانه اي و پتانسيل گرمايش جهاني ناشي از مصرف نهاده هاي شيميايي در زراعت محصولات مهم استان كرمان: II- محصولات باغي

Greenhouse Gases Emission and Global Warming Potential as Affected by Chemical Inputs for Main Cultivated Crops in Kerman Province: II- Horticultural Crops

مصرف بي رويه نهاده هاي شيميايي در بخش كشاورزي سبب افزايش انتشار گازهاي گلخانه اي در جهان شده است.اين مسئله،پديده گرمايش جهاني و اثرات زيست محيطي زيادي را به وجود آورده است. بنابراين، اين مطالعه با هدف بررسي ميزان انتشار گازهاي گلخانه اي و پتانسيل گرمايش جهاني حاصل از مصرف نهاده هاي شيميايي (انواع كودها و آفت كش ها) در كشت سيب زميني (.Solanum tuberosum L) و پياز (Allium cepa L.) و هنداونه (Citrullus lanatus L.) برخي شهرستان هاي استان كرمان در سال زراعي 1392-1391 انجام شد. سطح زير كشت محصولات مورد مطالعه از طريق آمار سازمان جهاد كشاورزي استان استخراج گرديد. ميزان نهاده هاي شيميايي مورد استفاده در محصولات فوق توسط محاسبه-هاي حضوري و پرسشنامه ها از شهرستان هاي مورد مطالعه استان (بردسير، بم، جيرفت، كرمان، راور، رفسنجان و سيرجان) جمع آوري گرديد. نتايج نشان داد كه در هر سه محصول بيشترين و كمترين ميزان انتشار گازهاي گلخانه اي به ترتيب مربوط به شهرستان هاي جيرفت و رفسنجان بود. ميزان ساليانه پتانسيل گرمايش جهاني در بين شهرستان هاي مختلف استان با روند انتشار گازهاي گلخانه اي هماهنگ بود و براياين صفت نيز جيرفت و رفسنجان به ترتيب بيشترين و كمترين ميزان پتانسيل گرمايش جهاني را نشان دادند. براي هر سه محصول مورد مطالعه، ميزان انتشار گازهاي گلخانه اي حاصل از مصرف كود نيتروژن بيش از ساير نهاده هاي شيميايي بود. ميزان انتشار CO2، N2O و CH4 برآورد شده در سيب زميني بيش از هنداونه و در هنداونه بيشتر از پياز گزارش شد. همچنين، ميزان ساليانه پتانسيل گرمايش جهاني معادل دي اكسيد كربن در كشت سيب زميني، هندوانه و پياز به ترتيب 6814/2 تن،6024/2 تن و 2125 تن بود. در بين نهاده هاي مورد بررسي، نيتروژن (91 درصد)، فسفر (6/9 درصد) و علف كش (يك درصد) بيشترين سهم را در پتانسيل گرمايش جهاني در محصولات مورد بررسي دارا بودند.

Introduction The latest report of the IPCC states that future emissions of greenhouse gases (GHGs) will continue to increase and will be the main cause of global climatic changes, as well as Iran. The three greenhouse gases associated with agriculture are CO2, CH4, and N2O. Chemical inputs consumption in agriculture has increased annually, while more intensive use of energy led to some important human health and environmental problems such as greenhouse gas emissions and global warming. Therefore, it is necessary to reduce the application of chemical inputs in agricultural systems. Agriculture contributes significantly to atmospheric GHG emissions, with 14% of the global net CO2 emissions coming from this sector. Chemical inputs have a major role in this hazards. There is even less data on CO2, N2O, and CH4 gas emission analysis as affected by cultivating various crops in Kerman province. Therefore, this study was conducted to assess the GHGs emission and Global warming Potential GWP caused by chemical inputs (various chemical fertilizers and pesticides) for cultivating potato, onion and watermelon in some regions of Kerman province at 2011-2012 growth season. Material and Methods The study was conducted in Kerman province of Iran. Data of planting area, application rates of the chemical inputs and other different parameter were collected from potato, onion and watermelon growers by using a face to face questionnaire in 2014 for different regions of Kerman(Bardsir, Bam, Jiroft, Kerman, Ravar, Rafsanjan and Sirjan). In addition to the data obtained by surveys, previous studies of related organization (Agricultural Ministry of Kerman) were also utilized during the study. Farm random sampling was done within whole population and the sample size was determined by proper equations. The amounts of GHG emissions from chemical inputs in the studied crops were calculated by using CO2, N2O and CH4 emissions coefficient of chemical inputs. Then the amount of each GHG changed into CO2using the specific GWP of each gas, which is the warming influence relative to that of carbon dioxide. Results and Discussion The results showed that N and P fertilizers had the highest application share of chemical inputs. Among the studied crops, the highest amount of chemical fertilizers was used in potato. Potato and watermelon were obtained the highest doses of herbicide and pesticide application, respectively. The results demonstrated that in all these three crops, the highest and lowest GHGs emission was related to Jiroft and Rafsanjan, respectively. The amount of annual GHGs emission was related to the regions planting area. The highest share of emission gas in all the three crops and all regions was related to CO2. In potato and onion, herbicide was caused higher CO2 emission compared to insecticide and fungicide. Watermelon cultivation contained no herbicide application. GWP in the studied regions had the same trend with GHGs emission. In all three studied crops, Jiroft and Sirjan were obtained the highest and lowest values of annual GWP, respectively. In all studied crops, N fertilizer led to more GHGs emission in comparison to other inputs. Potato had the highest emission of CO2, N2O and CH4 followed by watermelon, and the lowest amount was gained in onion. Also, annual GWP of potato, watermelon and onion were 6814.2, 6024.2 and 2125 ton CO2 equivalence, respectively. Among all chemical inputs, N (91%), P (6.9%) and herbicide (1%) were involved the highest share in GWP for studied plants. Conclusion The results showed that in all three studied crops, the highest and lowest GHGs emission was related to Jiroft and Rafsanjan, respectively. Annual GWP in the studied regions had the same trend with GHGs emission. In all three studied crops, Jiroft and Sirjan were obtained the highest and lowest values of annual GWP, respectively. In all studied crops, N fertilizer led to more GHGs emission in comparison to other inputs. Potato had the highest emission of CO2, N2O and CH4 followed by watermelon, and the lowest amounts was gained in onion. Among all chemical inputs, N (91%), P (6.9%) and herbicide (1%) were involved the highest share in GWP for studied plants.