Assessment of canola agroecosystems health in Gorgan township by geographic information system (GIS)

In recent years the development and intensification of agricultural activities and attempts to achieve more profitability, causes rapid deterioration in the structure and functional properties of agroecosystems and a lot of damage to ecosystems has arrived. Therefore, today’s agroecosystems health and management researches are increasingly considered. Considering the important role of Golestan province in production of oilseeds as canola and reducing the acreage of these crops in recent years, the need to investigation the status of these fields is necessary. This study was aimed to assess Canola-grown fields health in Gorgan township, Golestan province, Iran
Material and This study area was agricultural lands of Gorgan township. The present study was conducted using 58 fields in spring 2015. During maturity stage the weed species were sampled and detected using a W method. Then the crop yield of each quadrate was taken and in parallel, management data were recorded by questionnaire. In the first step, geographic information system (GIS) was applied to produce distribution maps of weeds in the studied region. Specific formula of Shannon-Wiener index, Simpson’s index of diversity and reverse Simpson index were used as weeds biodiversity assessment indices. After mapping and classifying of all layers, the three indices of biodiversity, crop yield and pesticide were interpolated in GIS. The fields with higher yield (>2 ton/ha), lower weed biodiversity indices and pesticides application than mean values of studied region, were considered as healthy fields.
The biodiversity indices range of Shannon-Wiener, Simpson’s and reverse Simpson were calculated as 0.9-2.2, 0.11-0.46 and 2.1-4.9, respectively. Our results revealed that just 3 percentage of surveyed fields were located in healthy condition. In this study, in 43 percent of surveyed farms, pesticides were higher than the average. And most of these farms were in east, north and west of studied area. The results of the yield map showed that 39 percent of farms have had above-average performance. Most of these farms were located within the east of studied area.
The standard amount in applied pesticides, the seeds with high quality, suitable cropping management and spraying equipment were the main reasons for the health of fields. But, existing the strong seed bank in fields can be causes low ability for seed germination, undesirable preparations in farms and higher consumption of pesticide than average of were identified as mean reasons of unhealthy in many canola fields of Gorgan.