javad shabahng

 Characteristics such as the high levels of agrobiodiversity, the efficiency of the nutrition, and also variety in ecological and socio-economic functions have altered home gardens into the appropriate model for achieving a sustainable agricultural system. So far, fewer studies in relation to these features have been done in home gardens of dry and semi-arid regions. Protection of diversity with a particular emphasis on agricultural biodiversity is fundamental to sustainable development in food production and hence food security. Expansion of industrial agriculture in the form of monoculture for the purpose of maximizing the yield with the aid of high-yielding varieties and intensive use of inputs has hampered the ecological functions of food production systems worldwide. This problem can be overcome by the application of a wide array of ecological agriculture practices, of which food production in home gardens is only one of them. This environmentally sound practice is an old system of land use almost in all parts of the world with a wide range of dimensions. A combination of different plants, from herbs to trees and in cases with poultry and other low-weight animals, provides a complex sustainable system of food production. This type of subsistence food production is based on local knowledge and normally is part of the residential area or, to the, low input. Food produced in this system is consumed locally, and women are the main element in both production and marketing. Exchanges of experience and knowledge, seed, and also tools, and labors are very common in neighboring communities. The purpose of the present study was to investigate the agrobiodiversity of home gardens in an arid environment of Khorasan Razavi Province.Materials and

Data collection for this study was based on the fieldwork with the distribution of questioners. For this purpose, 17 villages from 3 highly populated counties of Mashhad/ Quchan and Nyshabour were selected, and 164 questioners were distributed with a face-to-face procedure. After the collection and validation of data, only 136 questionnaires were selected, data were extracted, and finally, an analysis was carried out. Afterward, the Shannon biodiversity index, Simpson index, and species richness were calculated. The amount of carbon sequestered was also calculated by an equation referred to in the literature. For the calculation of biodiversity indices, the area under cultivation of each species was used. Based on the available previous studies, seven basic functions for home gardens were assigned.

Results showed the highest Shannon index of species diversity equal to 1.88 for the county of Neishabour; however, the highest functional diversity was found in Quchan. More the 79 percent of changes in the Shannon index are caused by changes in species richness. Stepwise regression analysis revealed that changes in species richness, home area, and household population were the factors that caused 84 percent of changes in functional diversity. Home gardens in these three counties sequester 8.1 tons of carbon dioxide per hectare, and this amount showed a decreasing trend where the distance from the vehicle roads was increased.

It was revealed that with taking distance from the main roads, the amount of carbon dioxide (kg per m2) decreased by tree species.AcknowledgmentsThe authors acknowledge the financial support of this project (grant number 2/19719) by the Vice President for Research and Technology, Ferdowsi University of Mashhad, Iran.

CO2 is considered the most important greenhouse gas, due to the dependence of world economies on fossil fuels. CO2 concentration are enhancing in the last decades, mainly due to the increase of anthropogenic emissions. Carbon dioxide capture is a technology aimed at mitigating greenhouse gas emissions from burning fossil fuels during industrial processes. Conservation tillage, crop rotation, and crop residue management are agronomic practices that potentially decrease CO2 and other greenhouse gas emissions from agriculture. Crop residues also improve organic matter decomposition due to declined soil-residue contact. Soil is one of the significant “friends” in combating climate change and global warming, and a zero-soil consumption approach is the best way to stop adverse effects, although it is not the only one that should be applied. The soil has been considered as a possible carbon sink for sequestering atmospheric CO2.
Our purposes were to determine a set of coefficients for calculating conversion coefficients, dry weight, organic carbon, and carbon sequestration of above-ground and below-ground tissues and assess global warming potential (GWP) for wheat as an essential crop in Khorasan-e Razavi province.

A systematic random sampling method was employed to select five samples from 25 fields situated in Khorasan-Razavi Province, Iran, during 2016 and 2017. The experimental design was a completely randomized design with three replications. Below-ground tissues by using a cylinder were manually sampled and then separated from the soil. After sampling, the above-ground tissues (such as flower and leaf) were isolated from below-ground tissues (including tunic and corm) to measure the above-ground and below-ground biomasses, respectively. Above-ground and below-ground biomasses were separately dried to constant weight and expressed on a dry matter basis. Conversion coefficients of above- ground and below- ground tissues were determined with the combustion method separately. Then, sequestration carbon potential for above- ground and below- ground tissues of saffron and soil were computed. The ash method was used to determine the conversion coefficients in spikes, stems, leaves, and roots. Finally, greenhouse gases (such as CO2, N2O, and CH4) emission were also calculated using emission coefficients. Cronbach's alpha was used for assessing the reliability of the questionnaire.
For statistical analysis, analysis of variance and Duncan’s test were performed using SAS version 9.3.

The results showed that dry weight, organic carbon content, conversion coefficients, and carbon sequestration for above- ground and below- ground tissues of wheat were significantly different. The biomass of above-ground tissues was higher than below-ground tissues of wheat. The results revealed that the maximum (52.0%) and minimum (31.99%) conversion coefficients of wheat were related to spikes (seeds included) and roots, respectively. Besides, the total carbon sequestration of below-ground and above-ground of wheat was calculated 8.25 t.ha-1 so that the maximum (4.28 t.ha-1) and minimum (0.35 t.ha-1) values were found in stems and roots, respectively. GWP was recorded as 8884.86 kg CO2-equiv. per one ton of seed.

This study shows that while there is significant potential for sequestering carbon in wheat agroecosystems through root and straw incorporations. It is recommended that returning wheat crop residues to the soil affected the soil's physical, chemical, and biological properties. Furthermore, as nitrogenous fertilizer application plays a crucial role in increasing GWP, thus it is suggested that organic fertilizers and legumes might be suitable alternatives for chemical fertilizers. It is therefore concluded that the application of crop residues in agroecosystems seems to be a rational ecological approach for sustainable management of wheat agroecosystems with a consequence of the reduction in greenhouse gases and mitigation of climate change. This could make a significant contribution to improving agricultural sustainability and stability in arid and semiarid regions.